Effect of polyphenols on calcium content and alkaline phosphatase activity in rat femoral tissues in vitro

The effect of various polyphenols on calcium content and alkaline phosphatase activity in the femoral-diaphyseal and -metaphyseal tissues of young rats in vitro was investigated. Bone tissues were cultured for 24 h in serum-free Dulbecco's modified Eagle's medium containing either vehicle or various polyphenols (10(-7)-10(-4) M). The presence of genistein (10(-6)-10(-4) M) caused a significant increase in calcium content and alkaline phosphatase activity in the femoral-diaphyseal and -metaphyseal tissues. Resveratrol (10(-4) M) decreased metaphyseal calcium content significantly, and it (10(-6)-10(-4) M) had a significant inhibitory effect on diaphyseal enzyme activity. Epigallocatechin gallate (EGCg; 10(-4) M) Significantly inhibited alkaline phosphatase activity in the diaphyseal and metaphyseal tissues. EGCg (10(-7)-10(-4) M) had no effect on bone calcium content. Meanwhile, glycitein, quercetin, or catechin in the range of 10(-7) to 10(-4) M did not have an effect on calcium content and alkaline phosphatase activity in the femoral-diaphyseal and -metaphyseal tissues. The present study suggests that a phytoestrogen genistein has a unique anabolic effect on bone calcification in vitro.