Ergothioneine is a naturally occurring amino acid and is a thiourea derivative of histidine, containing a sulfur atom on the imidazole ring.[1] This compound occurs in relatively few organisms, notably actinomycetota, cyanobacteria, and certain fungi.[2][3] Ergothioneine was discovered in 1909 and named after the ergot fungus from which it was first purified,[4] with its structure being determined in 1911.[5]
In humans, ergothioneine is acquired exclusively through the diet and accumulates in erythrocytes, bone marrow, liver, kidney, seminal fluid, and eyes.[6] Although the effect of ergothioneine in vivo is under preliminary research, its physiological role in humans is unknown.[6] Ergothioneine is sold as a dietary supplement.[7]