G. I. Polozov

Quinones as free-radical fragmentation inhibitors in biologically important molecules

Effects of a number of quinones and diphenols of various structures on free-radical fragmentation processes taking place in f -diols, glycerol, 2-aminoethanol, glycero-1-phosphate, ethylene glycol monobutyrate, maltose, and some lipids were investigated. Quinone additions have been found to change the direction of free-radical transformations of the compounds cited above by inhibiting formation of the respective fragmentation products owing to oxidation of radicals of the starting compounds. The results obtained and literature data available allow a suggestion to be made that the system quinone/diphenol is able to not only deactivate or generate such active species as O 2 ” m but also control the realization probability of free-radical processes of peroxidation and fragmentation in biologically important molecules.

Effects of Phenolic Compounds on Reactions Involving Various Organic Radicals

Investigation of effects produced by 26 various phenol and diphenol derivatives, including industrial and natural antioxidants (ionol, bis-phenol 2246, α-tocopherol), on final product yields of radiation-induced free-radical processes involving peroxyl, alkyl, α-hydroxyalkyl and α,β-dihydroxyalkyl radicals has been performed. Ionol and bis-phenol 2246 have been shown to be more effective than α-tocopherol or diphenol derivatives in suppressing hydrocarbon oxidation processes. At the same time, α-tocopherol and its water-soluble analogues, as well as diphenol-based substances, are more effective than phenol derivatives in regulating various homolytic processes involving carbon-centered radicals. This fact can be accounted for by taking into consideration the contribution to formation of the final product set and the respective yields made by semiquinone radicals and compounds with quinoid structure arising in the course of homolytic transformations in systems containing diphenol derivatives.

Synthesis and study of antiviral and anti-radical properties of aminophenol derivatives

A number of sterically-hindered o-aminophenol derivatives have been synthesized, and their antiviral activity in parallel with reactivity towards commonly encountered free-radical intermediates was investigated. Of the compounds tested, the highest activity in suppressing replication of Herpes simplex type l viruses was displayed by N-acyl and N-aryl derivatives of 4,6-di-tert-butyl-2-aminophenol, which were able to interact with organic free radicals and, at the same time, manifested low reactivity towards reactive oxygen species.

Manifestation of intramolecular hydrogen bonds in the IR spectra of bioactive aminophenols

The intermolecular interactions in solutions of aminophenols in CCl4 are studied by the methods of IR Fourier spectroscopy. If the hydroxyl groups of aminophenol molecules occupy the ortho positions with respect to the amino groups of the molecules, the hydroxyl and amino groups are involved in intramolecular interactions with the formation of hydrogen bonds O-H...N and N-H...O. The introduction of two additional tert-butyl groups into the structure of the aminophenol molecule facilitates the formation of O-H...N bonds and impedes the formation of N-H...O bonds. The occurrence of the carbonyl group in the structure of aminophenols leads to the formation of intramolecular hydrogen bonds O-H...O=C. The introduction of the methyl groups into carbonyl-containing aminophenols transforms the O-H...O=C bond into the hydrogen bond N-H...O=C.

Synthesis and antimicrobial activity of silver(I) and copper(II) complexes with 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl) acetic acid

Ag(I) and Cu(II) complexes with 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl)acetic acid ligands (L) have been synthesized and characterized using a combination of methods, including x-ray powder diffraction, elemental analysis, TG/DTA, FT-IR, and EPR. The antimicrobial properties of 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl]acetic acid and its complexes with Ag(I) and Cu(II) were tested against standard E. coli, Ps. aeruginosa, C. albicans, B. subtilis, St. aureus, and Pr. vulgaris strains.

Spectroscopic properties of pharmacologically active phenols

The IR Fourier-transform spectra of pharmacologically active phenol molecules in solutions in CCl4 and in the crystalline state have been studied. Phenol derivatives with different directivities and different levels of pharmacological efficiency have been examined. Based on analysis of the IR spectra of screened phenols, the antimicrobial activity of phenols with free hydroxyl groups has been shown to be highest. The high antimicrobial activity of aminophenols is related to the formation of intramolecular hydrogen bonds. For aminophenols that are active against herpesviruses, O-H...N hydrogen bonds are formed in molecules. The main characteristic of the high antiviral activity against A-type influenza is predominance of intramolecular hydrogen bonds of the O-H...O=C type in molecules. Sulfur-containing aminophenols, which manifest activity against HIV infection, are characterized by the occurrence of hydrogen bonds that involve the participation of the OH, NH, and SO2 groups.

Synthesis and Antiviral Activity of Hydroxy-Substituted Benzaldehydes and Related Compounds

A series of hydroxy-substituted benzaldehydes and related compounds were synthesized and studied in cell culture against herpes simplex type I (HSV-1) and influenza A (H7N1) viruses. It was found that salicylaldehyde, 2,3-dihydroxybenzaldehyde, and gossypol could suppress HSV-1 replication. The structure–activity relationship of the series of hydroxylated benzaldehydes was analyzed.

Bioactive Silver(I) Complexes with Phenolic Derivatives of Thioglycolic and Thiopropionic Acids

Ag(I) complexes formed by polydentate phenolic derivatives of thioglycolic and thiopropionic acids with Ag(I) ions could be a promising field of search for potential chemotherapeutic agents. Convenient synthetic methods to prepare these ligands have been developed on the basis of addition reactions occurring between S-nucleophiles and o- benzoquinones. The results are presented of physicochemical investigation of Ag(I) ions complexation with phenolic ligands, which made it possible to determine ionic and redox ligand forms with high nucleophilicity of metal-ion binding sites, the peculiarities of the structural organization of the coordination cores of the newly synthesized complexes. The in- vestigation of the molecular and electronic structure of Ag(I) complexes has been performed within the density functional theory framework. On the basis of the pharmacological screening results the selection is justified of a lead compound pos- sessing antibacterial, antifungal and antiherpetic activity comparable to those of some standard drugs to develop effective pharmaceuticals for combination therapy of mixed infections. Data have been obtained on the ability of some phenolic de- rivatives of thioglycolic and thiopropionic acids as well as their Ag(I) complexes to reduce bovine cytochrome c.

Effect of α-tocopherol and its sulfur-containing analogs on radiation-induced chemical transformations of hexane and ethanol

A series of sulfur-containing structural analogs of α-tocopherol was synthesized, and their effect on the formation of molecular products of ethanol and hexane radiolysis under aerated and deaerated conditions was studied. The O-H bond dissociation enthalpies (BDEs) were calculated for the compounds containing hydroxyl groups. It was found that α-tocopherol and its analogs have the most significant effect on the radiolysis of ethanol and hexane under air-free conditions when the products are formed in the reactions of carbon-centered radicals. The probability of the reaction of the test compounds with alkyl radicals increases with a decrease in the BDE for the OH groups present in these compounds. The carbonyl group in compounds (IV-VIII) makes them efficient oxidants of α-hydroxyalkyl radicals, thus resulting in a change in the product composition for the ethanol radiolysis in presence of these compounds.