L-(+)-Ergothioneine

L-(+)-Ergothioneine: A Comprehensive Overview Introduction L-(+)-Ergothioneine (EGT) is a naturally occurring amino acid derivative that has garnered significant attention in recent years due to its unique antioxidant properties and potential health benefits. This sulfur-containing compound, also known as thioneine, was first discovered in 1909 by Charles Tanret in the ergot fungus (Claviceps purpurea). Since its discovery, EGT has been identified in various organisms, including bacteria, fungi, plants, and animals, highlighting its widespread biological significance. Humans cannot endogenously synthesize EGT and must obtain it through dietary sources, primarily mushrooms, which are considered the richest natural source of this compound. Chemical Structure and Properties EGT is classified as a betaine derivative of histidine, featuring a sulfur atom attached to the imidazole ring. Its chemical name is 2-mercaptohistidine trimethyl inner salt, with the molecular formula C9H15N3O2S and a molecular weight of 229.3 g/mol. The compound exists as a white crystalline solid at room temperature and is highly soluble in water, with a solubility of approximately 0.9 mol/L at 25°C. EGT exhibits remarkable stability under physiological conditions, maintaining its integrity across a wide pH range (pH 4-9) and demonstrating exceptional thermal stability with a decomposition temperature between 262-265°C. One of the most distinctive features of EGT is its ability to exist in two tautomeric forms: the thione form (S-form) and the thiol form (T-form). Under physiological conditions, the thione form predominates, which contributes to EGT's unique antioxidant properties. Unlike other thiol-containing antioxidants such as glutathione, EGT does not undergo autoxidation at physiological pH, making it a more stable and effective antioxidant agent.