RESUMO
As part of our continuous research for the discovery of bioactive compounds against Trypanosoma cruzi and Leishmania infantum, the alkaloid (6aS)-dicentrine (1) was oxidized to afford (6aS,6S)- (2) and (6aS,6R)- (3) dicentrine-N-oxides. Evaluation of the cytotoxicity against NCTC cells indicated that 2 and 3 are non-toxic (CC50>200 µM) whereas 1 demonstrated CC50 of 52.0 µM. Concerning T. cruzi activity against amastigotes, derivatives 2 and 3 exhibited EC50 values of 9.9 µM (SI>20.2) and 27.5 µM (SI>7.3), respectively, but 1 is inactive (EC50>100 µM). Otherwise, when tested against L. infantum amastigotes, 1 and 3 exhibited EC50 values of 10.3 µM (SI=5.0) and 12.7 µM (SI>15.7), respectively, being 2 inactive (EC50>100 µM). Comparing the effects of positive controls benznidazol (EC50=6.5 µM and SI>30.7) and miltefosine (EC50=10.2 µM and SI=15.2), it was observed a selective antiparasitic activity to diastereomers 2 and 3 against T. cruzi and L. infantum. Considering stereochemical aspects, it was suggested that the configuration of the new stereocenter formed after oxidation of 1 played an important role in the bioactivity against amastigotes of both tested parasites.
RESUMO
This study aimed to assess the antiprotozoal efficacy of dicentrine, an aporphine alkaloid isolated from Ocotea puberula, against amastigote forms of Leishmania (L.) infantum. Our findings reveal that dicentrine demonstrated a notable EC50 value of 10.3 µM, comparable to the positive control miltefosine (EC50 of 10.4 µM), while maintaining moderate toxicity to macrophages (CC50 of 51.9 µM). Utilizing an in silico methodology, dicentrine exhibited commendable adherence to various parameters, encompassing lipophilicity, water solubility, molecule size, polarity, and flexibility. Subsequently, we conducted additional investigations to unravel the mechanism of action, employing Langmuir monolayers as models for protozoan cell membranes. Tensiometry analyses unveiled that dicentrine disrupts the thermodynamic and mechanical properties of the monolayer by expanding it to higher areas and increasing the fluidity of the film. The molecular disorder was further corroborated through dilatational rheology and infrared spectroscopy. These results contribute insights into the role of dicentrine as a potential antiprotozoal drug in its interactions with cellular membranes. Beyond elucidating the mechanism of action at the plasma membrane's external surface, our study sheds light on drug-lipid interface interactions, offering implications for drug delivery and other pharmaceutical applications.
Assuntos
Antiprotozoários , Antiprotozoários/farmacologia , Antiprotozoários/química , Relação Estrutura-Atividade , Membrana Celular/efeitos dos fármacos , Aporfinas/farmacologia , Aporfinas/química , Relação Dose-Resposta a Droga , Lauraceae/química , Estrutura Molecular , Leishmania infantum/efeitos dos fármacos , Testes de Sensibilidade Parasitária , AnimaisRESUMO
In the present work, the hexane extract of aerial parts of Baccharis quitensis Kunth. was subjected to chromatographic fractionation to afford two alkyl phenylpropanoids: n-docosyl (E)-p-coumarate (1) and n-tetracosyl (E)-p-coumarate (2) as well as five diterpenes: ent-kaurenoic acid (3), grandifloric acid (4), 15ß-senecioyl-oxy-ent-kaur-16-en-19-oic acid (5), and 15-oxo-ent-kaurenoic acid (6). Using an ex-vivo assay with macrophages infected with Trypanosoma cruzi, compounds 1 and 2 demonstrated high potency against intracellular amastigotes, with EC50 values of 7.5 and 6.9 µM, respectively. Compound 6 revealed a moderate potency against T. cruzi, with an EC50 of 25.6 µM, and compounds 3-5 showed no effectiveness. Additionally, compounds 1-6 compounds presented no toxicity for mammalian cells to the highest tested concentration of 200 µM. Based on potency and the selectivity indexes of 1, 2 and 6, these compounds could be future candidates for optimisation studies for the design of prototypes against Chagas disease.
RESUMO
The hexane extract from twigs of Piper truncatum Vell (Piperaceae) displayed activity against Trypanosoma cruzi and was subjected to chromatographic steps to afford six dibenzylbutyrolactolic lignans, being four knowns: cubebin (1), (-)-9α-O-methylcubebin (2), (+)-9ß-O-methylcubebinin (3) and 3,4-dimethoxy-3,4-demethylenedioxycubebin (4) as well as two new, named truncatin A (5) and B (6). Initially, inâ vitro activity against trypomastigotes was evaluated and compounds 1, 4 and 6 exhibited EC50 values of 41.6, 21.0 and 39.6â µM, respectively. However, when tested against amastigotes, the relevant clinical form in the chronic phase of Chagas disease, compounds 1-6 displayed activities with EC50 values ranging from 1.6 to 13.7â µM. In addition, the mammalian cytotoxicity of compounds 1-6 was evaluated against murine fibroblasts (NCTC). Compounds 2, 3 and 4 exhibited reduced toxicity against NCTC cells (CC50>200â µM), resulting in SI values of>21.9,>14.5 and>121.9, respectively. Compound 4 showed the highest potency with an SI value twice superior to that determined by the standard drug benznidazole (SI>54.6) against the intracellular amastigotes. These data suggest that lignan 4 can be considered a possible scaffold for designing a new drug candidate for Chagas disease.
Assuntos
Lignanas , Piper , Tripanossomicidas , Trypanosoma cruzi , Lignanas/farmacologia , Lignanas/química , Lignanas/isolamento & purificação , Piper/química , Animais , Trypanosoma cruzi/efeitos dos fármacos , Camundongos , Tripanossomicidas/farmacologia , Tripanossomicidas/química , Tripanossomicidas/isolamento & purificação , Relação Estrutura-Atividade , Testes de Sensibilidade Parasitária , Fibroblastos/efeitos dos fármacos , Estrutura Molecular , Relação Dose-Resposta a Droga , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Extratos Vegetais/isolamento & purificação , Sobrevivência Celular/efeitos dos fármacosRESUMO
Melanin is a substance that plays important roles in several organisms. Its function as an antioxidant and metal-complexing agent makes tyrosinase, the key enzyme that controls melanogenesis, an interesting target for designing inhibitors. In this article, we report a set of piperazine/piperidine amides of benzoic and cinnamic acid derivatives as tyrosinase inhibitors with improved potency and drug-likeness. The most potent compound 5b showed a pIC50 of 4.99 in the monophenolase assay, and only compound 3a showed reasonable potency in the diphenolase assay (pIC50, 4.18). These activities are not correlated to antiradical activity, suggesting that the activity is dependent on competition with the substrates. Molecular docking studies indicated that the benzyl substituent of 5b and other analogues perform important interactions in the enzyme that may explain the higher potency of these compounds. Moreover, the compounds present adequate lipophilicity and skin permeability and no relevant cytotoxicity (CC50 > 200 µM) to mammalian cells.
RESUMO
Natural products are a promising source of new compounds with a wide spectrum of pharmacological properties, including antiprotozoal activities. Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is one of several neglected tropical diseases with reduced options for treatment, which presents limitations such as toxicity and ineffectiveness in the chronic stage of the disease. Aiming to investigate the Brazilian flora for the discovery of new anti-T. cruzi compounds, the MeOH extract from Porcelia macrocarpa R.E. Fries (Annonaceae) fruit peels displayed potent activity against trypomastigotes and intracellular amastigotes and was subjected to bioactivity-guided fractionation. Using different chromatographic steps, a fraction composed of a mixture of four new chemically related acetogenins was obtained. The compounds were characterized as (2S*,3R*,4R*)-3-hydroxy-4-methyl-2-(n-octadeca-13',17'-dien-11'-inil)butanolide (1), (2S*,3R*,4R*)-3-hydroxy-4-methyl-2-(n-eicosa-13',19'-dien-11'-inil)butanolide (2), (2S*,3R*,4R*)-3-hydroxy-4-methyl-2-(n-octadec-13'-en-11'-inil)butanolide (3), and (2S*,3R*,4R*)-3-hydroxy-4-methyl-2-(n-eicosa-13'-en-11'-inil)butanolide (4) by NMR analysis and UHPLC/ESI-HRMS data. The mixture of compounds 1-4, displayed an EC50 of 4.9 and 2.5 µg/mL against trypomastigote and amastigote forms of T. cruzi, respectively, similar to the standard drug benznidazole (EC50 of 4.8 and 1.4 µg/mL). Additionally, the mixture of compounds 1-4 displayed no mammalian toxicity for murine fibroblasts (CC50 > 200 µg/mL), resulting in a SI > 40.8 and > 83.3 against trypomastigotes and amastigotes, respectively. Based on these results, the mechanism of action of this bioactive fraction was investigated. After a short-time incubation with the trypomastigotes, no alterations in the cell membrane permeability were observed. However, it was verified a decrease in the intracellular calcium of the parasites, without significant pH variations of the acidocalcisomes. The intracellular damages were followed by an upregulation of the reactive oxygen species and ATP, but no depolarization effects were observed in the mitochondrial membrane potential. These data suggest that the mixture of compounds 1-4 caused an irreversible oxidative stress in the parasites, leading to death. If adequately studied, these acetogenins can open new insights for the discovery of new routes of death in T. cruzi.
Assuntos
Annonaceae , Doença de Chagas , Tripanossomicidas , Trypanosoma cruzi , Animais , Camundongos , Acetogeninas/farmacologia , Acetogeninas/uso terapêutico , Cálcio/metabolismo , Doença de Chagas/tratamento farmacológico , Tripanossomicidas/metabolismoRESUMO
The absence of effective chronic treatment, expansion to non-endemic countries and the significant burden in public health have stimulated the search for novel therapeutic options to treat Chagas disease, a protozoan disease caused by Trypanosoma cruzi. Despite current efforts, no new drug candidates were approved in clinical trials in the past five decades. Considering this, our group has focused on the expansion of a series (LINS03) with low micromolar activity against amastigotes, considering the optimization of pharmacokinetic properties through increasing drug-likeness and solubility. In this work, we report a new set of 13 compounds with modifications in both the arylpiperazine and the aromatic region linked by an amide group. Five analogues showed activity against intracellular amastigotes (IC50 17.8 to 35.9 µM) and no relevant cytotoxicity to mammalian cells (CC50 > 200 µM). Principal component analysis (PCA) was performed to identify structural features associated to improved activity. The data revealed that polarity, hydrogen bonding ability and flexibility were key properties that influenced the antiparasitic activity. In silico drug-likeness assessments indicated that compounds with the 4-methoxycinammyl (especially compound 2b) had the most prominent balance between properties and activity in the series, as confirmed by SAR analysis.
RESUMO
As part of our ongoing studies involving the discovery of new natural prototypes with antiprotozoal activity against Trypanosoma cruzi from Brazilian plant species, the chromatographic fractionation of hexane extract from leaves of Nectandra barbellata afforded one new pseudo-disesquiterpenoid, barbellatanic acid. The structure of this compound was elucidated by NMR and HR-ESIMS data analysis. Barbellatanic acid displayed a trypanocidal effect with IC50 of 13.2 µM to trypomastigotes and no toxicity against NCTC cells (CC50 > 200 µM), resulting in an SI value higher than 15.1. The investigation of the lethal mechanism of barbellatanic acid in trypomastigotes, using both fluorescence microscopy and spectrofluorimetric analysis, revealed a time-dependent permeation of the plasma membrane. Based on these results, this compound was incorporated in cellular membrane models built with lipid Langmuir monolayers. The interaction of barbellatanic acid with the models was inferred by tensiometric, rheological, spectroscopical, and morphological techniques, which showed that this compound altered the thermodynamic, viscoelastic, structural, and morphological properties of the film. Taking together, these results could be employed when this prodrug interacts with lipidic interfaces, such as protozoa membranes or liposomes for drug delivery systems.
Assuntos
Antiprotozoários , Tripanossomicidas , Trypanosoma cruzi , Tripanossomicidas/farmacologia , Tripanossomicidas/química , Antiprotozoários/farmacologia , Membrana Celular , Folhas de PlantaRESUMO
Chagas disease is an endemic tropical disease caused by the protozoan Trypanosoma cruzi, which affects around 7 million people worldwide, mostly in development countries. The treatment relies on only two available drugs, with severe adverse effects and a limited efficacy. Therefore, the search for new therapies is a legitimate need. Within this context, our group reported the anti-Trypanosoma cruzi activity of gibbilimbol B, a natural alkylphenol isolated from the plant Piper malacophyllum. Two synthetic derivatives, LINS03018 (1) and LINS03024 (2), demonstrated a higher antiparasitic potency and were selected for mechanism of action investigations. Our studies revealed no alterations in the plasma membrane potential, but a rapid alkalinization of the acidocalcisomes. Nevertheless, compound 1 exhibit a pronounced effect in the bioenergetics metabolism, with a mitochondrial impairment and consequent decrease in ATP and reactive oxygen species (ROS) levels. Compound 2 only depolarized the mitochondrial membrane potential, with no interferences in the respiratory chain. Additionally, no macrophages response of nitric oxide (NO) was observed in both compounds. Noteworthy, simple structure modifications in these derivatives induced significant differences in their lethal effects. Thus, this work reinforces the importance of the mechanism of action investigations at the early phases of drug discovery and support further developments of the series.
RESUMO
Gibbilimbol B and analogues were isolated from the Brazilian plant Piper malacophyllum and displayed activity against trypomastigote forms of Trypanosoma cruzi as well as reduced toxicity against NCTC cells. These results stimulated the preparation of a series of 24 chemically related analogues to study the potential of these compounds against T. cruzi trypomastigotes and explore structure-activity relationships. Initially, 12 compounds were planned, maintaining the same extension of the linear side chain of gibbilimbol B and unsaturation on the C-4 position but changing the functional groups - ester and amide - and variating the substituent at the p-position in the aromatic ring. Other 12 compounds were prepared using a branched side chain containing an ethyl group at the C-2 position. Overall, these structurally-related analogues demonstrated promising activity against trypomastigote forms (EC50 < 20 µM) and no mammalian cytotoxicity to fibroblasts (CC50 > 200 µM). Using multivariate statistics and machine learning analysis, aspects associated with structure/activity were related to their three-dimensional structure and, mainly, to the substituents on the aromatic ring. Obtained results suggested that the presence of t-butyl or nitro groups at p-position with appropriate side chains causes an alteration in the electron topological state, Van der Waals volumes, surface areas, and polarizabilities of tested compounds which seem to be essential for biological activity against T. cruzi parasites.