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The effect of some hydroxylated aromatic aldehydes on the radiation-chemical transformations of deaerated ethanol during continuous radiolysis has been studied. The data obtained show that these compounds effectively inhibit radiation-induced processes involving α-hydroxyethyl radicals (α-HER). Benzaldehyde and its hydroxylated derivatives (II, III) predominantly oxidize, and compounds containing the cinnamic moiety, (IV-VI), add α-HER to a carbonyl group or -C=C bond. [ABSTRACT FROM AUTHOR]

Inhibition efficiency (antioxidant activity) of 26 oxygen-containing aromatic compounds was studied in methemalbumin-H202-o-phenylenediamine (PDA) or tetramethylbenzidine (TMB) pseudoperoxidase system at 20 degrees C in buffered physiological solution (pH 7.4) containing 6% DM F and 0.25% DMSO. The inhibitor's efficiency was quantitatively characterized by the inhibition constants (Ki, microM) or the inhibition degree (%). Ki values varied in the range of4 to 500 microM and were influenced by a substrate, the structure of an inhibitor, hydroxyl groups, electron-donating substituents in aromatic ring, and steric hindrances. The type of inhibition at cooxidation of eight pairs was noncompetitive, and that of five pairs was mixed and determined by the substrate nature and the inhibitor structure. Lignin phenolic compounds ofguaiacyl and syringal series exhibited high antioxidant activity (Ki in the range of 10-300 microM), and their efficiency decreased in the following order: caffeic acid > synapaldehyde > syringic acid > coniferyl aldehyde > para-hydroxycou maric acid.

Different approaches to liver-specific medicines, particularly silymarin, which exist in russian and foreign hepatology leads to formation of some difficulties in their medical usage. There is a necessity to discuss classification and terminology aspects and to study study present evidence about silymarin medicines content, pharmacokinetic and mechanisms of action, clinical efficacy and safety in patients with hepatic disorders. We had performed search in medical databases and analysed articles about silymarin. The results of clinical trials and systematic reviews of silymarin use show high efficacy of the drug in patients with amanitine, drugs, and other toxic injuries of liver, viral hepatitis, NASH. In patients with carcinoma and primarily biliary cirrhosis efficacy of silymarin is ambiguous.

Seven structurally diverse flavonoids have been shown to decrease glucose-6-phosphate dehydrogenase (G6PDH) inactivation in 0.1 M phosphate buffer (pH 7.4), induced by exposure to a high temperature (44 degrees C), or by a low-frequency ultrasound (27 kHz, 60 Wt/cm2). The activity of the compounds was assessed by their ability to change effective first-order rate constants characterizing the total (thermal and ultrasonic), thermal, and ultrasonic inactivation of 2.5 nM G6PDH (k(in), k(in)* [Russian characters: see text] kin(us), respectively). The value dependences of these constants on flavonoid concentrations (0.01-50 microM) were obtained. Rank order of potency exhibited by the compounds in protecting G6PDH appeared as follows: hesperidin > morin > silibin > naringin = quercetin > kampferol >> astragalin. The data obtained confirm the crucial role of free radicals formed in the field of ultrasonic cavitation (HO* and O2*-) in G6PDH inactivation in solutions.

A technology for processing bee corpses and obtaining chitin-melanin and melanoprotein complexes has been developed. The obtained complexes of biopolymers were studied by the methods of absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, thermogravimetry, and differential scanning calorimetry. The elemental composition of preparations was characterized. It was shown that the properties of the melanin-containing products of the processing of bee corpses are typical of chitin and melanin of animal origin. The results of EPR spectroscopy and thermal analysis are indicative of the diversity and structural complexity of the obtained products.

Physicochemical properties of pigments isolated from the naturally occurring sterile form of Inonotus obliquus (Fr.) Pil. known as Chagi and comprising the major constituent of the medicine befungin were compared with those of melanins synthesized by this fungus in the culture in order to develop a new medicine. Elemental and functional group analyses, as well as UV-visible, IR, and EPR spectra, and thermolysis studies revealed structural differences in these pigments and allowed for assignment of the naturally produced melanin to allomelanins, whereas that of cultivated fungus was assigned to eumelanins.

Dark pigments of melanin type were extracted from the rind of ripe grapes Vitis vinifera (ring "Alfa") and pack tea (Thea sinensis). The study of photoprotection activity of the extracted pigments have shown that they intensively absorb radiation in the UV and visible. The increase of the photoprotection effect correlates with the concentration of paramagnetic centers in the melanins. The pigments reduce the number of damaged molecules of plasmid DNA pBR-322 and inhibition the IUV-induced lipid peroxidation.

Fungal melanin pigments were shown to display a high antioxidant activity. An increase in the number of methyl substituents in benzidine molecules of melanins obtained from micromycetes and macromycetes was accompanied by a decrease in the efficiency of inhibition of peroxidase-catalyzed oxidation. Melanins were found to have considerable gene-protecting properties. Pigments isolated from macromycetes and applied at a much lower concentration than those obtained from micromycetes prevented damage to bacteriophage-lambda DNA induced by products of peroxidase-catalyzed degradation of aminobiphenyls.

It has been shown that benzidine administered in vivo attenuates the protective effect of the antioxidant system manifested as a reduction of the total antioxidant activity of rat liver cytosol and decreasing activities of superoxide dismutase and catalase. Enomelanin promotes the reconstitution of the superoxide dismutase activity. The data obtained suggest that the toxic effect of benzidine may be due to disturbances in the antioxidant protective mechanisms of liver cells responsible for the control over the free radical processes occurring in those cells.

The effects of diaminobiphenyl, biphenylamine and tetraaminobiphenyl on lipid peroxidation and antioxidant protective mechanisms in the subcellular fractions of rat liver have been studied. It was found that activation of lipid peroxidation plays a crucial role in the manifestation of hepatotoxic activities of diaminobiphenyl and biphenylamine, this effect being due to the decrease of the protective activity of the antioxidant system during intoxication by these compounds. Tetraaminobiphenyl does not influence the rate of lipid peroxidation. It is concluded that structural differences determine the differences in the mechanisms of adaptation of the antioxidant system to the effect of aromatic amines.

Contribution of various hemoproteins to peroxidase oxidation of benzidine and its derivatives as well as effects of these substances on functional state of hepatocytes are discussed. Benzidine and its derivatives were shown to induce those forms of cytochrome P-450 which were involved in accelerated oxidation of the carcinogenic drugs studied as well as affected the glutathione transferase, NADPH-dependent glutathione reductase activities and the activity of antioxidant system enzymes. Increase in content of cytochrome P-450, glutathione-dependent enzymes and other effects specific for adult hepatocytes, which occurred in presence of aminobiphenyls, were accompanied by decrease in content of receptors to epidermal factor of growth regulating the hepatocytes proliferation.