Mitochondrial As accumulation and speciation by SR-XRF-XANES at LNLS.

PEREZ, CARLOS A; BONGIOVANNI, GUILLERMINA A.

LNLS Activity Report 2012

Cubo

Año: 2013

1518 0204

It is well established that chronic exposure to arsenic can cause cancerous and non-cancerous health hazards. However, epidemiological and experimental evidence suggest that the development of arsenic-related diseases is not only determined by the dosage of exposure, but also by its chemical form. Methylation of arsenite to monomethylarsonic acid (MMA) or dimethylarsinic acid (DMA) followed by other organoarsenic compounds, constitute the major biological reactions in the arsenic cycle. It is generally accepted that the +3 methylated arsenic species are more cyto- and genotoxic, and more potent enzyme inhibitors than both their pentavalent counterparts and the inorganic arsenic species. In this regard, becomes necessary to know chemical species of accumulated arsenic in target organs in order to do more efficient therapy strategies. In previous reports, mapping of As distribution obtained by SR-µXRF showed its accumulation in renal cortex from exposed rats (figure 1). In order to As speciation, arsenic K-edge XANES measurements in fluorescence mode and conventional incidence geometry (SR-XRF-XANES) were carried out using the set-up recently developed at the D09B-XRF beamline from the Brazilian Synchrotron Light Laboratory. By this procedure it was possible to determine As species in the renal mitochondrias. We conclude that SR-XRF-XANES is a new methodology available at LNLS for the successful determination of chemical species in different matrices.