Detoxification of Neurotoxic Organomercurials by 1 to 2hydroxyethyl methyl 1H imidazole 2 3H thione and its Analogues through Efficient Desulfurization and Deselenization Processes

Abstract

Mercury exists within the environment in various chemical forms such as elemental mercury vapor (Hg0), inorganic mercury salts (Hg2+), and organomercurials such as methylmercury (MeHg+) and ethylmercury (EtHg+). Methylmercury (MeHg+) species are highly toxic to human and animal due to their high affinity toward thiol or selenol residues present in cellular systems. Mercury compounds enter in to aquatic system and the facile inter-conversion of one form to another takes place inside the ecosystem. Many microorganisms in aerobic sediments including corrinoid-producing anaerobes and sulfate-reducing bacteria (SRB) are known to methylate Hg2+ to produce toxic MeHg+. The consumption of seafood from MeHg+ contaminated water systems subjects human and wild-life to the toxicity related to methylmercury. The first chapter described the different ways through which human population is exposed to toxic mercury compounds and it also briefs about currently available detoxification processes of mercury and mercury-related compounds by many microorganisms.1 One important example about mercury resistance in bacteria conferred by the mer operon, which encodes a set of proteins that carry out the cleavage of otherwise inert Hg-C bond in various toxic organomercurials (RHg+) followed by the transport and reduction of Hg2+ to transform this toxic ion into less toxic, elemental Hg0. On the other hand, sulfate-reducing bacteria such as Desulfovibrio desulfuricans has the ability to detoxifying MeHg+ species by forming insoluble mercury sulphide (HgS). Whereas, the formation of HgSe has been observed in different tissues of marine mammals, wild animal and also in various organs of Hg mine workers. Insoluble HgS and HgSe are considered to be less toxic than the other soluble mercury species. It is worth to mention here that toxic newlinexiv newlinemethylmercury (MeHg+) is present in different forms.