Mushrooms: A rich source of the antioxidants ergothioneine and glutathione

•Glutathione levels varied >20-fold in different mushroom varieties and were highly correlated with ergothioneine levels.•Glutathione content of some mushroom species were higher than those previously found in other foods.•Mushroom species high in glutathione and ergothioneine are an excellent dietary antioxidant source.

While mushrooms are the highest dietary source for the unique sulfur-containing antioxidant ergothioneine, little is known regarding levels of the major biological antioxidant glutathione. Thus, our objectives were to determine and compare levels of glutathione, as well as ergothioneine, in different species of mushrooms. Glutathione levels varied >20-fold (0.11-2.41 mg/g dw) with some varieties having higher levels than reported for other foods. Ergothioneine levels also varied widely (0.15-7.27 mg/g dw) and were highly correlated with those of glutathione (r = 0.62, P < 0.001). Both antioxidants were more concentrated in pileus than stipe tissues in selected mushrooms species. Agaricus bisporus harvested during the third cropping flush contained higher levels of ergothioneine and glutathione compared to the first flush, possibly as a response to increased oxidative stress. This study demonstrated that certain mushroom species are high in glutathione and ergothioneine and should be considered an excellent dietary source of these important antioxidants.