The Mechanism Underlying the Extreme Sensitivity of Duck to Aflatoxin B₁

Figure 1

Metabolic process of aflatoxin B₁ (AFB₁) in the animal liver. (a) Aspergillus flavus grows in moldy feed, producing toxic metabolites, like AFB₁. Poultry consume feed contaminated with AFB₁. (b) In the liver, AFB₁ produces exo-AFB₁-8,9-epoxide (AFBO) under the action of phase I metabolic activating enzymes, such as cytochrome oxidase P450 (CYP 450), and binds to DNA and protein, causing gene damage and cytotoxicity and is potently carcinogenic. (c) At the same time, some phase I metabolic activating enzymes also convert AFB₁ into low-toxic metabolites; or under the action of phase II metabolic detoxification enzymes, such as glutathione S-transferases (GSTs), AFB₁ combines with antioxidants into nontoxic conjugates and is then excreted from the body to alleviate the toxicity of AFB₁.