Novel Osteoblastogenic Activity of Magnolia kobus: The Pharmacological Potential for Osteoporosis

Magnolia kobus (M. kobus) has long been used to treat nasal congestion, allergic rhinitis, and sinusitis. In the current study, we demonstrate the effects and underlying mechanisms of M. kobus flower water extract (ME) and ME-derived constituent magnolin on in vitro osteoblastogenic and anti-osteoclastogenic responses. Treatment with ME or magnolin markedly enhanced the osteoblast differentiation and mineralization in MC3T3-E1 pre-osteoblasts. This osteoblastogenic activity of ME or magnolin was closely associated with upregulation of osteoblast-specific molecules, including RUNX2, DLX5, OSX, alkaline phosphatase, collagen type I, and osteopontin, as well as the activation of mitogen-activated protein kinase (MAPK) signaling pathways. Concurrently, magnolin inhibited osteoclast differentiation through inactivating MAPK pathways and downregulating NFATc1, c-Fos, tartrate-resistant acid phosphatase, and cathepsin K in RANKL-treated RAW264.7 cells. These observations suggest that ME and magnolin have pharmacological potential for the treatment and prevention of metabolic bone disorders, including osteoporosis.