Electroanalytical chemisrty of OTA, ZEA, DON and ATX-I mycotoxins

HÉCTOR FERNÁNDEZ; P.G. MOLINA; M.B. MORESSI; E. A. RAMÍREZ; M.A. ZÓN

Monopoli,Bari, Italy

Workshop; International Conference " Advances in genomics, biodiversity and rapid systems for detection of toxigenic and mycotoxins"; 2006

integration of mycotoxin and toxigenic fungi MYCO-GLOBE research for food safety i global system

Ochratoxin A (OTA) is a mycotoxin with nephrotoxic, carcinogenic and immunosuppressive properties. It is produced by several Aspergillus and Penicillium species. The occurrence of OTA in food and feed has been reported world-wide. Cereal and derived products are assumed to be the major dietary source of OTA [1]. Zearalenone (ZEA) is an estrogenic mycotoxin produced by species of Fusarium and often occurs with trichothecenes in cereal crops [2]. The trichothecene most commonly found and analyzed is deoxynivalenol (DON) [3]. Altertoxin I (ATX-I) is a mycotoxin produced by fungi of Alternaria alternata genus. Many plant products, which are present in human and animal diets, are frequently infected by Alternaria species capable of mycotoxin production. Mutagenicity, one important aspect of Alternaria toxicity, has been ascribed mainly to altertoxins [4].             Chromatographic and enzyme-linked immunosorbent assay (ELISA) methods have been the most frequently used to determine these fungal metabolites [2]. One of the disadvantages they present is that they take long times in extraction and clean up steps.             Some results we found about electrochemical properties of OTA, DON, ZEA and ATX-I are shown in this work. Some of them were obtained on bare electrodes (OTA and DON) and some others on modified electrodes by antibodies (ZEA) and by self-assembled monolayers of thiols (ATX-I). We consider that these fundamental data are the basis to start the development of electroanalytical methods as an alternative to detect and quantify these fungal metabolites. Electroanalytical methods require cheaper equipments, short analysis times and they have a reasonably good sensitivity. Therefore, the electrochemical oxidation of OTA has been studied in buffer solutions of different pH values on glassy carbon (GC) electrodes by cyclic (CV) and square wave voltammetries (SWV). ZEA was determined by using an electrochemical immunosensor based on a ZEA rabbit polyclonal antibody adsorbed onto GC electrodes in pH 7.40 phosphate buffer solutions by SWV. The optimum experimental conditions to improve the ZEA determination will be discussed.  Moreover, the adsorptive accumulation of ATX-I onto gold electrodes modified by 1-dodecanethiol is studied in 20% acetone + 80% pH 7.0 phosphate buffer solutions. It has also been found that DON could be reduced electrochemically on GC electrodes in acetonitrile and tetrabutylammonium hexafluorphosphate solutions. The quantitative determination of these mycotoxins was performed by SWV. Calibration curves were obtained and parameters such as detection limit, linear range, stability and repeatability were analysed.  These preliminary studies have been performed in solutions of the pure commercial reagents and will be transferred to analyze these metabolites in real matrixes naturally infected.   References D. Ringot, A. Chango, Y-J. Schneider, Y. Larondelle, Chemico-Biological Interactions 159 (2006) 18. M. W. Trucksess, A. E. Poland, Mycotoxin Protocols, Methods in Molecular Biology, Humana Press, Totowa, New Jersey, Vol. 157, 2001. E. Schneider, V. Curtui, C. Seidler, R. Dietrich, E. Usleber, E. Martbauer, Toxicology Letters, 153 (2004) 113. A. Visconti, A. Sibilia, Mycotoxin in Grain. Compounds other than Aflatoxins, Eds. J.D. Miller and H. L. Trenholm, Eagan-Press, Minnesota, USA, 1994.