BOVINE HEPATIC-METABOLISM OF AFLATOXIN B-1

Differences in the expression and catalytic activity of hepatic biotra nsformation enzymes account for species differences in xenobiotic meta bolism, including that of aflatoxin B-1 (AFB(1)). The main objectives of this study were (1) to define the procedure for isolation and cultu re of bovine hepatocytes, (2) to characterize the biotransformation ca pacity of bovine hepatocytes for AFB(1), and (3) to develop an HPLC me thod for the simultaneous analysis of AFB(1) and its metabolites. Bovi ne hepatocytes were isolated and cultured in monolayers. Metabolic fun ction of these hepatocytes was assessed by measuring total cytochrome P450 (CYP450) content, glutathione S-transferase (GST) activity, ethox yresorufin O-deethylation (EROD), testosterone hydroxylation, and alph a-naphthol glucuronidation. When using these cultures to study the bio transformation of AFB(1), the principal metabolites of AFB(1) were AFM (1) and AFB(1)-dihydrodiol (AFB(1)-dhd). Minor amounts of AFB(1)-gluta thione conjugate (AFB(1)-GSH) and a polar metabolite were also detecte d. The polar metabolite was not specifically identified as a glucuroni dation product of AFB(1). No AFP(1), AFQ(1), AFB(2a), or aflatoxicol ( AFL) was detected. The HPLC method developed provided the simultaneous detection of AFB1 and the metabolites AFB(1)-dhd, AFM(1), AFP(1), AFQ (1), AFL, and AFB(1)-GSH as well as AFB(2a).