Abstract: Extraction and scavenging capacity of hydroxyl radical polysaccharide from Polygonum multiflorum Thunb were studied in this paper. The factors affecting the extraction of polysaccharide were investigated. Based on the single factors test, factors such as material to solvent ratio, extracting temperature and extracting time were optimized by orthogonal test. The optimum results are: material to ratio 1:12, temperature 84 ℃ and time 105 min. On these conditions the polysaccharides yield is up to 19.14%. The experimental results demonstrated that polysaccharide can scavenge hydroxyl radical, and IC50 is 0.27 mg/ml.

Key words: Polygonum multiflorum Thunb, polysaccharide, hydroxyl radical