Ergothioneine

Ergothioneine is an L-histidine derivative, specifically N(alpha),N(alpha),N(alpha)-trimethyl-L-histidine with the hydrogen at position 2 of the imidazole ring replaced by a mercapto group. It is a naturally occurring metabolite of histidine, synthesized by bacteria and fungi, and possesses antioxidant properties. Found ubiquitously in plants and animals, it is present in many human foodstuffs. It functions as an antioxidant, fungal metabolite, plant metabolite, xenobiotic metabolite, and chelator. Ergothioneine is an amino-acid betaine, a sulfur-containing amino acid, and a L-histidine derivative. It is the conjugate base of ergothioneine(1+) and a tautomer of the ergothioneine thione form.