Osteoprotective Effect of Phytoestrogen Rich Fraction of Ochna schweinfurthiana Stembark Extract on Ovariectomized Animal Model of Menopause

Abstract

Osteoporosis is one of the major disease conditions associated with estrogen deficiency in postmenopausal women. This study evaluated the osteoprotective effect of phytoestrogen rich fraction (PERF) of O. schweinfurthiana back extract on ovariectomized animal model of menopause. The methanol plant extract was partitioned into n-hexane, ethyl acetate, butanol and water fraction using liquid-liquid fractionation. The phytoestrogens in the fractions were quantified using genistein as standard. Ovariectomy induced osteoporosis was achieved by surgical removal of the ovaries. Body weight changes, relative uterine weight, serum estradiol, bone turnover markers (Alkaline phosphatase -ALP and Acid Phosphatase -ACP), bone mineral content and density as well as lipid peroxidation assays were used to establish ability of ovariectomy to induce osteoporosis and dose response effect of the PERF. Water fraction showed the highest content of phytoestrogen which was more than 10 fold higher than the content of other fractions. Ovariectomy induced weight gain was significantly (P<0.05) lowered by PERF compared to vehicle control. Significant (P<0.05) increase in serum estradiol following treatment with PERF produced corresponding uterotrophic effect with median effective dose (ED50) of 197 mg/kg. osteoprotective effect of PERF was evident from the significant (P<0.05) increases in both bone mineral content and density which corresponded with reduction in bone turnover markers. Ovariectomy induced oxidative stress was reduced by PERF with ED50 of 716 mg/kg. O. schweinfurthiana exhibited osteoprotective effect that may have been mediated by downstream signaling effects through estrogen receptor.