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 blo
od 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.
