Antioxidant effects of calcium antagonists in rat brain homogenates

We studied the antioxidant activities of calcium antagonists against autoxi dation in rat brain homogenates. The homogenates were incubated for 30 min at 37 degrees C with or without a calcium antagonist and subsequently assay ed for lipid peroxide content. Percent inhibition of the lipid peroxidation was used as an index of the antioxidant effect. Dihydropyridine calcium an tagonists exhibited concentration-dependent (3-300 mu mol/l) inhibitory eff ects against lipid peroxidation. The relative order of antioxidant potency and associated IC50 values (mu mol/l) of the calcium antagonists for inhibi tion of the lipid peroxidation were as follows: nifedipine (51.5)>barnidipi ne (58.6)>benidipine (71.2)>nicardipine (129.3)>amlodipine (135.5)>nilvadip ine (167.3)>nitrendipine (252.1)>> diltiazem (>300) verapamil (>300). These results suggest that some dihydropyridine calcium antagonists show antioxi dant properties, The antioxidant effects of the calcium antagonists may con tribute to their pharmacological actions.