Osteoporosis is characterized by a reduced bone mass, which results in increased bone fragility and fracture risk. Many osteoporotic patients have already lost a substantial amount of bone; therefore, a method of increasing bone mass by stimulating new bone formation is required. Bone is composed of mineralized organic matrix and bone cells. Osteoblasts are the active mature bone cells that synthesize the organic matrix and regulate its mineralization. Accelerated osteoblast growth and protein synthesis are the key factors for efficient bone repair. 1) Hormones, which regulate the calcium balance in the body, are used for the treatment of osteoporosis. The main action mechanism of these agents is the inhibition of bone resorption. However, a substance that inhibits bone resorption while stimulating bone formation would be more suitable for the treatment of bone diseases. There are several reports demonstrating improvement in clinical association with the use of traditional medicines in the treatment of fractures.2) Despite encouraging preliminary reports, basic sciences and clinical reports justifying the clinical application of specific traditional medicines are still not well established.Many plant-derived substances have been used as drugs for the treatment of various diseases since ancient times, and traditional oriental therapies are rich in phytotherapeutic regimens. These medications have fewer side effects and are more suitable for long-term use as compared to chemically synthesized medications. Plants belonging to the family Magnoliaceae are well known as rich sources of phenyl derivatives type neolignan and biphenyl ethers, which showed antimicrobial, muscle-relaxant, antifungal and cytotoxic activities.3-5) Manglietia phuthoensis DANDY (Magnolia phuthoensis DANDY), belonging to Magnoliaceae family, are woody trees distributed in northern Vietnam. In Vietnamese traditional medicine, the plant is used as an anti-inflammatory agent.6) Up to date, no study on phytochemistry and bioactivities of this plant has been reported.We report herein on the isolation and structural elucidation of two new phenyl glycosides, mangliesides A and B (1, 2), a new ionol glycoside, manglieside C (3), two new lignan glycosides, mangliesides D and E (4, 5), and two known compounds as 3-methoxymagnolol (6) and obovatol (7) from the leaves of M. phuthoensis. In an attempt to find pure lead compounds from plant origins to prevent bone loss without serious adverse side effects, we examined the effect of isolated compounds on the function of osteoblastic MC3T3-E1 cells, which has been well-characterized as an in vitro model for osteoblast differentiation.
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Results and DiscussionsManglieside A (1) was isolated as a white amorphous powder, its molecular formula was suggested as C 15 A and B (1, 2), a new ionol glycoside, manglieside C (3), two new lignan glycosides, mangliesides D and E (4, 5), were isolated from the leaves of Manglietia phuthoensis, along with two known lignans, 3-methoxymagnolol (6) and obovatol (7). Their struc...
