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

<i>Magnolia kobus</i> (<i>M. kobus</i>) has long been used to treat nasal congestion, allergic rhinitis, and sinusitis. In the current study, we demonstrate the effects and underlying mechanisms of <i>M. kobus</i> 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.