Detoxification of organomercurials by thiones and selones: A short review

[Display omitted] •Natural detoxification of organomercurials by sulfate-reducing bacteria and organomercurial lyase MerB.•Detoxification of organomercurials via formation of HgS and HgSe nanoparticles.•Detoxification of organomercurials via protolytic cleavage of Hg–C bond. Organomercurials, especially lipophilic methylmercury and ethylmercury, are the most toxic forms of mercury. Thiol-conjugates of organomercurials can easily cross the cellular membranes, including the blood–brain barrier, and thus cause severe damage to the central nervous system. However, the bacterial resistance to both inorganic mercury (Hg2+) and organomercurials is well known. For instance, two strains of the sulfate-reducing bacterium Desulfovibrio desulfuricans show high resistant to methylmercury by virtue of their ability to convert methylmercury into biologically inert HgS, CH4 gas, and dimethylmercury. On the other hand, certain gram-positive and gram-negative bacterial strains with mer operon also display resistance to organomercurials but in a completely different mechanism. The cytosolic organomercurial lyase MerB protein present in these bacteria has an excellent ability to protolytically cleave, otherwise inert, the HgC bond of organomercurials and converts them into inorganic mercury (Hg2+) and volatile hydrocarbon (RH) products. Interestingly, the mercury-resistant MerB enzyme is absent in higher species like animals and humans. Thus, developing a functional model of MerB with high efficiency to cleave the HgC bond of organomercurials under mild conditions will have therapeutic potential to treat patients suffering from methylmercury or ethylmercury poisoning. In this review, we discuss the use of N-heterocyclic-based thiones and selones on the detoxification of mercury-related compounds. Focus is given on how N-heterocyclic-based thiones and selones can suitably be designed to detoxify organomercurials in various ways, similar to that observed in bacteria.