Kobophenol A enhances proliferation of human osteoblast-like cells with activation of the p38 pathway

Bone cell proliferation, bone formation, and bone resorption are the main factors involved in the homeostasis of the bone mass. Osteoblast death is a problem experienced by postmenopause women. Herbal medicines have attracted considerable attention for use as a drug or a drug substitute in the treatment of bone-related diseases, such as osteoporosis. This study investigated the effects of kobophenol A on the proliferation in human osteoblast cells. Kobophenol A stimulated the proliferation of osteoblast cells by the increases in DNA synthesis and the enhancement of cell cycle progression. Kobophenol A stimulation induced the expression of the cyclin B1 and cyclin-dependent kinase 1 (CDK1). Treatment of osteoblast cells with p38 MAPK inhibitor SB203580 significantly inhibited kobophenol A-enhanced proliferation. In addition, kobophenol A induced phosphorylation of p38 MAPK. Treatment of osteoblast cells with kobophenol A resulted in improvement of ROS scavenging activity. Moreover, kobophenol A treatment up-regulated the Bcl-2 level, but down-regulated the level of Bax expression. We also demonstrate that kobophenol A increased alkaline phosphatase (ALP) activity after 2 days. Taken together, the results of this study reveal that kobophenol A has proliferative effects and enhances ALP activity in osteoblast cells and these findings provide insights into the development of a therapeutic approach of kobophenol A in the prevention of osteoporosis and other bone disorders.