20( R)-Ginsenoside Rh2, not 20( S), is a selective osteoclastgenesis inhibitor without any cytotoxicity

Ginsenoside 20( R)-Rh2 and ginsenoside 20( S)-Rh2 showed a significant inhibitory effect on osteoclast differentiation. Only ginsenoside 20( R)-Rh2 showed no cytotoxicity to osteoclast proliferation. 20( R)-Hydroxylation of the aliphatic side chain of Rh2 could be the main target in producing anti-osteoclast agent. Increased osteoclastic bone resorption plays a central role in the pathogenesis of many bone diseases, and osteoclast inhibitors are the most widely used treatments for these diseases. Ginsenosides, the main component of ginseng, have been known for their medicinal effects such as anti-inflammatory and anti-proliferative activities. In this study, we investigated the inhibitory effects of ginsenosides (ginsenoside 20( R)-Rh2 and ginsenoside 20( S)-Rh2) on osteoclastgenesis using RAW264 cells in vitro. Only ginsenoside 20( R)-Rh2 showed selective osteoclastgenesis inhibitory activity without any cytotoxicity up to 100 μM. These results implied that the stereochemistry of the hydroxyl group at C-20 may play an important role in selective osteoclastgenesis inhibitory activity.