INVESTIGADORES
FERNANDEZ Hector
congresos y reuniones científicas
Título:
Electroanalytical chemistry of OTA, ZEA, DON and ATX-I mycotoxins
Autor/es:
H. FERNÁNDEZ; P. G. MOLINA,; M. B. MORESSI; E. A. RAMÍREZ; M. A. ZÓN
Lugar:
Bari, Italia
Reunión:
Congreso; Myco-globe International Conference 2006: Advances on genomics, biodiversity and rapid systems for detection of toxigenic fungi and mycotoxins; 2006
Institución organizadora:
International Society for Micotoxicology (ISM)
Resumen:
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.