In vitro Antifungal and Antimycotoxigenic Activity of Extracts of Equisetum sp. and Stevia sp.

DAIANA GARCIA; ESTHER GARCIA-CELA; ANTONIO J. RAMOS; VICENTE SANCHIS; SONIA MARÍN

Cairo

Congreso; Mycotoxicological Risks in Mediterranean Countries: Economic Impact, Prevention, Management and control; 2010

Cereals are very important for human and animal diet. However, agricultural products can be contaminated by mycotoxins. The presence of mycotoxins in food products is a chemical hazard of increasing concern due to the wide range of food types where they can be found. These toxins can be produced in grains of cereals, in raw materials, in different foods and feeds, in field, in transports, in stored food and in different situations in which conditions are conducive for their production. In the other hand, the increased demand for safe and natural food, without synthetic preservatives, incites to investigate the antimicrobial effects of natural compounds. Thus, natural plant products with antimicrobial properties could be a possibility to replace the synthetic preservatives in foods and feeds in terms of preventing mould growth and mycotoxins production. Several plant extracts have been studied for their antioxidants contain and antimicrobial properties. However, there are few studies that determine the effects of these compounds on mould development. Aspergillus is a mould genus which can contaminate cereals and produce mycotoxins. Aspergillus flavus and A. parasiticus can synthesize aflatoxins, causing different damage to human and animal health. For this reason, the aim of this work was to evaluate the effect of two kinds of hydro-alcoholic plant extracts from Stevia sp. and Equisetum sp. on growth and aflatoxins production by A. flavus and A. parasiticus. Maize agar medium (MAM 2%) was used for this study to which plant extracts were added at different concentrations (1-3%) under different water activity (aw) levels (0.85-0.93). After inoculation with the two strains, plates were incubated at different temperatures (15-30 ºC) for 21 days. Two perpendicular diameters of the growing colonies were measured daily until the colony reached the edge of the plate. Aflatoxins were extracted after 7 and 21 days and were quantified by HPLC. In general, no growth was observed with Equisetum sp. extract at 3% in all studied conditions for both isolates. Besides, with Stevia sp. extract at 2-3%, growth was significantly decreased (p