Soybean isoflavones: estrogenic activity and isolation of two new isoflavones

A rapid method utilizing preparative high-performance liquid chromatography was developed for the isolation and purification of the soybean isoflavones genistin and daidzin;Significant differences in the estrogenic response of different mouse strains to diethylstilboestrol (DES) and the phytoestrogens were observed. The inbred strains B6D2F1 and B6C3F1 were significantly more sensitive to DES than the outbred ICR and CD-1 mice. The inbred mouse strain B6D2F1 was used to investigate the estrogenic potency of genistin and diadzin. The estrogenic response to 1.5 mg of genistin was equivalent to 1 mg of genistein, giving a 1:1 molar relationship in estrogenic potency between the two compounds. The estrogenic response to 3.8 mg of daidzin was equivalent to 1 mg of genistein;The isoflavones, 6''-O-acetyldaidzin and 6''-O-acetylgenistin were isolated and purified from toasted defatted soyflakes. Their structure was confirmed with nuclear magnetic resonance spectroscopy, mass spectroscopy, ultraviolet and infrared spectroscopy, acidic and enzymatic hydrolysis. Soyflakes contained 52 ppm of 6''-O-acetyldaidzin and 88 ppm of 6''-O-acetylgenistin. Acetone with 0.1N HCl was found to be superior to 80% methanol for extraction of these compounds.