CONTROL OF AFLATOXIN PRODUCTION BY TARGETING AFLATOXIN BIOSYNTHESIS
Location: Food and Feed Safety Research
Title: Extracts of Agave americana inhibit aflatoxin production in Aspergillus parasiticus
Submitted to: World Mycotoxin Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 2, 2010
Publication Date: February 14, 2011
Citation: Rosas-Taraco, A., Sanchez, E., Garcia, S., Heredia, N., Bhatnagar, D. 2011. Extracts of Agave americana inhibit aflatoxin production in Aspergillus parasiticus. World Mycotoxin Journal. 4(1):37-42.
Interpretive Summary: Aflatoxins are toxins produced by fungi such as Aspergillus flavus. These compounds are some of the most carcinogenic and toxic compounds found in nature. Toxin producing fungi invade crops prior to harvest as well as during storage and produce aflatoxins. Fungicides, at concentrations that are non-toxic, are not very effective in controlling the spread of these fungi. Therefore in order to produce safe food and feed supply novel methods need to be developed to control the growth of the toxigenic fungi, thereby preventing contamination of these commodities with aflatoxins. In this study, the effect of a natural product present in aqueous extracts of the Agave plant was studied for its effect on fungal growth and toxin production in culture. The results indicated that although fungal growth was higher in the presence of the extracts, the toxins level was highly significantly reduced. These results offer an alternative to fungicides to prevent the harmful effects of toxigenic fungi, with enhanced food safety.
Toxigenic fungi invade crops prior to harvest as well as during storage and produce harmful, even carcinogenic toxins such as aflatoxins. Since consumers demand safe commodities, and due to enhanced public awareness of the dangers of many synthetic fungicides, the importance of investigating alternative, natural products to control these toxigenic fungi is clear. This study investigated the effect of aqueous extracts of Agave americana on growth, conidia and aflatoxin production. Aspergillus parasiticus strains SRRC 148, SRRC 143 (Su-1), and A. parasiticus SRRC 162, a mutant (nor-) that accumulates norsolorinic acid (NOR, an orange-coloured intermediate of the aflatoxin pathway), were first inoculated into Adye and Mateles liquid medium, then plant extracts were added, and incubated at 28°C for 7 days. Aflatoxin and norsolorinic acid were assayed by HPLC and spectrophotometry, respectively. While the extract of A. americana stimulated growth of the studied fungi, conidiogenesis, norsolorinic acid accumulation (in the nor- mutant), and aflatoxin production were significantly affected. The reduction was produced by the extracts at concentrations higher than 5-10 mg/ml, where all types of total aflatoxin analysed (aflatoxins B1, B2, G1 and G2) were reduced from 64% to >99% in the whole culture, and a reduction of 75% of norsolorinic acid. The results of the present work indicate that extracts of A. americana may be promising safe alternatives to harmful fungicides for controlling aflatoxin contamination.