Abstract:

Crude polysaccharide from Dendrobium candidum (DSP) was successively fractionated with different concentration ethanol and three polysaccharides named DSP1, DSP2 and DSP3 were obtained at the concentrations of 90%, 70% and 40%, respectively. Subsequently, DSP and its three fractions were tested for antioxidant activity in vitro. Results showed that DSP1 had the strongest DPPH radical scavenging activity, total antioxidant activity, inhibition against Fe2+-VC-induced lipid peroxidation and inhibition against erythrocyte hemolysis induced by H2O2, DSP and DSP3 took the second place and DSP2. had the weakest biological activities. The hydroxyl radical scavenging capacity of these test samples followed the order of DSP > DSP3 > DSP1 > DSP2. In addition, all fractions of Dendrobium candidum polysaccharides showed potential for protecting against DNA damage mediated by hydroxyl radicals. These results suggested that polysaccharides from Dendrobium candidum had antioxidant potential, which might be closely associated with their molecule weight.

Key words: Dendrobium candidum, polysaccharide, free radical, antioxidant, relative molecular weight