ИСТИНА

Thiols are known as biological antioxidants which function by scavenging hydroxyl radicals, reducing hydroperoxides and H2O2, preventing protein oxidation and reducing disulfide bonds –S-S-. From other side, thiyl radicals (RS*) are known to be some of the most effective species to catalyze the cis/trans isomerization of unsaturated fatty acids (LH). Recently, we have found that mercaptoethanol can accelerate the oxidation of hydrocarbons and methyl linoleate due to its reaction with hydroperoxides (primary oxidation products) resulting in some yield of free radicals. In this study, the behavior of natural thiols glutathione (GSH), cysteine (CSH), and homocysteine (HSH) towards peroxyl radicals and hydrogen peroxide and the kinetics of free radical formation in reactions of thiols with H2O2have been investigated. Polymethine dyes were tested and used as free radical scavengers in water solutions. The antiradical activity of thiols appeared to increase in the sequence: GSH<HSH<CSH. The reactivity of thiols in the reaction with hydrogen peroxide changes as follows: GSH< HSH CSH.