L-Tryptophan is an aromatic amino acid containing
an indole ring system, having its origins in the shikimate pathway via anthranilic
acid. It acts as a precursor of a wide range of indole
alkaloids, but there is also definite proof that major
rearrangement reactions can convert the indole ring
system into a quinoline ring, thus increasing further the ability of this amino acid to act as an alkaloid precursor.