Figs, natural aflatoxins

Fig. 4 Typical chromatogram of aflatoxins B, B2, G, and G2 naturally contaminated pistachio nuts sample. Aflatoxin B, (AFB1) 0.75 fig/kg, aflatoxin B2 (AFB2) 0.12 fig/kg, aflatoxin G] (AFGl) 0.68 fig/kg, and aflatoxin G2 (AFG2) 0.15 /rg/kg. Mobile phase water methanol acetonitrile 54 29 17. Pump A regulated at 1 ml/min Pump B (postcolumn derivatization with bromine) regulated at 0.4 ml/min.

The following table includes carbon-13 shifts (in ppm) and supplemental references of selected natural products with physiological activity. Some representatives have been portrayed in figures. Examples are colchicine (Fig. 2.19), biotin (Fig. 2.52), actinomycin D (Fig. 5,13) and aflatoxin Bt (Fig. 5.17). 

Although A. flavus will grow on almost any natural or processed substrate, aflatoxin occurs naturally primarily in corn, peanuts, cottonseed, grain sorghum, tree nuts, millet, copra, and figs (34). Substrate factors must be involved in contamination, since it is limited to a relatively small number of agricultural commodities. The restricted access of zinc has been proposed as an explanation for the inability of A. flavus to elaborate aflatoxin in soybeans (35). The availability of zinc for aflatoxin biosynthesis appears to be blocked by the presence of phytic acid in soybeans (36). 

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