1 Free radical scavenging activity of some fungi indigenous to Tanzania

Abstract: The objective of this study was to evaluate free radical scavenging capacity of crude extracts from forest basidiomycetous fungi, domestic zygomycetous fungi and marine ascomycetous fungi. Lethal concentration values that kill 50 % of the brine shrimps (LC50) were determined from 19 fungal extracts using brine shrimp test (BST). The LC50 values of fungal extract ranged between 0.28– 40µg/ml. The basidiomycetous (Lactarius volemoides) was the most toxic fungi with LC50 of 0.28µg/ml while ascomycete Pichia guilliermondii showed the least toxicity with LC50 of 40µg/ml. The concentrations of eleven fungal extracts were further evaluated on their ability to scavenge free radical using 1-diphenyl-2-picrylhydrazyl (α,α-diphenyl-β-picrylhydrazyl) (DPPH) as a dye reagent for spectrophotometric assay at 517nm. The extract concentrations that decreased the initial DPPH radical by 50 % (EC50) were determined. The EC50 values ranged from 19–60.4µg/ml ascorbic acid equivalents. Extracts from an edible but undomesticated basidiomycetous fungus isolated from Miombo forest and identified as Termitomyces microcarpus showed the highest scavenging effect with EC50 at 19µg/ml while that from ascomycete Candida tropicalis showed the least EC50 at 60.4µg/ml. These results draw attention to wild undomesticated Miombo fungi as potential source of nutritional supplements worth further investigation