A naturally occurring metabolite of HISTIDINE that has antioxidant properties.

Synonyms: Ergothioneine, 1H-Imidazole-4-ethanaminium, alpha-carboxy-2,3-dihydro-N,N,N-trimethyl-2-thioxo-, inner salt, (S)-, BDZ3DQM98W, 2 Thiol L histidine betaine, Thioneine, 2-Thiol-L-histidine-betaine