Extraction of water-soluble polysaccharide and the antioxidant activity from Ginkgo biloba leaves

Water-soluble polysaccharide was isolated from Ginkgo biloba leaves with the method of water-dissolving and ethanol-precipitating. The optimized condition for polysaccharide by orthogonal experiment was water to sample as 30:1 (v/w), at 80A degrees C for 3.5 h. Under the condition the finally dried extract was 9.025%, and the content of polysaccharide was 20.9% in the extract and 1.887% in the leaves. The antioxidant activities of the extract were investigated. The scavenging rates of the present extract on hydroxyl, DPPH, and superoxide radicals were 64.05, 17.62, and 11.8%, at polysaccharide concentrations of 4.18, 8.36, and 4.18 mu g/ml, whereas with vitamin C at similar concentrations with polysaccharide, the scavenging rates were 9.15, 5.76, and 5.72%, respectively.