Photophysical and Photochemical Properties of Naturally Cccurring normelinonine F and Melinonine F Alkaloids and Structurally Related N(2)- and/or N(9)-methyl-beta-carboline Derivatives.
Rasse-Suriani, F. A. O., Garcia-Einschlag, F. S., Rafti, M., Leon, T. S., David Gara, P. M., Erra-Balsells, R. and Cabrerizo, F. M.
Instituto de Investigaciones Biotecnologicas - Instituto Tecnologico de Chascomus (IIB-INTECH)Universidad Nacional de San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Av. Intendente Marino Km 8.2, CC 164, (B7130IWA), Chascomus, Argentina.
INIFTA - CONICET, Universidad Nacional de La Plata, Diag. 113 y 64, (1900), La Plata, Argentina.
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Quimica Organica. Pabellon II, 3er P., Ciudad Universitaria, (1428), Buenos Aires, Argentina.
CONICET, Universidad de Buenos Aires, Centro de Investigacion en Hidratos de Carbono (CIHIDECAR), Facultad de Ciencias Exactas y Naturales. Pabellon II, 3er PCiudad Universitaria, (1428), Buenos Aires, Argentina.
Centro de Investigaciones Opticas (CIOP CONICET CIC), Universidad Nacional de La Plata, C.C. 3, (1897), La Plata, Argentina.
In the present work, we have synthesized and fully characterized the photophysical and photochemical properties of a selected group of N-methyl-beta-carboline derivatives (9-methyl-beta-carbolines and iodine salts of 2-methyl- and 2,9-dimethyl-beta-carbolinium) in aqueous solutions, in the pH-range 4.0 - 14.5. Moreover, despite the quite extensive studies reported in the literature regarding the overall photophysical behaviour of N-unsubstituted betaCs, this work constitutes the first full and unambiguous characterization of anionic species of N-unsubstituted betaCs (norharmane, harmane and harmine), present in aqueous solution under highly alkaline conditions (pH > 13.0). Acid dissociation constants (Ka ), thermal stabilities, room temperature UV-visible absorption and fluorescence emission and excitation spectra, fluorescence quantum yields (capital EF, CyrillicF ) and fluorescence lifetimes (tauF ), as well as quantum yields of singlet oxygen production (capital EF, CyrillicDelta ) have been measured for all the studied compounds. Furthermore, for the first time to our knowledge, chemometric techniques (MCR-ALS and PARAFAC) were applied on these systems, providing relevant information about the equilibria and species involved. The impact of all the foregoing observations on the biological role, as well as, the potential biotechnological applications of these compounds is discussed. This article is protected by copyright. All rights reserved.
Photochemistry and Photobiology : en prensa (2017)