A. V. Kutchin

Separation of racemic ortho-isobornylphenol into enantiomers and evaluation of their antioxidant activity

Racemic ortho-isobornylphenol was separated into enantiomers through diastereomeric camphanates. The absolute configuration of chiral centers of the isolated products was determined by X-ray studies. Antioxidant activity and membrane-protective properties of the enantiomers were studied on the model of H2O2-induced hemolysis of erythrocytes.

Reactions of chlorine dioxide with organic compounds. Selective oxidation of sulfides to sulfoxides by chlorine dioxide

A novel method for the selective oxidation of various types of sulfides to sulfoxides using chlorine dioxide as the oxidant is proposed.

Structural and chemical charactertistics of pectins, arabinogalactans, and arabinogalactan proteins from conifers

In this review, we summarized the research data on the contents and chemical structures of pectic polysaccharides, arabinogalactans, and arabinogalactan proteins from coniferous species. The presently known structures of these polymers are given. Special attention is given to the description of chemical structural features of pectic polysaccharides from the Abies sibirica and Picea abies tree verdures (branches and needles). Three models presently suggested for the description of pectin macromolecular structures are discussed.

Membrane protective properties of carboxy derivatives based on 2,6-diisobornyl-4-methylphenol

Toxicity, antioxidant activity, and membrane protective properties were studied on mammalian red blood cells for carboxy derivatives and esters of 2,6-diisobornyl-4-methylphenol in comparison with both diastereomers (meso-form and racemate) of this terpenophenol. The studies showed that all the synthesized compounds posses an antioxidant activity, however, the cytotoxicity of derivatives with a free carboxy group might be an obstacle to the use of these compounds in pharmacology. The most promising compound is methyl 4-hydroxy-3,5-diisobornylbenzoate distinguished by a low toxicity and high antioxidant and membrane protective activity, which is comparable to that of 2,6-diisobornyl-4-methylphenol.

Synthesis and asymmetric oxidation of thioglycosides derived from neomenthanethiol and α- d -galactose

Abstract6-Deoxy-6-[(1S,2S,5R)-2-isopropyl-5-methylcyclohexylsulfanyl]-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose was synthesized in 94% yield from 1,2 : 3,4-di-O-isopropylidene-α-d-galactopyranose and neomenthanethiol, and its oxidation gave the corresponding diastereoisomeric sulfoxides in up to 84% yield and de values of up to 52%. The isopropylidene protective groups were removed from the sulfide and sulfoxides by treatment with trifluoroacetic acid in chloroform.

Asymmetric oxidation of hetaryl neomenthyl sulfides

Previously unknown diastereoisomeric sulfoxides were synthesized by asymmetric oxidation of 2-neomenthylsulfanyl-substituted 1H-imidazole, 1-methyl-1H-imidazole, and 1H-benzimidazole.

Synthesis of novel terpenophenol-chlorin conjugates and evaluation of their membranotropic and membrane-protecting properties

A series of conjugates has been synthesized by the reaction of methylpheophorbide a with ortho-alkylaminomethyl derivatives of 2-isobornyl-4-methylphenol; the terpenophenol fragment in the conjugates is attached to the methylpheophorbide a macrocycle by an amide bond formed upon the amidation of the 13(2)-ester group. A scanning electron microscopy study of the surface structure of erythrocytes incubated with these compounds confirmed their ability to interact with the cell membrane. It was found, based on the ability of the conjugates to inhibit the H2O2-induced hemolysis of erythrocytes and slow down the accumulation of the secondary lipid peroxidation products, that they possess membrane-protecting and antioxidant properties.

Synthesis and membrane protective activity of 4-alkoxymethyl-2,6-diisobornylphenols

Bromination of 2,6-diisobornyl-4-methylphenol gave the corresponding 4-bromomethyl derivative, whose reaction with alcohols resulted in 4-alkoxymethyl-2,6-diisobornylphenols. Their toxicity, membrane protective and antioxidant activity were tested using red blood cells of laboratory mice. The synthesized compounds do not exhibit cytotoxicity at the concentrations of 10 and 100 μmol L–1 and are characterized by high membrane protective and antioxidant activity in the concentrations of 1 and 10 μmol L–1.

Synthesis of unsymmetrical hydroxybenzylphenols containing isobornyl fragments

Abstract4-(Bromomethyl)-2,6-diisobornylphenol was synthesized from 2,6-diisobornyl-4-methylphenol through intermediate 4-bromo-2,6-diisobornyl-4-methylcyclohexa-2,5-dien-1-one. Reactions of 4-(bromomethyl)-2,6-diisobornylphenol with 2,6- and 2,4-dialkylphenols gave new 4-(hydroxybenzyl)phenol derivatives containing bulky tert-butyl and isobornyl substituents.

Inhibiting activity of isocamphyl substituted phenols and their mixtures with 2,6-di- tert -butylphenol in the initiated oxidation of ethylbenzene

The stoichiometric coefficients of inhibition and rate constants for the reaction of several terpenephenols (isocamphyl substituted phenols) with ethylbenzene peroxy radicals were measured. Their reactivity was found to increase as the number of alkyl substituents grew and decreased with an o-alkoxyl compared with o-alkyl substituent because of the formation of an intramolecular H-bond. In spite of similar antiradical activities of terpenephenols with isocamphyl and isobornyl substituents, the reactivities of phenoxyl radicals formed from them in the interaction with sterically hindered phenol molecules are substantially different. They are higher for isocamphylphenols with substituents turned with respect to the aromatic ring plane.