title: Photodimerization of 7,8-dihydroneopterin in aqueous solution under UV-A irradiation.
abstract: 7,8-Dihydroneopterin (H(2) Nep) is secreted during the oxidative burst of stimulated macrophages. The photochemistry of H(2) Nep was investigated in neutral aqueous solutions exposed to UV-A radiation (320-400nm) at room temperature. The kinetics were followed by UV/Vis spectrophotometry and HPLC, whereas the photoproducts were analyzed by electrospray ionization mass spectrometry. Excitation of H(2) Nep leads to the formation of isomeric dimers with molecular masses equal to exactly twice the molecular mass of the reactant. The corresponding quantum yield of H(2) Nep consumption (Φ(-R) =(3.8±0.5)×10(-2)) was independent of O(2) and reactant concentrations. Mechanistic implications are discussed.
authors.affiliation: Departamento de Química, Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, CCT La Plata-CONICET, La Plata, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Vignoni
authors.forename: Mariana P
authors.initials: MP
authors.lastname: Serrano
authors.forename: Esther
authors.initials: E
authors.lastname: Oliveros
authors.forename: Andrés H
authors.initials: AH
authors.lastname: Thomas
mesh_terms: D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D008970:Molecular Weight; D019798:Neopterin / Q000031:analogs & derivatives* / Q000737:chemistry; D010777:Photochemistry; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D012996:Solutions; D014867:Water; C000976:7,8-dihydroneopterin; D019798:Neopterin