Mitochondrial As accumulation and speciation by SR-XRF-XANES at Laboratorio Nacional de Luz Sincrotron (LNLS).

PEREZ, CARLOS A; BONGIOVANNI, GUILLERMINA A.

LNLS Activity Report 2011

Cubo

Lugar: Campinas; Año: 2012

1518 0204

La publicación fue aceptada en 2012 pero los artículos serán cargados en 2013 a la versión on-line http://lnls.cnpem.br/ar2011 ........................................................... 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 organo-arsenic 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-microXRF showed its accumulation in spleen [1], kidney [2] and mitochondrial rich fraction from renal cortex (by SR-TXRF-XANES, [3] from exposed rats. 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 mitochondrias from As accumulating organs, kidney, liver and spleen. We conclude that SR-XRF-XANES is a new methodology available at LNLS for the successful determination of chemical species in different matrices.