Assessment of Leishmania major and Leishmania braziliensis promastigote viability after photodynamic treatment with aluminum phthalocyanine tetrasulfonate (AlPcS4)

Cutaneous leishmaniasis is an infectious disease caused by protozoans of the genus Leishmania, which is transmitted through the bite of hematophagous insects of the genus Lutzomyia. This study aimed at testing in vitro the phototoxic effect of aluminum phthalocyanine tetrasulfonate (AlPcS4) on the viability of Leishmania major and Leishmania braziliensis. Stationary phase promastigote forms were treated with AlPcS4 at 1.0 μM and 10.0 μM and incubated for one hour. Then 659 nm laser was applied at 5 and 10 J/cm2. Parasite viability was determined by differential count using the trypan blue dye exclusion method and by monitoring growth curves for nine days. Trypan blue exclusion assay showed a significant reduction of viable parasites compared to controls, L. major seemed more sensitive to the toxic effects of AlPcS4 in the dark. The most effective photodynamic therapy (PDT) was obtained with AlPcS4 at 10.0 μM and 10 J/cm2 whereas L. braziliensis showed the highest mortality rate after treatment.