UBIQUINOL-3 AND UBIQUINOL-7 EXHIBIT SIMILAR ANTIOXIDANT ACTIVITY IN MODEL MEMBRANES

This study was undertaken to compare, on a kinetic basis, the antioxid ant efficiency of an ubiquinol homologue having a short isoprenoid sid e-chain length, such as ubiquinol-3, with that of the long chain ubiqu inol-7, by determining their rate constants of inhibition with respect to alpha-tocopherol. To this purpose we incorporated ubiquinol-3, or ubiquinol-7, or alpha-tocopherol into liposomes of egg yolk lecithin, and triggered lipid peroxidation with the thermal decomposition of a l ipophilic azocompound. The results show that: i) the rate constants of inhibition for the two quinols are similar and slightly lower than th at of alpha-tocopherol; ii) the length of the radical chain obtained i n the presence of the two quinols is almost the same. From these data we concluded that the two homologues tested behave as chain-breaking a ntioxidants with quite similar effectiveness.