The effects of the soy
isoflavone glycoside,
daidzin,
genistin, and
glycitin on bone loss and lipid metabolism in ovariectomized (ovx) rats were compared with those of
estrone. Thirty-six 11-week-old female Sprague-Dawley rats were assigned to six groups,
sham-operated, ovx, ovx+glycitin, ovx+daidzin, ovx+genistin, and ovx+estrone and fed matched amounts of a commercial
calcium-deficient diet for 4 weeks. Throughout this period,
daidzin,
genistin or
glycitin (25, 50 or 100 mg/kg/d) was given orally using a stomach tube, or
estrone (7.5 microg/kg/d) was administered subcutaneously.
Daidzin,
genistin and
glycitin significantly prevented bone loss in ovx rats at a dose of 50 mg/kg/d, like
estrone. At this dose
glycitin and
daidzin also prevented ovx-induced uterine
atrophy and increases in
body weight gain, abdominal fat, serum total
cholesterol and
triglyceride, and urinary excretion of
pyridinoline and
deoxypyridinoline with statistical significance, like
estrone. On 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 dose of 50 or 100 mg/kg. These findings indicate that
daidzin,
glycitin, and
genistin are effective in preventing bone loss and the former two compounds are effective in reversing the unfavorable changes of lipid metabolism in this model. It is suggested that the preventive effect of
daidzin or
glycitin on bone loss in ovx rats is due to suppression of bone turnover, as in the case of
estrone, but
genistin has a different mechanism of action from the other compounds. Soy
isoflavone glycosides may represent a potential alternative
therapy in the treatment of bone loss and lipid metabolism abnormality in ovarian
hormone-deficient women.