Rational-Based Discovery of Novel ß-Carboline Derivatives as Potential Antimalarials: From In Silico Identification of Novel Targets to Inhibition of Experimental Cerebral Malaria.

Malaria is an infectious disease widespread in underdeveloped tropical regions. The most severe form of infection is caused by Plasmodium falciparum, which can lead to development of cerebral malaria (CM) and is responsible for deaths and significant neurocognitive sequelae throughout life. In this context and considering the emergence and spread of drug-resistant P. falciparum isolates, the search for new antimalarial candidates becomes urgent. ß-carbolines alkaloids are good candidates since a wide range of biological activity for these compounds has been reported. Herein, we designed 20 chemical entities and performed an in silico virtual screening against a pool of P. falciparum molecular targets, the Brazilian Malaria Molecular Targets (BRAMMT). Seven structures showed potential to interact with PfFNR, PfPK7, PfGrx1, and PfATP6, being synthesized and evaluated for in vitro antiplasmodial activity. Among them, compounds 3−6 and 10 inhibited the growth of the W2 strain at µM concentrations, with low cytotoxicity against the human cell line. In silico physicochemical and pharmacokinetic properties were found to be favorable for oral administration. The compound 10 provided the best results against CM, with important values of parasite growth inhibition on the 5th day post-infection for both curative (67.9%) and suppressive (82%) assays. Furthermore, this compound was able to elongate mice survival and protect them against the development of the experimental model of CM (>65%). Compound 10 also induced reduction of the NO level, possibly by interaction with iNOS. Therefore, this alkaloid showed promising activity for the treatment of malaria and was able to prevent the development of experimental cerebral malaria (ECM), probably by reducing NO synthesis.

Avaliação in silico e in vivo do perfil de metabolismo e toxicidade hepática de alcaloides ß-carbolínicos sintéticos com prévia atividade antimalárica / In silico and in vivo evaluation of the metabolism profile and hepatic toxicity of synthetic ß-carboline alkaloids with previous antimalarial activity

Introdução: A malária continua sendo um grave problema de saúde pública mundial, dado os elevados índices anuais de morbimortalidade. O tratamento baseia-se no uso de medicamentos, entretanto, a resistência dos parasitos aos medicamentos disponíveis tem se tornado uma realidade alarmante, o que torna urgente o desenvolvimento de novos fármacos com atividade antimalárica. Em um estudo prévio, selecionou-se três alcaloides ß-carbolínicos que apresentaram atividade antimalárica. Dessa forma, o presente trabalho se propôs a dar continuidade ao estudo dessas moléculas avaliando o perfil de metabolismo e toxicidade hepática. Objetivo: Avaliar o perfil de metabolismo e toxicidade hepática de três alcaloides ß-carbolínicos (1, 2 e 3) selecionados em estudo prévio, que apresentaram atividade antimalárica in vitro e in vivo.Material e Métodos: Trata-se de um estudo de abordagem tanto qualitativa quanto quantitativa com caráter experimental e analítico. Foi realizada análise in silico das propriedades de metabolismo e toxicidade dos alcaloides empregando a notação SMILES por meio do programa AdmetSAR 2.0. A toxicidade hepática foi avaliada por meio da análise bioquímica da aspartato aminotrasferase (AST) e alanina aminotransferase (ALT) no soro de camundongos da linhagem C57BL/6, tratados com os alcaloides ou com cloroquina. Resultados: Na análise in silico foi observada a predição de baixo potencial hepatotóxico para os alcaloides 1 e 2, sendo este resultado corroborado pela dosagem de ALT, que apresentou resultados semelhantes ao do grupo controle. O alcaloide 3, no entanto, apresentou dados contrastantes, indicando potencial hepatotóxico na predição in silico, porém, baixo potencial em análise in vivo, com valores de ALT também próximos do grupo controle. Todos os alcaloides em estudo apresentaram potencial para interações medicamentosas. Conclusão: Os alcaloides avaliados nesse estudo apresentaram parâmetros metabólicos e de toxicidade promissores, podendo ser bons adjuvantes à farmacoterapia da malária. Entretanto, esses resultados precisam ser confirmados para seguimento das moléculas nos estudos pré-clínicos.

Introduction: Malaria continues to be a serious global public health problem, given the high annual morbidity and mortality rates. It is caused by protozoa of the genus Plasmodium, with P. falciparum responsible for most serious cases and deaths. Treatment is based on the use of drugs, however, the resistance of parasites to available drugs has become an alarming reality, which makes the development of new drugs with antimalarial activity urgent. In a previous study, our research group selected three ß-carboline alkaloids that showed antimalarial activity. Therefore, the present work proposed to continue the study of these molecules by evaluating the metabolism profile and liver toxicity. Objective: To evaluate the metabolism and liver toxicity profile of three ß-carboline alkaloids (1, 2 and 3) selected in a previous study, which showed antimalarial activity in vitro and in vivo. Material and Methods: This is a study with both a qualitative and quantitative approach with an experimental and analytical nature. In silico analysis of the metabolism and toxicity properties of alkaloids was carried out using the SMILES notation through the AdmetSAR 2.0 program. Liver toxicity was evaluated through biochemical analysis of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the serum of mice of the C57BL/6 lineage, treated with the alkaloids or chloroquine. Results: In the in silico analysis, the prediction of low hepatotoxic potential for alkaloids 1 and 2 was observed, and this result was corroborated by the ALT dosage, which presented results similar to those of the control group. Alkaloid 3, however, presented contrasting data, indicating hepatotoxic potential in in silico prediction, however, low potential in in vivo analysis, with ALT values also close to the control group. All alkaloids under study showed potential for drug interactions. Conclusion: The alkaloids evaluated in this study showed promising metabolic and toxicity parameters and could be good adjuvants for malaria pharmacotherapy. However, these results need to be confirmed to follow the molecules in preclinical studies.