Share Email Print
cover

Proceedings Paper

Photophysical and photochemical properties of Bauhinia megalandra (Caesalpinaceae) extracts as new PDT photosensitizer
Author(s): Franklin Ramon Vargas Tovar; C. Rivas; O. Estrada; Aristides Alfredo Marcano O.; Lorenzo Echevarria; Yrene Diaz; I. Alexander; L. Rodriguez; L. Padron; I. Ramon Rivera
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

Recently new photosensitizers, chlorophyll "a and b" derivatives, for photodynamic therapy (PDT) have been presented. It already passed complete pre-clinical investigations. This prompted us to carry out an extensive study of photophysical properties of chlorine derivatives, important both for optimization of their clinic applications and for study of mechanisms of chlorine PDT&. The fresh leaves of Bauhinia megalandra (Caesalpinaceae) were extracted with methanol by percolation, and re-extract with a mixture of methanol-water (1:1), the insoluble fraction was then separated by column chromatography [RP18/hexane-ethylacetate (9:1)] to obtain four fractions named 1 to 4. These compounds were identified by NMR data. We found that 3 and 4 efficiently generates singlet oxygen when irradiated with visible light. Detection of the singlet oxygen was fulfilled by its reaction with histidine and detected by bleaching p-nitrosodimethylaniline under 440 nm irradiation. The quantum yields of singlet oxygen determined by us were 0.088 (1), 0.151 (2), 0.219 (3) and 0.301 (4). We measured absorption and fluorescence spectra of compounds 1 to 4 (Mg-chlorophyll-a, Pheophytin, Mg-chlorophyll-b and chlorophyll-b respectively) in different media and in aqueous solutions of human serum albumin. The association constant of the compounds 1, 2, 3 and 4 in the presence of HSA were estimated. The binding and quenching studies suggest that only 1 and 3 may serve as a useful fluorescence probe for structure/function studies of different chlorophyll binding proteins. No photoinduced binding was observed after irradiation by all the studied compounds in presence of human serum albumin.

Paper Details

Date Published: 21 October 2004
PDF: 7 pages
Proc. SPIE 5622, 5th Iberoamerican Meeting on Optics and 8th Latin American Meeting on Optics, Lasers, and Their Applications, (21 October 2004); doi: 10.1117/12.589314
Show Author Affiliations
Franklin Ramon Vargas Tovar, Instituto Venezolano de Investigaciones Cientificas (Venezuela)
C. Rivas, Instituto Venezolano de Investigaciones Cientificas (Venezuela)
O. Estrada, Univ. Central de Venezuela (Venezuela)
Aristides Alfredo Marcano O., Instituto Venezolano de Investigaciones Cientificas (Venezuela)
Lorenzo Echevarria, Instituto Venezolano de Investigaciones Cientificas (Venezuela)
Yrene Diaz, Instituto Venezolano de Investigaciones Cientificas (Venezuela)
Univ. Central de Venezuela (Venezuela)
I. Alexander, Univ. Santa Maria (Venezuela)
L. Rodriguez, Instituto Venezolano de Investigaciones Cientificas (Venezuela)
Univ. Central de Venezuela (Venezuela)
L. Padron, Instituto Venezolano de Investigaciones Cientificas (Venezuela)
Univ. Central de Venezuela (Venezuela)
I. Ramon Rivera, Instituto Venezolano de Investigaciones Cientificas (Venezuela)


Published in SPIE Proceedings Vol. 5622:
5th Iberoamerican Meeting on Optics and 8th Latin American Meeting on Optics, Lasers, and Their Applications

© SPIE. Terms of Use
Back to Top