Antioxidative activities of the polysaccharides extracted from the mushroom Ganoderma lucidum

Dried carpophores of Ganoderma lucidum were exposed to the hot water extraction and alcohol precipitation to obtain polysaccharides, which were than refined by the dialyses. Dry polysaccharide extract (GL-I) was partially purified and used for the investigation of antioxidant properties. The antioxidant activity was determined by the conjugated diene method, ascorbic acid and α-tocopherol were used as the positive control. DPPH free radical scavenging activity assay was performed with ascorbic acid, BHT and α-tocopherol as the positive control. For determining reducing power ascorbic acid was used as the positive control. Chelating ability on ferrous ions was performed by addition of ferrozine to initialize reaction, while citric acid and EDTA were used for comparison. GL-I showed high antioxidant activity of 85.7 ± 0.7%, at 10 mg/ml. Reducing power reached a plateau of 3.4 ± 0.1 at 20 mg/ml, while GL-I chelated 81.6 ± 3.6 % of ferrous ions at 20 mg/ml. At 10 mg/ml, scavenging ability on DPPH radicals of GL-I increased to 96.8 ± 2.5%. The antioxidative activities of GL-I were concentration dependent and increased with increasing concentration. Regarding the fact that some of synthetic antioxidants, additives may possess mutagenic activity, using wild mushrooms in diet as sources of naturally-derived antioxidants might be beneficial for human health in reducing oxidative demage.