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The coenzymes Q and Vitamin K(3), as well as their synthetic analogues, have been found to inhibit free-radical processes of fragmentation of hydroxyl-containing organic compounds and oxidation of the latter by molecular oxygen. It has been established that the observed effects are due to the ability of quinones to oxidize the alpha-hydroxyl-containing carbon-centered radicals formed from the starting compounds.

Effects of alpha-tocopherol, PMC, and a number of the respective sulfur-containing analogues on reactions involving various organic radicals were studied. The test compounds were found to interact with alkyl radicals more effectively than with peroxyl radicals. The presence of a sulfur atom in structures of the respective analogues did not produce significant effects on reactivity. Derivatives of 5-hydroxy-1,3-benzoxathiol-2-one and 6-hydroxy-1,4-benzoxathiin-2(3H)-one displayed a high reactivity toward alpha-hydroxyalkyl radicals.

Effects of vitamins B1, B2, B6, and pyridoxal phosphate (PPh) on final product formation in radiolysis of aqueous solutions of ethanol, ethylene glycol, alpha-methylglycoside, and maltose were studied. It has been found that vitamin B2 and PPh effectively oxidize R*CHOH species, while suppressing their recombination and fragmentation reactions, thereby increasing the yields of the respective oxidation products. Vitamins B1 and B2 are capable of reducing alcohol radicals to the respective initial molecules, decreasing the yields of the radical transformation products.