In vitro cytotoxic and leishmanicidal activity of isolated and semisynthetic ent-pimaranes from Aldama arenaria

Two pimaranes ent-pimara -8(14),15-dien-19-oic acid (1) and ent-8(14),15-pimaradien-3β-ol (2), isolated from Aldama arenaria, and six semi-synthetic derivatives methyl ester of the ent-pimara-8(14),15-dien-19-oic acid (3), ent-pimara-8(14),15-dien-19-ol (4), acetate of ent-pimara-8(14),15-dien-19-ol (5), ent-pimara-8(14),15-dien-19-ol succinic acid (6), acetate of ent-8(14),15-pimaradien-3β-ol (7), ent-8(14),15-pimaradien-3β-ol succinic acid (8) were evaluated in vitro for their cytotoxic activities to childhood leukemia cell lines and leishmanicidal activity against the parasite Leishmania amazonensis. Among these compounds, 1 to 6 presented moderate cytotoxic activity, with compound 4 being the most active (GI50 of 2.6 µM for the HL60 line) and the derivatives 7 and 8 inactive. Against the parasite Leishmania amazonensis, the most promising derivative was acetate of ent-pimara-8(14),15-dien-19-ol (5), with EC50 of 20.1 µM, selectivity index of 14.3, and significant reduction in the parasite load. Pimarane analogues 1, ent-pimara-8(14),15-dien-19-oic acid, and 2, ent-8(14),15-pimaradien-3β-ol, presented different activities, corroborating the application of such molecules as prototypes for the design of other derivatives that have greater cytotoxic or leishmanicidal potential.

A Ligand-Based Approach to Lead Optimization of N, Nʹ-Substituted Diamines for Leishmanicidal Activity

Several N, N-substituted diamines such as putrescine and N-monoalkylated derivatives have demonstrated potential as lead compounds against Leishmania donovani at submicromolar levels. There is a need to refine available diamines for enhanced leishmanicidal activity. A 3D-QSAR by Comparative molecular field analysis (CoMFA) on a series of tested diamines for their activities against L. donovani was conducted to understand better the mechanism of action and SARs of the compounds. The model was constructed with AM1 energy minimized conformers of the training set compounds (n=20) by the PLS algorithm method, cross-validated by the method of leave-one-out (LOO), and externally validated using the test set compounds (n=5). A robust model with high predictability of untested compounds was obtained for 2PC (latent variables). The coefficients of determinations for PLS regression R2, internal cross-validation, Q2 and external prediction P2 were 0.97 (SDEC=0.095), 0.82 (SDEP=0.102) and 0.73 (SDEP=0.115) respectively with F-value 618.8 for 2PC. The model coefficients graphically translated into contour maps showed regions where steric (62 %) and electrostatic (38 %) properties influence the leishmanicidal activity of the compounds. In addition to the optimum chain length (n=4), a steric effect at position 4 alone or combined with the electrostatic effect at position 3 of the diamine backbone significantly enhanced the leishmanicidal activity. It could further be explored for even higher activity. The model supported the empirical data, which identified N, N'-substituted diamine as the scaffold for leishmanicidal activities and further provided insights for further optimization of the lead compound.

ALTERNATIVAS FARMACOLÓGICAS PROMISSORAS PARA O TRATAMENTO DA LEISHMANIOSE

Introdução: A leishmaniose é um complexo de doenças ocasionadas por protozoários do gênero Leishmania, que ainda caracteriza-se como emergente e sem controle, com uma incidência anual de 1,5 a 2 milhões de casos. Dentre as opções de tratamento existentes, a farmacoterapia é a mais ideal, entretanto, limitada, pois a maioria destas drogas apresentam elevada toxicidade e ocasionam efeitos adversos graves. Assim, impulsionando a busca por fármacos mais efetivos e menos tóxicos. Objetivos: Apresentar novas farmacoterapias promissoras no tratamento da leishmaniose. Material e métodos: Trata-se de uma revisão de literatura produzida a partir da análise de estudos científicos no idioma inglês, publicados entre os anos de 2018 e 2021. A pesquisa foi realizada nos bancos de dados ScienceDirect e LILACS, utilizando os descritores: “leishmania potential drugs”, “anti-leishmania drugs” e “leishmanicidal activity”. Inicialmente, dos 621 estudos encontrados nas bases de dados, vinte foram selecionados para leitura e fichamento, dos quais, o total de dez enquadraram-se no tema, por contemplarem de forma concisa os objetivos da revisão. O critério de exclusão, por sua vez, foi a não correlação direta dos artigos com os objetivos do trabalho. Resultados: As recentes pesquisas têm apresentado inúmeras alternativas terapêuticas promissoras para o tratamento da leishmaniose, por meio de fármacos projetados com base em moléculas de atividade já conhecida, porém de maior atividade e menor potencial tóxico. Neste sentido, derivados indol-tiossemicarbazonas demonstraram efeitos leishmanicidas, após levar o parasita à inviabilidade celular e exibir baixa citoxicidade em células animais. Ensaios envolvendo um derivado quinolina, por sua vez, apresentaram uma redução significativa na carga parasitária, além de baixos níveis de toxicidade e propriedades farmacocinéticas adequadas. Além disso, diferentes estudos envolvendo complexos metálicos ligados a trimetroprima e diclofenaco, apontaram considerável atividade leishmanicida e menor citotoxicidade, para ambos os candidatos. A literatura relata ainda, a existência de incontáveis outras moléculas em análise, que possuem o conjunto de critérios necessários para sua aplicação como agentes anti-leishmania. Conclusão: As evidências sugeriram que existem diversas possibilidades de novos fármacos leishmanicidas que apresentam efetividade e segurança, o que, só reforça a necessidade do desenvolvimento destes estudos para definir melhorias nos tratamentos da doença.

Anti-Leishmanial Activity of Artemisia persica, A. spicigera, and A. fragrance against Leishmania major

Background: Neglected tropical diseases (NTDs) like zoonotic cutaneous leishmaniasis (ZCL), is a widespread infectious disease with high mortality and morbidity. Various medications are used for treating the disease, but several side effects and drug resistance have been reported. Herbal medicines are unlimited sources for discovering new medications to treat infectious diseases. We aimed to determine the leishmanicidal activity of three species of Iranian Artemisia herbal plant extracts in in-vitro. Methods: In-vitro anti-leishmanial activity of ethanolic extracts on both promastigotes and amastigotes was determined by using MTT method. IC50, CC50, EC50 and SI were calculated. The study was done in 2019-2020 in Iran University of Medical Sciences, Tehran, Iran. Results: All of the three Artemisia species significantly reduced the number of parasite promastigotes. Among them, A. persica had the highest leishmanicidal activity against parasite promastigotes. Cytotoxicity assay elucidated that the Artemisia had no toxicity to the host cells, and killed the L. major amastigotes very efficiently. By increasing the dose of extracts, the parasite number in both phases (promastigotes and amastigotes) was reduced significantly. Conclusion: These results indicated satisfactory anti-leishmanial activity of Artemisia extracts against ZCL in-vitro. Accordingly, Artemisia ethanolic extracts might be considered as a strong, effective and safe herbal compound for clearing the L. major with less toxicity to the host macrophages cells. Hence, it may be recognized as an excellent herbal therapy for treating the ZCL.

Leismanicidal Activity of Propolis Collected in the Semiarid Region of Brazil

Objective: The aim of the current study is to investigate the chemical composition, cytotoxic effect, and leishmanicidal activity of propolis collected in the semi-arid region of Bahia, Brazil.Methods: EtOH extract, hexane, EtOAc and MeOH fractions from propolis were analyzed by ultra-performance liquid chromatography coupled with diode array detector and quadrupole time-of-flight mass spectrometry. The identification was based on the exact mass, general fragmentation behaviors and UV absorption of the flavonoids. The in vitro cytotoxic effect and leishmanicidal activity of ethanolic extract, hexane, ethyl acetate, and methanolic fractions of propolis were evaluated.Results: Five triterpenes and twenty-four flavonoids were identified. The propolis did not present toxicity to the host cell up to the maximum concentration tested. In addition, all tested samples showed statistically significant activity against promastigotes of Leishmania chagasi and Leishmania amazonensis. Regarding the activity against amastigote forms of L. amazonensis, the hexane fraction, presented statistically significant activity with IC50 of 1.3 ± 0.1 μg/ml.Conclusion: The results support the idea that propolis can be used for future antileishmania studies.

Flavonoides isolados de Sida santaremnensis H. Monteiro (“Guanxuma”) e avaliação das atividades biológicas

Introduction: Sida santaremnensis H. Monteiro (Malvaceae) is a plant popularly known as "vassourinha" or "guanxuma" that has been described as vasorelaxant, antiulcerogenic, antinociceptive and antiedematogenic. Objective: To contribute with the phytochemical and pharmacological profile of Sida santaremnensis through the isolation, purification and determination of chemical constituents of this plant, as well as through the evaluation of the anti-inflammatory and antitumor activity and leishmanicidal effect of the isolated constituent in a greater amount. Methods: The isolation of substances from the plant herein studied was performed with column chromatographic and analytical thin-layer methods and structural determination made by spectroscopic methods, such as Nuclear Magnetic Resonance, Hydrogen and Carbon 13, and comparisons with data from the literature. To assess pharmacological activities, cell viability tests, determination of nitric oxide levels, leishmanicidal activity, among others, were performed. Results: Two flavonoids from S. santaremnensis were obtained, kaempferol (S-1) and kaepferol 3-O-β-D-glycosyl-6’’-α-L-rhamnoside (S-2), the latter in a greater amount. The evaluation of the antitumor activity of the glycosylated flavonoid demonstrated that it does not present hemolytic activity against the human promyelocytic leukemia cell line (HL-60), and that it presented weak leishmanicidal activity. The immunopharmacological evaluation of kaempferol 3-O-β-D-glucosyl-6’’-α-L-rhamnoside revealed that it presents a possible anti-inflammatory action related to the inhibition of the production of nitrite by LPS-stimulated macrophages. Conclusion: These data demonstrate that kaempferol 3-O-β-D-glucosyl-6’’-α-L-rhamnoside has low toxicity, in addition to antileishmania, anti-inflammatory and immunomodulatory properties, which makes it a therapeutic potential for infectious and inflammatory diseases mediated by macrophages.