Prospecção in silico, in vitro e in vivo de derivados aminoquinolínicos e β-carbolínicos com potencial antimalárico

Abstract

With 241 million new cases and 650,000 deaths estimated in 2020, malaria remains one of the greatest public health challenges worldwide, with the highest incidence of cases (94%) in sub-Saharan Africa. Among the Plasmodium species responsible for human malaria, P. falciparum is the most prevalent in Africa and responsible for the most serious infection, cerebral malaria. In the absence of an effective vaccine and due to the spread of Plasmodium resistance to antimalarials available, there is an urgent need to develop new drugs that are effective against P. falciparum. In this context, alkaloids represent an important warning group that have been used as a tool in the search for new drugs. Among the different classes of alkaloids existing in nature, the quinoline and β-carboline stand out, which have different biological activities, including antimalarials. Based on this assumption, this work controlled synthetics of 4 aminoquinolines and β-carbolines for their antimalarial potential in silico and in vitro in order to select the most promising drugs for in vivo studies against experimental cerebral malaria (ECM). The β-carbolines were initially tested against 35 molecular targets of P. falciparum, selecting 7 with interaction with essential enzymes for the metabolism of the parasite, which could cause its death. The physicochemical and pharmacokinetic properties of absorption of these symptoms, as well as the quinoline derivatives, were symptoms using computational tools. Cytotoxicity parameters were evaluated in human lung fibroblasts (WI26VA4) and in human hepatocarcinoma cells (HepG2) and an antiplasmodial activity was evaluated against chloroquine-resistant P. falciparum strain (W2). A mechanism of action was investigated, in vitro, through interaction with ferriprotoporphyrin or following nitric oxide synthesis. Finally, in vivo antimalarial activity was determined by Peters' curative and/or suppressive testes, performed in C57BL/6 mice infected with P. berghei ANKA and treated with the drug candidates. In general, the molecules showed good oral bioavailability, predicted in silico, with low cytotoxicity and adequate selectivity for the parasites in the in vitro assays, highlighting quinolinic 3 and β-carbolinic 10. Quinolinic derivative 3 resulted in important parasite multiplication inhibition (IMP) values on the 7th day post infection (dpi) (76.9% (15mg/kg), 90.1% (30mg/kg) and 92.9% (50mg/kg)), with high survival rates to the critical period of ECM and a better liver and kidney toxicity profile than chloroquine. This result may be related to the interaction of the test compound with ferriprotoporphyrin, identified through an in vitro assay, preventing the formation of hemozoin crystals in the parasite's digestive vacuole, causing its death. Regarding the in vivo activity of β-carboline alkaloids, compound 10 showed important IMP values at the 5th dpi (67.92% (10mg/kg) and 82.07% (10mg/kg)) in the curative treatment scheme and suppressive, respectively, with high rates of survival to the critical period of ECM and absence of hemorrhage and vascular occlusion observed macro and microscopically in brain tissue. However, despite survival, the animals developed hyperparasitemia in the subsequent days, suggesting that the compound may have weak antimalarial activity in vivo, but adequate anti-inflammatory activity to prevent ECM. Such activity, determined in vitro through the reduction of nitric oxide synthesis by peritoneal macrophages stimulated and treated with the test compound, may be related to the interaction of compound 10 with the inducible nitric oxide synthase enzyme (iNOS) predicted through molecular modeling. Together, our results suggest that the two classes of compounds tested have important characteristics for antimalarial drugs, highlighting the quinolinic derivative 3 and the β-carbolinic 10 as HIT (bioactive) compounds, given their low IC50 values, high CC50 and IS, adequate pharmacokinetic absorption profile and in silico prediction of good oral bioavailability. We also suggest that the quinolinic derivative 3 is a candidate for an early lead compound, as it presents IC50 in nM scale, reduction of parasitemia with values above 90%, high survival rate, protection against the development of ECM, in addition to Liver and kidney safety. Therefore, the process of synthesizing the series of 4- aminoquinoline and β-carboline derivatives in this study was promising, producing antimalarial HITs.