In search of a physiological function for L-ergothioneine--II

Recently a number of possible functions for ergothioneine (ERT) have been suggested (1). This paper elaborates on some of these in light of overlooked or recent publications and presents additional hypotheses including: 1. Reduced ERT (ergothionol) may be an acyl carrier. 2. ERT, in conjunction with thyroid hormone and iodine, may be a cofactor in peroxidative and oxidative reactions. 3. ERT and thyroid hormone may be required for the oxidation of reduced pyridine nucleotides and the coupling of this to oxygen consumption (respiration) and ATP generation/ATPase action (heat production). 4. ERT may be required for both gene expression and repair. 5. 2-Thioimidazoles (ERT and 2-thiourocanic acid in particular) may be immunoregulatory. 6. ERT may be involved in the protection from oxidation (inactivation) of methionine and methionine containing chemoattractants, hormones, tRNA, etc. Some future research activities are suggested.