title: Photochemistry of norharmane in aqueous solution.
abstract: The photochemistry of norharmane (9H-pyrido[3,4-b]indole) in acidic (pH 5.0+/-0.1) and alkaline (pH 10.0+/-0.1) aqueous solutions was studied. The photochemical reactions were monitored by TLC, UV/VIS absorption spectroscopy, high-performance liquid chromatography (HPLC), electronic ionization-mass spectrometry (EI-MS), UV-laser desorption/ionization-time of flight-mass spectrometry (UV-LDI-TOF-MS) and an enzymatic method for H2O2 determination. The neutral (nHoN) and the protonated (nHoH+) forms of norharmane irradiated under Ar atmosphere were photostable, but they suffered a photochemical transformation in the presence of O2, yielding as photoproducts norharmane dimers, trimers and tetramers. nHoN shown to be more photostable than nHoH+. The nHoH+ and nHoN consumption quantum yields were 1.82x10(-3) and 0.51x10(-3), respectively, and the mechanisms involved in its photochemistry are discussed. H2O2 and singlet oxygen (1O2) were also detected and quantified in irradiated solutions of norharmane, and their role in the photochemistry of norharmane is discussed.
authors.affiliation: CIHIDECAR-CONICET, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, 3p, Ciudad Universitaria, 1428, Buenos Aires, Argentina.
authors.forename: M Micaela
authors.initials: MM
authors.lastname: Gonzalez
authors.forename: M Laura
authors.initials: ML
authors.lastname: Salum
authors.forename: Yousef
authors.initials: Y
authors.lastname: Gholipour
authors.forename: Franco M
authors.initials: FM
authors.lastname: Cabrerizo
authors.forename: Rosa
authors.initials: R
authors.lastname: Erra-Balsells
mesh_terms: D002243:Carbolines; D006247:Harmine / Q000031:analogs & derivatives* / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D009153:Mutagens / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry*
chemical_list: D002243:Carbolines; D009153:Mutagens; D017382:Reactive Oxygen Species; D012996:Solutions; D014867:Water; D026082:Singlet Oxygen; D006247:Harmine; C010262:norharman; D006861:Hydrogen Peroxide; D010100:Oxygen