Promotion of Osteogenesis by Sweroside via BMP-2 Related Signaling in Postmenopausal Osteoporosis

Phlomis umbrosa has been traditionally used for bone diseases such as bone fracture and rheumatism in traditional Korea Medicine. Sweroside (SOS), which is one of the active compounds of P. umbrosa , has been known to promote osteoblast differentiation. In this study, ameliorative effects of SOS on osteoporosis and potential target pathway were investigated. Ovariectomized mice were administered 3 doses of SOS for 4 weeks after inducing osteoporosis. Bone mineral content (BMC) and bone mineral density (BMD) were analyzed by dual energy X-ray absorptiometry. SaOS-2 osteoblasts were differentiated to clarify the promoting effects of SOS on osteoblast differentiation and bone formation. Osteoblastic bone-forming markers were evaluated by RT-PCR in lumbar vertebrae (LV) and mineralized SaOS-2 cells. Treatment of SOS increased BMC and BMD levels. SOS markedly attenuated the bone marrow adipocytes in the central bone cavity of the femoral shaft. SOS increased the formation of bone matrix in SaOS-2 cells. BMP-2 and RUNX2 in LV and SaOS-2 cells were up-regulated by treating with SOS. BMP-2/RUNX2-activated ALP, OPN and BSP-1 expressions were increased by SOS. In conclusion, SOS induced the formation of mineralized bone matrix by regulating BMP-2/RUNX2-mediated osteoblastic molecules. Therefore, SOS could be a therapeutic active compound of treatment for osteoporosis by producing the new bone matrix.