Osteoprotective effect of extract from Achyranthes bidentata in ovariectomized rats

A Chinese herbal drug, root of Achyranthes bidentata showed a potent inhibitory activity on bone resorption induced by parathyroid hormone (PTH) in a bone organ culture using neonatal mouse parietal bones. The present study is to clarify the fractions responsible for the activity and further explore the osteoprotective effect of the fraction in vivo.

The hexane, ethyl acetate (EtOAc), n-butanol (n-BuOH) and water soluble fractions of methanol extract of the root of Achyranthes bidentata were prepared and screened for their anti-bone resorption activity using the bone organ culture system. The n-BuOH soluble fraction was further administered orally at doses of 25, 50 and 100mg/(kgday) to ovariectomized (OVX) rats. The analyses of the rat body weight, serum estradiol (E2), total cholesterol and triglyceride levels, uteri weight and measurement of bone mineral density (BMD) were conducted.

The EtOAc and n-BuOH fractions showed the most potent inhibitory activity on PTH-induced bone resorption. Further research using OVX rat model revealed that the n-BuOH fraction significantly prevented BMD loss due to OVX operation. While, the uteri weight and serum estradiol (E2), total cholesterol and triglyceride levels displayed no differences compared with those of control group (OVX rats), suggesting the n-BuOH fraction should have no estrogen-like side effects.

The results reveal that the n-BuOH soluble fraction of the root of Achyranthes bidentata is effective at preventing bone loss in OVX rats and has a great potential as an alternative tool for the treatment of osteoporosis.