Submerged Culture of Grifola gargal and G. sordulenta (Higher Basidiomycetes) from Argentina as a Source of Mycelia with Antioxidant Activity.

Abstract

Submerged culture is an alternative mycelium source for Grifola gargal and G. sordulenta, two rare edible mushrooms related to Grifola frondosa. This work studies their mycelia as a source of antioxidants. The efficient concentrations of methanolic extracts in both radical scavenging (RS) and reducing power (RP) abilities in G. gargal and in G. sordulenta showed a high antioxidant activity. In the experimental design used, the antioxidant activity mainly depended on the culture conditions rather than on the media composition. Irrespective of the basal culture medium, mycelium methanolic extracts of G. sordulenta obtained from culture in Erlenmeyer flasks showed equivalents to ascorbic acid (EQ(AA)) RS-EQ(AA) and RP-EQ(AA) contents higher than the corresponding values obtained with jar cultures. Under stationary cultivation, G. sordulenta produced approximately 50% higher content in both RS-EQ(AA) and RP-EQ(AA) than the medicinal mushroom G. frondosa. Phenolics correlated with RS-EQ(AA) and RP-EQ(AA) in G. gargal and with RP-EQ(AA) in G. sordulenta; besides, thin-layer chromatography showed these compounds to be at least in part related to the RS capacity. It is concluded that G. gargal and G. sordulenta mycelia are excellent sources of antioxidant metabolites.