Norharman

Norharman is a β-carboline alkaloid formed from the amino acid tryptophan during heating, a demethylated analogue of harman and, like it, a co-mutagen that can enhance the activity of other mutagens. These heterocyclic compounds arise in the crusts of well-done meats, grilled fish, and roasted coffee through high-temperature reactions of amino acids. Though present at low levels, they contribute to the complex toxicology of heavily browned foods and are studied alongside heterocyclic aromatic amines. Mitigation follows familiar routes: moderating cooking temperatures, avoiding charring, and marinating, which together reduce formation of heat-generated mutagens.