Ergothioneine stands out from hercynine in the reaction with singlet oxygen: resistance to glutathione and TRIS in the generation of specific products indicates high reactivity.

Ergothioneine stands out from hercynine in the reaction with singlet oxygen: resistance to glutathione and TRIS in the generation of specific products indicates high reactivity. Free Radic Biol Med. 2017 Oct 23;: Authors: Stoffels C, Oumari M, Perrou A, Termath A, Schlundt W, Schmalz HG, Schäfer M, Wewer V, Metzger S, Schömig E, Gründemann D Abstract The candidate vitamin ergothioneine (ET), an imidazole-2-thione derivative of histidine betaine, is generally considered an antioxidant. However, the precise physiological role of ET is still unresolved. Here, we investigated in vitro the hypothesis that ET serves specifically to eradicate noxious singlet oxygen ((1)O2). Pure (1)O2 was generated by thermolysis at 37°C of N,N'-di(2,3-dihydroxypropyl)-1,4-naphthalenedipropanamide 1,4-endoperoxide (DHPNO2). Assays of DHPNO2 with ET or hercynine (= ET minus sulfur) at pH 7.4 were analyzed by LC-MS in full scan mode to detect products. Based on accurate mass and product ion scan data, several products were identified and then quantitated as a function of time by selected reaction monitoring. All products of hercynine contained, after a [4+2] cycloaddition of (1)O2, a carbonyl at position 2 of the imidazole ring. By contrast, because of the doubly bonded sulfur, we infer from the products of ET as the initial intermediates a 4,5-dioxetane (after [2+2] cycloaddition) and hydroperoxides at position 4 and 5 (after Schenck ene reactions). The ...
Source: Free Radical Biology and Medicine - Category: Biology Authors: Tags: Free Radic Biol Med Source Type: research