STUDY FOR THE MECHANISM OF THE ACTION OF FLAVONOIDS AGAINST THE OXIDATION STRESS

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Purpose of the work was to study hesperidin, diosmin, flavicin, and quercetine for the activity of NADPH-GSH-dependent fermentative system and the indices of energetic exchange in liver with the course administration to healthy animals. Materials and methods of the study: hesperidin, diosmin, and flavicin were isolated at the department of Organic Chemistry at Pyatigorsk Medical and Pharmaceutical Institute from the raw plants under the direction of Professor E.T. Oganesyan; quercetine was produced by Merk business. Using physical and chemical methods of analysis: melting temperature, UV, IR, and PMR spectroscopy thin layered and paper chromatography, probes of blending we have proven the structure of the isolated substances. The trials were carried out using 30 outbred rats of both sexes weighed 180-200 g. Experimental animals received hesperidin, diosmin, quercetine, and flavicin at dose 100 mg/kg perorally in form of water excipient during 12 days. The animal group with the same volume of solvent was taken as the control. In a postnuclear section of liver we measured activities of glutathione peroxidase (GP), glutathione reductase (GR), glutathione S-transferase (G-S-TR), NADP+-reductases: malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G-6-PDH), and isocitrate dehydrogenase (IDH). In a liver homogenate we determined the content of GSH, glucoses, glycogen, pyruvate, lactate, and ATP. In mitochondrial section of lever we measured the activity of succinate dehydrogenase (SDH), cytochrome oxydase (CTO), Mg2+-ATPase. Results: we have established that as the result of a course administration of the flavonoids under study we could note the raise of the content of GSH in rats’ liver and increase of MDH, G-6-PDH, and IDH activity. Taking into the consideration the role of GSH in the enhancement of resistance to the action of different damaging factors, including an activation of free radical oxidation, the enhancement of glutathione link of antioxidant protection by means of flavonoids conduces the formation of a hidden reserve which increases the capacity of endogenous antioxidant system and allow obtainment of an efficient work of this system in conditions of an oxidation stress. The increase of NADP+-reductases activity, which took part in GSH regeneration from an oxidized form, may be connected with protonophore properties of flavonoids and the capability to produce a reserve of oxidized by nicotinamide coferments (NAD+ and NADP+) in a cell - cofactors of NADP+-reductases. Concerning the indices of energetic exchange we have revealed in our trials that the increase of pyruvate content in liver with simultaneous decrease of lactate, decrease of glucoses content with preservation of glycogen content, increase of Mg2+-ATPase activity and ATP content in liver. The data obtained can give evidence about the capability of flavonoids to activate energy production in the course of glycolysis without the development of metabolic acidosis, which is an important factor in the enhancement of total resistance to the action of a damaging factor like hypoxia. Augmentation of Mg2+-ATPase activity may be connected with the capability of the flavonoids to evoke a fractional uncoupling of respiration on certain parts of respiratory chain of mitochondria. Quoting V.P. Skulachev, 1995, this “soft” uncoupling is one of the mechanisms which prevent one-electron recovery of oxygen, which decrease the production of free oxygen radicals and hamper the growth of the oxidation stress. Conclusions: a direct antioxidant activity is not the only one which has a big significance in the mechanisms of protective action of flavonoids against an oxidation stress due to its anti-radial and chelated properties, but also an indirect protection by means of the activation of endogenic NADPH-GSH-dependant enzymic system of antioxidant protection, and also the raise of unspecific resistance by means of energy production improvement and protection of mitochondria from the oxidation damage.