Antioxidant properties of several commercial mushrooms

Winter (strains white and yellow), shiitake (strains 271 and Tainting 1) and oyster mushrooms (abalone and tree oyster mushrooms) were obtained commercially and methanolic extracts were prepared from these mushrooms and their antioxidant properties were studied. The antioxidant activities by the 1,3-diethyl-2-thiobarbituric acid method were moderate to high at 1.2 mg ml(-1). Reducing powers were excellent (and higher than 1.28 absorbance) at 40 mg ml(-1). Scavenging effects on 1,1-diphenyl-2-picrylhydrazyl radicals were moderate to high (42.9-81.8%) at 6.4 mg ml(-1). With regards to the scavenging effect on hydroxyl free radicals, tree oyster mushrooms were the highest (54.3%) at 40 mg ml(-1) whereas other commercial mushrooms were low. Chelating effects on ferrous ions were 45.6-81.6% at 1.6 mg ml(-1). Total phenols were the major naturally occurring antioxidant components found. Overall, tree oyster mushrooms were better in antioxidant activity, reducing power and scavenging abilities and higher in total phenol content. (C) 2002 Elsevier Science Ltd. All rights reserved.