Emodin stimulates the osteoblast differentiation via activating bone morphogenetic protein-2 gene expression at low concentration

Emodin is one of the main active components of a traditional Korean medicine isolated from the root and rhizomes of Rheum palmatum L. In this study, of 222 natural compounds to evaluate the anabolic activities, emodin activated bone morphogenetic protein (BMP)-2 promoter in the differentiation process of mouse osteoblastic MC3T3-E1 cells. Emodin was shown to significantly stimulate the activity and expression of alkaline phosphatase, an earlyphase marker of osteoblastic differentiation, on the differentiation day 7, and induce the osteopontin mRNA expression from the differentiation day 14. In addition, low concentration (up to 5 M) of emodin dramatically promoted the induction of mineralization in MC3T3-E1 subclone 4 cells. The stimulatory effect of emodin on the osteoblast differentiation/mineralization could be associated with its potential to stimulate the BMP-2 gene expression. Although further studies are needed to determine the precise mechanism, this study suggests that the use of herbal medicine containing natural compounds with anabolic activity such as emodin could have a beneficial effect on bone health.