title: One-electron oxidation of ergothioneine and analogues investigated by pulse radiolysis: redox reaction involving ergothioneine and vitamin C.
abstract: Redox reactions of endogenous and exogenous sulphur-containing compounds are involved in protection against oxidative damage arising from the incidence and/or treatment of many diseases, including cancer. We have investigated, via pulse radiolysis, the one-electron oxidation of ergothioneine, a molecule with antioxidant properties which is detected at millimolar concentrations in certain tissues and fluids subject to oxidative stress, including erythrocytes and plasma. The spectrum of the transient species, assigned to the product of one-electron oxidation, observed after reaction of ergothioneine with the oxidizing radicals OH., N3. and CCl3O2. has a maximum absorption at 520 nm and is very similar to that obtained by oxidation of analogous molecules such as 2-mercaptoimidazole, 1-methyl-2-mercaptoimidazole, S-methyl- and S,N-dimethyl-ergothioneine. In the presence of vitamin C, the oxidized form of ergothioneine is repaired by a rapid reduction (k = 6.3 x 10(8) M(-1).s(-1)) producing ascorbyl radicals. This co-operative interaction between ergothionine and ascorbate, similar to that previously observed between vitamin E and ascorbate, may contribute to essential biological redox protection.
authors.affiliation: Radiation Laboratory, University of Notre Dame, IN 46556, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Asmus
authors.forename: R V
authors.initials: RV
authors.lastname: Bensasson
authors.forename: J L
authors.initials: JL
authors.lastname: Bernier
authors.forename: R
authors.initials: R
authors.lastname: Houssin
authors.forename: E J
authors.initials: EJ
authors.lastname: Land
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D001205:Ascorbic Acid / Q000737:chemistry / Q000378:metabolism*; D001386:Azides / Q000737:chemistry / Q000378:metabolism; D002251:Carbon Tetrachloride / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D003683:Dehydroascorbic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D004583:Electrons; D004880:Ergothioneine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D017665:Hydroxyl Radical / Q000737:chemistry / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D015394:Molecular Structure; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011675:Pulse Radiolysis
chemical_list: D000975:Antioxidants; D001386:Azides; D005609:Free Radicals; C025280:trichloromethyl free radical; D017665:Hydroxyl Radical; C000820:semidehydroascorbic acid; D004880:Ergothioneine; D002251:Carbon Tetrachloride; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid