[Effects of harman and norharman on aflatoxin B1 and aminopyrine metabolism by phenobarbital and 3-methylcholanthrene-induced rat liver microsomes].

Harman and norharman are two beta-carboline derivatives known to be present in certain foods and are formed during pyrolysis of amino-acids. Their effects on the metabolism of aflatoxin B1 and aminopyrine by 3-methylcholanthrene and phenobarbital-induced rat liver microsomes were studied. Both harman and norharman markedly inhibited the metabolism of aflatoxin B1 to its hydroxylated derivative, aflatoxin M1. However, only norharman showed an inhibitory effect on aminopyrine N-demethylation; harman had no effect. Harman and norharman inhibited aflatoxin B1 binding to DNA, mediated by hepatic microsomes in vitro.