Photodynamic effects of zinc phthalocyanines on intracellular amastigotes of Leishmania amazonensis and Leishmania braziliensis

This study investigated the photoactivity of four zinc phthalocyanines (PcZns) on a murine macrophage cell line infected with Leishmania amazonensis or Leishmania braziliensis. Infected and uninfected cells were incubated with PcZns at different concentrations (1–10 μM) for 3 h and then exposed to an LED device in continuous wave mode at 660 nm with a fluency of 50 J/cm² (25 mV). Enzymatic activity was determined by MTT assay 24 h after light treatment. The results demonstrated that all PcZns exhibited high photoactivity, particularly when used at 10 μM. The photodynamic effects were different for uninfected cells versus parasite-infected cells and among the four PcZns. Uninfected cells were more sensitive to photoactivity than infected cells. Although PcZns photodynamic therapy provided promising results, further studies are necessary to better understand its mechanism of action in the treatment of leishmaniasis.