Highlights: Caramboxin concentration is higher in the seeds and surrounding areas.

In recent years, some studies have demonstrated several cases of star fruit (Averrhoa carambola) intoxication in patients with chronic kidney disease (CKD), since then its has sought to know the cause of these effects. In 2013, Garcia-Cairasco and collaborators identified and characterized the compound responsible for triggering this intoxication and called it caramboxin (CBX). However, the caramboxin distribution in the fruit was still unknown, due to the fact that the researchers isolated this toxin from the whole fruit, without separating the different parts. Thus, this study aimed to identify the caramboxin tissue distribution in star fruit. Star fruits were collected Ribeirão Preto downtown - São Paulo, sectioned crosswise in cryostat and the slices transferred immediately to a conductive glass plate specific for MALDI-imaging (Bruker Daltonics®), then a suspension of inorganic titanium dioxide matrix in water:acetonitrile was sprayed. The plate covered with matrix was inserted in the MALDI-TOF/TOF Ultraflextreme equipment, the analyzes were performed and the data were treated generating the images, using the SCLIS® software. The images obtained show that caramboxin is concentrated in the seeds and surrounding areas. Knowledge of the caramboxin tissue distribution may be relevant in the investigation of its biosynthetic origin, beyond to contributing to doctors and nutritionists in guiding patients that are at risk groups for star fruit intoxication.