Free radical scavenging activity of antitumour polysaccharide fractions isolated from Ganoderma lucidum (Fr.) P. Karst

The study was conducted to investigate the free radical scavenging activities of polysaccharide fractions extracted from the fruiting body of medicinal mushroom, Ganoderma lucidum (Fr.) P. Karst (Reishi) using different antioxidant capacity assays. Four intracellular polysaccharide fractions were obtained by the hot-water extraction and precipitation with ethanol, by ammonium oxalate extraction and by extraction with sodium hydroxide (NaOH), followed by precipitation with acetic acid and precipitation with ethanol. The results revealed that out of four fractions, acetic acid-NaOH fraction exhibited potent antioxidant activity and effectively scavenged free radicals in a dose dependent manner from 50 to 250μg/ml followed by hot water fraction and ammonium oxalate fraction. However, ethanol-NaOH fraction showed least inhibition in all in vitro models. Thus, the antitumour activities of Reishi may be due to the antioxidants present in its polysaccharide fractions.