Two acidic polysaccharides (MDP-A1 and MDP-A2) were isolated from the rhizome of Menispermum dauricum and their apparent molecular weight are 9.1×10(4) and 5.8×10(4) Da, respectively. Both contained glucose, mannose, galactose, arabinose, glucuronic acid and galacturonic acid, but differed in the molar ratio. We also investigated the antitumor activities and mechanisms of MDP-A1 and MDP-A2 in human ovarian carcinoma SKOV3 cells. The MTT assay showed that MDP-A1 and MDP-A2 were able to inhibit cell proliferation of SKOV3 cells in a bell-shaped concentration-response manner, due to a significant increase in the number of apoptotic cells. Furthermore, treatment with MDP-A1 or MDP-A2 caused significant induction of caspase-3 and caspase-8, but slightly affected caspase-9 activity. In addition, a significant reduction in tumor volume was observed in mice treated with MDP-A1 or MDP-A2. Taken together, these results suggested that MDP-A1 and MDP-A2 had a potential application as natural antitumor drugs.
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