The fate of methylmercury through the formation of bismethylmercury sulfide as an intermediate in mice.

A previous study by our group indicated that methylmercury (MeHg) is biotransformed to bismethylmercury sulfide [(MeHg) ₂ S)] by interaction with reactive sulfur species (RSS) produced in the body. In the present study, we explored the transformation of MeHg to (MeHg) ₂ S in the gut and the subsequent fate of (MeHg) ₂ S in vitro and in vivo. An ex vivo experiment suggested the possibility of the extracellular transformation of MeHg to (MeHg) ₂ S in the distal colon, and accordingly, the MeHg sulfur adduct was detected in the intestinal contents and feces of mice administered MeHg, suggesting that (MeHg) ₂ S is formed through reactions between MeHg and RSS in the gut. In a cell-free system, we found that (MeHg) ₂ S undergoes degradation in a time-dependent manner, resulting in the formation of mercury sulfide and dimethylmercury (DMeHg), as determined by X-ray diffraction and gas chromatography/mass spectrometry, respectively. We also identified DMeHg in the expiration after the intraperitoneal administration of (MeHg) ₂ S to mice. Thus, our present study identified a new fate of MeHg through (MeHg) ₂ S as an intermediate, which leads to conversion of volatile DMeHg in the body.
(© 2021. The Author(s).)