Avaliação da atividade e do mecanismo de ação de derivados de pentamidina em diferentes espécies de Leishmania

Abstract

Leishmaniasis includes diseases caused by more than 20 species of protozoa of the genus Leishmania, and is a global public health problem. Chemotherapy is the main treatment, but it has high toxicity, high cost, side effects and parasite resistance, highlighting the need for new therapeutic options. Pentamidine, although effective, is highly toxic, which motivates the search for derivatives with lower toxicity. This study evaluated the leishmanicidal activity of pentamidine derivatives (PQM 250 to PQM 262) in Leishmania (L.) amazonensis and Leishmania (L.) infantum chagasi and their toxicity in mammalian macrophages. In addition, the mechanism of action of the promising compounds was investigated, focusing on mitochondrial bioenergetics through mitochondrial membrane potential and ATP production, oxidative stress through the production of hydrogen peroxide production (H2O2), NADPH and trypanothione reductase (TryR) activity, as well as apoptosis, in silico and in vivo studies. The compounds PQM 250, PQM 254 and PQM 261 showed significant activity against promastigote and amastigote forms in the two species studied and with lower toxicity, being selected for mechanism of action studies. The results with Leishmania (L.) amazonensis showed that pentamidine and PQM 254 caused mitochondrial depolarization (10.9 and 10.44%, respectively) while PQM 261 induced hyperpolarization (13.16%). PQM 261 also increased ATP and NADPH production (32 and 18.35%, respectively), while pentamidine reduced these parameters (73 and 35.86%, respectively), as well as reducing H2O2 production (37.9%) and promoting apoptosis. PQM 250 increased H2O2 and NADPH production (18.9 and 14.89%, respectively), inhibiting TryR by 21%, thus causing a redox imbalance. PQM 254 reduced H2O2 production by 41.7%, but inhibited TryR by 13.38%, impairing redox homeostasis. With regard to Leishmania (L.) infantum chagasi, the preliminary results show that the compounds PQM 254 and PQM 261 promoted an increase of 211.3% and 311.3% in the concentration of H2O2, respectively, and that only the compound PQM 254 showed a significant reduction of 21.6% in NADPH rates compared to the control group. In the in vivo tests, qPCR showed that the PQM 250 and 254 compounds significantly reduced the parasite load in the liver and spleen of the animals compared to the control group. The data suggest that pentamidine derivatives show promise in the development of more effective therapies against Leishmaniasis by interfering with critical mechanisms related to the parasite's survival. This study offers valuable insights into the metabolic pathways on which the compounds affect, providing an important basis for future therapeutic approaches.