INMIBO ( EX - PROPLAME)   14614
INSTITUTO DE MICOLOGIA Y BOTANICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of plant extracts on mycotoxin production by Alternaria spp.
Autor/es:
DA CRUZ CABRAL, L.; RÍO CARRIÓN, GERALDINE; REGGI, FERNANDO; PATRIARCA, A.
Lugar:
Mendoza
Reunión:
Conferencia; MycoRed ISM conference; 2011
Institución organizadora:
International Society for Mycotoxicology
Resumen:
Mycotoxin production on food products is an important issue that concerns its safety. Fungal colonization may occur in the field or during post-harvest period. This can be controlled using chemical antifungals, but they are usually very toxic and could lead to the development of resistant strains. An alternative solution is needed. Several studies have demonstrated that plant extracts could contain different bioactive components which would control mould growth. Alternaria is an important genus found commonly in several fruits, vegetables and cereals. Mycotoxins produced by this genus belong to three different structural groups: (i) the dibenzopyrone derivatives, alternariol (AOH), alternariol monomethyl ether (AME), and altenuene (ALT); (ii) the perylene derivatives altertoxins (ATX-I and II); and (iii) the tetramic acid derivative, tenuazonic acid (TA). TA, AOH, AME and ATX-I are the main Alternaria mycotoxins found as contaminants of food commodities. AOH and AME showed mutagenic activity in some cell systems; TA has been associated with haemorrhages in several organs and precancerous changes in some animals’ esophagus. The aim of this work was evaluate the effect of plant extracts on the production of AOH and AME by two strains: Alternaria alternata y Alternaria arborescens, and of TA by A. arborescens. Both strains were isolated from tomato fruits. The extracts were obtained from Eucalyptus globulus and Calendula officinalis using chloroform, ethanol, methanol and methanol:water (70:30) as extraction solvents. Each of them was evaluated at three concentration levels: 500, 1250 and 2500 µg/g agar. Three MEA plates were inoculated for each treatment. They were incubated in the dark 21 days at 25ºC. Mycotoxin extraction was carried out following the method described by Pose et al. (2010). Mycotoxin quantification was performed by HPLC with UV detector. The wavelength for recording chromatograms was 258 nm for AOH and AME, and 280 nm for TA. The results did not follow a regular tendency. Although some extracts inhibited the mycotoxins production, others enhanced its synthesis. There wasn’t a correlation observed between the extracts’ concentration and the amount of mycotoxin accumulated, although the inhibition was dependent on the species. The extracts which showed the higher inhibition against the three toxins evaluated were the ethanolic and the chloroformic fractions obtained from eucalyptus; all calendula extracts produced a lower response. A reduction of AOH produced by A. arborescens of 89.8 % and 93.8 % was achieved when the mentioned eucalyptus extracts were applied at the lowest concentration. The AME synthesis was also heavily inhibited by the eucalyptus metanolic extract (98.8% by A. arborescens). The TA production was not highly affected by the plant extracts. The only significant inhibition was obtained with both the ethanolic and chloroformic eucalyptus extracts at the higher concentration evaluated (89.7 and 89.1% respectively).