Photochemical and thermal reactivity of kynurenine

The thermal and photochemical reactivity of kynurenine (KN), a tryptophan metabolite found in human lenses, has been studied in aqueous solution. The decarboxylation reaction of KN, resulting in the formation of 4-hydroxyquinoline, is reported for the first time. Rate constants for KN deamination and decarboxylation were determined in the temperature range 50-90 °C. The quantum yields for KN photodecomposition under argon were measured to be ΦAr = (2.0 ± 0.2) × 10−5 and under oxygen ΦO2 = (1.1 ± 0.1) × 10−4.