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.

Metabolic activation enhances the cytotoxicity, genotoxicity and mutagenicity of two synthetic alkaloids with selective effects against human tumour cell lines.

The pharmacological potential of drugs must be evaluated to establish their potential therapeutic benefits and side effects. This evaluation includes assessment of the effects of hepatic enzymes that catalyse their metabolic activation. Previously, our research group synthesized and characterized a set of synthetic 3-alkyl pyridine alkaloid (3-APA) analogues that cause in vitro cytotoxic, genotoxic, and mutagenic effects in various human cancer cell lines. The present study aimed to evaluate these activities with the two most promising synthetic 3-APAs (3-APA 1 and 3-APA 2) against cell lines derived from breast cancer (MDA-MB-231), ovarian cancer (TOV-21 G) and lung fibroblasts (WI-26-VA4) with and without metabolic activation (S9 fraction). The cytotoxicity of the compounds was evaluated employing MTT and clonogenic assays. In addition, comet assays, γH2AX immunocytochemistry labelling assays and cytokinesis-block micronucleus tests were carried out to evaluate the potential of these compounds to induce chromosomal damage. The results obtained in the MTT assay showed that compound 3-APA 2 exhibited high selectivity index (SI) values (ranging between 21.0 and 92.6). In addition, the cytotoxicity of the compounds was clearly enhanced by metabolic activation. Moreover, both compounds were genotoxic and induced double-strand breaks in DNA and chromosomal lesions with and without S9. The cancer cell lines tested showed higher genotoxic sensitivity to the compounds than did the non-tumour cell line used as a reference. The genotoxic and mutagenic effects of the compounds were potentiated in experiments with metabolic activation. The data obtained in this study indicate that compound 3-APA 2 is more active against the human cancer cell lines tested, both with and without metabolic activation, and can therefore be considered a candidate drug to treat human ovarian and breast cancer.

Nanoemulsion composed of 10-(4,5-dihydrothiazol-2-yl)thio)decan-1-ol), a synthetic analog of 3-alkylpiridine marine alkaloid: development, characterization, and antimalarial activity.

Malaria treatment is based on a reduced number of antimalarial drugs, and drug resistance has emerged, leading to the search for new antimalarial drugs incorporated into pharmaceutical formulations. In this study, 10-(4,5-dihydrothiazol-2-yl)thio)decan-1-ol) (thiazoline), a synthetic analog of 3-alkylpiridine marine alkaloid, and a potent antimalarial substance, was incorporated into O/W nanoemulsion. This formulation was prepared by a 23 factorial design. It was characterized by globule diameter, polydispersity index, zeta potential, encapsulation efficiency, in vitro thiazoline release at pH 2 and 6.86, and accelerated stability. In vitro and in vivo antimalarial activity was determined against P. falciparum and P. berghei, respectively. Thiazoline nanoemulsion showed 248.8 nm of globule diameter, 0.236 of polydispersity index, -38.5 mV of zeta potential, 96.92% encapsulation efficiency, and it was stable for 6 months. Thiazoline release profiles differed in acidic and neutral media, but in both cases, the nanoemulsion controlled and prolonged the thiazoline delivery. Thiazoline nanoemulsion exerted in vitro antimalarial activity against the parasite (IC50 = 1.32 µM), and it significantly reduced the in vivo parasitemia for 8 days without increasing the survival time of animals. Therefore, the thiazoline nanoemulsion represents a strategy to treat malaria combining an antimalarial candidate and a new nanocarrier.

Improvement of antimalarial activity of a 3-alkylpiridine alkaloid analog by replacing the pyridine ring to a thiazole-containing heterocycle: Mode of action, mutagenicity profile, and Caco-2 cell-based permeability.

The development of new antimalarial drugs is urgent to overcome the spread of resistance to the current treatment. Herein we synthesized the compound 3, a hit-to­lead optimization of a thiazole based on the most promising 3-alkylpyridine marine alkaloid analog. Compound 3 was tested against Plasmodium falciparum and has shown to be more potent than its precursor (IC50 values of 1.55 and 14.7 µM, respectively), with higher selectivity index (74.7) for noncancerous human cell line. This compound was not mutagenic and showed genotoxicity only at concentrations four-fold higher than its IC50. Compound 3 was tested in vivo against Plasmodium berghei NK65 strain and inhibited the development of parasite at 50 mg/kg. In silico and UV-vis approaches determined that compound 3 acts impairing hemozoin crystallization and confocal microscopy experiments corroborate these findings as the compound was capable of diminishing food vacuole acidity. The assay of uptake using human intestinal Caco-2 cell line showed that compound 3 is absorbed similarly to chloroquine, a standard antimalarial agent. Therefore, we present here compound 3 as a potent new lead antimalarial compound.

New 3-alkylpyridine marine alkaloid analogues as promising antitumor agents against the CD44+/high /CD24-/low subset of triple-negative breast cancer cell line.

Triple-negative breast cancer (TNBC) is one of the most aggressive cancers in women. Additionally, presence of residual cancer stem cells (CSC) in TNBC has challenged the efficacy of chemotherapy. Thus, the development of new molecules with potential action against CSC is fundamental. In this study, six synthetic analogues of theonelladin C, a 3-alkylpyridine marine alkaloid, were tested for cytotoxic activity against human TNBC cell line (BT-549) and tumorspheres derived from BT-549. Cytotoxicity assay was performed by sulforhodamine B (SRB). BT-549 and tumorspheres were examined for CD44+/high /CD24-/low markers, indicative of CSC profile, by flow cytometry. Clonogenic assay was performed to verify inhibiting growth of tumorspheres by the synthetic analogues. Cell death by apoptosis was investigated employing annexin V assay. SRB assay on BT-549 cells revealed that compounds 1c and 2c were the most active of the series, with IC50 values of 18.66 and 9.8 µm, respectively. Compounds 1c and 2c were able to reduce both CSC-like population (CD44+/high /CD24-/low ) and non-CSC population (CD44+/high /CD24+/high ) in tumorsphere model. Clonogenic and annexin V assays confirmed the ability of 1c and 2c to induce growth inhibition and apoptosis in BT-549 cells and tumorspheres. These preliminary data indicate that these compounds are a promising class for development of anticancer agents.

Synthesis and biological evaluation of novel 3-alkylpyridine marine alkaloid analogs with promising anticancer activity.

Cancer continues to be one of the most important health problems worldwide, and the identification of novel drugs and treatments to address this disease is urgent. During recent years, marine organisms have proven to be a promising source of new compounds with action against tumoral cell lines. Here, we describe the synthesis and anticancer activity of eight new 3-alkylpyridine alkaloid (3-APA) analogs in four steps and with good yields. The key step for the synthesis of these compounds is a Williamson etherification under phase-transfer conditions. We investigated the influence of the length of the alkyl chain attached to position 3 of the pyridine ring on the cytotoxicity of these compounds. Biological assays demonstrated that compounds with an alkyl chain of ten carbon atoms (4c and 5c) were the most active against two tumoral cell lines: RKO-AS-45-1 and HeLa. Micronucleus and TUNEL assays showed that both compounds are mutagenic and induce apoptosis. In addition, Compound 5c altered the cellular actin cytoskeleton in RKO-AS-45-1 cells. The results suggest that Compounds 4c and 5c may be novel prototype anticancer agents.