Abstract:

Total polysaccharides extracted from seedlings of Dendrobium huoshanense C.Z. Tang et S.J. Cheng were subjected to a sequential precipitation with ethanol at 40%, 50%, 60% and 80% to obtain four fractions of S1, S2, S3 and S4. The antioxidant activities of both the total polysaccharides and four polysaccharide fractions were evaluated in vitro by radical scavenging assay such as O2·, H2O2 and ·OH, reducing power, anti-lipid peroxidation induced by Fe2+-VC and anti-erythrocyte hemolysis induced by H2O2 assays. The four fractions exhibited different antioxidant activities, and among them fraction S1 with the highest relative molecular mass had the strongest scavenging activities to H2O2 and ·OH radicals with IC50 values of 0.15 mg/ml and 1.81 mg/ml, respectively and the highest reducing power and anti-lipid peroxidation induced by Fe2+-VC which reached 0.312 at 1 mg/ml and 45.67% at 0.5 mg/ml, respectively. The results showed that the antioxidant potential of polysaccharides from Dendrobium huoshanense is presumably related to their relative molecular mass.

Key words: Dendrobium huoshanense, polysaccharides, molecular mass, in vitro antioxidant activity