32 research outputs found

    A new look at acid catalyzed deacetylation of carbohydrates : A regioselective synthesis and reactivity of 2-O-acetyl aryl glycopyranosides

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    Abstract In the present work we report that acetyl groups of per – acetylated aryl glycosides have different reactivity during the acidic deacetylation using HCl/EtOH in CHCl3, which leads to preferential deacetylation at O-3, O-4 and O-6. Thereby, the one-step preparation of 2-O-acetyl aryl glycosides with simple aglycon was accomplished for the first time. It was proved that the found reagent is to be general and unique for the preparation of series of 2-О-acetyl aryl glycosides. We have determined the influence of both carbohydrate moiety and the aglycon on the selectivity of deacetylation reaction by kinetic experiments. Using DFT/B3LYP/6-31G(d,p) and semi-empirical АМ1 methods we have found that the highest activation barrier is for 2-О-acetyl group. This completely explains the least reactivity of 2-О-acetyl group.Peer reviewe

    The first example of a one-step synthesis of 2'-O-acetyl aryl-D-glucopyranosides

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    A selective acidic system for partial deacetylation of phenolic d-glucopyranosides per-acetates has been developed that allows synthesis of the corresponding 2′-O-acetyl-d-glucosides. Many disadvantages of generally used methods for preparing such mono-acyl derivatives involving multistep procedures or the use of enzymes are avoided. The ion at m/z 289 in mass spectra of their TMS derivatives indicates a particular and characteristic fragmentation pattern of these 2′-O-acetyl derivatives of d-glucopyranosides. Quantum-chemical calculations applying B3LYP/TZVP level of theory revealed the stability of 2′-O-acetyl glucopyranoside if compare with 3′-, 4′- and 6′- O-acetyl glucopyanosides

    The first example of a one-step synthesis of 2'-O-acetyl aryl-D-glucopyranosides

    No full text
    A selective acidic system for partial deacetylation of phenolic d-glucopyranosides per-acetates has been developed that allows synthesis of the corresponding 2′-O-acetyl-d-glucosides. Many disadvantages of generally used methods for preparing such mono-acyl derivatives involving multistep procedures or the use of enzymes are avoided. The ion at m/z 289 in mass spectra of their TMS derivatives indicates a particular and characteristic fragmentation pattern of these 2′-O-acetyl derivatives of d-glucopyranosides. Quantum-chemical calculations applying B3LYP/TZVP level of theory revealed the stability of 2′-O-acetyl glucopyranoside if compare with 3′-, 4′- and 6′- O-acetyl glucopyanosides

    A new approach for the immobilization of poly(acrylic) acid as a chemically reactive cross-linker on the surface of poly(lactic) acid-based biomaterials

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    A new approach for the immobilization of poly(acrylic) acid (PAA) as a chemically reactive cross-linker on the surface of poly(lactic) acid-based (PLA) biomaterials is described. The proposed technique includes non-covalent attachment of a PAA layer to the surface of PLA-based biomaterial via biomaterial surface treatment with solvent/non-solvent mixture followed by the entrapment of PAA from its solution. Surface morphology and wettability of the obtained PLA-PAA composite materials were investigated by AFM and the sitting drop method respectively. The amount of the carboxyl groups on the composites surface was determined by using the fluorescent compounds (2-(5-aminobenzo[d]oxazol-2-yl)phenol (ABO) and its acyl derivative N-(2-(2-hydroxyphenyl)benzo[d]oxazol-5-yl)acetamide (AcABO)). It was shown that it is possible to obtain PLA-PAA composites with various surface relief and tunable wettability (57°, 62° and 66°). The capacity of the created PAA layer could be varied from 1.5 nmol/cm2 to 0.1 μmol/cm2 depending on the modification conditions. Additionally, using bovine serum albumin (BSA) it was demonstrated that such composites could be modified with proteins with high binding density (around 0.18 nmol/cm2). Obtained fluoro-labeled PLA-PAA materials, as well as PLA-PAA composites themselves, are valuable since they can be used for biodegradable polymer implants tracking in living systems and as drug delivery systems

    A new approach for the immobilization of poly(acrylic) acid as a chemically reactive cross-linker on the surface of poly(lactic) acid-based biomaterials

    No full text
    A new approach for the immobilization of poly(acrylic) acid (PAA) as a chemically reactive cross-linker on the surface of poly(lactic) acid-based (PLA) biomaterials is described. The proposed technique includes non-covalent attachment of a PAA layer to the surface of PLA-based biomaterial via biomaterial surface treatment with solvent/non-solvent mixture followed by the entrapment of PAA from its solution. Surface morphology and wettability of the obtained PLA-PAA composite materials were investigated by AFM and the sitting drop method respectively. The amount of the carboxyl groups on the composites surface was determined by using the fluorescent compounds (2-(5-aminobenzo[d]oxazol-2-yl)phenol (ABO) and its acyl derivative N-(2-(2-hydroxyphenyl)benzo[d]oxazol-5-yl)acetamide (AcABO)). It was shown that it is possible to obtain PLA-PAA composites with various surface relief and tunable wettability (57°, 62° and 66°). The capacity of the created PAA layer could be varied from 1.5 nmol/cm2 to 0.1 μmol/cm2 depending on the modification conditions. Additionally, using bovine serum albumin (BSA) it was demonstrated that such composites could be modified with proteins with high binding density (around 0.18 nmol/cm2). Obtained fluoro-labeled PLA-PAA materials, as well as PLA-PAA composites themselves, are valuable since they can be used for biodegradable polymer implants tracking in living systems and as drug delivery systems

    Surface modification of biomaterials based on high-molecular polylactic acid and their effect on inflammatory reactions of primary human monocyte-derived macrophages: perspective for personalized therapy

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    Polylactic acid (PLA) based implants can cause inflammatory complications. Macrophages are key innate immune cells that control inflammation. To provide higher biocompatibility of PLA-based implants with local innate immune cells their surface properties have to be improved. In our study surface modification technique for high-molecular PLA (MW=1,646,600g/mol) based biomaterials was originally developed and successfully applied. Optimal modification conditions were determined. Treatment of PLA films with toluene/ethanol=3/7 mixture for 10min with subsequent exposure in 0.001M brilliant green dye (BGD) solution allows to entrap approximately 10(-9)mol/cm(2) model biomolecules. The modified PLA film surface was characterized by optical microscopy, SERS, FT-IR, UV and TG/DTA/DSC analysis. Tensile strain of modified films was determined as well. The effect of PLA films modified with BGD on the inflammatory reactions of primary human monocyte-derived macrophages was investigated. We developed in vitro test-system by differentiating primary monocyte-derived macrophages on a coating material. Type 1 and type 2 inflammatory cytokines (TNFα, CCL18) secretion and histological biomarkers (CD206, stabilin-1) expression were analyzed by ELISA and confocal microscopy respectively. BGD-modified materials have improved thermal stability and good mechanical properties. However, BGD modifications induced additional donor-specific inflammatory reactions and suppressed tolerogenic phenotype of macrophages. Therefore, our test-system successfully demonstrated specific immunomodulatory effects of original and modified PLA-based biomaterials, and can be further applied for the examination of improved coatings for implants and identification of patient-specific reactions to implants
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