46I-10 |
Evaluation of the effect of phytic (inositol phosphate) and linoleic acids on the biosynthesis of aflatoxin |
S. SHAHID-ALI1, D. L. PARK2, and H. Njapau2. (1) Food Science Department, Louisiana State University, 111-Food Science Bldg., Baton Rouge, LA 70803, (2) Center for Food Safety & Applied Nutrition, Food and Drug Administration (FDA), 200 C St. S.W., Washington D.C., DC 20204 Consumption of mycotoxins, especially aflatoxin B1 (AFB1), is associated with occurrence of liver cancer. Naturally aflatoxin contaminated corn extracts show a lower mutagenic potential than pure AFB1 in the Salmonella/microsomal assay, presumably due to the presence of inositol phosphates (InsPs) and linoleic acid. The role of InsPs and linoleic acid on the overall risk posed by AFB1 occurrence is important since they comprise more than 1% of the dry weight of cereals, oilseeds and nuts. This study was conducted to evaluate the effect of the presence of InsP analogs and linoleic acid, on aflatoxin production by Aspergillus flavus in Czapek-Dox liquid medium, and on corn during storage. Czapek-Dox medium, containing different phytic acid concentrations was inoculated with a spore suspension of Aspergillus flavus and AFB1 production was monitored by TLC during 25-days incubation at 28°C, in the presence/absence of various ions. In the storage study, whole kernel and cracked corn was also inoculated in the presence of varying amounts of phytic and linoleic acids, in a controlled environment for 5-weeks. Aflatoxin biosynthesis was monitored every 4-days using HPLC. Inhibition of AFB1 biosynthesis in liquid medium was observed as the concentration of InsP increased. Complete inhibition of AFB1 production was recorded at InsP levels of 0.5 and 1 mg/100ml in the absence of Fe++ and Zn++ ions. In storage, aflatoxin levels were ~50% lower in samples separately treated with phytic and linoleic acids after 14-days. Aflatoxin production in InsP-treated samples was substantially lower than Linoleic acid-treated samples. No such reductions were recorded in samples treated with phytic-linoleic acids combination. Although individually phytic and linoleic acids lower aflatoxin production, their simultaneous presence negates this effect. These results do not, however, reduce the benefits arising from reported inhibition of aflatoxin mutagenicity/biosynthesis by the same compounds.
Session 46I, Toxicology & Safety Evaluation
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