Extraction, purification and anti-osteoporotic activity of a polysaccharide from Epimedium brevicornum Maxim. in vitro

Osteoporosis is the most widespread metabolic bone disease characterized by decreased bone mass and bone quality, and its diagnosis and treatment remains challenging. To date, medicinal plants have received increasing attention from researchers for researching effective and less toxic therapeutic ingredients, including polysaccharide, to treat osteoporosis. The present study aims to evaluate the osteoprotective effects of a polysaccharide (EBP) from Epimedium brevicornum in glucocorticoid-induced osteoporosis in vitro and investigate the underlying mechanism. EBP (25 and 100 μg/ml) pretreatment could significantly prevent decreased cell proliferation of osteoblasts (OBs) treated only with 100 μM of dexamethasone (Dex) via induction of apoptosis. The osteoblastic differentiation of EBP pretreatment on OBs at early and later phase was further confirmed by the increased alkaline phosphatase (ALP) activity and calcium content, respectively. Meanwhile, the increased expression of cleaved caspase-3 and Bax, as well as a decrease of Bcl-2 and the phosphorylation of PI3K, Akt and mTOR protein in Dex-treated OBs were totally reversed by EBP pretreatment. Moreover, the protein expression of Lrp-5, β-catenin, Runx2 and Osx were significantly up-regulated in the presence of EBP pretreatment. In conclusion, these results demonstrated that EBP pretreatment may be a potential therapeutic agent for patients with glucocorticoid-induced osteoporosis (GIO).