Combined inhibitory effect of sulfur-containing phenol SO-4 with natural and synthetic antioxidants in the oxidation of methyl oleate

In a model system of initiated oxidation of methyl oleate, the antioxidant activities of 3-hydroxy-2-ethyl- 6 -methylpyridinesuccinate (mexidol) and bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propyl] disulfide (SO-4) were studied and compared with those of alpha-tocopherol and 1-hydroxy-2,6-di-tert-butyl-4-methylbenzene (dibunol). A linear pattern of dependence of the inhibitory effect on the concentration of compounds was established. The ability of antioxidants to decompose hydroperoxides and inhibit their accumulation was revealed. The combined inhibitory effects of SO-4 with mexidol, alpha-tocopherol, and phospholipids were described for the first time. The rate constant for disproportionation of the SO-4 phenoxyl radicals, k(9) = 0.90.10(3) L mol(-1) s(-1), was determined by steady-state photolysis. The rate constant k(10)(eff) for the reactions of SO-4 phenoxyl radicals with lipids characterized by different unsaturation degrees were determined for methyl oleate, linolic and arachidonic acids containing one, two, and four multiple bonds, and phospholiopids containing polyunsaturated fatty acids.