An intermediate in the formation of L-egothioneine, a natural amino acid ubiquitously present in cells and tissues of most plants and mammalian species. In humans, L-ergothioneine is found in red blood cells, liver, kidney, brain, seminal fluid, and cataract-free lenses at concentrations ranging from 100 uM to 2 mM. L-ergothioneine is exclusively biosynthesized in fungi and mycobacteria. Hence, humans assimilate it through dietary intake.L-ergothioneine has been proven to act as an antioxidant in vivo and to afford protection from g and UV radiation as well as from singlet oxygen in vivo. Recently, it has been shown that L-ergothioneine protects isolated perfused heart against the deleterious effect of post-ischemic reperfusion.The intermediate, 2-mercaptohistine has been used for the
