Antioxidative action of soyasaponin monomers I, A1, A2, and their inhibitory effects on action potential and beating of myocardiocytes in culture

Ventricular myocardiocytes from newborn Wistar rats were cultured. Soyasaponin monomers I, A1, A2 2 micrograms.ml-1 added to the culture medium, like nimodipine 1.25 microgram.ml-1, decreased the number of spontaneously beating clusters and the action potential parameters of myocardiocytes, which restored after washing out and were reversed by Ca2+ 80 micrograms.ml-1 or epinephrine 10 micrograms.ml-1, indicating the Ca2+ channel blockade action of the saponin monomers. Adding xanthine 0.42 mmol.L-1 and xanthine oxidase 5.4 nmol.L-1 into culture medium led to the increase of free radical content of the myocardiocytes and the decrease of action potential parameters, which were reversed by I 2 micrograms.ml-1, indicating the antioxidative action of saponin monomer I.