Objective:To study the antioxidant activity and anticancer activity of tea polysaccharide.Methods:Tea polysaccharide was extracted and purified by gel permeation chromatography from coarse old green tea leaves obtained from Wuyuan county of Jiangxi province in China.The antioxidant activity of the tea polysaccharide was evaluated by determining the change in absorbancy after heat-induced oxidation in a linoleic acid system with ?-carotene,the decoloration of the 1,1-diphenyl-2-picrylhydrazyl and the elimination of superoxide generated from autoxidation of pyrogallol.On the other hand,the anticancer activities of tea polysaccharide at different concentrations were evaluated by MTT assay using two colon cancer cell lines(HCT-15,Caco-2).Results:Tea polysaccharide possessed distinctive antioxidative activity.The anti-proliferation capabilities of the tea polysaccharide against the tested human colon cancer cell lines were different under the designed experiment conditions.The tea polysaccharide with high purity exhibited good anti-proliferation activity against HCT-15 at concentration of 7.0?mol/L.Conclusion : Tea polysaccharide has remarkable antioxidative and anticancer bioactivities..

Objective To study the application of the genetic algorithm with two populations in optimization of both IMRT beam weight and orientation.Methods The genetic algorithm with two populations was used to optimize IMRT beam weight and orientations with three dimensional pencil beam dose calculation model. The algorithm was implemented in Visual c#. Net. And the results were analyzed. Results The modest change of the beam orientation resulted in more conformal dose distribution in target volume, and large high dose area was included. Further more, genetic algorithm with two populations gave such a clinically acceptable computation time. Conclusion Little change had distinct influence on dose distribution when there were few beam orientations. The genetic algorithm with two populations was an effective and global optimization method because of its parallel, robust and global. It provided satisfying results when used to optimize IMRT beam weight and orientations