Towards an insight on photodamage in hair fibre by UV-light: An experimental and theoretical study

International Journal of Cosmetic Science Volume: 35 Issue: 6 Pages: 539-545 Published: 2013

Proposed ab initio calculated reaction for Trp degradation.

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Writers:  V. M. Longo, A. da Silva Pinheiro, J. R. Sambrano, J. A. M. Agnelli, E. Longo and J. A. Varela

Keywords: ab initio calculation; hair fibre; kynurenine; N-formylkynurenine; photodegradation; tryptop han


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 kynure-nine) were assayed by excitation and emission spectroscopic analysis.
RESULTS: For the theoretical study, reactions involved in the pho-todegradation of Trp were evaluated by high-level quantum mechanical calculations in a density functional theory (DFT) frame-work 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.

Robson Lima
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Atua no Centro de Desenvolvimento de Materiais Funcionais.