Antioxidant and cytotoxic effects of isolated polysaccharides from cultured Ophiocordyceps sinensis

Abstract

The Ophiocordyceps sinensis is well-known as a traditionally valued medicine. Recently, the cultured O. sinensis biomass have been producing and commercializing in Vietnam. Besides, the O. sinensis - isolated polysaccharides have been revealed possessing great biological activities, especially the potential antioxidant. Hence, this study focused on antioxidant activity and cytotoxicity of polysaccharides isolated from cultured O. sinensis biomass.Methods: Firstly, crude polysaccharides (PS) including IPS (endo-polysaccharide extracted from biomass) and EPS (exo-polysaccharide extracted from broth) were isolated from O. sinensis, respectively. Then, the crude IPS and EPS were separated into fractions using a Sephadex G-200 column with a flow rate of 0.6 ml/min. The PSs and their fractions including IPS-1, IPS-2 and EPS-1, EPS-2 were screened for antioxidant (ABTS·+ free radical scavenging assay) and cytotoxic (HepG2 assay) activites.Results: Both EPSs and IPSs were mixtures of peptide-polysaccharide. In the ABTS assay, the IC50 value of EPS and EPS-2 fractions were 2,688.80 ± 19.83 µg/ml and 1,885.90 ± 2.90 µg/ml, respectively. This result indicated that the antioxidant activity of EPS and EPS-2 fractions were higher than that of IPSs as well as EPS-1 fraction. Furthermore, only crude EPS exhibited HepG2 cell growth inhibitory ability (IC50 = 15.59 ± 0.17 µg/ml) among the samples. Taken together, the EPSs exhibited greater antioxidant and cytotoxic activity than the IPSs. Thus, the EPSs could be considered as an antioxidant source.