title: Ultrafast excited-state dynamics of kynurenine, a UV filter of the human eye.
abstract: The excited-state dynamics of kynurenine (KN) has been examined in various solvents by femtosecond-resolved optical spectroscopy. The lifetime of the S(1) state of KN amounts to 30 ps in aqueous solutions, increases by more than 1 order of magnitude in alcohols, and exceeds 1 ns in aprotic solvents such as DMSO and DMF, internal conversion (IC) being shown to be the main deactivation channel. The IC rate constant is pH independent but increases with temperature with an activation energy of about 7 kJ/mol in all solvents studied. The dependence on the solvent proticity together with the observation of a substantial isotope effect indicates that hydrogen bonds are involved in the rapid nonradiative deactivation of KN in water. These results give new insight into the efficiency of KN as a UV filter and its role in cataractogenesis.
authors.affiliation: International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia. sherin@tomo.nsc.ru
authors.forename: Peter S
authors.initials: PS
authors.lastname: Sherin
authors.forename: Jakob
authors.initials: J
authors.lastname: Grilj
authors.forename: Yuri P
authors.initials: YP
authors.lastname: Tsentalovich
authors.forename: Eric
authors.initials: E
authors.lastname: Vauthey
mesh_terms: D005123:Eye / Q000737:chemistry*; D006801:Humans; D007737:Kynurenine / Q000031:analogs & derivatives / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013696:Temperature; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D007737:Kynurenine