Cytotoxic effects of six isoflavonoids, tectorigenin, glycitein, tectoridin, glycitin, 6''-O-xylosyltectoridin, and 6''-O-xylosylglycitin isolated from the flower of Pueraria thunbergiana Benth. together with genistein, a known differentiation and apoptosis inducer, were examined. Among these