Spectroscopic and biological testing of photobleaching of porphyrins in solutions.
Fiche publication
Date publication
août 1996
Journal
Photochemistry and photobiology
Auteurs
Membres identifiés du Cancéropôle Est :
Pr BARBERI-HEYOB Muriel, Dr BEZDETNAYA-BOLOTINE Lina, Pr MERLIN Jean-Louis
Tous les auteurs :
Bezdetnaya L, Zeghari N, Belitchenko I, Barberi-Heyob M, Merlin JL, Potapenko A, Guillemin F
Lien Pubmed
Résumé
The photobleaching of protoporhyrin IX (PP IX) and hematoporphyrin derivative (HpD) solutions was followed using three different methods: spectrophotometry, fluorometry and photodynamically induced cytotoxicity. The latter entails photoirradiation of HT29 human colon adenocarcinoma cells in the presence of preirradiated solutions of HpD and PP IX (lambda < or = 415 nm). The highest cytotoxicity was observed in the presence of unirradiated dye and decreased with the time of preirradiation. This decay in photocytotoxicity was further used to determine the porphyrin photobleaching kinetics in solution. For both sensitizers, quantum yields of photobleaching obtained by matching fluorescence were higher than that obtained from absorbance measurements (10 and 11 times for HpD and PP IX, respectively). This difference reflects preferential photobleaching of photolabile monomeric forms compared to aggregated. The highest quantum yield was obtained in the biological test (decay in cytotoxicity) which was 14 times higher for HpD and 30 times higher for PP IX than the quantum yield obtained from absorbance measurements. The absence of correlation between biological and fluorescence measurements has to be taken into account in the in vivo situation. Dark storage of preirradiated sensitizers (37 degrees C, 24 h) completely restored photocytotoxity for PP IX but only partially for HpD, whereas fluorescence patterns were partially restored for both sensitizers.
Mots clés
Fluorometry, HT29 Cells, drug effects, Hematoporphyrin Derivative, chemistry, Humans, Photochemistry, Photochemotherapy, Photosensitizing Agents, chemistry, Protoporphyrins, chemistry, Solutions, Spectrophotometry
Référence
Photochem. Photobiol.. 1996 Aug;64(2):382-6