2-Aminomuconic semialdehyde is a metabolite of tryptophan which is an unstable open-chain biochemical precursor of picolinic acid.
2-Aminomuconic semialdehyde is an intermediate in the kynurenine pathway of tryptophan metabolism, which leads to picolinic acid or quinolinic acid. The enzyme aminocarboxymuconate-semialdehyde decarboxylase produces it from 2-amino-3-carboxymuconic semialdehyde, a compound which would form quinolinic acid in the absence of that enzyme.
2-Aminomuconic semialdehyde itself is chemically unstable and spontaneously ring-closes to picolinic acid, with loss of water.