Abstract:

Polysaccharides were isolated from seeds of Plantago asiatica L. by water extraction and ethanol precipitation, and then subjected to protein removal by Sevag method and purification using gel permeation chromatography on SephacrylTM S- 400HR column. Extraction conditions were optimized by orthogonal design and response surface methodology on the basis of extraction rate of polysaccharides. Three fractions were obtained and named as PLCP-1, PLCP-2 and PLCP-3. Results showed that PLCP-2 (also named as PLP) was a kind of homogeneous polysaccharides with molecular weight of 1849268 Da determined by high performance gel permeation chromatography. The contents of polysaccharides and protein were 87.32% and 1.16%, respectively; while the content of uronic acid was 14.66%. The optimal extraction conditions were extraction temperature of 99℃, material-liquid ratio of 1:30 (g/mL) and extraction time of 5.45 h. Under these optimal extraction conditions, the extraction rate of polysaccharides from Plantago asiatica L. was 13.79%, which was in agreement with the predicted value. This optimal extraction conditions are economic, simple and feasible, and also provide a theoretical reference for industrial preparation of polysaccharides from seeds of Plantago asiatica L..

Key words: Plantago asiatica L., purification, physico-chemical properties, response surface methodology