Hydrogels on the Base of Modified Chitosan and Hyaluronic Acid Mix as Polymer Matrices for Cytostatics Delivery.

The development of biodegradable polysaccharide hydrogel matrices for cytostatic delivery can improve the therapeutic results of patients by prolonging the action of the drug, reducing its toxicity and providing additional biological activity by polysaccharides. In this work, N-succinyl chitosan/hyaluronic acid dialdehyde/cytostatic formulations have been prepared using two different chitosan grades (30 kDa and 150 kDa) and hyaluronic acid dialdehyde. The interaction of amino groups of N-succinyl chitosan and aldehydes of hyaluronic acid resulted in the formation of azomethine bonds and was demonstrated using C NMR.

Comparative study of chemical and topological structure of macromolecules of lignins of birch (Betula verrucosa) and apple (Malus domestica) wood.

Recent advances in investigations of chemical structure of lignin give rise to questions about relationship between chemical structure and topology of the macromolecules. In this paper, we made a comparison of results of the studies of chemical and topological structures of lignins. The features of topological structure of lignins of birch and apple wood were identified on the basis of the study of dilute solutions of the lignins by the sedimentation-diffusion analysis and viscometry.

Synthesis and Antiviral Activity of Quercetin Brominated Derivatives.

Reaction of quercetin (QR) (1) with bromine under various conditions was studied. Interaction of QR with 2-3 equiv. of bromine in glacial acetic acid at 35-40°C for 2-4 h and 20-22°C for 24 h led to the formation of QR 6,8-dibromide (2) (52-54% yields, 96-98% purity by HPLC).

A revised mechanism of thermal decay of arylnitroso oxides.

The electronic spectra were measured and the unimolecular decay kinetics of the isomeric forms (cis and trans) of 4-methoxyphenylnitroso oxide in acetonitrile, benzene, and hexane was studied using flash photolysis. The cis form absorbed in a shorter wavelength region and was more labile than the trans form. The difference between the reactivity of the two species increased on going from hexane to acetonitrile.