A histidine derivative that is Nα,Nα,Nα-trimethyl-L-histidine substituted by a selenoxo group at position 2 on the imidazole ring. This selenium-containing antioxidant was found in tuna blood and is a major selenium compound in fish muscle. Ths compound has strong antioxidant capacity and binds to heme proteins, such as hemoglobin and myoglobin, to protect them from iron auto-oxidation, and it reacts with radicals and methylmercury (MeHg).

Formula: C9H15N3O2Se
Mol. Weight: 276.19000