Objectives: In this research, an experimental and theoretical study was conducted to design a photodegradation mechanism of the amino acid tryptophan (Trp) in hair fibres.
Methods: For the experimental research, Caucasian hair fibres were exposed to several different solar radiation simulation periods. Then, Trp and its photoproducts (N-formylkynurenine and kynurenine) were assayed by excitation and emission spectroscopic analysis.
Results: For the theoretical study, reactions involved in the photodegradation of Trp were evaluated by high-level quantum mechanical calculations in a density functional theory (DFT) framework which indicate a probable Trp degradation mechanism with a minimum expended energy pathway.
Conclusion: The biochemistry concerning these reactions is essentially important for a biological system where the degradation of Trp occurs.
Keywords: N-formylkynurenine; ab initio calculation; hair fibre; kynurenine; photodegradation; tryptophan.
© 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.