Comparison of selenoneine found in marine organisms with selenite in the interaction with mercury compounds in vitro.

Selenium (Se) is an essential micronutrient because it forms the active center of selenoenzymes/selenoproteins in the form of selenocysteine. Another biological significance of Se is that it detoxifies inorganic mercury (iHg) by directly interacting with it. Recently, a novel selenometabolite, selenoneine (2-selenyl-N,N,N-trimethyl-L-histidine), was identified in several marine animals. However, its biological significance is still unclear. In this study, the ability of selenoneine to form a complex with iHg and methyl Hg (MeHg) was evaluated in vitro. Whereas selenite serving as the positive control reacted with iHg by direct interaction after being converted into selenide by endogenous reductants, such as glutathione (GSH), selenoneine did not interact with iHg or MeHg in the liver homogenate of marine turtle. This indicates that selenoneine may not play a role in the detoxification of Hg.