RESUMO
Bis(indazol-3-ol) derivatives (5, 30-38) were prepared by alkylation of 3-alkoxyindazoles with alpha,omega-dibromides, followed by removal of the O-protecting groups. These compounds were subsequently evaluated as inhibitors of biocrystallization of ferriprotoporphyrin IX (heme) to hemozoin, a Plasmodium detoxification specific process. Most bis(5-nitroindazol-3-ols) were good inhibitors, however, a denitro analogue (38), the intermediate bis(3-alkoxyindazoles) (15-29) as well as bis(indazolin-3-ones) (39-42) were not active, showing the importance of the NO(2) and OH groups in the inhibition process.
Assuntos
Antimaláricos/química , Hemeproteínas/antagonistas & inibidores , Hemina/antagonistas & inibidores , Indazóis/química , Animais , Antimaláricos/síntese química , Antimaláricos/farmacologia , Hemeproteínas/química , Hemina/química , Indazóis/síntese química , Indazóis/farmacologia , Concentração Inibidora 50 , Camundongos , Plasmodium berghei/efeitos dos fármacosRESUMO
Bond-based quadratic indices, new TOMOCOMD-CARDD molecular descriptors, and linear discriminant analysis (LDA) were used to discover novel lead trichomonacidals. The obtained LDA-based quantitative structure-activity relationships (QSAR) models, using nonstochastic and stochastic indices, were able to classify correctly 87.91% (87.50%) and 89.01% (84.38%) of the chemicals in training (test) sets, respectively. They showed large Matthews correlation coefficients of 0.75 (0.71) and 0.78 (0.65) for the training (test) sets, correspondingly. Later, both models were applied to the virtual screening of 21 chemicals to find new lead antitrichomonal agents. Predictions agreed with experimental results to a great extent because a correct classification for both models of 95.24% (20 of 21) of the chemicals was obtained. Of the 21 compounds that were screened and synthesized, 2 molecules (chemicals G-1, UC-245) showed high to moderate cytocidal activity at the concentration of 10 microg/ml, another 2 compounds (G-0 and CRIS-148) showed high cytocidal activity only at the concentration of 100 microg/ml, and the remaining chemicals (from CRIS-105 to CRIS-153, except CRIS-148) were inactive at these assayed concentrations. Finally, the best candidate, G-1 (cytocidal activity of 100% at 10 microg/ml) was in vivo assayed in ovariectomized Wistar rats achieving promising results as a trichomonacidal drug-like compound.
Assuntos
Antitricômonas/química , Antitricômonas/farmacologia , Desenho Assistido por Computador , Avaliação Pré-Clínica de Medicamentos/métodos , Software , Trichomonas vaginalis/efeitos dos fármacos , Adulto , Animais , Antitricômonas/uso terapêutico , Análise Discriminante , Farmacorresistência Bacteriana , Feminino , Humanos , Estrutura Molecular , Ovariectomia , Ratos , Ratos Wistar , Tricomoníase/tratamento farmacológicoRESUMO
Trichomonas vaginalis (Tv) is the causative agent of the most common, non-viral, sexually transmitted disease in women and men worldwide. Since 1959, metronidazole (MTZ) has been the drug of choice in the systemic treatment of trichomoniasis. However, resistance to MTZ in some patients and the great cost associated with the development of new trichomonacidals make necessary the development of computational methods that shorten the drug discovery pipeline. Toward this end, bond-based linear indices, new TOMOCOMD-CARDD molecular descriptors, and linear discriminant analysis were used to discover novel trichomonacidal chemicals. The obtained models, using non-stochastic and stochastic indices, are able to classify correctly 89.01% (87.50%) and 82.42% (84.38%) of the chemicals in the training (test) sets, respectively. These results validate the models for their use in the ligand-based virtual screening. In addition, they show large Matthews' correlation coefficients (C) of 0.78 (0.71) and 0.65 (0.65) for the training (test) sets, correspondingly. The result of predictions on the 10% full-out cross-validation test also evidences the robustness of the obtained models. Later, both models are applied to the virtual screening of 12 compounds already proved against Tv. As a result, they correctly classify 10 out of 12 (83.33%) and 9 out of 12 (75.00%) of the chemicals, respectively; which is the most important criterion for validating the models. Besides, these classification functions are applied to a library of seven chemicals in order to find novel antitrichomonal agents. These compounds are synthesized and tested for in vitro activity against Tv. As a result, experimental observations approached to theoretical predictions, since it was obtained a correct classification of 85.71% (6 out of 7) of the chemicals. Moreover, out of the seven compounds that are screened, synthesized and biologically assayed, six compounds (VA7-34, VA7-35, VA7-37, VA7-38, VA7-68, VA7-70) show pronounced cytocidal activity at the concentration of 100 mug/ml at 24 h (48 h) within the range of 98.66%-100% (99.40%-100%), while only two molecules (chemicals VA7-37 and VA7-38) show high cytocidal activity at the concentration of 10 mug/ml at 24 h (48 h): 98.38% (94.23%) and 97.59% (98.10%), correspondingly. The LDA-assisted QSAR models presented here could significantly reduce the number of synthesized and tested compounds and could increase the chance of finding new chemical entities with anti-trichomonal activity.
Assuntos
Antitricômonas/química , Desenho de Fármacos , Relação Quantitativa Estrutura-Atividade , Algoritmos , Animais , Antitricômonas/farmacologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Fenômenos Químicos , Físico-Química , Biologia Computacional/métodos , Análise Discriminante , Modelos Lineares , Metronidazol/farmacologia , Estrutura Molecular , Quinoxalinas/química , Quinoxalinas/farmacologia , Software , Validação de Programas de Computador , Processos Estocásticos , Trichomonas vaginalis/efeitos dos fármacosRESUMO
A non-stochastic quadratic fingerprints-based approach is introduced to classify and design, in a rational way, new antitrypanosomal compounds. A data set of 153 organic chemicals, 62 with antitrypanosomal activity and 91 having other clinical uses, was processed by a k-means cluster analysis to design training and predicting data sets. Afterwards, a linear classification function was derived allowing the discrimination between active and inactive compounds. The model classifies correctly more than 93% of chemicals in both training and external prediction groups. The predictability of this discriminant function was also assessed by a leave-group-out experiment, in which 10% of the compounds were removed at random at each time and their activity predicted a posteriori. In addition, a comparison with models generated using four well-known families of 2D molecular descriptors was carried out. As an experiment of virtual lead generation, the present TOMOCOMD approach was finally satisfactorily applied on the virtual evaluation of 10 already synthesized compounds. The in vitro antitrypanosomal activity of this series against epimastigotes forms of Trypanosomal cruzi was assayed. The model was able to predict correctly the behaviour of these compounds in 90% of the cases.
Assuntos
Biologia Computacional/métodos , Simulação por Computador , Desenho de Fármacos , Tripanossomicidas/química , Animais , Análise por Conglomerados , Análise Discriminante , Testes de Sensibilidade Parasitária , Tripanossomicidas/classificação , Trypanosoma cruzi/efeitos dos fármacosRESUMO
A computational (virtual) screening test to identify potential trichomonacidals has been developed. Molecular structures of trichomonacidal and non-trichomonacidal drugs were represented using stochastic and non-stochastic atom-based quadratic indices and a linear discrimination analysis (LDA) was trained to classify molecules regarding their antiprotozoan activity. Validation tests revealed that our LDA-QSAR models recognize at least 88.24% of trichomonacidal lead-like compounds and suggest using this methodology in virtual screening protocols. These classification functions were then applied to find new lead antitrichomonal compounds. In this connection, the biological assays of eight compounds, selected by computational screening using the present models, give good results (87.50% of good classification). In general, most of the compounds showed high activity against Trichomonas vaginalis at the concentration of 100 microg/ml and low cytotoxicity to this concentration. In particular, two heterocyclic derivatives (VA7-67 and VA7-69) maintained their efficacy at 10 microg/ml with an important trichomonacidal activity (100.00% of reduction), but it is remarkable that the compound VA7-67 did not show cytotoxic effects in macrophage cultivations. This result opens a door to a virtual study considering a higher variability of the structural core already evaluated, as well as of other chemicals not included in this study.
Assuntos
Antitricômonas/química , Avaliação Pré-Clínica de Medicamentos/métodos , Compostos Heterocíclicos/química , Interface Usuário-Computador , Animais , Antitricômonas/classificação , Simulação por Computador , Relação Estrutura-Atividade , Trichomonas vaginalis/efeitos dos fármacosRESUMO
Computational approaches are developed to design or rationally select, from structural databases, new lead trichomonacidal compounds. First, a data set of 111 compounds was split (design) into training and predicting series using hierarchical and partitional cluster analyses. Later, two discriminant functions were derived with the use of non-stochastic and stochastic atom-type linear indices. The obtained LDA (linear discrimination analysis)-based QSAR (quantitative structure-activity relationship) models, using non-stochastic and stochastic descriptors were able to classify correctly 95.56% (90.48%) and 91.11% (85.71%) of the compounds in training (test) sets, respectively. The result of predictions on the 10% full-out cross-validation test also evidenced the quality (robustness, stability and predictive power) of the obtained models. These models were orthogonalized using the Randic orthogonalization procedure. Afterwards, a simulation experiment of virtual screening was conducted to test the possibilities of the classification models developed here in detecting antitrichomonal chemicals of diverse chemical structures. In this sense, the 100.00% and 77.77% of the screened compounds were detected by the LDA-based QSAR models (Eq. 13 and Eq. 14, correspondingly) as trichomonacidal. Finally, new lead trichomonacidals were discovered by prediction of their antirichomonal activity with obtained models. The most of tested chemicals exhibit the predicted antitrichomonal effect in the performed ligand-based virtual screening, yielding an accuracy of the 90.48% (19/21). These results support a role for TOMOCOMD-CARDD descriptors in the biosilico discovery of new compounds.
Assuntos
Antitricômonas/síntese química , Desenho de Fármacos , Relação Quantitativa Estrutura-Atividade , Software , Análise por ConglomeradosRESUMO
The syntheses and biological evaluation of the first anti-protozoa imidazole N-oxide and benzimidazole N-oxide and their derivatives are reported. They were tested in vitro against two different protozoa, Trypanosoma cruzi and Trichomonas vaginalis. Derivative 7c, ethyl-1-(i-butyloxycarbonyloxy)-6-nitrobenzimid-azole-2-carboxylate, displayed activity on both protozoa. Lipophilicity and redox potential were experimentally determined in order to study the relationship with activity of the compounds. These properties are well related with the observed bioactivity. Imidazole and benzimidazole N-oxide derivatives are becoming leaders for further chemical modifications and advanced biological studies.
Assuntos
Antiprotozoários/síntese química , Benzimidazóis/síntese química , Óxidos N-Cíclicos/síntese química , Imidazóis/síntese química , Animais , Antiprotozoários/química , Antiprotozoários/farmacologia , Benzimidazóis/química , Benzimidazóis/farmacologia , Óxidos N-Cíclicos/química , Óxidos N-Cíclicos/farmacologia , Desenho de Fármacos , Imidazóis/química , Imidazóis/farmacologia , Técnicas In Vitro , Relação Estrutura-Atividade , Trichomonas vaginalis/efeitos dos fármacos , Trypanosoma cruzi/efeitos dos fármacosRESUMO
Clone CL B5 of Trypanosoma cruzi is a beta-galactosidase expressing organism that was genetically transfected to be used for in vitro pharmacological screening. Biological parameters were determined, evaluating growth kinetics of epimastigotes, metacyclogenesis, infectivity to mammalian cell lines, parasitemia kinetics in mice and sensibility to nifurtimox and benznidazole. Differences in relation to other strains and CL parental strain were found, the most important being the incapability to produce death to mice in spite of the high inoculum used. However, it possesses the required features to be used for in vitro drug screening. Data obtained demonstrate that heterogeneity of T. cruzi appears even among clones of the same strain, and that these differences found do not prevent the use of clone CL B5 for the purpose that was engineered
Assuntos
Animais , Camundongos , beta-Galactosidase , Trypanosoma cruzi , beta-Galactosidase , Clonagem de Organismos , Nifurtimox , Nitroimidazóis , Parasitemia , Testes de Sensibilidade Parasitária , Tripanossomicidas , Trypanosoma cruziRESUMO
Cytotoxicity assays of 24 new 3,5-disubstituted-tetrahydro-2H-1,3,5-thiadiazin-2-thione derivatives were performed. The 17 compounds with higher anti-epimastigote activity and lower cytotoxicity were, thereafter, screened against amastigote of Trypanosoma cruzi. Out of these 17 derivatives S-2d was selected to be assayed in vivo, because of its remarkable trypanocidal properties. To determine toxicity against J774 macrophages, a method based on quantification of cell damage, after 24 h, was used. Cell respiration, an indicator of cell viability, was assessed by the reduction of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] to formazan. Anti-amastigote activity was estimated after 48 h by microscopic counts of May Grünwald-Giemsa-stained monolayers. Nifurtimox and benznidazole were used as reference drugs. For the in vivo experiences, mice were infected with 10(4) blood trypomastigotes and then treated during 15 days with S-2d or nifurtimox by oral route. All of the compounds were highly toxic at 100 micro g/ml for macrophages and a few of them maintained this cytotoxicity even at 10 microg/ml. Of the derivatives assayed against amastigotes 3k and S-2d showed an interesting activity, that was held even at 1microg/ml. It is demonstrated that the high anti-epimastigote activity previously reported is mainly due to the non-specific toxicity of these compounds. In vivo assays assessed a reduction of parasitemia after administration of S-2d to infected mice.
Assuntos
Antiprotozoários/farmacologia , Macrófagos/efeitos dos fármacos , Tiadiazinas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Antiprotozoários/química , Camundongos , Testes de Sensibilidade Parasitária , Tiadiazinas/químicaRESUMO
Cytotoxicity assays of 24 new 3,5-disubstituted-tetrahydro-2H-1,3,5-thiadiazin-2-thione derivatives were performed. The 17 compounds with higher anti-epimastigote activity and lower cytotoxicity were, thereafter, screened against amastigote of Trypanosoma cruzi. Out of these 17 derivatives S-2d was selected to be assayed in vivo, because of its remarkable trypanocidal properties. To determine toxicity against J774 macrophages, a method based on quantification of cell damage, after 24 h, was used. Cell respiration, an indicator of cell viability, was assessed by the reduction of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] to formazan. Anti-amastigote activity was estimated after 48 h by microscopic counts of May Grünwald-Giemsa-stained monolayers. Nifurtimox and benznidazole were used as reference drugs. For the in vivo experiences, mice were infected with 10(4) blood trypomastigotes and then treated during 15 days with S-2d or nifurtimox by oral route. All of the compounds were highly toxic at 100 µg/ml for macrophages and a few of them maintained this cytotoxicity even at 10 µg/ml. Of the derivatives assayed against amastigotes 3k and S-2d showed an interesting activity, that was held even at 1µg/ml. It is demonstrated that the high anti-epimastigote activity previously reported is mainly due to the non-specific toxicity of these compounds. In vivo assays assessed a reduction of parasitemia after administration of S-2d to infected mice
Assuntos
Animais , Camundongos , Antiprotozoários , Macrófagos , Tiadiazinas , Trypanosoma cruzi , Antiprotozoários , TiadiazinasRESUMO
Clone CL B5 of Trypanosoma cruzi is a beta-galactosidase expressing organism that was genetically transfected to be used for in vitro pharmacological screening. Biological parameters were determined, evaluating growth kinetics of epimastigotes, metacyclogenesis, infectivity to mammalian cell lines, parasitemia kinetics in mice and sensibility to nifurtimox and benznidazole. Differences in relation to other strains and CL parental strain were found, the most important being the incapability to produce death to mice in spite of the high inoculum used. However, it possesses the required features to be used for in vitro drug screening. Data obtained demonstrate that heterogeneity of T. cruzi appears even among clones of the same strain, and that these differences found do not prevent the use of clone CL B5 for the purpose that was engineered.
Assuntos
Trypanosoma cruzi/enzimologia , beta-Galactosidase/biossíntese , Animais , Chlorocebus aethiops , Clonagem de Organismos , Camundongos , Nifurtimox/farmacologia , Nitroimidazóis/farmacologia , Testes de Sensibilidade Parasitária , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Células Vero , beta-Galactosidase/genéticaRESUMO
Foram ensaiados, frente a uma cepa boliviana de Trypanosoma cruzi, dois novos derivados trifenilmetânicos obtidos por síntese: T-7A, bis (4-dimetilamino-fenil) 2-benzotienil carbinol e T-7B, tetrafluorborato de bis (4-dimetilamino - fenil) 2-benzotienil carbonio. As experiências foram realizadas em camundongos NMRI através da administraçäo dos produtos por via intraperitoneal. Foram realizados, também, testes de atividade tripanomicida, in vitro, com sangue contaminado e conservado sob refrigeraçäo