Antioxidant Chinese yam polysaccharides and its pro-proliferative effect on endometrial epithelial cells.

Chinese yam polysaccharide (CYP) was successfully isolated from the rhizoma of Dioscorea opposita and its chemical characteristics were determined. Antioxidant and pro-proliferative activity of CYP on human endometrial epithelial cells in vitro were investigated. Role of CYP on cell proliferation was also evaluated by examining pro-apoptotic and anti-apoptotic proteins Bax and Bcl-2 by Western blot analysis. Chemical composition analysis indicated that CYP was mainly composed of mannose, glucose, galactose and glucuronic acid in the ratio of 0.5:1.2:0.3:0.3. In vitro, CYP exhibited a potent scavenging activity on the DPPH radical, hydroxyl radical and superoxide radical. Furthermore, CYP apparently promoted the proliferation of human endometrial epithelial cells, especially beyond the concentration of 100 μg/ml after 36 h exposure. Western blot revealed that the anti-apoptotic protein Bcl-2 was upregulated after endometrial epithelial cells were treated with CYP, while the protein level of Bax was attenuated, thus leading to the downregulation of Bax/Bcl-2 ratio. Our findings provide the first evidence that CYP may prove to be a potential candidate of the natural antioxidants as a therapeutic agent for female infertility.