Effects of veraguensin and galgravin on osteoclast differentiation and function.

The dried flower buds of Magnolia sp. are widely used as herbal medicines because of their anti-inflammatory, anti-malarial and anti-platelet activities. Here, we found that veraguensin and galgravin, lignan compounds derived from Magnolia sp., dose-dependently inhibited osteoclast formation in co-cultures of bone marrow cells and osteoblastic cells. These compounds also inhibited receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation in RAW264.7 cells and bone marrow macrophages. In the RANKL-induced signaling pathway, veraguensin and galgravin reduced p38 phosphorylation and suppressed the expression of c-Fos, a key transcription factor for osteoclastogenesis. Veraguensin and galgravin also inhibited osteoclastic pit formation, which was accompanied by decreased mature osteoclast viability. In conclusion, these results indicate that veraguensin and galgravin can inhibit bone resorption and may offer novel compounds for the development of drugs to treat bone-destructive diseases such as osteoporosis.