Extract from wild strain of mushroom Ganoderma lucidum as natural antioxidant

Recently, much attention has been paid to revealing natural biomaterials for clinical purposes since use of synthetic antioxidants is restricted due to their carcinogenicity. Among various natural antioxidants, polysaccharides, in general, have strong antioxidant activities and can be explored as novel potential antioxidants. The aim of this work was to examine the antioxidant properties of hot water extracted polysaccharides from Ganoderma lucidum in the form of mature fruit bodies, collected from the Bojčinska forest near Belgrade, the Republic of Serbia. Antioxidant properties were assayed in vitro, by the conjugated diene method, reducing power, scavenging abilities against 1.1-diphenyl-2-picrylhydrazyl (DPPH) radicals and chelating ability on ferrous ions. At concentrations of 1 mg/ml, the scavenging ability of G. lucidum polysaccharide extract on DPPH radicals was 74.7 %. At 1 mg/ml, the radical scavenging ability of the positive controls BHT, ascorbic acid and α-tocopherol were 11.5, 77.1 and 79.4 %, respectively. The antioxidant activity of the polysaccharide extract increased as the concentration increased to 78.0% at 20 mg/ml. Antioxidant activities of ascorbic acid and α-tocopherol were 63.8 % and 65.4% at 20 mg/ml. Polysaccharide extract from G. lucidum showed steady increase in the reducing activity as concentrations increased to 2.9 at 20 mg/ml. Ascorbic acid, used as a positive control, had a reducing power of 3.9 at 5 mg/ml. Chelating effects of the polysaccharide extract on ferrous ion increased with the increased concentrations. At 0.1-20 mg/ml, the chelating ability of G. lucidum polysaccharide extract was between 10.3-87.8%. The chelating effect of the synthetic metal chelator EDTA was 100% at 0.1-20 mg/ml, while citric acid did not prove to be good chelating agent for ferrous ions in this assay since its chelating ability was 10.3% at 20 mg/ml.