Structure elucidation, anticancer and antioxidant activities of a novel polysaccharide from Gomphus clavatus Gray

A novel heteropolysaccharide from the fruiting bodies of Gomphus clavatus Gray was isolated through Sephadex G-200 and DEAR-cellulose columns. The Gomphus clavatus Gray polysaccharide (GCG-1) was mainly composed of beta-D-glucosepyranose (beta-D-Glu) and a-D-galactopyranose (alpha-D-Gal) in a ratio of 3:2 and had a molecular weight of similar to 50,000 Da. The structure of GCG-1 was investigated by a combination of total hydrolysis, gas chromatography-mass spectrometry, methylation analysis, nuclear magnetic resonance spectroscopy and infrared spectra. The results indicated that GCG-1 had a backbone of (1-4)-beta-D-glucosepyranose residues with branches at 0-6 and the branches consisted of two with (1 -> 3)-alpha-D-galactopyranose residue. Antioxidation test in vitro showed that it possessed-strong free radical scavenging activity, which may be comparable to vitamin C and butylated hydroxytoluene. GCG-1 also induced the apoptosis of HepG-2 cells and affected the mRNA expression of various housekeeping genes in the HepG-2 cells. The results indicated that Gomphus clavatus Gray may be an ideal sources for antioxidant and anticancer agents.