Avaliação do efeito sinérgico dos compostos protoporfirina IX e azure A incorporados na forma mista em sistemas micelares nanoestruturados

Abstract

Photodynamic therapy (PDT) is the combination of a photosensitizing compound and suitable wavelength of light in the presence of oxygen. The drugs, called photosensitizers (PS), must have some favorable characteristics to the technique, such as low dark toxicity and high absorption of light in "phototherapeutic window". This clinical modality can be used in the treatment of diseases that have in common the abnormal growth of cells, such as cancer or, in the photodynamic inactivation of microorganisms (PDI). The search for new drugs has shown that porphyrins and phenothiazines compounds are promising photosensitizers for PDT/PDI. The application of these compounds can have their photodynamic action enhanced by the combination of both, fact which may act synergistically in the degree of cell death. Thus, this study aimed to formulate a mixed system containing the photosensitizers Protoporphyrin IX and Azure A in polymeric micelles of P-123. This system has the advantage of both dyes absorb light in the same wavelength region (630 nm). The photosensitizers were maintained in monomeric form for a long period, either in single or combined form, demonstrating that the formulation process was satisfactory. The analysis indicated that Protoporphyrin IX, more hydrophobic, is internalized in the micelle, while the Azure A is on the interface micelle/water. The increase in ionic strength, a parameter which favors self-aggregation of the dye, it seems to impact only on Azure A. This indicates that this dye is more exposed to aqueous environment, which agrees with the localization studies. Finally, the values of Chemical Photodynamic Efficiency () suggested that in the mixed formulation the generation of singlet oxygen is caused only by the Azure A, which can be associated to the internal location of the porphyrin or because their self-aggregation.