Biochanin A stimulates osteoblastic differentiation and inhibits hydrogen peroxide-induced production of inflammatory mediators in MC3T3-E1 cells

Phytoestrogens are plant chemicals that are structurally analogous to estrogen and are known to affect estrogenic activity. Biochanin A, a naturally occurring isoflavone, has been identified and detected in various diets and plant species. We examined the effects of biochanin A on the differentiation of osteoblastic MC3T3-E1 cells and the production of local factors in osteoblasts. Biochanin A (1-50 mu m) caused a significant elevation of cell growth, alkaline phosphatase (ALP) activity, collagen content, and osteocalcin secretion in osteoblastic MC3T3-E1 cells (p < 0.05). The effect of biochanin A (10 mu m) in increasing ALP activity and collagen content was completely prevented by the presence of 10(-6) M cycloheximide and 10-6 M tamoxifen, suggesting that biochanin A's effect results from a newly synthesized protein component and might be partly involved in estrogen action. We then examined the effect of biochanin A on the H2O2-induced production of inflammatory mediators in osteoblasts. Biochanin A (1-10 mu m) decreased the 0.2 mm H2O2-induced production of TNF-alpha, IL-6 and NO in osteoblasts. These results suggest that biochanin A may be useful as potential phytoestrogens, which play important physiological roles in the prevention of postmenopausal osteoporosis.