4‐(Azulen‐1‐yl) six‐membered heteroaromatics substituted with thiophen‐2‐yl or furan‐2‐yl moieties in 2 and 6 positions

Pyranylium perchlorates with azulen‐1‐yl moiety in 4‐position and thiophen‐2‐yl or furan‐2‐yl in 2 and 6‐positions were obtained by the substitution of 4‐chloro corresponding salts with azulenes. The pyranylium salts are used as starting materials for the synthesis of pyridine and pyridinium salts. The products were characterized and for pyridines pKa was spectroscopically determined. Several attempts were made for pyridine complexation with metal cations as Hg²⁺ or Ag⁺. J. Heterocyclic Chem., (2011).     

Modification of chitosan for construction of efficient antioxidant biodegradable macromolecular systems

The chitosan derivatives containing antiradical fragments in the polymer side chain have been synthesized by interaction of the partially quaternized chitosan(QCH) with gallic acid (GA). The antioxidative activity of the chitosan derivatives — QCH-GA was investigated by thiobarbituric method. Introduction of GA fragment in amount of 2. 0 mass % in the structure of QCH resulted in appearance of pronounced antioxidative activity of the polymeric system contrary to initial chitosan for which this activity was equal to zero. It was found that QCH-GA was a markedly higher effective inhibitor in a peroxidase — catalyzed oxidation of the model amine than the low-molecular antioxidant — GA. Targetted chitosan modification resulted in a substantial raize of the polymeric antimutagenic (at γ-irradiation) efficiency, which for QCH-GA was equal to 92% in comparison with the protective effect of the initial chitosan — 42% (plant test-system, barley seeds, γ = 15 Gr).     

Macromolecular design of cationic polyelectrolytes on the chitosan basis for achievement of high antimutagenic efficiency at gamma-irradiation

A new approach to the problem of construction of efficient antimutagenic (at γ-irradiation) systems has been developed on the basis of the models- synthetic cationic polyelectrolytes- polyquaternary salts of diallyldimethyl-ammonium type.     

Dextran as antioxidant's activity carrier

Two series of conjugates of dextran and antioxidants from the class of sterically hindered phenols were prepared. The conjugates were characterized by the substitution degree of glycoside units, solubility in different solvents, intrinsic viscosity. The investigation of radical scavenging activity (RSA) of conjugates was carried out in their reactions with two free radicals — 2,2-diphenyl-1-picrylhydrazyl (DPPH) and sodium salt of 2,2-diphenyl-1-picrylhydrazyl sulfonic acid (DPPH-salt). The usage of water soluble DPPH-salt enabled to estimate the RSA of the conjugates in water. It was shown that the rate constants of interaction of the DPPH-salt and the conjugates were 10–30 times higher than this value for low-molecular analogue of phenoxan. High RSA of the conjugates in water can be explained by large solvation shell formed due to high content of hydroxy groups in dextran.