Abstract
Oxidation of succinate and NADH in UQ-depleted mitochondrial preparations was restored by some low molecular weight quinones including QSA-10 (idebenone). QSA-10 inhibited lipid peroxidation dependent on NADH (NADPH)/ADP-Fe^lt:3+> in canine brain mitochondria and protected the resulting inactivation of NADH-Cyt c reductase activity. QSA-10 did not virtually affect the activities of succinate oxidase in canine and rat brain mitochondria and suppressed the oxygen consumption in NADH oxidation, which might be related to the inhibition of lipid peroxidation. These results, supported by those from ex vivo tests, suggest that QSA-10 acts as an electron carrier in respiratory chains and functions as an antioxidant against membrane damage caused by lipid peroxidation in brain mitochondria.
