title: Towards an insight on photodamage in hair fibre by UV-light: An experimental and theoretical study.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  The biochemistry concerning these reactions is essentially important for a biological system where the degradation of Trp occurs.
authors.affiliation: INCTMN, Universidade Estadual Paulista, P.O. Box 355, CEP 14801-907, Araraquara, SP, Brazil.
authors.forename: V M
authors.initials: VM
authors.lastname: Longo
authors.forename: A
authors.initials: A
authors.lastname: da Silva Pinheiro
authors.forename: J R
authors.initials: JR
authors.lastname: Sambrano
authors.forename: J A M
authors.initials: JA
authors.lastname: Agnelli
authors.forename: E
authors.initials: E
authors.lastname: Longo
authors.forename: J A
authors.initials: JA
authors.lastname: Varela
mesh_terms: D006197:Hair / Q000737:chemistry* / Q000528:radiation effects*; D006801:Humans; D007737:Kynurenine / Q000031:analogs & derivatives / Q000032:analysis; D056004:Molecular Dynamics Simulation; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry*; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: C007772:N'-formylkynurenine; D007737:Kynurenine; D014364:Tryptophan
keywords: N-formylkynurenine; ab initio calculation; hair fibre; kynurenine; photodegradation; tryptophan