Selenoneine In Marine Organisms

A novel selenium-containing compound, selenoneine, 2-selenyl-N-alpha,N-alpha,N-alpha-trimethyl-lhistidine, has been identified as the predominant form of organic selenium in the blood and tissues of tuna. This selenium compound has a selenium atom in the imidazole ring, and is a selenium analog of a thiol compound, ergothioneine. Selenoneine has radical scavenging activity and exerts an antioxidant effect by binding to hemoglobin and myoglobin, protecting them from iron auto-oxidation. In addition, selenoneine has detoxifying activity against methylmercury (MeHg). Selenoneine has been found to be a specific substrate for the organic cation/carnitine transporter OCTN1 (solute carrier family 22 member 4, SLC22A4), and mediated the excretion and demethylation of MeHg by exosomal small vesicle formation. The dietary intake of selenoneine through fish consumption is an important selenium source in the human diet. Since selenoneine and its related selenoproteins have strong antioxidant activities, disease protective functions, such as anticarcinogenesis and aging effects, may be expected.