Formation of formylkynurenine by the action of X-rays on tryptophan in aqueous solution

Abstract

It was shown that formylkynurenine is one of the products formed when DL-tryptophan is irradiated with X-rays in aqueous solution in the presence of molecular O2. It was concluded that oxindolylalanine (alpha-amino-beta-oxindol-3-ylpropionic acid) is not an intermediate in the reaction mechanism since irradiation of this substance itself does not lead to any significant amounts of formylkynurenine. The mechanism of these processes was discussed, with particular reference to the role played by molecular O2, and attention was drawn to the similarity to the biological oxidation of tryptophan.