Is a relay mechanism of antioxidant effect of tocopherols valuable for membrane systems?
The efficiency of the inhibitory action of 3 tocols derivatives--alpha-tocopherol (alpha-T), 2, 2, 5, 7, 8-pentamethylchromane (PMC) and alpha-tocopherylacetate (alpha-TA) on lipid peroxidation (LPO) in rat liver microsomes was compared. LPO was induced by O2-generating systems (Fe2+ + NADPH, Fe2+ + ascorbate) or by ROO generating system (Fe2+ + tert-butyl hydroperoxide). It was found that PMC was much more potent LPO inhibitor than alpha-T, whereas alpha-TA was ineffective in all LPO-initiating systems used. The protective effect against cytochrome P-450 (cyt. P-450) degradation induced by LPO-products was also maximal for PMC and minimal for alpha-TA. The data obtained suggest that the presence of phytyl radical is not necessary for antioxidant activity of tocols and contradict the hypothesis about a relay mechanism of antioxidant action of tocopherols in biomembranes.
D000818:Animals; D002839:Chromans / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005609:Free Radicals; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical; D007425:Intracellular Membranes / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013481:Superoxides / Q000378:metabolism; D024505:Tocopherols; D014810:Vitamin E / Q000031:analogs & derivatives / Q000494:pharmacology*; D024502:alpha-Tocopherol / Q000031:analogs & derivatives*
C048427:2,2,5,7,8-pentamethylchroman; D002839:Chromans; D005609:Free Radicals; D006878:Hydroxides; D008054:Lipid Peroxides; D013481:Superoxides; D014810:Vitamin E; D017665:Hydroxyl Radical; D003577:Cytochrome P-450 Enzyme System; D024502:alpha-Tocopherol; D024505:Tocopherols