Electrochemical oxidation of ochratoxin A at a glassy carbon electrode and in situ evaluation of the interaction with deoxyribonucleic acid using an electrochemical deoxyribonucleic acid-biosensor.

Ochratoxin A (OTA) is a fungal metabolite that occurs in foods, beverages, animal tissues, human blood and presents carcinogenic, teratogenic and nephrotoxic properties. This study concerns the redox properties of OTA using electrochemical techniques which have the potential for providing insights into the biological redox reactions of this molecule. The in situ evaluation of the OTA interaction with DNA using a DNA-electrochemical biosensor is also reported. The oxidation of OTA is an irreversible process proceeds with the transfer of one electron and one proton in a diffusion-controlled mechanism. The diffusion coefficient of OTA was calculated in pH 7 phosphate buffer to be D(O) = 3.65x10(-6) cm2 s(-1). The oxidation of OTA is also pH dependent for electrolytes with pH<7 and involves the formation of a main oxidation product which adsorbs strongly at the GCE surface undergoing reversible oxidation. In alkaline electrolytes OTA undergoes chemical deprotonation, the oxidation involving only the transfer of one electron. The electrochemical dsDNA-biosensor was also used to evaluate the possible interaction between OTA and DNA. The experiments have clearly proven that OTA interacts and binds to dsDNA strands immobilized onto a GCE surface, but no evidence of DNA-damage caused by OTA was obtained.