Antioxidant properties of phenolic compounds occurring in edible mushrooms

Total phenolic and flavonoid contents occurring in eight types of edible mushrooms (Agaricus bisporus, Boletus edulis, Calocybe gambosa, Cantharellus cibarius, Craterellus cornucopioides, Hygrophorus marzuolus, Lactarius deliciosus and Pleurotus ostreatus) have been respectively evaluated by the Folin–Ciocalteau assay and by the colorimetric reaction with NaNO2 and AlCl3 in a basic media. Generally, the assayed mushrooms contained between 1 and 6 mg of phenolics per gram of dried mushroom, depending on the species, while the flavonoid concentrations ranged between 0.9 and 3.0 mg per gram of dried matter. The profile and concentration of individual phenolics was determined by means of high performance liquid chromatography. Homogentisic acid was the free phenolic acid significantly present in all mushrooms although the content varied considerably among the analysed species. Flavonoids, such as myricetin and catechin were also detected in the mushrooms studied. The antioxidant properties of the methanolic extracts from mushrooms were evaluated by monitoring the linoleic acid autoxidation, and all the mushrooms species showed inhibition, with C. cibarius being the most effective against lipid oxidation (74% of inhibition) and A. bisporus the species with lowest antioxidant activity (10% of inhibition).