| Abstract
| - Effects of naturally occurring compounds from plants on biotransformation of a mycotoxin, aflatoxinB1, were evaluated. Among 77 naturally occurring compounds tested, anthraquinones, coumarins,and flavone-type flavonoids were shown to be potent inhibitors of aflatoxin B1-8,9-epoxide formation.Addition of the flavonoids galangin, rhamnetin, and flavone strongly inhibited mouse livermicrosomal conversion of aflatoxin B1 to aflatoxin B1-8,9-epoxide, a metabolically activated mutagenicproduct. In contrast to these results, addition of isoflavonoids, catechins, terpenes, alkaloids, andquinones to mouse liver microsomes did not inhibit formation of aflatoxin B1-8,9-epoxide. Formationof the aflatoxin B1 reductase product, aflatoxicol, by chicken liver cytosols was strongly inhibitedby curcumin, the diferuloylmethane present in turmeric and other Curcuma species. Curcuminanalogues also showed inhibitory effects, and a structure−activity study established that β-diketonegroups linked with two benzyl moieties were essential for inhibition of aflatoxicol formation. Anadditional 37 naturally occurring compounds tested did not inhibit formation of aflatoxicol. Theseresults demonstrate that dietary constituents in certain fruits, vegetables, and spices may havesignificant inhibitory effects on metabolic transformation of aflatoxins to their hepatotoxic orcarcinogenic derivatives or, alternatively, may promote their transformation into nontoxic products. Keywords: Aflatoxin B1; aflatoxin B1-8,9-epoxide; cytochrome P450; flavones; galangin; aflatoxicol;aflatoxin B1 reductase; curcumin
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