The relevance of arsenic speciation analysis in health & medicine

Long term exposure to arsenic through consumption of contaminated groundwater has been a global issue since the last five decades; while from an alternate standpoint, arsenic compounds have emerged as unparallel chemotherapeutic drugs. This review highlights the contribution from arsenic speciation studies that have played a pivotal role in the progression of our understanding of the biological behaviour of arsenic in humans. We also discuss the limitations of the speciation studies and their association with the interpretation of arsenic meta-bolism. Chromatographic separation followed by spectroscopic detection as well as the utilization of biotinylated pull-down assays, protein microarray and radiolabelled arsenic have been instrumental in identifying hundreds of metabolic arsenic conjugates, while, computational modelling has predicted thousands of them. However, these species exhibit a variegated pattern, which supports more than one hypothesis for the metabolic pathway of arsenic. Thus, the arsenic species are yet to be integrated into a coherent mechanistic pathway depicting its chemicobiological fate. Novel biorelevant arsenic species have been identified due to significant evolution in experimental methodologies. However, these methods are specific for the identification of only a group of ar-senicals sharing similar physiochemical properties; and may not be applicable to other constituents of the vast spectrum of arsenic species. Consequently, the identity of arsenic binding partners in vivo and the sequence of events in arsenic metabolism are still elusive. This resonates the need for additional focus on the extraction and characterization of both low and high molecular weight arsenicals in a combinative manner.

Automated summary

Long term exposure to arsenic through consumption of contaminated groundwater is a global issue, but arsenic compounds are also emerging as potential chemotherapeutic drugs. Arsenic speciation studies have significantly contributed to our understanding of the biological behavior of arsenic in humans, but there are limitations and challenges in interpreting arsenic metabolism. Various technologies have identified hundreds of metabolic arsenic conjugates, but the relationship between these species and the metabolic pathway of arsenic remains unclear. New experimental methodologies have revealed novel biorelevant arsenic species, but there is still a need to focus on identifying and characterizing different types of arsenicals in a comprehensive manner.