Dried root of Rehmannia glutinosa prevents bone loss in ovariectomized rats.

Dried root of Rehmannia glutinosa is a kidney-tonifying herbal medicine with a long history of safe use in traditional folk medicine for the treatment of joint diseases. This study was conducted to investigate prevention of bone loss by a standardized dried root of R. glutinosa in an ovariectomized (OVX) rat model of osteoporosis. The OVX groups were divided into five groups treated with distilled water, 17β-estradiol (E2 10 µg/kg, once daily, i.p) and dried root of R. glutinosa extracts (DRGE 30, 100, and 300 mg/kg, twice daily, p.o) for eight weeks. We measured the body, organs, and uterus weights, and femur and lumbar vertebrae bone mineral density (BMD), serum alkaline phosphatase (ALP), estradiol levels. The treatments with DRGE 300 mg/kg significantly inhibited BMD decrease in the femur and lumbar (17.5% and 16.4%, p < 0.05, respectively) by OVX without affecting the body, organs, and uterus weights. Also, serum ALP level in the DRGE 300 mg/kg treated group was significantly decreased, but the estradiol level did not change in serum of the DRGE 300 mg/kg treated group. These results show that DRGE is able to prevent OVX-induced bone loss without influencing hormones such as estrogen.