Daidzein, a natural isoflavonoid found in Leguminosae, has received increasing attention because of its possible role in the prevention of
osteoporosis. In the present investigation, primary osteoblastic cells isolated from newborn Wistar rats were used to investigate the effect of this isoflavonoid on osteoblasts.
Daidzein (2-50 microM) increased the viability (P<0.05) of osteoblasts by about 1.4-fold. In addition,
daidzein (2-100 microM) increased the
alkaline phosphatase activity and
osteocalcin synthesis (P<0.05) of osteoblasts by about 1.4- and 2.0-fold, respectively.
Alkaline phosphatase and
osteocalcin are phenotypic markers for early-stage differentiated osteoblasts and terminally differentiated osteoblasts, respectively. Our results indicated that
daidzein stimulated osteoblast differentiation at various stages (from osteoprogenitors to terminally differentiated osteoblasts). We also investigated the effect of
daidzein on
bone morphogenetic protein (BMP) production in osteoblasts that display the mature osteoblast phenotype. The results indicated that BMP2 synthesis was elevated significantly in response to
daidzein (the
mRNA increased 5.0-fold, and the
protein increased 7.0-fold), suggesting that some of the effects of
daidzein on the cell may be mediated by the increased production of BMPs by the osteoblasts. In conclusion,
daidzein has a direct stimulatory effect on bone formation in cultured osteoblastic cells in vitro, which may be mediated by increased production of BMPs in osteoblasts.