Abstract:The exopolysaccharide（EPS）from Lactobacillus strains with the higher antiproliferative effect on colon cancer cell line HT-29 was screened from 15 strains of Lactobacillus plantarum provided by Dalian probiotic functional property key laboratory in Dalian Polytechnical University.Lactobacillus strains with higher exopolysaccharide yield was selected by using phenol sulfuric acid method，and the antiproliferative effects of EPS on HT-29 cells were determined by 3-（4，5-dimethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2-（4-sulfophenyl）-2H-tetrazolium （MTS）method.The results showed that L.plantarum 12 had the highest EPS yield and the EPS showed the higher antiproliferative effect among the 15 strains.The carbohydrate content of the crude L.plantarum 12 EPS was 54%and the protein content was 3.6%.The crude EPS of the L.plantarum 12 was separated and purified by DEAE-Sepharose Fast flow ion column and Sepharose CL-6B gel column，and two components were obtained，neutral polysaccharide fraction EPS12-1 and acidic polysaccharide group EPS12-2.The carbohydrate contents of the two components were 31.82%and 35.21%.The inhibiting rates on HT-29 cells of the crude EPS，EPS12-1 and EPS12-2 of L.plantarum 12 at the concentration of 250 μg/mL were 27.58%，7.11%and 12.00%respectively，higher than those at the concentrations of 50 μg/mL，100 μg/mL and 500 μg/mL，which was consistent with the higher apoptosis，reactive oxygen species（ROS）levels and caspase 8 activity of the HT-29 cells treated by EPS at the concentration of 250 μg/mL.L.plantarum12 EPS showed antiproliferative by increased ROS activity and activated caspase 8.