Chemical and analytical screening of some edible mushrooms

Fractionation of extracts of the edible mushroom, Volvariella volvacea, led to the isolation of two heterocyclic carboxylic acids, namely pyridine-3-carboxylic acid [nicotinic acid, (5)] and pyrazole-3(5)-carboxylic acid (6) and the four steroidal metabolites ergosterol (1), 5-dihydroergosterol (2), ergosterol peroxide (3), cerevisterol (4). Significantly, compound (6) was identified for the first time, to our knowledge, in the mushroom kingdom and is of taxonomic significance. Compounds (2–4) were isolated for the first time from the Volvariella genus. In view of the structural similarity of compound (6) to pyrazole-3-carboxylic acids, which act as agonists for nicotinic acid receptors, the levels of compounds (5) and (6) were estimated for the first time using HPTLC in V. volvacea and two other edible mushrooms, namely Agaricus bisporus and Calocybe indica. Significant levels of compound (5) were found in C. indica, and compound (6) was found in abundance in A. bisporus. Correlations are suggested between the occurrence of these compounds in mushrooms and consumption as well as beneficial health effects of this food.