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 wasnt 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).