Although many species contain ergothioneine, only a few make it; the others absorb it from their diet or, in the case of plants, from their environment.[12] Biosynthesis has been detected in Actinomycetota, such as Mycobacterium smegmatis and certain fungi, such as Neurospora crassa.[2]
Ergothioneine is a thiourea derivative of the betaine of histidine and contains a sulfur atom bonded to the 2-position of the imidazole ring.[19] Typical of thioureas, ergothioneine is less reactive than typical thiols such as glutathione towards alkylating agents like maleimides. It also resists oxidation by air.[9] However, ergothioneine can be slowly oxidized over several days to the disulfide form in acidic solutions.[20]
Ergothioneine derivatives
Various derivatives of ergothioneine have been reported in the literature, such as S-methyl-ergothioneine[21] or selenium-containing selenoneine.[22]
Characteristics
Adaptogenic Antioxidant: Ergothioneine is an adaptogenic antioxidant that preferentially accumulates in cells and tissues exposed to oxidative stress and damage. The organic cation transporter OCTN1 (now known as SLC22A4, a transporter protein with 551 amino acids and three glycosylation sites) in the human body can transport ergothioneine to where it is needed.[23]
Regenerative Pathway: The human body has a regenerative pathway for ergothioneine. When ergothioneine combines with glutathione, it can regenerate, allowing it to react with singlet oxygen in a cyclical manner, achieving a more comprehensive and lasting antioxidant effect.
Slow Excretion: Ergothioneine is excreted very slowly in the body, allowing it to be highly retained in the tissues and red blood cells of humans and other animals, thereby maximizing its effectiveness.
Stable Form: Ergothioneine mainly exists in the form of thione, which has ideal thermal stability and pH stability.
Preliminary research
Although potential effects of ergothioneine are under preliminary research, its physiological role in vivo has not been determined.[1][7]
Safe intake levels
The Panel on Dietetic Products for the European Food Safety Authority reported safe daily limits of 2.82 mg/kg of body weight for infants, 3.39 mg/kg for small children, and 1.31 mg/kg for adults, including pregnant and breastfeeding women.[8]
^ ab"Ergothioneine". PubChem, National Center for Biotechnology Information, US National Library of Medicine. 2 November 2019. Retrieved 7 November 2019.
^Pfeiffer C, Bauer T, Surek B, Schömig E, Gründemann D (2011). "Cyanobacteria produce high levels of ergothioneine". Food Chemistry. 129 (4): 1766–1769. doi:10.1016/j.foodchem.2011.06.047.
^ abcdEy J, Schömig E, Taubert D (August 2007). "Dietary sources and antioxidant effects of ergothioneine". Journal of Agricultural and Food Chemistry. 55 (16): 6466–74. doi:10.1021/jf071328f. PMID17616140.
^Markova NG, Karaman-Jurukovska N, Dong KK, Damaghi N, Smiles KA, Yarosh DB (April 2009). "Skin cells and tissue are capable of using L-ergothioneine as an integral component of their antioxidant defense system". Free Radical Biology & Medicine. 46 (8): 1168–76. doi:10.1016/j.freeradbiomed.2009.01.021. PMID19439218.
^Seebeck FP (May 2010). "In vitro reconstitution of Mycobacterial ergothioneine biosynthesis". Journal of the American Chemical Society. 132 (19): 6632–3. doi:10.1021/ja101721e. PMID20420449.
^Bello MH, Barrera-Perez V, Morin D, Epstein L (February 2012). "The Neurospora crassa mutant NcΔEgt-1 identifies an ergothioneine biosynthetic gene and demonstrates that ergothioneine enhances conidial survival and protects against peroxide toxicity during conidial germination". Fungal Genetics and Biology. 49 (2): 160–72. doi:10.1016/j.fgb.2011.12.007. PMID22209968.