In this paper, the enzymatic detoxification of aflatoxin B1 (AFB1) by laccase was studied, and the prooxidant properties and mutagenicity of the detoxification products were compared with those of AFB1. The optimal enzymatic reaction occurred in 0.1M of citrate buffer containing 20% DMSO at 35 °C, a pH of 4.5, and a laccase activity of 30 U mL(-1). After 2 d, sixty-seven percent of the toxic substrate was removed. The prooxidative properties of the detoxified products (27% versus 86%) and the mutagenicity were significantly decreased in comparison with the parent toxin. Unlike AFB1, which promoted metabolism-dependent genetic mutations by base-pair substitution, the detoxified products did not induce genotoxicity. Comparison of the Km values for AFB1 and riboflavin, a valuable food nutrient, indicated that laccase showed greater affinity for the toxin than for riboflavin.
Keywords: Aflatoxin B1; Enzyme affinity; Laccase; Mutation; Prooxidant.
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