RIBOFLAVIN-SENSITIZED PHOTOPROCESSES OF TRYPTOPHAN

The photodegradation of tryptophan in oxygen saturated aqueous solutio n sensitized by riboflavin is accompanied by the generation of the fol lowing reactive oxygen species: O-1(2), OH., H2O2 and O-2(.-). When pa rallel photodegradation experiments are run with C-14-riboflavin in on e case and C-14-tryptophan in the other and the irradiation products a re separated by Sephadex G-15 and C-18-HPLC, the generation of the fol lowing species is detected: aggregate forms of riboflavin, indolic pro ducts associated to flavins, indolic products of molecular weight high er than tryptophan, formylkynurenine, and other tryptophan photodecomp osition products. The significance of the riboflavin anion radical and tryptophan cation radical as intermediates in the photoproduct format ion is discussed.