Toxicometallomics for Research on the Toxicology of Exotic Metalloids Based on Speciation Studies

Abstract

Tellurium and antimony are widely used in industry because of their unique chemical and physical properties. Although these metalloids, which belong to period 5 of the periodic table of elements, are known to be non-essential and harmful, or the so-called "exotic" elements, little is known about their toxic effects and metabolism. The present review describes the role of speciation in considering the metabolism of tellurium and antimony from the viewpoint of toxicometallomics. Inorganic tellurium in the form of tellurite is reduced and simply methylated in the body. Rat red blood cells accumulate tellurium in the form of dimethylated tellurium, and tellurium is excreted into urine as trimethyltelluronium. Although selenium, which belongs to the same group as tellurium, is known to be excreted in the form of selenosugar as the major urinary metabolite, tellurosugar was not detected by an inductively coupled plasma-mass spectrometer hyphenated with an HPLC. Speciation studies revealed that the major metabolic pathway of antimony is oxidation in human and rat, and methylation also occurs as a minor metabolic pathway in humans.

Sulfate Assimilation Mediates Tellurite Reduction and Toxicity in Saccharomyces cerevisiae

“…Te species are absorbed in the body, but telluroamino acids have not been found in humans. The present view holds that Te(IV) is metabolized in a manner mimicking that of selenite, implying rapid reduction to telluride followed by methylation to mono-, di-, or trimethylated Te species (37). However, in contrast to selenium, tellurium does not appear to be glycosylated in higher eukaryotes, and trimethyltelluronium, rather than tellurosugars, is the dominating Te species (39).…”

“…In yeast, however, viable knockout mutants lacking genes involved in DNA repair and replication and in cell cycle checkpoints showed normal Te phenotypes, suggesting that DNA damage contributes little to Te toxicity. Similar to arsenic, which is accumulated as dimethyl arsenical, but in contrast to selenium, tellurium reaches high concentrations in red blood cells as dimethylated Te (37). Hence, arsenic and tellurium may share mechanistic features in mammals.…”

Diphenyl ditelluride induces neurotoxicity and impairment of developmental behavioral in rat pups

“…O objetivo deste estudo foi investigar se a exposição aguda ao ditelureto de difenila [(PhTe) 2 ] causaria prejuízo no desenvolvimento comportamental de filhotes de ratos. Os filhotes receberam uma injeção subcutânea de (PhTe) 2 (0,1 mg kg -1 , 3 mL kg -1 ) ou veículo (3 mL kg -1 ) no 14º dia após o nascimento (DPN).…”

“…Os filhotes receberam uma injeção subcutânea de (PhTe) 2 (0,1 mg kg -1 , 3 mL kg -1 ) ou veículo (3 mL kg -1 ) no 14º dia após o nascimento (DPN). Do 15º ao 21º DPN, foram realizados testes comportamentais nos filhotes e, imediatamente após estes testes, os filhotes foram submetidos à eutanásia.…”

“…As análises histológicas, a determinação do conteúdo de mielina e a atividade da acetilcolinesterase (AChE) foram realizadas. O período crítico de intoxicação ocorreu no 4º e 5º dias após a injeção de (PhTe) 2 , quando os sinais de toxicidade foram mais evidentes, caracterizados pelo aparecimento de sinais sistêmicos de toxicidade, disfunções comportamentais, neurotoxicidade e uma alteração no sistema colinérgico. Desta forma, conclui-se que o (PhTe) 2 induziu neurotoxicidade e prejuízos no desenvolvimento comportamental de filhotes de ratos.…”