In vitro antioxidant activity of calcium antagonists against LDL oxidation compared with alpha-tocopherol.

The dose-dependent (1, 5, 10, 50 microM) antioxidative activity of calcium antagonists (verapamil, diltiazem, nifedipine, amlodipine, isradipine or lacidipine) and alpha-tocopherol against copper-induced LDL (0.25 mg/ml) oxidation was compared by measuring the diene formation and the content of TBARS. For diltiazem no antioxidant effect could be found, whereas the other calcium antagonists and alpha-tocopherol have demonstrated antioxidant activity at least at concentrations of 10 and 50 microM: alpha-tocopherol > lacidipine > nifedipine > isradipine, verapamil, amlodipine. Additionally, alpha-tocopherol and lacidipine were able to attenuate LDL-oxidation significantly at 1 and 5 microM. These results indicate in vitro antioxidative activity of calcium antagonists especially from the dihydropyridine-type with greatest activity for the strongly lipophilic lacidipine. This might be one possible antiatherogenic mechanism of calcium antagonists, since oxidative modification enhances the atherogenic potential of LDL.