PORPHYRIN PHOTOSENSITIZATION AND REACTIVE OXYGEN SPECIES SCAVENGERS PROTECTION IN 5- AMINOLEVULINIC ACID- BASED PHOTODYNAMIC THERAPY

HAYDÉE FUKUDA ; MARÍA JULIETA TEIJO ; MARÍA DEL CARMEN MARTINEZ; MARÍA VICTORIA ROSSETTI; ALCIRA BATLLE

Congreso; LXI Reunión Científica de la Sociedad Argentina de Investigación Clínica. Organizadores: Sociedad Argentina de Investigación Clínica.; 2016

(802) PORPHYRIN PHOTOSENSITIZATION AND REACTIVE OXYGEN SPECIES SCAVENGERS PROTECTIONIN 5- AMINOLEVULINIC ACID- BASED PHOTODYNAMICTHERAPYHaydée Fukuda1, María Julieta Teijo1, María del Carmen Martínez 2, María Victoria Rossetti1, Alcira Batlle1.1Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP, CONICET_UBA). Hospital de Clínicas José de SanMartín. Av Córdoba 2351. 1120 AAR, CABA 2Departamentode Química Biológica, Facultad de Ciencias Exactas y Naturales, UBA. Pab II, Ciudad Universitaria. 1428 EHA, CABAPhotosensitization of endogenously synthesized porphyrinsafter administration of 5- aminolevulinic acid (ALA), are used inPhotodynamic Therapy of tumours and microorganisms infections.Irradiation with appropriate wavelength light triggers photochemical reactions and ROS production are induced, leading to celldeath. Several ROS scavengers agents (ascorbate , trolox, mannitol, GSH, l-tryptophan) were assayed to their ability to modulateALA-PDT performed on A549 human lung adenocarcinoma cells,by incubating 3h with 1mM ALA, followed by irradiation with orwithout 1 h pre-incubation with the modulators. The ratio betweencell survival after ALA-PDT in the presence and in the absence ofthe scavenger agent (protection grade: PG) was determined, andthe concentrations showing no cytotoxicity/ photoactivity and providing the highest PG were used. ALA-PDT alone induced a highpercentage of apoptotic cell death (98.4±3.5%). Pre-incubationwith modulators at their highest PG concentration signifcantlyreduced apoptotic cells to 48.3±2.7% (ascorbate), 58.8±4.2%(trolox), 78.5±3.1% (GSH), 64.3±1.6% (mannitol), and 74.6±2.3%(l-tryptophan). ROS production in early cell death induction afterALA-PDT was tested by flow cytometry; ROS increased afterALA-PDT (H2-DCFDA + cells: control: 1.1±0.1%; 10 min-PDT:69.3±5.6%; MVP positive cells: control: 0.65±0.35%; 10 min-PDT:83.5±1.9%). Ascorbate prevented peroxide formation and singletoxygen increased, whereas trolox limited peroxides generation, butdid not affect signifcantly singlet oxygen production. These resultssuggest that undesired photodamage to normal tissue might beattenuated by antioxidant agents administration, showing strongcorrelation between porphyrins, ROS production, scavengers andcell death, reinforcing the photodynamic properties of endogenously synthesized porphyrins, which are of high relevance inthe photosensitization of porphyric patients.