Metabolic differences between two dimethylthioarsenicals in rats.

Area of Science:

• Environmental Chemistry
• Toxicology
• Biochemistry

Background:

• Thioarsenicals, such as dimethylmonothioarsinic acid (DMMTA(V)) and dimethyldithioarsinic acid (DMDTA(V)), are newly identified arsenic metabolites in humans, animals, and marine life.
• The toxicological and biological significance of these thioarsenicals remains largely unknown.
• Understanding their role in arsenic metabolism is crucial for assessing arsenic toxicity.

Purpose of the Study:

• To investigate the metabolic significance and distribution of DMMTA(V) and DMDTA(V) in vivo.
• To compare the metabolic fate of thioarsenicals with their non-thiolated counterparts.

Main Methods:

• Chemical synthesis of DMMTA(V) and DMDTA(V).
• Intravenous injection into rats at a dose of 0.5 mg As/kg body weight.
• Arsenic distribution analysis in organs, tissues, and body fluids at 10 min and 12 h post-injection.
• Arsenic speciation analysis using High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS).

Main Results:

• DMMTA(V) and DMDTA(V) exhibited distinct distribution patterns compared to each other and to non-thiolated arsenicals.
• DMMTA(V) was retained in red blood cells (RBCs) at 12 h, similar to trivalent dimethylarsinous acid (DMA(III)).
• DMDTA(V) was efficiently excreted in its intact form via urine within 12 h, similar to pentavalent dimethylarsinic acid (DMA(V)).

Conclusions:

• DMMTA(V) displays an unexpected distribution pattern, mimicking DMA(III) rather than DMA(V).
• DMDTA(V) follows a distribution similar to DMA(V) but is excreted more efficiently.
• These findings highlight the unique metabolic pathways and toxicological implications of thioarsenicals in arsenic metabolism.