Antioxidant Effects of Calcium Antagonists in Rat Brain Homogenates

Abstract

We studied the antioxidant activities of calcium antagonists against autoxidation in rat brain homogenates.The homogenates were incubated for 30 min at 37°C with or without a calcium antagonist and subsequently assayed for lipid peroxide content. Percent inhibition of the lipid peroxidation was used as an index of the antioxidant effect. Dihydropyridine calcium antagonists exhibited concentration-dependent (3-300 μmol/l) inhibitory effects against lipid peroxidation. The relative order of antioxidant potency and associated IC₅₀ values (μmol/l) of the calcium antagonists for inhibition of the lipid peroxidation were as follows : nifedipine (51.5)>barnidipine(58.6)>benidipine (71.2)>nicardipine (129.3)>amlodipine (135.5)>nilvadipine (167.3)>nitrendipine (252.1)>>diltiazem (>300)=verapamil (>300). These results suggest that some dihydropyridine calcium antagonists show antioxidant properties. The antioxidant effects of the calcium antagonists may contribute to their pharmacological actions.