Inhibitory Effects of Water Extracts of Eucommiae Cortex and Psoraleae Semen Alone and in Combination on Osteoclast Differentiation and Bone

Objectives : The purpose of this study was to evaluate the effects of water extracts of Eucommiae cortex (EC), Psoraleae semen (PS), and their combination on receptor activator of nuclear factor-kappa-B ligand (RANKL)-induced osteoclast differentiation. Methods : We assayed the protein expression levels of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), c-Fos, mitogen-activated protein kinases (MAPKs), and ${\beta}-actin$ in cell lysates using western blotting. Similarly, mRNA expression levels of NFATc1, c-Fos, tartrateresistant acid phosphate (TRAP), and glyceraldehyde-3-phosphate dehydrogenase, spermatogeni (GAPDHS) from bone marrow macrophages (BMMs) were analyzed using reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, we determined the anti-osteoporotic effects of the water extracts of EC, PS, and their combination in a lipopolysaccharide (LPS)-induced bone-loss mouse model. Results : The in vitro data revealed showed that the combination of EC and PS extract showed a more remarkable inhibition of osteoclast differentiation than each herb did alone. The combination downregulated the induction of c-Fos, NFATc1, and TRAP by suppressing the phosphorylation of p38 and c-Jun N-terminal kinases (JNKs) and inhibiting nuclear factor kappa-light-chain-enhancer of activated B cells ($NF-{\kappa}B$). Lastly, the in vivo data showed that PS reduced the LPS-induced bone erosion. Conclusion : The result of this study suggests that EC and PS could be potential therapeutic agents for bone loss diseases such as osteoporosis.