Wiadomości Chemiczne

Wiadomości Chemiczne, 2010, Vol.64

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  1. Metalloorganic Compounds in Synthesis of Phosphonates
    Monika Prokopowicz, Piotr Młynarz, Paweł Kafarski

  2. Perspectives of Applicability of New Carbon Nanomaterials for Controlled Drug Delivery
    Agnieszka M. Pacholczyk, Artur P. Terzyk, Marek Wiśniewski

  3. Prospects of the Industrial Biotechnology Development in Eu
    Krzysztof W. Szewczyk

  4. Planar Electrochromatography in Closed System
    Paweł W. Płocharz, Piotr Ślązak, Aneta Hałka-Grysińska, Adam Chomicki, Tadeusz H. Dzido

  5. The Role of Albumin in the Diagnostics. Binding of Ions and Metal Complexes
    Lilianna Trynda-Lemiesz, Katarzyna Wiglusz, Igor Mucha

  6. Equilibrium Dialysis. A Method for the Study of Ligand-Dna Binding Selectivity
    Izabella Czerwińska, Agata Głuszyńska, Bernard Juskowiak

  7. Mathematical Modelling and Physicochemical Studies on Acid-Base Equilibria in Binary-Solvent Systems
    Tadeusz Michałowski, Bogusław Pilarski, Agnieszka Dobkowska, Janusz Młodzianowski

  8. Okruchy. XV. O Strzegomskiej Ziemi Pieczętnej
    Ignacy Z. Siemion, Alicja Szastyńska-Siemion

  9. Single-Molecule RNA Enzymology: Using Fret to Explore Folding and Conformational Dynamics of Ribozymes
    Marta Hajdziona, Andrzej Molski

  10. Primary Explosives from a Group of Coordination Compounds
    Stanisław Cudziło, Marcin Nita

  11. Properties and Applications of Sub- and Supercritical Water
    Dorota Światła-Wójcik

  12. Determination of Hydrogen Sulfide in Biological Samples
    Grażyna Chwatko

  13. Interplay between Resonance-Assisted Hydrogen Bond and Aromaticity
    Marcin Palusiak

  14. The Supramolecular Architectures as a Result of Self-Assembly in Complexes of D- and F-Metal Ions
    Violetta Patroniak

  15. Identification of Diuretics in Urine by Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC/MS/MS)
    Włodzimierz Tszyrsznic, Danuta Stańczyk, Andrzej Pokrywka, Dorota Kwiatkowska

  16. Okruchy. XVI. O Moich Studiach Chemicznych
    Ignacy Z. Siemion

  17. Ruthenium Complexes in Cancer Therapy
    Monika Richert, Elżbieta Budzisz

  18. Zinc(II), Cadmium(II) and Cobalt(II) Tri-Tert-Butoxysilanethiolate Complexes as Models of the Active Site of Alcohol Dehydrogenase and some other Enzymes
    Anna Dołęga

  19. Application of Ionic Liquids in Organic Synthesis Catalyzed by Candida Antarctica Lipase B
    Renata Kołodziejska, Lidia Jasińska, Aleksandra Karczmarska-Wódzka, Marcin Dramiński

  20. Asymmetric Aldol Reaction: Part I - New Concepts, Catalysts and their Applications in the Synthesis of Natural Products
    Maciej Stodulski, Jacek Młynarski

  21. Bioactive Compounds in Edible Oils
    Jan Małyszko, Sławomir Michałkiewicz

  22. Possibilities of Chloroorganic Wastes Utilization
    Jerzy Myszkowski, Eugeniusz Milchert, Waldemar Paździoch, Marcin Bartkowiak, Robert Pełech

  23. Okruchy. XVII. O Saletrze Filozofów
    Ignacy Z. Siemion

  24. Direct Arylation via C-H Bonds Activation
    Oleg M. Demchuk, Elżbieta Łastawiecka

  25. Asymmetric Aldol Reaction: Part II - Catalytic Asymmetric Aldol Reaction in Aqueous Media
    Joanna Paradowska, Maria Rogozińska, Jacek Młynarski

  26. Therapeutical Activity of Peptides Applied in Cosmetic Products for Aging Skin
    Monika Kukowska, Krystyna Dzierzbicka

  27. From Amyloidogenic Proteines to Nanostructures Formed by Simple Peptides
    Kamil K. Rożniakowski, Zbigniew J. Kamiński

  28. Asymmetric Synthesis of α,α-disubstituted α-amino Acids
    Beata Kolesińska

  29. Okruchy. XVIII. Dwa Listy Augusta Freuda i Jeden - Tadeusza Urbańskiego
    Ignacy Z. Siemion

  30. 3-Hydroxyproline and its Substituted Derivatives
    Anetta Hałajewska-Wosik

  31. Derivatives of Phosphorylated Aminosugars as Inhibitors of Glcn-6-Synthase
    Anna Melcer

  32. Preparation of Fragrance Ingredients on the Way of Terpenes Oxidation by Using Sustainable Chemistry Rules
    Agnieszka Feliczak-Guzik, Izabela Nowak

  33. Occurrence of Surfactants in Environmental Samples
    Ewa Olkowska, Żaneta Polkowska, Jacek Namieśnik

  34. Serine Derivatives β-Lactones as Precursors of Multifunctional Amino Acids
    A. Olma, A. Kudaj

  35. Influence of Cation Substitution on Structural and Magnetic Properties of Selected Chromium Selenides
    Izabela Jendrzejewska

  36. Okruchy. XIX. Pułapki Interpretacji
    Ignacy Z. Siemion

  37. Silica-Metal Nanostructures I. Synthesis and Modification of Silica Nanoparticles
    Bartłomiej J. Jankiewicz, Jerzy Choma, Dominik Jamioła, Mieczysław Jaroniec

  38. Silica-Metal Nanostructures II. Synthesis, Properties and Aplication
    Bartłomiej J. Jankiewicz, Jerzy Choma, Dominik Jamioła, Mieczysław Jaroniec

  39. The Metods of Synthesis of Phenyl-Fluoromethyl Sulfides
    Łukasz Banach, Zbigniew Ochal

  40. Analogs of Glutamine as Inhibitors of Synthase Glcn-6-P
    Anna Melcer

  41. 5',8-Cyclo-2'-Deoxyadenosine. Tandem Lesion of Single Nucleoside/Nucleotide
    Bolesław T. Karwowski

  42. The Role of Active Ingredients in the Process of Skin Aging
    Beata Łubkowska, Beata Grobelna, Zbigniew Maćkiewicz

  43. Modified and Alternative Mediators of the Mitsunobu Reaction
    Aleksandra S. Kołodziejczyk

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METALLOORGANIC COMPOUNDS IN SYNTHESIS OF PHOSPHONATES

Monika Prokopowicz, Piotr Młynarz, Paweł Kafarski

Zakład Chemii Bioorganicznej, Wydział Chemiczny, Politechnika Wrocławska, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław
e-mail: monika.prokopowicz@pwr.wroc.pl


Phosphonates constitute a class of compounds with variety of applications in organic synthesis (as reagents in the Horner-Wadsworth-Emmons reaction), medicine (biologically active compounds) or industry (as e.g. water softeners) [1, 2]. Therefore, the original synthetic methods were developed in order to obtain phosphonates possessing vast and desired properties [3].

This work focuses on the methods employing metalloorganic compounds to a new C-P bond formation. This approach is achieved in most cases by substitution at a trigonal phosphorus atom. The reactions are characterized by high yields and lack of side-products what facilitates the isolation and purification of the target compounds. These benefits are provided mainly by application of lithium and magnesium derivatives.

The other method involves modification of a ready molecule skeleton. The procedures utilizing a new C-C or C-halide bond formation are commonly used. Suitable for these synthetic routes are such soft nucleophiles as copper- zinc- and cadmium-organic compounds.

Additionally, examples of an application of mercury-, lead- and aluminium-organic reagents to the synthesis of other organic phosphorus compounds are discussed. Although their use is rather marginal, they appeared to be crucial for specific and original syntheses.

Keywords: phosphonates, metaloorganic compounds, phosphorus


Wiadomości Chemiczne, 2010, 64, 1.
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PERSPECTIVES OF APPLICABILITY OF NEW CARBON NANOMATERIALS FOR CONTROLLED DRUG DELIVERY

Agnieszka M. Pacholczyk, Artur P. Terzyk*, Marek Wiśniewski

Wydział Chemii Uniwersytetu Mikołaja Kopernika w Toruniu,
Katedra Chemii Materiałów, Adsorpcji i Katalizy, Zespół Fizykochemii Materiałów Węglowych,
ul. Gagarina 7, 87-100 Toruń
*aterzyk@chem.uni.torun.pl


Drug delivery systems have many advantages compared to typical therapy and due to progress in nanotechnology still new systems are proposed for this purpose. The major advantages are for example: applicability of drugs poorly soluble in water, controlled transport, combined therapy where one or more drugs can be simultaneously applied and generally, better efficiency. In this review we analyze a group of "model" drugs applied for testing of those systems [5] and pay also attention to other important drugs [7, 8, 13, 14]. The applicability of older (for example polymers [2]) as well as new nanomaterials (silicas [6, 7, 9, 10, 12-17], gels [6, 18]) in drug delivery systems is discussed. Special attention is paid to new carbon materials i.e. carbon nanotubes and carbon nanohorns (Figs. 1-3) [1, 2, 20-24, 28-41]. We report recent advances in this field showing the potential applicability of those materials in drug delivery systems. Special attention is paid to the systems where anti-cancer drug cisplatin was covalently bound to the edges or incorporated inside single-wall carbon nanohorns. We also discuss the applicability of buckysomes, especially in delivery of hydrophobic anti-cancer drugs.

Finally reports about toxicity of new forms of carbon are discussed and it is shown that many of them lead to contradictory conclusions [22, 42-55].

Keywords: drug delivery, adsorption, carbon materials, carbon nanotubes, nanohorns


Wiadomości Chemiczne, 2010, 64, 23.
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PROSPECTS OF THE INDUSTRIAL BIOTECHNOLOGY DEVELOPMENT IN EU

Krzysztof W. Szewczyk

Wydział Inżynierii Chemicznej Procesowej, Politechnika Warszawska, ul. Waryńskiego 1, 00-645 Warszawa
e-mail: K.Szewczyk@ichip.pw.edu.pl


White, or industrial, biotechnology is the application of biotechnology for the processing and production of chemicals, materials, and energy. White biotechnology uses enzymes and microorganisms to generate products in industrial sectors as diverse as pharmaceuticals and chemistry, food and feed, pulp and paper, textiles or detergents. This review gives an overview of the possible developments in the transition to bio-based production with a focus on the production of chemicals.

Implementation of industrial biotechnology offers significant ecological advantages. Renewable agricultural crops are the preferential starting materials, instead of dwindling fossil resources such as crude oil and natural gas. This technology consequently has a beneficial effect on greenhouse gas emissions and at the same time supports the agricultural sector, delivering these raw materials. Moreover, industrial biotechnology frequently shows significant performance benefits compared to conventional chemical technology, such as a higher reaction rate, increased conversion efficiency, improved product purity, lowered energy consumption and significant decrease in chemical waste generation. The combination of these factors has led to the recent strong penetration of industrial biotechnology in all sectors of the chemical industry, particularly in fine chemicals but equally so for bulk chemicals such as plastics and fuels.

The chemical industry in Europe, which contributes about 28% of the world demand for chemicals, has identified industrial biotechnology as a key emerging technology area. The biorefinery concept offers numerous possibilities to integrate the production of bio-energy and chemicals. This will also provide substantially higher value-added economic activities, besides promoting production in agriculture and forestry. Shifting the resource base for chemical production from fossil feedstocks to renewable raw materials provides exciting possibilities for the use of industrial biotechnology-based process tools.

In a bio-based production, industrial biotechnology also interfaces with plant biotechnology (green biotechnology), where gene technology is applied to accelerate the process of plant breeding for crop improvement or for altering the composition of the feedstock for a desired product.

The concept of Knowledge-Based Bio-Economy and the vision of bio-economy in Europe to 2030 presented in so called "Cologne Paper" [82] are also briefly outlined.

Keywords: industrial biotechnology, biorafineries, biofuels, biotransformations


Wiadomości Chemiczne, 2010, 64, 45.
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PLANAR ELECTROCHROMATOGRAPHY IN CLOSED SYSTEM

Paweł W. Płocharz, Piotr Ślązak, Aneta Hałka-Grysińska, Adam Chomicki, Tadeusz H. Dzido*

Zakład Chemii Fizycznej, Katedra Chemii, Uniwersytet Medyczny w Lublinie, ul. Staszica 6, 20-081 Lublin
*e-mail: tadeusz.dzido@umlub.pl


Planar electrochromatography in closed system (pressurized planar electrochromatography, PPEC) is the separation mode in which mobile phase is driven into movement by electroosmotic effect relative to adsorbent layer of the chromatographic plate. Solute band migration in the PPEC mode is governed by two effects: solute partition in a mobile phase - stationary phase system and electrophoresis when solutes undergo dissociation.

Development of the methodology and equipment for PPEC are described in the paper. Attributes of the mode such as high separation efficiency and selectivity changes relative to liquid chromatography, especially thin-layer chromatography, are discussed. The mode is characterized by relatively short separation time and high performance of the separating system. Plate height approaches the value equal to two particle diameter of the stationary phase (adsorbent layer). Different separation selectivity mentioned is especially advantageous for application in two dimensional separation. The example of such separation of a test dye mixture, applying high performance thin layer chromatography in the first dimension and pressurized planar electrochromatography in the second one, is also presented and discussed in the paper.

The mentioned advantages are very promising for development of the mode and its future application in laboratory practice. However, few main challenges concerned with production of chromatographic plates dedicated to the mode and construction of the equipment convenient for the operator are primary concern of future development of the mode.

Keywords: planar electrochromatography in closed system, pressurized planar electrochromatography, PPEC, development of PPEC, advantages and challenges of PPEC


Wiadomości Chemiczne, 2010, 64, 61.
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THE ROLE OF ALBUMIN IN THE DIAGNOSTICS. BINDING OF IONS AND METAL COMPLEXES

Lilianna Trynda-Lemiesz1,2, Katarzyna Wiglusz1, Igor Mucha*,1

1 Akademia Medyczna im. Piastów Śląskich, Katedra i Zakład Chemii Analitycznej, ul. Szewska 38, 50-139 Wrocław
2 Uniwersytet Wrocławski, Wydział Chemii, ul Joliot - Curie 14, 50-383 Wrocław
*e-mail: igor@cheman.am.wroc.pl


T Human serum albumin (HSA), the most prominent protein in plasma, binds different classes of ligands at multiple sites. HSA provides a depot for many compounds, affects pharmacokinetics of many drugs, holds some ligands in a strained orientation providing their metabolic modification, renders potential toxins harmless transporting them to disposal sites, accounts for most of the antioxidant capacity of human serum, and acts as a NO-carrier. Transport of metal ions is another prominent function of HSA. Metal ions carried by HSA include physiological Ca2+, Zn2+, Co2+ and Cu2+, toxic Cd2+ and Ni2+, and drug-derived Au+ and Pt2+. This broad specificity is due to the presence of distinct binding sites on HSA surface. The N-terminal binding site (in brief NTS, alternatively labeled as ATCUN motif) was the earliest to be identified. It is composed of the first three amino-acid residues of the HSA sequence, Asp-Ala-His. Another specific binding site for metal ions in HSA is located at the interface of domains I and II of the protein molecule. This site, labeled multimetal binding site (MBS), the coordination of metal ions at MBS is provided by His67, His247, Asn99 and Asp249. Cys34 provides the sole thiol group of HSA which is not engaged in intramolecular disulfide bridges. The Cys34 side chain is located at the bottom of a crevice, what results in a limited accessibility and elevated specificity in metal ion interactions. Cys34 was proposed to be the major site of Pt2+ and Au+ complexes interaction. HSA had been indicated to be a physiological carrier of Co2+ ions a long time ago. The interest in the binding of Co(II) ions to HSA has surged recently due to a proposal by Bar-Or et al. [1] of a new rapid clinical assay for myocardial ischemia. This assay (ACB test) is based on an interaction of Co(II) ions with HSA derived from blood serum, followed by DTT treatment. This test is based on an assumption that the clipping of two first residues of HSA is related to ischemia. The proposed molecular mechanism for this test is based on a further assumption of NTS is the primary binding site for Co2+ ions. However, several questions regarding the ACB test are still open, and the molecular mechanism is not clear. Recent studies strongly suggest that the primary binding sites of Co(II) are sites A and B and not the N-terminus.

In the field of MR imaging, there is a considerable interest in contrast agents that target serum albumin because they are retained in the vascular space for longer periods of time than low molecular weight MR agents and also have an enhanced water relaxivity due to slower rotation when bound to the large protein. Albumin in this case serves two purposes, to enhance the sensitivity of the contrast agent by slowing its rotation and to slow diffusion of the agent from blood vessels into the spaces between cells. Both features are useful for imaging of blood vessels (MR angiography). Simple aliphatic chains are sufficient to facilitate binding to HSA. A derivative of Gd-DOTMP bearing an 11-carbon chain, was found to bind at a minimum of five fatty acid binding sites on HSA molecule.

Keywords: human albumin, albumin metal binding, biochemical markers, ischemia modified albumin


Wiadomości Chemiczne, 2010, 64, 81.
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EQUILIBRIUM DIALYSIS. A METHOD FOR THE STUDY OF LIGAND-DNA BINDING SELECTIVITY

Izabella Czerwińska, Agata Głuszyńska, Bernard Juskowiak

Wydział Chemii Uniwersytet im. Adama Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań
juskowia@amu.edu.pl


Equilibrium or competition dialysis is a powerful tool for binding study of ligands that are expected to bind to nucleic acids with selectivity related to their structure or sequence. In the equilibrium dialysis experiment, a set of nucleic acid samples that differ in structure and sequence is dialyzed against a test ligand solution. After equilibration, the concentration of ligand bound to each structure or sequence is determined by UV-Vis absorption or fluorescence spectroscopy in each dialysis unit. Since all nucleic acid samples are in equilibrium with the same free ligand concentration, the amount of bound ligand is directly related to the ligand binding affinity. Thus, equilibrium provides a direct measure of selectivity and identifies the nucleic acid sample, which is preferred by a particular ligand. We describe here the principles and practice of the method. Examples of an application of the method are limited to the discovery of small molecules that selectively recognize the unique structural features of G-quadruplexes.

There are proofs for important functional roles of G-quadruplex structures in biology (maintenance of telomeres, transcriptional regulation, and modulation of mRNA translation). G-quadruplex DNA can exist in a variety of structural forms that may possess numerous potential binding sites for small molecules. Therefore equilibrium dialysis provides a useful tool for discovery of new small-molecule therapeutic agents targeting G-quadruplexes.

Keywords: drug discovery; duplex; equilibrium dialysis; G-quadruplex; ligand binding; nucleic acids; structural selectivity; triplex


Wiadomości Chemiczne, 2010, 64, 105.
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MATHEMATICAL MODELLING AND PHYSICOCHEMICAL STUDIES ON ACID-BASE EQUILIBRIA IN BINARY-SOLVENT SYSTEMS

Tadeusz Michałowski1*, Bogusław Pilarski2, Agnieszka Dobkowska2, Janusz Młodzianowski2

1 Wydział Inżynierii i Technologii Chemicznej, Politechnika Krakowska, ul. Warszawska 24, 31-155 Kraków,
2 P.P.H.U. Cerko s.c., ul. Afrodyty 9, 80-299 Gdańsk
*e-mail: michalot@o2.pl


Conductometric titration (CT) is used as a complementary, non-specific technique against potentiometric (pH) titration (PT). The CT + PT procedure is applied to binary-solvent systems: HmL + Z/A + B (or HmL + Z/W + B) formed of a weak acid HmL and a pH-modifying agent Z (e.g. NaOH, NH3 or HCl), and totally miscible organic solvents A and B (or W = H2O and B) chosen as co-solvents, where acid-base equilibria are considered. The solvent composition in such systems is expressed by the mole fraction x of B. Concentrations of solutes: HmL and Z are the same in the solution titrated (titrand, D) and in titrant (T) and changes in pH value resulted only from differences in acid-base properties of solvents applied in D and T. On the basis of results obtained from PT and CT, the functional relationships related to the solutions of weak acids HmL (m = 1, 2, ...) were formulated, namely: (1) pKi = pKi(x) for acidity parameters; (2) Λp = Λp(x) for molar conductivities, related to the species formed by di- and triprotic acids. For this purpose, the Kohlrausch law on the independence of migrating ions has been applied. The pKi = pKi(x) relationships were formulated for diprotic and triprotic acids on the basis of Henderson-Hasselbalch functions and modeled with use of polynomial functions. The pKi(1) and Λ p(1) values were obtained by extrapolation. The approach suggested is the essential novelty in contemporary literature related to the subject in question. This way, the paper provides a new methodology, a new dimension (x-scale) to the problems known hitherto.

In the experimental part, the pK1 = pK1(x) relationships were formulated for results of mutual pH titrations: HmL/B - HmL/W or HmL/B - HmL/A, obtained for the systems not involving Z. The systems were modeled with the use of Redlich-Kister (R-K) and orthogonal (normal, shifted) Legendre polynomials. Asymmetric functions by Myers-Scott (M-S) and by Michałowski were also suggested for this purpose. It was stated that all approximating functions fit the experimental data very well. The asymmetric functions are applicable for modeling of more bended relationships pK1 = pK1(x), particularly when referred to the limiting x-values in the interval < 0, 1 >. A software that enables to formulate the relationships pKi = pKi(x) according to different approximating functions after introducing the experimental data {(Vj, pHj) | j = 1, ..., N} obtained from PT, was also prepared, together with statistical evaluation of pKi(0) and pKi(1) values, obtained by extrapolation. The results thus obtained are presented in tables and figures.

Some criteria of validity of the results obtained according to PT for pK1(0) and pK1(1) are also presented. The first criterion testifying about reversibility of indications of the measuring system is a position of the point of intersection of the plots obtained in the mutual titrations. The second criterion stems from comparison of results obtained from three pH titrations: (1) HmL/B ↔ HmL/W, (2) HmL/B↔ HmL/A and (3) HmL/A ↔ HmL/W. The convergence of the related plots at x = 0 and x = 1, where x = xB in (1) and (2) and x = xA in (3) testifies on account of the calibration procedure applied for glass electrode.

Keywords: binary-solvent systems, pH titration, conductometric titration, acidity parameters, molar conductivity, curve-fitting


Wiadomości Chemiczne, 2010, 64, 123.
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OKRUCHY. XV. O STRZEGOMSKIEJ ZIEMI PIECZĘTNEJ

1Ignacy Z. Siemion, 2Alicja Szastyńska-Siemion

1Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław
2Instytut Studiów Klasycznych, Śródziemnomorskich i Orientalnych,
Uniwersytet Wrocławski, ul. Szewska 49, 50-139 Wrocław



Wiadomości Chemiczne, 2010, 64, 155.
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SINGLE-MOLECULE RNA ENZYMOLOGY: USING FRET TO EXPLORE FOLDING AND CONFORMATIONAL DYNAMICS OF RIBOZYMES

Marta Hajdziona, Andrzej Molski

Pracownia Dynamiki Procesów Fizykochemicznych, Wydział Chemii, Uniwersytet im. Adama Mickiewicza
ul. Grunwaldzka 6, 60-780 Poznań
e-mail: Marta.Hajdziona@amu.edu.pl, amolski@amu.edu.pl


Ribozymes are biologically important macromolecules that play a crucial role in cell metabolism and functions. Knowledge of folding and catalytic properties of ribozymes can be useful in biotechnology and medicine. In this work, we present a review of single-molecule RNA enzymology with particular emphasis on folding and catalysis observed with single-molecule FRET. Single-molecule spectroscopy provides insight into behaviors of individual molecules without averaging inherent in bulk measurements.

In the first section we introduce ribozymes as RNA enzymes [1, 2]. In the second section, we present the structure of RNA molecules and examples of reaction mechanisms (Fig. 1) and function of different types of ribozymes (Fig. 2-5). Next, we review single-molecule FRET spectroscopy (Fig. 6, 7, Eqs. 1, 2). In the fourth section, we present examples of folding dynamics of ribozymes. In the fifth part, we focus on ribozyme catalysis (Fig. 8, 9). We discuss the coupling of conformational dynamics with catalytic reactions. In the last part we present methods of data analysis that can be used to obtain the kinetic rates from single molecule FRET experiments (Fig. 10).


Keywords: ribozymes, single-molecule fluorescence spectroscopy, FRET


Wiadomości Chemiczne, 2010, 64, 173.
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PRIMARY EXPLOSIVES FROM A GROUP OF COORDINATION COMPOUNDS

Stanisław Cudziło, Marcin Nita

Wojskowa Akademia Techniczna, Wydział Nowych Technologii i Chemii, Instytut Chemii
ul. gen. Sylwestra Kaliskiego 2, 00-908 Warszawa
e-mail: scudzilo@wat.edu.pl


For more than one hundred years, mercury fulminate (MF), lead azide (LA) and lead styphnate (LS) have been used as primary explosives (Fig. 1). They are very good initiatory explosives but they also suffer from serious drawbacks, such as: (a) extremely high sensitivity to mechanical stimuli, (b) thermal, hydrolytic, and chemical instability or lack of resistance to light, (c) incompatibility with metals commonly used in initiating devices, (d) high toxicity of the compounds themselves and their decomposition products [1, 2].

The ongoing search for new primary explosives is aimed at finding materials safer in production and use which do not contain heavy metals and exhibit better initiating performance than the multicomponent compositions being used now. The replacements of the present primaries should be more resistant to accidental stimuli (electrostatic discharge, impact, friction), but they must reliably inflame or detonate, e.g. upon exposure to flame, electrically heated wire or strike with a firing pin in stab and percussion initiators. However their thermal stability should not be too low in order to avoid unexpected explosions of ammunition exposed to heat flow from a fire. On the other hand some of the materials (detonants) must be capable of fast transition from deflagration to detonation. It is not easy to reconcile so many contradictory demands, but from the recently published papers, it appears that it may be possible [3-5].

It has been confirmed many times that some complex compounds with a general formula Mx(L)y(XO)z where M denotes a transition metal cation, L is a nitrogen rich ligand, and XO is an oxygen containing anion are effective primary explosives [3]. The cation plays structure-creating role (i.e. coordinates other molecules) providing stability of the compound and required level of safety. Usually it is also a catalyst of the first stage of decomposition which assures a rapid deflagration to detonation transition - inherent feature of primary explosives. In order to maximize the heat effect of decomposition, the oxygen balance of the compounds ought to be close to zero. Thanks to this the initiating performance of the new primaries may be higher than that of azides and flumintaes.

In this work we present a review of papers devoted to synthesis, chemical composition, molecular structure and explosive properties of primary explosives from the group of coordination compounds. A lot of attention was paid especially to the explosives that have already been used in initiating devices and those with unique properties, e.g. highly sensitive to laser radiation. To systematize the review, the title compounds were divided into groups which distinguishing feature was the kind of ligand.


Keywords: primary explosives, coordination compounds

Wiadomości Chemiczne, 2010, 64, 195.
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PROPERTIES AND APPLICATIONS OF SUB- AND SUPERCRITICAL WATER

Dorota Światła-Wójcik

Międzyresortowy Instytut Techniki Radiacyjnej, Politechnika Łódzka,ul. Żeromskiego 116, 90-924 Łódź
e-mail: swiatlad@p.lodz.pl


In the last decades, sub- and supercritical water has received continuously increasing attention as a reaction medium. As safe, non-toxic, readily accessible it is used in chemical synthesis, waste destruction and biomass processing [1-4]. A broad area of technological and industrial applications of sub- and supercritical water arises from its physical and transport properties falling between those of a gas and a liquid. The solvent properties of water can rapidly change with increasing pressure and temperature [2, 5, 10]. Above the critical point (Tc = 647.1 K, Pc = 22.06 MPa) water becomes highly compressible and diffusive. The static dielectric constant approaches values characteristic for low-polar solvent (Fig. 5). Contrary to liquid water at ambient conditions, supercritical water is a poor solvent for ionic species but is well miscible with hydrocarbons and gases (Fig. 6). The ionic product of supercritical water can be a few orders of magnitude higher than in ambient water (Fig. 4) with consequent effect on the kinetics and mechanisms of chemical reactions. By adjustment of thermodynamic conditions one can tune density, viscosity, polarity or pH of water to the desired solvation properties without any change in the chemical composition. An alternation in the character of water solvent near and above the critical point is the consequence of the structural transformations in the hydrogen-bonded network. As evidenced by many experimental and simulation studies the average number of hydrogen bonds per molecule and the lifetime of H-bonds decrease with increasing temperature and decreasing density [2, 10, 19]. With respect to experiment computer simulation plays an equal, and sometimes pivotal role, in quantitative characterization and understanding of water under extreme conditions. Precise definition of an H-bond employed in computer simulation allows one to examine size and topology of clusters of hydrogen-bonded molecules for various thermodynamic states [17, 19]. Such knowledge is invaluable to link features of the hydrogen bonding with the macroscopic properties of water [10, 19].

This article provides an overview of three aspects concerning water from ambient to supercritical conditions. In Chapter 1 the physical and transport properties are reviewed. Features of hydrogen bonding and a relationship between the molecular engagement in hydrogen-bonded clusters and macroscopic properties of water are discussed in Chapter 2. Chapter 3 focuses on technological and industrial applications of sub- and supercritical water. The summary concludes on main research needs.


Keywords: subcritical water, supercritical water, hydrogen bonding, molecular clusters, SCWO

Wiadomości Chemiczne, 2010, 64, 225.
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DETERMINATION OF HYDROGEN SULFIDE IN BIOLOGICAL SAMPLES

Grażyna Chwatko

Zakład Chemii Środowiska Katedry Technologii Chemicznej i Ochrony Środowiska, Uniwersytet Łódzki,
ul. Pomorska 163, 90-236 Łódź
e-mail: gchwatko@uni.lodz.pl


Hydrogen sulfide is a well known toxic gas that has recently been synthesized from the amino acids by the use of two enzymes (Fig. 1): cystathionine-β-synthase and cystathionine-γ-lyase [1-3, 16, 17]. Hydrogen sulfide is a signaling molecule of the inflammatory and nervous systems, and in particular the cardiovascular system where it regulates vascular tone, cardiac work, and exerts cardioprotection [2, 3, 16, 17, 16-21, 29]. The endogenous metabolism and physiological functions of H2S position this gas well in the novel family of gasotransmitters together with nitric oxide and carbon monoxide.

This review summarizes the methods of hydrogen sulfide determination in biological samples. Biological tissue preparation procedures can include different steps: homogenization [7, 9, 10, 12, 19, 23-25, 29, 32-35], H2S release from tissues [9-14, 29], derivatization (Scheme 1-3) [1, 5, 6, 8, 11, 12, 23-25, 29], and deproteinization [23-25, 30, 31, 33, 42, 43]. Finally analysis is possible by various methods, including spectrophotometry [6, 8, 11, 23-25, 34], high-performance liquid chromatography [6, 12-14, 29, 31, 41], gas chromatography [9-11, 27, 29, 32], potentiometry [22, 35, 36, 45] and polarography [19, 30]. However, there is much doubt about the reliability of the assay methods used. Determination of hydrogen sulfide is often hindered by numerous artifacts, as: the instability of sulfide, its high volatility, its great susceptibility to oxidation, its adherence to various materials (e.g. glass). This might lead to artificially elevated or lowered levels and explains the large discrepancy among the various reports.


Keywords: hydrogen sulfide, sulfane sulfur, determination, biological sample

Wiadomości Chemiczne, 2010, 64, 243.
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INTERPLAY BETWEEN RESONANCE-ASSISTED HYDROGEN BOND AND AROMATICITY

Marcin Palusiak

Katedra Krystalografii i Krystalochemii, Wydział Chemii Uniwersytetu Łódzkiego, ul. Tamka 12, 91-403 Łódź,
e-mail: marcinp@uni.lodz.pl


Among the so called non-covalent interactions the hydrogen bond (H-bond) is probably the most frequently and the most thoroughly investigated. This is due to the fact that H-bond plays an essential role in many physical, chemical and biochemical processes. The strongest H-bonds are those assisted with additional effects, as for instance the resonance assisted H-bonds (RAHBs). The concept of RAHB was first proposed by Gilli and co-workers in 1989, and with the time it has become one of the most thoroughly investigated aspects from the field of structural chemistry. Originally, the definition of RAHB was directly connected with the resonance effect acting in RAHB motif (either intra- or intermolecular). Many scientists were exploring the phenomena of the RAHB. Thus, some controversies appeared in connection with the extra stabilization of the RAHB if comparing with its "non-resonance-assisted" counterparts. Some authors criticized the original explanation introduced by Gilli et al. and proposed alternative mechanism responsible for the relatively stronger H-bonding in the RAHB motifs. Since the resonance effect accompanying the formation of H-bridge in RAHBs is in fact a π-electron effect, it may interact with other π-electron effects acting in specific molecules, e.g. with substituent effect or aromatic π-electron delocalization. In this way the mutual interaction between different π-electron effects may occur, which may influence many physical and chemical properties of molecular systems under consideration, as for instance the strength of RAHB, local aromaticity, proton transfer barrier and many others.

In this paper a short review on the current state of knowledge on RAHB will be presented. The special attention will be paid onto the interrelation between RAHB and local aromaticity in derivatives of polycyclic aromatic hydrocarbons.


Keywords: resonance-assisted hydrogen bond, π-electron effect, aromaticity, aromatic hydrocarbons

Wiadomości Chemiczne, 2010, 64, 263.
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THE SUPRAMOLECULAR ARCHITECTURES AS A RESULT OF SELF-ASSEMBLY IN COMPLEXES OF d- AND f-METAL IONS

Violetta Patroniak

Wydział Chemii Uniwersytetu im. A. Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań
e-mail: violapat@amu.edu.pl


The use of transition metal complexes of bridging multidentate ligands to construct predictable, self-assembled small inorganic systems and multi-dimensional infinite networks is an area of chemistry which has received ever-increasing attention over the recent years. Self-organization occurs usually from a mixture of components (organic ligands, salt crystals, and sometimes solvent molecules). The products exhibit a notable thermodynamic and kinetic stability and their components should contain all the information necessary for a correct assembly to occur [1-6]. Self-assembly has recently been studied in many types of organic and inorganic systems. This latter approach has proven particularly successful for the generation of a wide spectrum of architectural topologies such as for example, helicates [7-11], rotaxanes [12, 13], clusters [14-16], ladders [17-19], cages [20-22], grids [23-25] and molecular wheels [26-28], etc., based on ligand design and an application of suitable coordination geometries for the assembling system. The structure of supramolecular complexes depends strongly on the ligand substituent, the ligand conformation, the metal ion, the counterion, the solvent, and the reaction conditions [29-37]. Such compounds may exhibit novel physical and chemical properties with a potential use in supramolecular engineering, nanotechnology, biomedical inorganic chemistry, biological catalysis, and in the area of sensors [38-46].

The review has been prepared on the results of my own studies in the field [47-59] and focused on structural diversity and characterization of supramolecular complexes. The architectures of these compounds generated by self-assembly of polypirydyl ligands with d-and f-metal ions are fascinating and attractive because of their unusual properties and prospective implementation in many application [60-74].


Keywords: supramolecular chemistry, coordination chemistry, self-assembly, d- and f-metal ions

Wiadomości Chemiczne, 2010, 64, 283.
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IDENTIFICATION OF DIURETICS IN URINE BY ULTRA PERFORMANCE LIQUID CHROMATOGRAPHY TANDEM MASS SPECTROMETRY (UPLC/MS/MS)

Włodzimierz Tszyrsznic, Danuta Stańczyk, Andrzej Pokrywka, Dorota Kwiatkowska

Zakład Badań Antydopingowych, Instytut Sportu, ul. Trylogii 2/16, 01-982 Warszawa
e-mail: wlodzimierz.tszyrsznic@insp.waw.pl


Diuretics are medicines that intensify the diuresis process. There are several types of diuretics (high ceiling loop diuretics, thiazides, calcium-sparing diuretics, potassium-sparing diuretics, osmotic diuretics). Generally all of them increase excretion of water from a body.

According to the Prohibited List published by the World Anti-Doping Agency diuretics make a group of substances which is prohibited in sport at all times (in- and out-of-competition). This review describes shortly an ultra performance liquid chromatography technique, chemical properties of diuretics named in the WADA Prohibited List as well as a developed analytical method with the use of UPLC/MS/MS technique for determination of diuretics and other doping agents (stimulants, masking agents) in urine samples in comparison with a GC/MS method used earlier. Detailed extraction procedure and comparison of application of several organic solvents during extraction process were given. Parameters of MS/MS method have also been given.

The described method was validated in accordance with EURACHEM "The Fitness for Purpose of Analytical Methods: A Laboratory Guide to Method Validation and Related Topics". Limits of detection and recovery level for all compounds in the method were evaluated.

The developed method allows to detect most of diuretics at the levels of 1/5 MRPL (Minimum Required Performance Limits) and fulfills all requirements of the World Anti-Doping Agency.


Keywords: diuretics, doping, ultra performance liquid chromatography, tandem mass spectrometry, extraction

Wiadomości Chemiczne, 2010, 64, 319.
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OKRUCHY. XVI. O MOICH STUDIACH CHEMICZNYCH

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2010, 64, 335.
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RUTHENIUM COMPLEXES IN CANCER THERAPY

Monika Richert1, Elżbieta Budzisz1,2

1 Katedra i Zakład Chemii Nieorganicznej i Analitycznej, Wydział Farmaceutyczny Collegium Medicum w Bydgoszczy, UMK w Toruniu ul. Skłodowskiej-Curie 9, 85-094 Bydgoszcz
e-mail: monika.richert@cm.umk.pl
2 Zakład Chemii Surowców Kosmetycznych, Wydział Farmaceutyczny Uniwersytetu Medycznego w Łodzi, ul. Muszyńskiego 1, 90-151 Łódź


Chemotherapy is a major cancer treatment besides surgery and ratiotherapy. One of the most popular chemotherapeutic drugs that are currently in use are platinum compounds. Despite the success of cisplatin and other platinum-based anticancer compounds in cancer therapy [1, 2] there is still a need for new improved drugs with lower toxicity against healthy cells, better activity against tumor, less side effects, and without problems with drug resistance in primary and metastatic cancers [3, 4].

One of the most promising metals in the cancer treatment is ruthenium [6, 21, 22]. Ruthenium complexes appear generally less toxic than platinum-based complexes and show activity in cisplatin-resistant cells or in cells where cisplatin is inactive. In spite of development of promising ruthenium(II) compounds, in particular organometallics [50, 51], only ruthenium(III) complexes like (H2Im)[trans-Ru(DMSO)Cl4(HIm)], (NAMI-A) [62] (Ryc. 7a) and (HInd)[Ru(III)Cl4(Ind)2], (KP1019) [23] (Ryc. 7b) gain the phase II of clinical trials.

The complex NAMI-A showed marked efficacy against metastases whereas KP1019 was highly active against a colorectal tumor cells both in vivo and in vitro. Moreover the second compound is completely devoid of side effects and drug induced lethality at therapeutically relevant doses. Its therapeutic index is better than that of (HIm)[Ru(III)Cl4(Im)2]. The complex (HInd)[Ru(III)Cl4(Ind)2] has been shown to be efficiently taken up into the cells probably via interaction with transferrin. It induces apoptosis, but the cellular mechanisms of the apoptosis induction are still largely unknown [30].

Non-cross-resistance in cisplatin-resistant cancer cells and reduced toxicity, which is in part due to the ability of ruthenium complexes to mimic the binding of iron to molecules of biological significance, exploiting the mechanisms that the body has evolved for non-toxic transport of iron, is a particularly attractive feature of ruthenium complexes [16]. In addition, some chemical properties, such as rate of ligand exchange, range of accessible oxidation states, and ability of ruthenium to mimic iron in binding to certain biological molecules make these compounds well suited for medicinal applications as an alternative to platinum antitumor drugs in the treatment of cancer cells resistant to cisplatin and its analogues justifying further development of this novel and interesting group of metal complexes [30].


Keywords: ruthenium(III/II), cancer therapy

Wiadomości Chemiczne, 2010, 64, 357.
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ZINC(II), CADMIUM(II) AND COBALT(II) TRI-TERT-BUTOXYSILANETHIOLATE COMPLEXES AS MODELS OF THE ACTIVE SITE OF ALCOHOL DEHYDROGENASE AND SOME OTHER ENZYMES

Anna Dołęga

Katedra Chemii Nieorganicznej, Wydział Chemiczny Politechniki Gdańskiej, ul. Narutowicza 11/12, 80-233, Gdańsk
e-mail: anndoleg@pg.gda.pl


Zinc is ubiquitous in living organisms and second only to iron among the transition metals. Catalytic zinc sites have been found in all six classes of enzymes. Liver alcohol dehydrogenase (EC 1.1.1.1, LADH, Fig. 1) is a zinc enzyme, which catalyzes reversible oxidation of alcohols to aldehydes utilizing as a co-substrate NAD+. The mechanism of an action of the enzyme is summarized by an equation:

R1R2CHOH + NAD+ = R1R2CO + NADH + H+

The coordination of zinc in LADH is usually described as pseudotetrahedral but there were several findings supporting penta-coordination of zinc during the catalytic cycle (Fig. 1 and 2) [1-7].

Studies on synthetic analogues of functional sites of the enzymes are used to elucidate the substrate - metal interactions [8]. Tri-tert-butoxysilanethiol which was used as a ligand to model cysteinate - metal ion centers has several advantageous features. It secures formation of mononuclear transition-metal complexes, exhibits resistance towards hydrolysis, and additionally its pKa value is close to that of cysteine mercapto group [9-11]. Over 20 tri-tert-butoxysilanethiolate complexes with MS2NO2 (M = transition metal) cores were synthesized to model the enzymatic centre of alcohol dehydrogenase, including complexes with water, methanol and ethanol (Fig. 5). Crystal structures of zinc(II), cobalt(II), cadmium(II), and manganese(II) complexes were determined and compared to the structures of LADH [12-17]. Structural features of zinc(II) and cadmium(II) complexes were analyzed (Fig. 9, Tab. 2) [15].

113Cd CP/MAS NMR spectra of tri-tert-butoxysilanethiolate cadmium(II) complexes were determined and compared with the 113Cd NMR spectra of the cadmium-substituted alcohol dehydrogenase. Solid state 113Cd NMR shifts of five-coordinate cadmium(II) complexes with the CdNO2S2 coordination core were found to be identical to that of cadmium-substituted alcohol dehydrogenase in complex with NAD+ [15,18]. The equilibrium character of the reactions between bis(bis(tri-tert-butoxysilanethiolate) cadmium(II) and nitrogen ligands, with a low equilibrium constant of heteroleptic complex formation, were proved by 113Cd NMR studies in solution [18, 19].

The electronic absorption spectra of heteroleptic cobalt(II) complexes with tri-tert-butoxysilanethiolate and imidazole ligands were measured in methanol and solid state. The equilibrium reactions in the methanolic solutions of cobalt complexes were described on the basis of the analysis of charge transfer bands S→dCo LMCT and the molecular structures of the obtained complexes [17]. EPR spectra revealed the high-spin configuration of the studied cobalt(II) compounds [17].

Quantum mechanical calculations performed on the model zinc complex indicate ca 10-20% decrease in enthalpy of ethanol deprotonation due to complexation with Zn2+ [15].

Keywords: zinc; cadmium; cobalt; silanethiolate complexes; crystal structure; NMR spectroscopy; UV-Vis spectroscopy


Wiadomości Chemiczne, 2010, 64, 389.
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APPLICATION OF IONIC LIQUIDS IN ORGANIC SYNTHESIS CATALYZED BY CANDIDA ANTARCTICA LIPASE B

Renata Kołodziejska, Lidia Jasińska, Aleksandra Karczmarska-Wódzka, Marcin Dramiński

Katedra i Zakład Chemii Ogólnej, Collegium Medicum w Bydgoszczy UMK Toruń ul. Dębowa 3, 85-626 Bydgoszcz
email: Renatakol@poczta.fm


In organic reactions chemical catalysts as well as catalytic proteins are used. Biocatalysts have become a useful tool for organic chemists, allowing selective, one-step syntheses. Lipases, hydrolytic enzymes, have gained a considerable attention [1]. Lipase-catalyzed reaction proceeds according to the "bi-bi ping-pong" (Scheme 1) [16].

Catalytic potential of lipases allows to obtain a wide range of organic compounds by formation of C-C, C-N, and C-S bonds [6-8]. Enzyme-catalyzed reactions depend on change of basic-acidic properties or redox potential and an application of appropriate solvent can increase the control over chemical balance.

The solvent used as the reaction medium should allow enzyme stability, increase its activity and selectivity. In organic hydrophobic solvents, enzyme is more stable and selective, its activity, however, is reduced in comparison to polar solvents [6-8]. During a search for optimal solvent special attention was paid to a typical organic solvents - ionic liquids.

Ionic liquids are organic salts (Scheme 2) [9-13]. They do not mix with hydrophobic solvents such as hexane (Tab. 2) [9, 12, 13, 23] and their polarity is similar to low molecular weight alcohols (Tab. 3) [9, 12, 13, 22, 23, 32]. Because of their specific physical properties, ionic liquids may be optimal microenvironment for enzymes, influencing their activity and stability.

CALB is widely used in organic syntheses because of its adaptive capability (Tab. 1) as well as regio- and enantioselective properties [18-21]. Due to its exceptional conformation stability in ionic liquids, CALB can be successfully applied both in heterogeneous (Tab. 4) [22, 36] and homogeneous catalysis (Scheme 4, Tab. 5) [37]. The activity of CALB after incubation in ionic liquids is comparable or greater than in conventional organic solvents (Tab. 6, Fig. 1) [9, 13, 23, 38]. A solvent used as a reaction medium should help to maintain enzyme stabilizing its active conformation and protecting it from deactivating factors such as temperature and scCO2 (Tab. 7) [38-43].

Some ionic liquids constitute a bridge between conventional organic solvents and physiological enzyme environment. They provide exceptional activity of catalytic proteins, which allows efficient and selective reaction catalysis (Tab. 8) [6, 38-40, 43-61].

Keywords: ionic liquids, biocatalysis, lipase activity and stability, green chemistry


Wiadomości Chemiczne, 2010, 64, 413.
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ASYMMETRIC ALDOL REACTION: PART I - NEW CONCEPTS, CATALYSTS AND THEIR APPLICATIONS IN THE SYNTHESIS OF NATURAL PRODUCTS

Maciej Stodulskia, Jacek Młynarskia,b

a Instytut Chemii Organicznej Polskiej Akademii Nauk, ul. Kasprzaka 44/52, 01-224, Warszawa
b Wydział Chemii, Uniwersytet Jagieloński, ul. Ingardena 3, 30-060, Kraków
e-mail: jacek.mlynarski@gmail.com, www.jacekmlynarski.pl


The aldol reaction is one of the most important method for the stereoselective construction of polyketide natural products in both - living organisms and laboratory. The tremendous development in this field has led to development of many new variants of the aldol addition. There has been some success in the use of asymmetric catalysts, although they normally rely on a Mukaiyama-type process. This reaction required a conversion of a donor substrate into more reactive species such as enol silyl ether using not less than stoichiometric amounts of a silicon reagent and a base. From atom economic perspectives, such stoichiometric amounts of reagents should be excluded from the procedures. An exciting challenge in enhancement of the efficiency of the aldol reaction is to find a compound that will catalyze direct aldol addition without pre-formation of a nucleophile and to do so asymmetrically.

Direct asymmetric aldol reaction, catalyzed by both metallic complexes and purely organic molecules now becomes one of the most desired tools in organic chemistry. After an initial period of validating methodology by using a wide range of important model reactions, the time has now been reached to address specific synthesis and solve pending problems of practical relevance. In this review we describe recently discovered, most important and most flexible catalysts for direct asymmetric aldol reaction and their application in total synthesis of target natural products and known compounds of biological and pharmaceutical relevance.

Keywords: direct aldol reaction, asymmetric aldol reaction, tandem aldol-reduction reaction, bifunctional catalysts, organocatalysis, total synthesis

Wiadomości Chemiczne, 2010, 64, 435.
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BIOACTIVE COMPOUNDS IN EDIBLE OILS

Jan Małyszko*, Sławomir Michałkiewicz

Uniwersytet Humanistyczno-Przyrodniczy Jana Kochanowskiego, Instytut Chemii, ul. Świętokrzyska 15, 25-406 Kielce
*e-mail: malyszko@ujk.edu.pl


Recently, the food industry, the agricultural community and consumers have shown a growing interest in the so-called functional food [1-3]. Natural bioactive compounds in some dietary products are claimed to prevent various diseases such as inflammation, degenerative diseases and cancer [5]. This paper reviews molecular structures, nutritional importance and availability of natural bioactive compounds present in vegetable and fish oils.

Chapter 1 includes general description of polyunsaturated fatty acids (PUFA's), their physiological role and metabolism in mammalian organisms ([7-20], Schemes 1 and 2, Figs. 1 and 2). There is a link between dietary PUFA intake, inflammation and immunity. A composition of fatty acids in mammalian cells is sensitive to change in the fatty acids diet. The n-6 PUFA's are the precursors of prostaglandines and related compounds, which play an important role in inflammation and in regulation of immunity. On the contrary, the n-3 PUFA's abundant in fish oils and also present in some plant seed oils have anti-inflammatory properties and are therapeutically useful in several diseases. DHA from this family may also exert beneficial effects on development of the nervous system. Irrespective of PUFA's, vegetable oils contain a variety of bioactive compounds, mainly lipid-soluble antioxidants. This class of antioxidants includes vitamin E ([21-37], Figs. 3 and 4), which is a generic term that constitutes a group of structurally related compounds comprising of tocopherols and tocotrienols. A presence of the phenolic hydroxyl group in these compounds is critical for their antioxidant activity and enables to scavenge free-radical species both in vitro and in vivo. Other bioactive compounds present in vegetable oils are plant lignans ( [38-64], Fig. 5). In a human body, the plant lignans are converted to the mammalian lignans enterodiol and enterolactone. In the literature cited, lignans are discussed as anticancer agents, especially against breast and prostate cancer. Apart from a weak estrogenic properties, their anticancer activity may be supported on the antioxidation capacity.

Vegetable oils are also a good source of phytosterols ([65-80], Figs. 6 and 7). Despite their similar chemical structures, phytosterols and cholesterol differ markedly from each other in regard to their pharmacological characteristics including intestinal absorption and further metabolism. Phytosterols produce a wide spectrum of therapeutic effects in the human organism including anti-tumor properties.

In addition, another compounds present in edible oils are described, e.g. carotens and coenzyme Q10, all of which have potent biological activity, and exert beneficial effects in regard to cardiovascular and cancer diseases ([81-101], Fig. 8).

The majority of the bibliography included in the present review is selected from that published since 2000 by the year 2009.

Keywords: edible oils, essential fatty acids, tocols, lignans, phytosterols


Wiadomości Chemiczne, 2010, 64, 467.
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POSSIBILITIES OF CHLOROORGANIC WASTES UTILIZATION

Jerzy Myszkowski, Eugeniusz Milchert, Waldemar Paździoch, Marcin Bartkowiak, Robert Pełech*

Instytut Technologii Chemicznej Organicznej, Zachodniopomorski Uniwersytet Technologiczny w Szczecinie, ul. Pułaskiego 10, 70-322 Szczecin
*e-mail: Robert.Pelech@ps.pl


Possible ways of utilization of waste chloroorganic compounds have been presented. The methods like isomerization, hydrodechlorination, ammonolysis and chlorolysis have been described. Practical application of these methods allows the management of chloroorganic wastes coming from waste water and waste streams formed e.g. in the production of vinyl chloride by dichloroethane method [2] and in the production of propylene oxide by chlorohydrin method [1]. Four valuable methods of chlorocompounds utilization have been discussed. The first one is isomerization of 1,1,2-trichloroethane [3, 4] to 1,1,1-trichloroethane as the valuable product with a less toxicity than the substrate. The second method is ammonolysis of waste 1,2-dichloropropane and 1,2,3-trichloropropane. Third described method is hydrodechlorination [5, 6] of chloroorganic compounds, especially used for reduction of chlorophenols, vinyl chloride and 1,2-dichloroethan. The last discussed method is the chlorolysis [1, 7]. This method can be used for utilization of all types of waste chloroorganics. Separation of waste chloroorganic compounds by adsorption methods [8-11] has also been described in the article.

Keywords: ammonolysis, isomerization, chlorolysis, hydrodechlorination, waste water

Wiadomości Chemiczne, 2010, 64, 493.
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COSMETIC APPLICATIONS OF WHEY

K. Śliwa, E. Sikora*, J. Ogonowski

Instytut Chemii i Technologii Organicznej, Wydział Inżynierii i Technologii Chemicznej, Politechnika Krakowska, ul. Warszawska 24, 31-155 Kraków
*email: esikora@pk.edu.pl


Milk, as colloidal mixture of proteins, lipids and vitamins is applied by known cosmetic producers. In cosmetics, milk occurs as moistening and biologically active agent (i.e. the source of vitamins and proteins), which is able to rebuilt structural proteins of skin. Moreover, milk products, such as lactose, casein or whey are potential cosmetic raw materials.

Whey, which is a waste from dairy industry is a valuable raw material for further processing. Chemically, whey contains lactose, proteins, fats, lactic acid, group B vitamins and minerals, so it can be a natural source of valuable cosmetic components. Apart from biological activity, also other functional properties of whey proteins like binding of water, foams stabilizing and emulsifying properties are worth attention.

The application of whey as the cosmetic raw material from one side affords another way of whey utilization and on the other side it allows to obtain natural cosmetic products.

Keywords: whey, cosmetics

Wiadomości Chemiczne, 2010, 64, 507.
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OKRUCHY. XVII. O saletrze filozofów

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2010, 64, 541.
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DIRECT ARYLATION VIA C-H BONDS ACTIVATION

Oleg M. Demchuk, Elżbieta Łastawiecka

Uniwersytet Marii Curie-Skłodowskiej w Lublinie, Wydział Chemii, Zakład Chemii Organicznej, ul. Gliniana 33, 20-614 Lublin
e-mail: Oleh.Demchuk@UMCS.Lublin.pl, lastawiecka@wp.pl


An efficient and selective introduction of diversified substituents in place of hydrogen is the main task of synthetic organic chemistry. An application of transition metal catalysts has made possible to effect these transformations not only on active C-H bonds amenable to classical methods but also on unactivated C-H sites via its direct activation. Thus, activation of C-H bonds is certainly one of the most rapidly developing research areas in organic chemistry of the 21th century. Although pioneering work in this field dates back to the 1980s, the development of new C-H activation strategies presented herein are one of the most promising and cost-affordable synthetic approaches starting from inexpensive and easily available substrates and towards the valuable organic compounds, which have already found industrial application and high academic interest.

The aim of this text is presentation of literature sketch related to the transition metal mediated direct functionalisation of uncreative C-H bonds, especially in its enantioselective version. With the intention to cover all variety of studied field we have tried to make the deliberate selection of rich literature material to isolate the most striking examples of each type of catalytic arylation passing throughout the C-H activation step. Next we compact chosen data in a short review directed primarily towards young generation of chemists and graduate students interested in new promising but yet weakly studied areas of organic synthesis.

Keywords: C-H bond activation, Direct-Metalation directed Group, DMG, direct arylation


Wiadomości Chemiczne, 2010, 64, 559.
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ASYMMETRIC ALDOL REACTION: PART II - CATALYTIC ASYMMETRIC ALDOL REACTION IN AQUEOUS MEDIA

Joanna Paradowskaa, Maria Rogozińskaa, Jacek Młynarskia,b

a Instytut Chemii Organicznej Polskiej Akademii Nauk ul. Kasprzaka 44/52, 01-224, Warszawa
b Wydział Chemii, Uniwersytet Jagieloński, ul. Ingardena 3, 30-060, Kraków
e-mail: jacek.mlynarski@gmail.com; www.jacekmlynarski.pl


Asymmetric organometallic and organocatalytic processes in aqueous systems are currently of great interest. A few years ago, only a few practitioners studied the subject; now organic reactions in water have become one of the most exciting research areas. Nature has perfected the stereospecific aldol reaction by using aldolase enzymes. While virtually all the biochemical aldol reactions use unmodified donor and acceptor carbonyls and take place under catalytic control in an aqueous environment, the chemical domain of the aldol addition has mostly relied on prior transformation of carbonyl substrates, and the whole process traditionally is carried out in anhydrous solvents. The area of asymmetric aldol reactions in water has received much attention recently in light of the perception of both its green chemistry advantages and its analogy to eon-perfected enzyme catalysis. Only recently catalytic asymmetric reactions promoted by water-compatible Lewis acids with chiral ligands have been developed; most Lewis acids are not stable in water. Seminal work by List, Lerner, and Barbas on the intermolecular proline-catalyzed direct asymmetric aldol reaction opened a new platform for designing metal-free asymmetric catalysts, although their application was initially limited to organic solvents. Most recently, the challenge of developing efficient aqueous-phase organocatalytic processes has also been tackled. Recent progress in the area initiated constructive discussion on the role and practical merits of water as a solvent. This article describes recent developments in this area.

Keywords: direct aldol reaction, asymmetric aldol reaction, Mukaiyama reaction, water, Lewis acids, amino acids, organocatalysis, total synthesis


Wiadomości Chemiczne, 2010, 64, 599.
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THERAPEUTICAL ACTIVITY OF PEPTIDES APPLIED IN COSMETIC PRODUCTS FOR AGING SKIN

Monika Kukowska*, Krystyna Dzierzbicka

Katedra Chemii Organicznej, Wydział Chemiczny, Politechnika Gdańska, ul. G. Narutowicza 11/12, 80-233 Gdańsk
*e-mail: monika2806@op.pl


Dryness of skin, lack of elasticity, laxity, pigmentation, fine lines and wrinkles are the effects of skin aging [1-11]. Researchers and technologists try to fight with these problems. Researchers are still looking for new biologically active substances, which would improve the appearance of skin and technologists are creating a special composition of skin care products. The following publication is a review of currently used biologically active peptides applied in cosmetic products for skin aging (Tab. 1). There are three main groups of peptides with different mechanism of action: neurotransmitter-affecting peptides, carrier peptides and signal peptides [16]. Neuropeptides are peptides, which mimic the action of botulinum neurotoxin (the structure of active toxin is presented in the Fig. 1). These peptides decrease muscle contraction through interactions at the neuromuscular junction [13, 16, 18]. Carrier peptides take part in delivering a cofactor required for wound healing and enzymatic processes into the dermis [16, 28, 29]. Instead, signal peptides are able to stimulate collagen synthesis and cause growth of human dermal skin fibroblasts [16, 18].

Keywords: skin aging, neurotransmitter-affecting peptides, carrier peptides, signal peptides


Wiadomości Chemiczne, 2010, 64, 629.
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FROM AMYLOIDOGENIC PROTEINES TO NANOSTRUCTURES FORMED BY SIMPLE PEPTIDES

Kamil K. Rożniakowski, Zbigniew J. Kamiński

Instytut Chemii Organicznej Politechniki Łódzkiej, ul. Żeromskiego 116, 90-924 Łódź
email: zbigniew.kaminski@p.lodz.pl


Molecular self-assembly offers unique opportunity for the fabrication of novel supramolecular structures and advanced materials. The inspiration for the development of such structures is often resulting from self-assembling modules in biology, as natural systems always form complex structures from relatively simple building blocks [1, 2]. Several studies had demonstrated the versatility of peptide to form well organized assemblies. This includes cyclic peptides designed with alternating D- and L-amino acids, amphiphile peptides, peptide-conjugates and ionic self-complementary peptides. The 37-residue amylin (Fig. 5), also known as islet amyloid polypeptide, forms fibrils that are the main component of amyloid that develops in the pancreas of type 2 diabetes patients. Amylin also in vitro readily forms amyloid fibrils that are highly polymorphic under typical experimental conditions [21-33]. The molecular structure of amylin protofilaments in striated ribbons closely resembles the protofilament in amyloid fibrils with a similar morphology formed by the 40-residue beta-amyloid peptide that is associated with Alzheimer's disease [48-54]. But not only amylin is a self-assembling peptide. We can also find another examples in biological proteins and peptides that have the intrinsic ability to self-assemble into elongated solid nanofibrils, which may give rise to amyloid diseases or alternatively, inspire applications ranging from tissue engineering to nanoelectronics (Fig. 4). Proteinaceous fibrils are extensively studied searching for detailed theoretical models explaining the mechanism of formation, morphology and properties of self-assembled structures. Especially intriguing state of protein-like self-assemblies are nanotubes (NTs), defined as an elongated nano-object with a definite inner hole. In contrast to proteinaceous fibrils, nanotubes are much less frequently observed and far less well understood. However, they have attracted research interest as key components for nanotechnology (Fig. 13). The simplest objects prone to self-assembly are aromatic dipeptides diphenylalanine, diphenylglycine, and their simple derivatives form nanotubes or spherical nanometric assemblies. Remarkable flexibilities of peptides fragments in formation of nanostructures recently have been considered important for many applications in various fields including molecular electronics, tissue engineering, and material science [87-92].

Keywords: β-amyloid, amylin, self-assembling, peptide, nanotechnology


Wiadomości Chemiczne, 2010, 64, 645.
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ASYMMETRIC SYNTHESIS OF α,α-DISUBSTITUTED α-AMINO ACIDS

Beata Kolesińska

Instytut Chemii Organicznej, Politechniki Łódzkiej, ul. Żeromskiego 116, 90-924 Łódź
e-mail: beata.kolesinska@p.lodz.pl


In the last decade it has been observed rapid increas of application of non-coded α-amino acids as building blocks used for synthesis of analogues with improved and well defined advantageous properties. It has been found that the presence of αα-disubstituted α-amino acid residues exhibit a pronounced helix-inducing potential which is responsible for a membrane destabilisation exerted by peptaibols [1]. Moreover, peptides containing αα-disubstituted α-amino acid residues were found to exhibit enhanced resistance against chemical and enzymatic hydrolysis [2, 3], and acting as enzyme inhibitors, by mimicking ligand properties of their natural analogues, but preventing subsequent enzymatic reaction [6]. The increasing interest in the proprieties of αα-disubstituted α-amino acids stimulates the search for new, effective methods of their synthesis. Among many methods of synthesis of αα-disubstituted α-amino acids some can undeniably be regarded as classic approaches in asymmetric synthesis of αα-disubstituted α-amino acids such as the bislactim ether method proposed by Schöllkopf [25-35]. The others include the self-reproduction of stereogenic centre (the SRS method) discovered by Seebach [9-15] and developed by O'Donnel and the method of alkylation of benzofenone imine in the presence of chiral phase transfer catalysts [55, 56].

Depend on a character of bond which is created in asymmetric process all approaches to asymmetric synthesis of αα-disubstituted α-amino acids can be divide into three categories. First of them is based on an introduction of alkyl substituents at the α carbon atom. This approach can involve electrophilic alkylation of enolates, nucleophilic alkylation of C=N double bond, Mannich reaction etc. Second approach involves an introduction of α-amine group [70-78]. The last approach is based on an substitutionat α carbon atom of carboxylic function [82-95]. Another less general approaches consist of utilization of indirect methods including rearrangements or ring-opening reactions [100-112].

Keywords: αα-disubstituted α-amino acids, diasteroselective alkylation, enantioselective alkylation, electrophilic α-amination, nucleophilic addition to multiple C-N bonds


Wiadomości Chemiczne, 2010, 64, 673.
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OKRUCHY. XVIII. DWA LISTY AUGUSTA FREUDA I JEDEN - TADEUSZA URBAŃSKIEGO

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2010, 64, 729.
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3-HYDROXYPROLINE AND ITS SUBSTITUTED DERIVATIVES

Anetta Hałajewska-Wosik

Zakład Chemii Bioorganicznej, Wydział Farmaceutyczny, Uniwersytet Medyczny w Łodzi, ul. Muszyńskiego 1, 90-151 Łódź
e-mail: anetta.halajewska-wosik@umed.lodz.pl


This article describes a biological activity of natural compounds containing 3-hydroxyproline and its substituted analogues. 3(S)-3-Hyp 3 was isolated from collagen in cattle's Achilles tendon in 1961 [4]. This amino acid in mammalian collagen is located only in the repeating sequence Gly-3-Hyp-4-Hyp [5] but its frequency is extremely low. Hydroxylation of prolyl residue to 3-Hyp 3 in collagen is catalyzed by prolyl-3-hydroxylase [6, 9]. It was proved that 4(R)-Hyp 2 greatly enhance the conformational stability of the collagen triple helix in contrast with 3(S)-Hyp 3, which destabilizing effect has been extensively investigated [7, 11, 12, 15].

The 3-hydroxyproline is also present in the invertebrates in the Fasciola hepatica [21].

The compounds 3 and/or 4 have been found in some peptide antibiotics: Telomycin 5, Plusbacin A3 6, Tripropeptins 7, Cyclothialidine 8 and in the antifungal drugs: Caspofungin 9 and Pneumocandin 10 [22-29]. Substituted derivatives of 3-hydroxyproline were also identified as components of biologically active compounds such as Polyoxypeptins A, B 12, Actinomycin 14, Paraherquamide 15 and Lactacystin 16 [30-36].

Due to the lack of a general synthetic methods for a stereoselective synthesis of substituted derivatives of 3-hydroxyproline some possibilities to obtain these compounds have been described in the second part of this paper [30-33, 36, 62, 65, 66, 68, 70, 73, 74, 76].

Keywords: collagen, 3-hydroxyproline, synthesis, peptide antibiotics, antifungal drugs


Wiadomości Chemiczne, 2010, 64, 747.
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DERIVATIVES OF PHOSPHORYLATED AMINOSUGARS AS INHIBITORS OF GLCN-6-SYNTHASE

Anna Melcer

Politechnika Gdańska, Wydział Chemiczny, Katedra Aparatury i Maszynoznawstwa Chemicznego, ul G. Narutowicza 11/12, 80-233 Gdańsk Wrzeszcz


A reaction catalyzed by glucosamine-6-phosphate synthase (L-glutamine: D-fructose-phosphate amidotransferase, Glms) is the first step committed to the amino-sugar biosynthetic pathway of all living organisms [1]. This is in particular the only endogeneous access to hexosamines which are absolutely required in the edification of microbial cell walls.

Glucosamine-6-phosphate synthase was proposed as a target for antifungal chemotherapy and a search for its selective inhibitors as potential antifungals has been continued [2].

This enzyme catalyzes two coupled enzymatic reactions. The first is the hydrolysis of glutamine to yield glutamate and nascent ammonia, which is transferred to Fru-6-P. The second reaction is the isomerization of Fru-6-P to an aldose, corresponding to Heyns rearrangement (3, 4). Like other amidotransferases, GlmS is organized into two domains: the NH2-terminal glutamine amidotransferase domain, which catalyzes the hydrolysis of glutamine, and the COOH-terminal synthase domain, which catalyzes the isomerization (5-8). The glutamine hydrolysis reaction has been studied extensively and utilises the NH2-terminal cysteine thiol, which forms a g-glutamyl thioester intermediate during the reaction. This catalytic role was confirmed by conversion of the NH2-terminal cysteine to alanine using site-directed mutagenesis which abolished enzymatic activity [2].

The already known specific inhibitors of GlcN-6-P synthase belong to two different structural groups: L-glutamine mimics and analogues of the putative transition state intermediates. In general, glutamine amidotransferases are inactivated by glutamine afinity analogues such as 6-diazo-5-oxo-L-norleucine and 6-chloro-5-oxo-L-norleucine (chloroketone), which alkylate the essential cysteine residue (5, 6, 9). Indeed, many of the active site-directed irreversible inactivators developed for GlmS contain an electrophilic function at the ?-position of glutamate and react irreversibly with the NH2-terminal cysteine residue. More recently, attempts to develop carbohydrate-based inhibitors have been made with the hope of developing higher specificity (10-13).

The second group of compounds comprises derivatives of phosphorylated aminosugars, including: 2-amino-2-deoxy-D-glucitol-6-phosphate (ADGP), arabinose-5-phosphate oxime and 5-methylenephosphono-D-arabinohydroximolactone, as the most powerful GlcN-6-P synthase inhibitors [11-15]. These compounds exhibit a very poor, if any, antifungal activity.

This paper describes the inhibition of GlmS by several analogues of the cis-enolamine intermediate in an attempt to probe the structural requirements for potent inhibition of this enzyme. The energetic contribution of the 2-amino group to binding of the product and the cis-enolamine intermediate is determined.

Keywords: Glucosamine-6-P synthase, inhibitors of GlcN-6-P, antifungals, phosphorylated aminosugars, analogues of the cis-enolamine


Wiadomości Chemiczne, 2010, 64, 771.
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PREPARATION OF FRAGRANCE INGREDIENTS ON THE WAY OF TERPENES OXIDATION BY USING SUSTAINABLE CHEMISTRY RULES

Agnieszka Feliczak-Guzik, Izabela Nowak

Uniwersytet im. Adama Mickiewicza w Poznaniu, Wydział Chemii, ul. Grunwaldzka 6, 62-780 Poznań
e-mail: agaguzik@amu.edu.pl; nowakiza@amu.edu.pl


The review presents some of the key catalytic transformations of a major monoterpene feedstocks. Green chemistry is a philosophy of chemical research and engineering that encourages design of products and processes that reduce the use and generation of dangerous substances. Thus one of the challenging goals of organic synthesis and catalysis is to develop stable heterogeneous catalysts capable to operate at ambient conditions perform selectivity as high as that of homogeneous catalysts. Terpenes represent one of the largest and most diverse classes of compounds, with over 55,000 members isolated to date. Their further oxidation and rearrangement results in an almost endless number of conceivable structures. Monoterpenes are key ingredients in the flavor and fragrance industry, with α- and θ-pinene (obtained from turpentine) being some of the most important. The review focuses on the terpenes: pinene, limonene, and the interconversion of the monooxygenates: geraniol, nerol, citronellol, and citronellal. The major areas covered are catalytic hydrogenation/hydrogenolysis, dehydrogenation, rearrangement/isomerization. However, this review focuses mainly on the oxidation of pinene and geraniol on heterogeneous catalysts.

Keywords: green chemistry, fragrances, terpenes, pinene, geraniol, oxidation of terpenes


Wiadomości Chemiczne, 2010, 64, 787.
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OCCURRENCE OF SURFACTANTS IN ENVIRONMENTAL SAMPLES

Ewa Olkowska, Żaneta Polkowska, Jacek Namieśnik

Katedra Chemii Analityczne, Wydział Chemiczny, Politechnika Gdańska, ul. G. Narutowicza 11/12, 80-233 Gdańsk
e-mail: ewaolkow@wp.pl


Surfactants (ionic and nonionic compounds, Fig. 1) have specific properties and they are applied in various areas of human activity (Tab. 2). The most important properties of surfactants are: amphiphilicity (Fig. 3), solubility in liquids of different polarity, formation of micellar structures (Fig. 4), adsorption and absorption in various media, toxicity (Tab. 1) [12-23] and susceptibility to degradation.

The widely used various types of surfactants contribute to emission of pollutants to the environment (Fig. 6) [32-40]. So it is necessary to monitor their presence in ecosystems (also products of their incomplete degradation) and thus, the development of analytical methodologies, which allow for quick determination of many surfactants at low levels is needed.

Therefore environmental samples have to be prepared for analysis using techniques of isolation and enrichment of analytes (usually LLE, ASE, SPE) [41-56]. For quantitative and qualitative determination of the analytes in extracts following analytical techniques are used: spectrophotometry, tensammetry, chromatography, capillary electrophoresis [57-78].

In the literature one can find information about determination of surfactants in different environmental samples. There is data available about levels of surfactants (especially anionic and nonionic) in solid (sediments and sludges, soil, street dust) and liquid samples (surface water and groundwater, wastewater, atmospheric deposits) (Tab. 3) [79-91].

Keywords: surfactants, properties, application, classification, environmental fate, environmental samples, analytical techniques


Wiadomości Chemiczne, 2010, 64, 809.
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SERINE DERIVATIVES β-LACTONES AS PRECURSORS OF MULTIFUNCTIONAL AMINO ACIDS

A. Olma, A. Kudaj

Instytut Chemii Organicznej, Wydział Chemiczny, Politechnika Łódzka, ul. Żeromskiego 116, 90-924 Łódź
e-mail: aleksandra.olma@p.lodz.pl


Optically active unnatural amino acids play important roles in bioorganic and medicinal chemistry [1]. Thus, development of novel methods for the synthesis of these amino acids is of great interest for organic chemists. Incorporation of these building blocks often results in peptidomimetics with limited conformational flexibility, enhanced enzymatic stability, improved pharmacodynamics and bioavailability. This review summarizes the utilization of β-lactones of serine and of α-alkylserines in the enantioselective synthesis of β-substituted alanines. N-Protected β-hydroxy-α-amino acids can be cyclized under modified Mitsunobu conditions to β-lactones [2-19]. Serine and threonine β-lactones can be also obtained by carboxyl group activation using coupling reagents (DIC, TBTU, HBTU, BOP, PyBOP, HBTU) [16, 21-27]. Readily accessible β-lactone ring opening with various nucleophiles provides many unnatural amino acids and other chiral building blocks. In the first part, the synthesis of N-protected β-hydroxyamino acid β-lactones and the ring opening mechanism are discussed [30, 31]. The second part of this review describes the ring opening with various nucleophiles, including halogens, thiols, selenes and tellures, nitrogen, phosphorus and carbon nucleophiles.

Reactions of N-protected β-hydroxyamino acid and α-alkylserines β-lactones with halogen nucleophiles (HCl, HBr, LiCl, and MgX2) in all described cases yield α-halogenomethyl derivatives [2, 20, 25, 32, 33]. α-Halogenomethyl-α-amino acids are potential enzyme-activated irreversible inhibitors of parent amino acid decarboxylases. Only a few synthetic strategies directed towards the synthesis of the selected α-halogenomethylamino acids have been described. The difficulty associated with the synthesis of these molecules lies in the presence of a halogen atom on the carbon atom vicinal to quaternary center bearing amine and carboxylic acid functionalities (like the neopenthyl position). Sulphur, selenium and tellurium nucleophiles were used to obtain S-substituted cysteines, α-alkylcysteines and lanthionine derivatives and their seleno and telluro analogues [2, 28, 32, 33, 44, 45, 49-54]. The use of nitrogen nucleophiles leads to β-amino-, β-cyano-?and β-azidoalanines [2, 11, 13-15, 32, 33, 55-71]. Properties of the nucleofile and of β-lactone determine regioselectivity of ring opening, giving β-aminoalanines or amides. The use of sodium azide as the nucleophile led to the formation of β-azidoalanine and β-azido-α-alkylalanines, useful building blocks in peptide synthesis and precursors of α,β-diamino acids. Among nitrogen nucleophiles the cyclic secondary amine (pyrolidine, morpholine), aromatic amines and heterobases were used to synthesize β-aminoalanine derivatives. The β-lactone ring openings were carried out with phosphorus [10, 18, 72, 73] and carbon nucleophiles [5, 74-76].

Serine, threonine and α-alkylserines β-lactones are widely used intermediates for the synthesis of new optically pure unnatural, multifunctional amino acids, which are difficult to obtain in other ways.

Keywords: serine and α-alkylserines β-lactones, Mitsunobu reaction, β-substituted alanines


Wiadomości Chemiczne, 2010, 64, 831.
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INFLUENCE OF CATION SUBSTITUTION ON STRUCTURAL AND MAGNETIC PROPERTIES OF SELECTED CHROMIUM SELENIDES

Izabela Jendrzejewska

Instytut Chemii, Uniwersytet Śląski, ul. Szkolna 9, 40-006 Katowice
e-mail:izajen@poczta.wp.pl


Selenospinels with general formula ACr2Se4 (A = Zn, Cu, Cd) were doped with nickel and tin ions. The chemical synthesis was carried out based on solid phase reactions. To estimate the chemical composition of the mono- and polycrystalline compounds, the following methods were applied: JEOL scanning microscope and ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectrometry). For the obtained polycrystalline compounds, their structural parameters were defined using X-ray diffraction analysis and Rietveld method. Definition of structure of the monocrystals was carried out using KM4 four-circle diffractometer and SHELX software. Magnetic properties were investigated with strong stationary magnetic fields up to 14 T in the temperature range of 4.2÷300 K using an induction magnetometer and with stationary magnetic fields up to 0.5 T in the temperature range of 1.8÷300 K using a SQUID superconducting magnetometer.

In the systems doped with nickel, depending on the reaction stoichiometry, nickel ions were directed to tetrahedral or octahedral positions. When the octahedral positions are fully occupied by chromium ions, small amounts of nickel directed to tetrahedral positions are able to occupy them. The increasing amount of Ni2+ ions tends to occupy the octahedral positions in accordance with preference energy, leading to change in structure from cubic to monoclinic one [19, 37, 38]. Nickel ions present in the spinel crystal lattice influence the magnetic properties of these compounds. For ZnCr2-xNixSe4 system, an increase in values of effective magnetic moment and saturation magnetic moment accompanying the increase in nickel ions concentration was ascertained. It was caused by the presence of another magnetic ions in ZnCr2Se4 crystal lattice. The values of paramagnetic Curie-Weiss point and Néel point decrease with the increase in nickel concentration. It is associated with an increase in antiferromagnetic interactions in the system caused by nickel ions [39-41]. Like in the Cd1-xNixCr2Se4 system, saturation magnetic moment does not depend on the amount of nickel built-in, and the crystals exhibit strong ferromagnetic interactions. Lack of a change in saturation indicates that nickel is built in with compensated magnetic moment, or in a low-spin state (S = 0). Cadmium and nickel ions occupy tetrahedral positions and chromium ions - octahedral ones [42].

In the systems doped with tin, the reactions carried out in the solid phase were aimed to build in tin ions in tetra- and octahedral positions. X-ray diffraction studies confirmed the presence of tin ions in selected chromites. Mössbauer spectroscopy applied for the complex system Zn1-xSnxCr2Se4 confirmed the presence of tin ions in two inequivalent positions: in tetrahedral and in octahedral environments. Based on theses considerations, the general formula of these compounds may be as follows: ZnxSnδCrySnηSe4, where δ - parameter describing the share of tin ions in tetrahedral sublattice, η - parameter describing the share of tin ions in octahedral sublattice [43]. Although tin ions does not contribute to a magnetic share, their presence in the crystal lattice promotes an increase in antiferromagnetic interactions

in the studied compounds. Under the influence of tin ions, conductance changes from p-type (hole conduction) occurring in pure ZnCr2Se4 to n-type (electron conduction) [44, 45]. In CuCr2-xSnxSe4 system, magnetic properties change from ferromagnetic for nominal value x = 0.2 to antiferromagnetic for nominal value x = 1.0. These changes are caused by the presence of Sn4+ ions in the system, generating Cr2+ ions. The observed change in structure is caused by Jahn-Teller effect, occurring in the presence of Cu2+ and Cr2+ ions [46].

Keywords: crystal structure, X-ray diffraction, ferromagnetism, antiferromagnetism


Wiadomości Chemiczne, 2010, 64, 859.
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OKRUCHY. XIX. PUŁAPKI INTERPRETACJI

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2010, 64, 899.
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SILICA-METAL NANOSTRUCTURES I. SYNTHESIS AND MODIFICATION OF SILICA NANOPARTICLES

Bartłomiej J. Jankiewicz1, Jerzy Choma2, Dominik Jamioła2, Mieczysław Jaroniec3

1 Instytut Optoelektroniki, Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa, e-mail: bjankiewicz@wat.edu.pl
2 Instytut Chemii, Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa, e-mail: jchoma@wat.edu.pl
3 Department of Chemistry, Kent State University, Kent, Ohio 44 242, USA, e-mail: jaroniec@kent.edu.pl


Silica-metal nanostructures consisting of siliceous cores and metal nanoshells attract recently a lot of attention because of their unique properties, mainly catalytic and spectroscopic. The core of these nanostructures is coated with a thin layer (nanoshell) of another material, often being a noble metal, of a thickness between 1 and 20 nm. The silica-metal nanostructures are highly functional materials of properties different from those of the siliceous core and the metal nanoshell. Already nowadays these nanostructures have found various applications such as for an exaltation of chemical stability of colloids, for an enhancement of luminescence properties of materials, for biosensing, drug delivery and other medical applications.

The main goal of this two-part review is the presentation of various methods for the preparation of silica-metal nanostructures, description of the most important physicochemical properties of these materials, and presentation of their potential applications. The first part is focused on the main preparation methods of silica particles being used as cores for the aforementioned core-shell nanostructures and methods for their surface modification.

A special emphasis is given on the Stöber method, which is relatively simple, effective and well verified for the synthesis of large silica particles (with diameters from 100 nm to several microns). A typical preparation of silica particles is based on mixing ethanol, ammonia (as a catalyst), and often small amount of water, followed by rapid or gradual addition of tetraethyl orthosilicate (TEOS) under vigorous stirring. This article reviews numerous studies reporting the effects of various factors on the structural properties of silica particles, especially the steps required for controlling their size, assuring narrow particle size distribution and high uniformity of the resulting particles.

The surface chemistry of siliceous cores is essential in the process of metal nanoshells formation. Therefore, in this work the main methods for modification of the silica surface are presented in details in order to prepare this surface for the formation of metal nanoshells. This modification is often based on the replacement of silanols with specific organic groups (often aminopropyl and mercaptopropyl groups), which interact strongly with metal nanoparticles. In 1998 Halas and co-workers elaborated a simple method for the preparation of core-shell nanostructures involving attachment of specific organic groups to the silica surface followed by deposition of gold nanoparticles and subsequent reduction of tetrachloroauric acid in order to obtain continuous gold nanoshells. The first modifier of the silica surface was 3-aminopropyltriethoxysilane. Later, several other modifiers have been tested. The aforementioned modification of the silica surface can be single- or two-step process. The single-step process involves hydrolysis and condensation of TEOS in the presence of functional organosilane, which results in silica particles with desired organic groups attached. The two-step process involves the synthesis of silica particles in the first step and their surface modification with organosilanes in the second step. The presented literature survey shows that the proper modification of the surface of silica particles is a necessary condition for the formation of uniform metal nanoshells.

Keywords: silica-metal nanostructures, preparation of silica nanoparticles, modification of silica surface


Wiadomości Chemiczne, 2010, 64, 913.
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SILICA-METAL NANOSTRUCTURES II. SYNTHESIS, PROPERTIES AND APLICATION

Bartłomiej J. Jankiewicz1, Jerzy Choma2, Dominik Jamioła2, Mieczysław Jaroniec3

1 Instytut Optoelektroniki, Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa, e-mail: bjankiewicz@wat.edu.pl
2 Instytut Chemii, Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa, e-mail: jchoma@wat.edu.pl
3 Department of Chemistry, Kent State University, Kent, Ohio 44 242, USA
e-mail: jaroniec@kent.edu.pl


In the past decade the silica-metal nanostructures consisting of siliceous cores and metallic nanoshells have been intensively studied. The second part of this review article presents recent advances in the synthesis, characterization and application of silica-gold core-shell nanostructures. A special emphasis is given to the nanostructures composed of the silica core and gold or silver nanoshell.

Nowadays gold is often used metal for the formation of nanoshells. The reason for this interest is a great application potential of SiO2-Au nanostructures in catalysis, chemical and biological detection of various substances, optoelectronics, photonic crystals, plasmonics, and in analytical techniques utilizing surface enhanced Raman spectroscopy. Silver nanoshells formed on siliceous cores show similar properties as those of gold nanoshells. Silica-gold nanostructures can be prepared using various methods, for instance, by growing up gold nanoshells on the siliceous cores with deposited gold nanoparticles, by precipitating gold nanoparticles with their simultaneous deposition on modified silica cores, by reducing gold ions on Sn-modified silica particles, or by forming gold nanoshells under ultrasonic conditions.

This article presents several methods for the formation of silica-metal nanostructures. A special emphasis is given to the method of growing up gold nanoshell on the modified silica core with deposited gold nanoparticles. This method assures a good control of the nanoshell thickness as well as its surface properties. In this method the organically modified silica particles are initially covered with gold nanoparticles, which facilitate a further growth of gold nanoshell by reduction of tetrachloroauric acid with agents such as formaldehyde. In the case of aminopropyl-modified silica particles, about 25-30% coverage of the silica surface with gold nanoparticles can be achieved. The effect of other than aminopropyl organic groups on the coverage of the silica surface with gold nanoparticles was studied showing that amino and mercaptopropyl groups assure about 30% surface coverage with gold, while this coverage is very small when methyl and diphenylphospine groups are on the silica surface.

The aforementioned reduction of gold ions and growth of gold nanoparticles depend on the uniformity of the initial coverage of the silica surface with gold nanoparticles, the concentration of reduced gold ions as well as the nature and the concentration of reducing agent. The most often used reducing agents are formaldehyde and sodium borohydride, although hydroxylamine hydrochloride, carbon monoxide, hydrogen peroxide and trisodium citrate are also used. Silver is the next popular metal after gold used for the formation of nanoshells. The other metal used are platinum, palladium, nickel and copper.

The final sections of this review are devoted to a brief presentation of various techniques used for characterization of core-shell nanostructures as well as to their applications. The most often used methods include scanning (SEM) and transmission (TEM) electron microscopy, wavelength (WDS) and energy (EDS, EDX) dispersion spectroscopy, photoacoustic spectoscopy (PAS), dynamic light scattering (DLS), surface plasmon resonance (SPR), powder X-ray diffraction (XRD), IR and UV-Vis spectroscopy, Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimery (TG) and adsorption (ADS).

As regards applications of silica-metal core-shell nanostructures, the prospects are enormous ranging from catalysis, optoelectronics, to drug delivery, and other medical applications.

Keywords: silica-metal nanostructures (core-shell), synthesis, properties, characterization, application


Wiadomości Chemiczne, 2010, 64, 943.
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THE METODS OF SYNTHESIS OF PHENYL-FLUOROMETHYL SULFIDES

Łukasz Banach, Zbigniew Ochal

Wydział Chemiczny, Politechnika Warszawska, ul. Noakowskiego 3, 00-664 Warszawa


Aromatic compounds containing halogenomethylsulfonyl or halogenomethylsulfanyl group are often biologically active as fungicides or herbicides [1-6]. Especially important plant protection agents are fluorine compounds [7-12].

Through to specific activity in living organisms, fluorine compounds found wide application. One of the reasons of high activity of these compounds is their high lipophilicity, which provides increase of solubility in lipides. Due to this fact absorption of fluorine compounds is easier and their transport in organism is faster what increase their efficiency [13-15].

In this paper the methods of synthesis of aromatic compounds containing fluoromethylsulfanyl group are described. Aryl-fluoromethyl sulfides can be easily transformed into sulfones by oxidation [16-18].

Methods of preparation of aryl-fluoromethyl sulfides can be divided into three groups:

Keywords: flouromethylphenyl sulfides, flouromethylphenyl sulfones, pesticides, herbicides, fluoromethylation, fluorination


Wiadomości Chemiczne, 2010, 64, 983.
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ANALOGS OF GLUTAMINE AS INHIBITORS OF SYNTHASE GLCN-6-P

Anna Melcer

Politechnika Gdańska, Wydział Chemiczny, Katedra Aparatury i Maszynoznawstwa Chemicznego, ul G. Narutowicza11/12, 80-233 Gdańsk Wrzeszcz
e-mail: anna.melcer@pg.gda.pl


Glucosamine-6-P (GlcN-6-P) synthase catalyzes the first committed step in chitin biosynthesis pathway, that is, transformation of D-fructose-6-phosphate (Fru-6-P) to D-glucosamine-6-phosphate [1]. Although the enzyme is also present in mammalian systems, substantial difference in physiological consequences of GlcN-6-P synthase inhibition in fungi and in mammals, constitute a firm molecular basis for the selective toxicity of specific enzyme inhibitors. The enzyme was proposed as a target for antifungal chemotherapy and a search for its selective inhibitors as potential antifungals has been continued. So far, two main groups of such compounds were identified: L-glutamine analogs and mimics of a putative cis-enolamine transition state intermediate but none of them demonstrated high antifungal activity, due to the inefficient uptake by the fungal cells. Among a number of known glutamine analogues some are selective inhibitors of GlcN-6-P synthase, not interacting with other enzymes utilising L-glutamine as substrate. One of them, N3-(4-methoxyfumaroyl)-l-2,3-diaminopropanoic acid (FMDP), gave rise to oligopeptidic compounds demonstrating remarkable antifungal activity [2]. Incorporation of FMDP into peptide structure allowed effective internalisation of the enzyme inhibitor by the way of peptide permeases, but on the other hand was a reason of substantial specific resistance, since peptides permeases are not essential for fungal cells [3, 4].

The second group of compounds comprises derivatives of phosphorylated aminosugars, including: 2-amino-2-deoxy-D-glucitol-6-phosphate (ADGP), arabinose-5--phosphate oxime and 5-methylenephosphono-D-arabinohydroximolactone, as the most powerful GlcN-6-P synthase inhibitors [5-7]. These compounds exhibit very poor, if any, antifungal activity. This article provides a comprehensive overview of the present knowledge about inhibitors of glucosamine-6-phosphate and their synthesis.

Keywords: glucosamine-6-P synthase. inhibitors of GlcN-6-P, antifungals, glutamine analogues, enzyme active center


Wiadomości Chemiczne, 2010, 64, 995.
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5',8-CYCLO-2'-DEOXYADENOSINE. TANDEM LESION OF SINGLE NUCLEOSIDE/NUCLEOTIDE

Bolesław T. Karwowski

Zakład Biofarmacji, Katedra Biofarmacji, Wydział Farmaceutyczny Uniwersytetu Medycznego w Łodz i, ul. Muszyńskiego 1, 90-151 Łódź
e-mail: Bolek.Karwowski@wp.pl


Free radicals can react with different biomolecules present in the cells such as lipids, sugars or nucleic acid peptides. These free radicals initiate reactions with DNA or RNA molecules and then can lead to changes in the genome sequence. These mutations are most probably responsible for a number of different diseases (involving a change in the genome sequence) or, at least, can accompany them.

Reactive oxygen species and more specifically - hydroxyl radical can react with DNA molecules and lead to changes in their structures. Formation of radicals at C5' and C8 atoms of 2'-deoxyadenosine leads, through intramolecular cyclisation, to 5',8-cyclo-2'-deoxyadenosine (cdA) derivatives.

Frequency of DNA damage occurrence surges with an increase of an ionizing radiation dose. Different repair systems are however present in cellular machinery: BER, which exploits glycosylase and NER - a more complex process involving the removal of damaged oligonucleotides. The later is the basic mechanism for removal the 5',6-cyclo-2'-deoxynucleosides and 5',8-cyclo-2'-deoxynucleosides like cdA. Their defective activity may be responsible for many types of diseases, such as Parkinson, Alzheimer, chronic hepatitis, HCV, atopic dermatitis and different types of cancer.

The mechanistic, structural and biochemical studies presented in this work produce quite clear answer as to the approximate range level of the (5'R)-cdA and (5'S)-cdA accumulation in the genome after the lesion period.

Using quantum chemistry methods (DFT) paths of the cyclisation reaction have been determined. From the structural analysis point of view, it has been demonstrated that the covalent bond between C(5') and C(8) in nucleoside induces an unusual West conformation of the furanose ring. Based on the NMR data analysis it can be postulated that the rigid and fixed structure of cdA can strongly influence the global geometry of oligonucleosides. Moreover, using the quantum mechanic study of double strand DNA it has been demonstrated that the presence of (5'S)-cdA provokes a "domino effect" extending towards the 5'-end of the strand with this lesion. No domino effect is observed for the 3'-end. The obtained biological results indicate that the presence of (5'S)-cdA in the complementary strand to the strand under repair on the 5'-end side is the critical factor for the inhibition of the BER process of DNA.

Keywords: DNA damage, 5',8-cyclo-2'-deoxyadenosine, free radicals, reactive oxygen species, ionisation radiation


Wiadomości Chemiczne, 2010, 64, 1013.
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THE ROLE OF ACTIVE INGREDIENTS IN THE PROCESS OF SKIN AGING

Beata Łubkowska1, Beata Grobelna2, Zbigniew Maćkiewicz1

1Pracownia Chemii Polipeptydów,
2Katedra Chemii Analitycznej,
Wydział Chemii, Uniwersytet Gdański, ul. J. Sobieskiego 18/19, 80-952 Gdańsk, e-mail: b.lubkowska@gmail.com


Skin is the coating of all human and animal organisms. It is a kind of space where different processes take place. Skin is the largest and the heaviest organ in the body. Also, it is a barrier, that stops water and the part of body, which should be particularly protected [1]. The skin is composed of three main layers: epidermis (Fig. 1), dermis (Fig. 3) and subcutaneous tissue (Fig. 5). Each of these layers has completely different role and is characterized by various properties.

Epidermis is the outermost layer of skin. It consists of a living and a dead zone. The living area forms new cells which are the subject to further changes, while in the zone of dead cells they are highly flattened and devoid of nuclei [2]. In the epidermis, exactly in the reproductive output layer there are melanocytes, which are cells responsible for production of the pigment - melanin (Fig. 2). Melanin is responsible for color of hair, eyes and skin. It is formed from tyrosine as a result of numerous biochemical reactions [3]. Biological activity of melanin is determined by the presence of appropriate peptide. The sequences of its active components are: Ser-Tyr, Ser-Met-Glu-His-Phe-Arg, and Trp-Gly-Lys-Pro-Val.

It is possible to protect the skin also against the solar radiation. The hormone MSH absorbs and reflects UV radiation. Under the influence of UV radiation the amount of melanin increases, causing temporary changes in skin color [3].

Under the epidermis there is a proper skin, which is composed of elastic fibers, collagen fibers, and the basic substance, which fuses the fiber elements. The elastic fibers are scattered among collagen fibers. Proper skin is the place where a valuable protein - very important in cosmetics - occurs - the native collagen. It is the main protein of connective tissue. Collagen has a very high tensile strength and is a major component of tendons. It is responsible for skin elasticity. Loss of collagen from the skin causes wrinkles [4].

A distinctive layer of skin is the subcutaneous tissue. It combines dermis with muscles. It is composed of fat cells separated by connective tissue. The size and the shape of fat cells vary depending on gender, diet and also age [5].

Skin, like other authorities is aging. These process may be accelerated or delayed under the influence of various endogenous and exogenous elements (Tab. 1). Also genetic predisposition are of significant importance. It seems that, as soon as we age, we inherit from our ancestors. To delay the aging process, it is necessary to properly take care of and protect the skin. There are many ways to delay aging of the skin. The most successful, for example cosmetics with active ingredients such as peptides, will be presented here.

Keywords: skin, aging process, collagen, elastin, peptides, MSH hormone


Wiadomości Chemiczne, 2010, 64, 1053.
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MODIFIED AND ALTERNATIVE MEDIATORS OF THE MITSUNOBU REACTION

Aleksandra S. Kołodziejczyk

Katedra Chemii Medycznej, Wydział Chemii, Uniwersytet Gdański, ul. Sobieskiego 18, 80-952 Gdańsk
e-mail: ola@chem.univ.gda.pl


The Mitsunobu reaction provides an extremely useful and versatile synthetic route for a large array of products involving formation of a new C-O, C-N, C-S, C-X, or C-C bond. The reaction is a dehydrative coupling of an alcohol with an acid/pronucleophile using a combination of an oxidizing azo reagent and a reducing phosphine reagent - equation (1). The reaction is very popular due to its stereoselectivity and compatibility with a wide range of functional groups. However, the use of this method is complicated by the resulting complex reaction mixtures containing a product, triphenylphosphine oxide and the reduced azodicarboxylate, as well as unreacted starting material.

Due to omnipresence of the Mitsunobu reaction, it was a subject of numerous reviews [1-12]. The mechanism and the stereochemical result of the reaction are still thoroughly studied [22-38] and the current, generally accepted mechanism is outlined in Scheme 1.

This article provides an overview of the separation-friendly strategies introduced to facilitate product isolation in the Mitsunobu reaction and its modified and alternative mediators. As two comprehensive reviews devoted to modified Mitsunobu reagents and separation techniques facilitating isolation of the condensation product appeared fairly recently [7, 8], this work concentrates on examples of isolation-friendly strategies and studies subsequent to mentioned reviews.

Separation facilitating strategies are based on tagging one of Mitsunobu reagents or substrates with a "separation tag" (phase tag, affinity tag), which controls the behaviour of the component and allows to separate the tagged reaction component from untagged ones.

There are four main separation techniques used in the Mitsunobu reaction: polymer-assisted phase-switching or solid phase immobilization (2.1.1.), acidic/basic aqueous work-up (2.1.2.), fluorous approach (2.1.3.), and post-reaction sequestration.

Both phosphine and azodicarboxylate can be attached to insoluble polymer and the derived side-products (phosphine oxide or hydrazodicarboxylate) can be removed by filtration at the end of the reaction.

Fluorous tagging makes possible the separation of a fluorous compound from non-fluorous ones either by partitioning between a fluorous and an organic liquid or by fluorous solid-phase extraction (FSPE) - Scheme 6. A fluorous-tagged acid was also applied to achieve inversion of an alcohol configuration (Scheme 8).

Another separation-facilitating strategy uses polymerizable Mitsunobu reagents and post-reaction sequestration, e.g. by ring opening metathesis polymerization (ROMP), either of a condensation product (Scheme 9), or side products (impurity anihilation).

The scope of the Mitsunobu reaction was greatly widened by introduction of alternative Mitsunobu reagents by the Tsunoda-Itô group [69-79]. Some of these reagents (1-4, Scheme 12) mediate C-alkylation reactions of very weak acids (pKa > 23) [77, 78]. Several other modified Mitsunobu reagents are also described.

Keywords: Mitsunobu reaction, condensation, phosphines, separation tags, azo reagents


Wiadomości Chemiczne, 2010, 64, 1073.
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