Comparative study on reduction of bone loss and lipid metabolism abnormality in ovariectomized rats by soy isoflavones, daidzin, genistin, and glycitin

The effects of the soy isoflavone glycoside, daidzin, genistin, and glyciti n on bone loss and lipid metabolism in ovariectomized (ovx) rats were compa red with those of estrone. Thirty-six 11-week-old female Sprague-Dawley rat s were assigned to six groups, sham-operated, ovx, ovx+glycitin, ovx+daidzi n, ovx+genistin, and ovx+estrone and fed matched amounts of a commercial ca lcium-deficient diet for 4 weeks. Throughout this period, daidzin, genistin or glycitin (25, 50 or 100mg/kg/d) was given orally using a stomach tube, or estrone (7.5 mug/kg/d) was administered subcutaneously: Daidzin, genisti n and glycitin significantly prevented bone loss in ovx rats at a dose of 5 0 mg/kg/d, like estrone. At this dose glycitin and daidzin also prevented o vx-induced uterine atrophy and increases in body weight gain, abdominal fat , serum total cholesterol and triglyceride, and urinary excretion of pyridi noline and deoxypyridinoline with statistical significance, like estrone, O n the other hand, genistin prevented ovx-induced uterine atrophy only at a dose of 100 mg/kg, but did not block any. other change of ovx rats at a dos e of 50 or 100 mg/kg, These findings indicate that daidzin, glycitin, and g enistin are effective in preventing bone loss and the former two compounds are effective in reversing the unfavorable changes of lipid metabolism in t his model. It is suggested that the preventive effect of daidzin or glyciti n on bone loss in ovx rats is due to suppression of bone turnover, as in th e case of estrone, but genistin has a different mechanism of action from th e other compounds. Soy isoflavone glycosides may represent a potential alte rnative therapy In the treatment of bone loss and lipid metabolism abnormal ity in ovarian hormone-deficient women.