Antioxidant activity of the species Agrocybe aegerita in relation to total phenolic (flavonoid) content

Abstract

In the last couple decades inedible polypore fungal species became of great importance as sources of new natural bioactive substances expressing various medical effects: antioxidative, anticancer, antimicrobial, and others. Recently, some edible mushroom species were also detected for their high bioactive potentials which are mostly influenced by the origin of the species. The species Agrocybe aegerita (Brig.) Sing., (syn. Agrocybe cylindracea, syn. Pholiota aegerita) is an edible, medium-size species broadly distributed in our region, mostly on poplar wood (lignicolous species). It is white-rot fungi containing many bioactive metabolites such as indole derivatives with free radical cavenging activity, cylindan with anticancer activity and agrocybenine with antifungal activity. Aiming to discover antioxidative activity of this indigenous fungal species, crude ethanolic extract from wildgrowing species originated from Novi Sad (Serbia) was analyzed for DPPH free radical scavenging capacity (RSC) and total redox potential (FRAP assay)-in relation to total phenol (Folin-Ciocalteu assay) and total flavonoid content. RSC and total redox potential of extracts were in direct positive correlation with total phenol content. A. aegerita showed excellent RSC activity reaching EC50≈28.88μg/ml in DPPH assay, the total phenol content (21.58±5.70 mg gallic acid equivalents/g of d.w.) and total flavonoid content (0.84±0.16 mg equivalent of quercetine/g d.w) and the FRAP value (13.47±2.64 mg ascorbic acid eq. mg/gd.w.). The HPLC determination showed that analyzed species contain caffeic, gallic, protocatechic and vanilic acids. Demonstrated results suggest that analyzed fungus contain phenolics that directly contribute to expressed activities and could be valuable sources of natural antioxidants in nutrition.