[Antioxidant activity of oxygen-containing aromatic compounds].

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.

[Hepatoprotective properties of silymarin].

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.

[Flavonoids: efficient protectors of glucose-6-phosphate dehydrogenase from ultrasonic cavitation-induced inactivation].

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.

[Flavonoids as effective protectors of urease from ultrasonic inactivation in solutions].

Inactivation of soybean urease in aqueous solution at pH 5.4, 36 degrees C, and high-frequency sonication (2.64 MHz, 1.0 W/cm2) is substantially reduced in the presence of seven structurally different flavonoids. A comparative kinetic study of the effect of these flavonoids on the effective first-order rate constants that characterize the total (thermal and ultrasonic) inactivation k(i), thermal inactivation k(i)*, and ultrasonic inactivation k(i)(US) of 25 nM enzyme solution was carried out. The dependences of the three inactivation rate constants of the urease on the concentrations of flavonoids within the range from 10(-11) to 10(-4) M were obtained. The following order of the efficiency of the flavonoids used in respect of the urease protection from ultrasonic inactivation was found: astragalin > silybin > naringin > hesperidin > quercetin > kaempferol > morin. The results confirm a significant role in the inactivation of the urease of HO* and HO2*, free radicals, which are formed in the ultrasonic cavitation field.

[Physicochemical properties of chitin-melanin and melanoprotein complexes from bee corpses].

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.

[Photoprotective properties of melanins from grape (Vitis vinifera) and black tea (Thea sinensis)]. / Fotoprotektornye svoistva melaninov iz vinograda (Vitis vinifera) i chernogo chaia (Thea sinensis).

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.

[Optimization of the use of horseradish peroxidase and its antibodies in immunoenzyme analysis]. / Optimizatsiia ispol'zovaniia peroksidazy khrena i ee antitel v immunofermentnom analize.

The steady-state kinetics of peroxidation of 8 aromatic amines was studied. p-Phenylenediamine, o-dianisidine (o-DA) and 3,5,3',5'-tetramethylbenzidine were found to be optimal substrates of horse-radish peroxidase. The kinetics of oxidation of these substrates by horseradish peroxidase modified with three molecules of Strophanthin K was studied as well. Within the temperature range from 37 to 53 degrees C the inactivation rate constants were determined for peroxidase and its conjugate with Strophanthin K. The effect of sugars and polyols on thermal stability of the conjugate peroxidase-Strophanthin K was investigated. A comparative kinetic study was performed of oxidation of o-DA and its conjugate with dextran. The results obtained made a basis for an enzyme immunoassay of cardiac glycosides during their isolation from plant raw material.

[Physicochemical properties of melanins produced by Inonotus obliquus("chagi") in the nature and the cultivated fungus]. / Fiziko-khimicheskie svoistva melaninov, obrazuemykh chagoi v prirodnykh usloviiakh i pri kul'tivirovanii.

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.

[Antioxidant features of fungal melanin pigments]. / Antioksidantnye svoistva melaninovykh pigmentov gribnogo proiskhozhdeniia.

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.

[The role of carcinogenic aminobiphenyls in hepatocyte differentiation]. / Rol' kantserogennykh aminobifenilov v differentsirovke gepatotsitov.

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.

[Immunochemical study of catalytic activity of cytochrome P-450-LM4 from rabbit liver microsomes]. / Immunokhimicheskoe izuchenie kataliticheskoi aktivnosti tsitukhroma P-450-LM4 iz mikrosom pecheni krolika.

Immunization of rats by a homogeneous cytochrome P-450-LM4 from liver microsomes of rabbits pretreated with 3-methylcholanthrene resulted in antibodies to this hemoprotein - anti-P-450-LM4. Using the Ouchterlony method, a reaction of precipitation of anti-P-450-LM4 with cytochrome P-450-LM4 from MeCh- and PB-induced microsomes of rabbit liver has been carried out. The anti-P-450-LM4 at different concentrations does not practically exert any inhibitory action on oxidation of aniline and N,N-dimethylaniline by intact and PB- and MeCh-induced rabbit hepatic microsomes. It is concluded that rabbit liver cytochrome P-450-LM4 does not practically reveal any catalytic activity in ther metabolism of aniline and N,N-dimethylaniline.

[Inhibitory action of divalent copper compounds on cumene hydroperoxide oxidative demethylation of N,N-dimethylaniline by cytochrome P-450]. / Ingibiruiushchee deistvie soedinenii medi na okislitel'noe demetilirovanie dimetilanilina gidroperekis'iu kumila pri uchastii tsitokhorma P-450.

The inhibitory action of divalent copper compounds on hydroperoxide-dependent oxidative demethylation of N,N-demethylaniline involving rabbit liver microsomes and highly purified cytochrome P-450 has been studied. CuCl2 is a non-competitive inhibitor, whereas copper tyrosine and lysine complexes are characterized by a mixed type inhibition. The inhibitory action of copper complexes is based on a decrease of cumene hydroperoxide concentration. The reaction results in formation of RO and RO2 radicals destroying cytochrome P-450 CuCl2 (0,001 M) also destroys cytochrome P-450 in the absence of cumene hydroperoxide; the destruction process is characterized by two phases with different rate constants. The nature of the inhibitory action of CuCl2 on N,N-demethylaniline oxidation by hydroperoxides is discussed.

[Reactivity of the LM4 form of cytochrome P-450 from rabbit liver microsomes]. / Reaktsionnaia sposobnost' LM4-formy tsitokhroma P-450 iz mikrosom pecheni krolikov.

Aniline oxidation and oxidative dimethylaniline demethylation with participation of the LM4 form of cytochrome P-450 from rabbit liver microsomes were studied under different conditions: e. g. after incorporation of LM4 form into microsomes of phenobarbital- and 3-methylcholanthrene-pretreated rabbits and after incorporation of this hemoprotein into liposomes in hydroperoxide-dependent reactions. The results obtained suggest that the LM4 form of cytochrome P-450 is catalytically inactive during aniline oxidation and dimethylaniline demethylation in both cases. The absence of catalytic activity of the LM4 form of cytochrome P-450 is due to the structural peculiarities of the active site of this hemoprotein rather than to its environment.

[Peroxidase activity of succinylated catalase]. / Peroksidaznaia aktivnost' suktsinilirovannoi katalazy.

The catalase succinylation by succinic anhydride excess results in an almost complete dissociation of the enzyme into subunits possessing no catalase activity. The catalase subunits show the peroxidatic activity on o-dianisidine oxidation. The oxidation kinetics of this substrate by the succinylated enzyme was studied at various temperatures. The activation energy for this process is 10.1 kcal/mole. Within the temperature range of 31-65.5 degrees, the succinylated enzyme thermostability was studied by monitoring the peroxidatic activity decrease upon o-dianisidine oxidation. The activation energy for the succinylated catalase thermoinactivation equals to 15.5 kcal/mole. The peroxidatic activity of catalase subunits obtained by enzyme succinylation and acidic solution treatment was compared to that of horseradish peroxidase in the oxidation of the same substrate, i.e., o-dianisidine.

[Activity of the antioxidant system of rat liver in benzidine poisoning and administration of enomelanin]. / Aktivnost' antioksidantnoi sistemy pecheni krys pri benzidinovoi intoksikatsii i vvedenii énomelanina.

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.

[Status of the antioxidant system and lipid peroxidation in rat liver after poisoning animals with aminobiphenyl]. / Sostoianie antioksidantnoi sistemy i perekisnogo okisleniia lipidov v pecheni krys posle intoksikatsii zhivotnykh aminobifenilami.

It was found that intoxication of animals with aminobiphenyls leads to the activation of such glutathione-dependent enzymes as glutathione-S-transferase and glutathione reductase. This is accompanied by the induction of activities of individual isoforms of the multifunctional family of glutathione-S-transferases. There was a decrease in the glutathione peroxidase activity after intoxication with benzidine derivatives. It was found that the GSH content in rat liver decreased after benzidine intoxication and sharply increased after effects of 3,3'-dimethylbenzidine and 3,3'-dimethoxybenzidine. In all cases studied there was a diminution in the level of diene conjugates. It was supposed that the specificity of the catalytic glutathione redox system reaction is due to structural peculiarities of the aminobiphenyls being injected. Analysis of functional pairs of glutathione-dependent enzymes revealed a certain imbalance in the antioxidant system function after aminobiphenyl poisoning.

[Rat liver antioxidant defense mechanism to the action of aromatic amines]. / Mekhanizm antioksidantnoi zashchity pecheni krys pri deistvii aromaticheskikh aminov.

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.

[Peroxidase activity of catalase with respect to aromatic amines]. / Peroksidaznaia aktivnost' katalazy po otnosheniiu k aromaticheskim aminam.

The catalase dissociation into subunits has been studied at pH less than 3.5 and greater than 11.0. This process is characterized by pseudo-first order rate constants, depending on the initial concentrations of the enzyme and H+. At pH 2.85, the steady-state kinetics of five aromatic amines oxidation by catalase monomers has been studied for orthodianisidine (o-DA), 3,5,3',5'-tetramethylbenzidine (TMB), ortho- and para-phenylene diamine (p-PDA) and 5-aminosalycilic acid. The optimal substrates for catalase in acidic solutions are o-DA, TMB and p-PDA. A comparison has been carried out for the catalase peroxidative activity, and the catalytic characteristics of horseradish peroxidase in the oxidation of the same substrate. The mechanisms of peroxidatic amines oxidation by catalase and horseradish peroxidase are discussed.

[Immunochemistry of catalytic activity of cytochrome P-450-LM2 from rat liver microsomes]. / Immunokhimicheskoe izuchenie kataliticheskoi aktivnosti tsitokhroma P-450-LM2 iz mikrosom pecheni krolika.

A systematic study of inhibition by antibodies of dimethylaniline (DMA) and aniline oxidation has been carried out under different conditions: e. g. with participation of intact, phenobarbital- and 3-methylcholantrene-induced microsomes, NADPH and O2; during hydroperoxide-dependent oxidation with three types of microsomes; in a reconstituted system containing cytochrome P-450 LM2, NADPH cytochrome P-450 reductase, NADPH and O2; in systems containing cytochrome P-450 LM2 and cumene hydroperoxide. In all cases the antibodies effectively inhibited oxidation of both substrates. The degree of inhibition increased in the following order: intact less than 3-methylcholantrene- less than phenobarbital-induced microsomes. In the case of hydroperoxide-dependent oxidation of aniline and DMA no complete inhibition was achieved.