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SARS-CoV-2 cysteine proteases are essential nonstructural proteins due to their role in the formation of the virus multiple enzyme replication-transcription complex. As a result, those functional proteins are extremely relevant targets in the development of a new drug candidate to fight COVID-19. Based on this fact and guided by the bioisosterism strategy, the present work has selected 126 out of 1050 ligands from DrugBank website. Subsequently, 831 chemical analogs containing bioisosteres, some of which became structurally simplified, were created using the MB-Isoster software, and molecular docking simulations were performed using AutoDock Vina. Finally, a study of physicochemical properties, along with pharmacokinetic profiles, was carried out through SwissADME and ADMETlab 2.0 platforms. The promising results obtained with the molecules encoded as DB00549_BI_005, DB04868_BI_003, DB11984_BI_002, DB12364_BI_006 and DB12805_BI_004 must be confirmed by molecular dynamics studies, followed by in vitro and in vivo empirical tests that ratify the advocated in-silico results.

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Chagas disease and leishmaniasis are neglected diseases of high priority as a public health problem. Pharmacotherapy is based on the administration of a few drugs, which exhibit hazardous adverse effects and toxicity to the patients. Thus, the search for new antitrypanosomatid drugs is imperative to overcome the limitations of the treatments. In this work, 46 2-nitroimidazole 3,5-disubstituted isoxazole compounds were synthesized in good yields by [3 + 2] cycloaddition reaction between terminal acetylene (propargyl-2-nitroimidazole) and chloro-oximes. The compounds were non-toxic to LLC-MK2 cells. Compounds 30, 35, and 44 showed in vitro antichagasic activity, 15-fold, 12-fold, and 10-fold, respectively, more active than benznidazole (BZN). Compounds 30, 35, 44, 45, 53, and 61 acted as substrates for the TcNTR enzyme, indicating that this might be one of the mechanisms of action involved in their antiparasitic activity. Piperazine series and 4-monosubstituted compounds were potent against T. cruzi parasites. Besides the in vitro activity observed in compound 45, the in vivo assay showed that the compound only reduced the parasitemia levels by the seventh-day post-infection (77%, p > 0.001) compared to the control group. However, 45 significantly reduced the parasite load in cardiac tissue (p < 0.01) 11 days post-infection. Compounds 49, 52, and 54 showed antileishmanial activity against intracellular amastigotes of Leishmania (L.) amazonensis at the same range as amphotericin B. These findings highlight the antitrypanosomatid properties of 2-nitroimidazole 3,5-disubstituted isoxazole compounds and the possibility in using them as antitrypanosomatid agents in further studies.

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BACKGROUND: Cancer is one of the most important barriers to increasing life expectancy in all countries in the 21st century. Investigations of new anti-cancer drugs with low side effects are an urgent demand for medicinal chemists. Considering the known antitumor and immunomodulatory activity of thiazoles, this work presents the synthesis and antineoplastic activity of new thiazoles. METHODS: The 22 new compounds (2a-v) were synthesized from different thiosemicarbazones and 2-bromoacetophenone. The compounds were evaluated on: MOLT-4, HL-60, HL-60/MX1, MM1S, SKMEL-28, DU145, MCF-7, and T47d. RESULTS: Compound 2b induced cellular viability on MOLT-4 (37.1%), DU145 (41.5%), and HL- 60/MX1 (58.8%) cells. On MOLT-4 cells, compound 2b exhibited an IC50 of 8.03 µM, and against DU145 cells, an IC50 of 6.04µM. Besides, at IC50 and fold of IC50, 20% to 30% of dead cells were found, most due to necrosis/late apoptosis. Most compounds no showed cytotoxicity against fibroblast cells L929 at the concentrations tested. The compound did not alter the cell cycle of DU145 cells when compared to the negative control. Therefore, compound 2b stands out against DU145 and MOLT-4 cells. CONCLUSION: Our study reinforced the importance of 1,3-thiazoles nuclei in antitumor activity. In addition, derivative 2b stands out against DU145 and MOLT-4 cells and could be a starting point for developing new antineoplastic agents.

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Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory tract infections in infants. Currently, ribavirin, a nucleoside analog containing a 1,2,4-triazole-3-carboxamide moiety, is a first-line drug for its treatment, however, its clinical use has been limited due to its side effects. Here, we designed two new nitroaryl-1,2,3-triazole triterpene derivatives as novel anti-RSV drugs. Their anti-RSV and cytotoxic activity were evaluated in vitro, RSV protein F gene effects by RT-PCR and molecular modeling with inosine monophosphate dehydrogenase (IMPDH) were performed. Compound 8 was the best performing compound, with an EC50 value of 0.053 µM, a TI of 11160.37 and it inhibited hRSV protein F gene expression by approximately 65%. Molecular docking showed a top-ranked solution located in the same region occupied by crystallographic ligands in their complex with IMPDH. The results obtained in this study suggest that compound 8 might be a new anti-RSV candidate.

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A recent screen of 67,012 compounds identified a new family of compounds with excellent nematicidal activity: the ortho-substituted benzamide families Wact-11 and Wact-12. These compounds are active against Caenorhabditis elegans and parasitic nematodes by selectively inhibiting nematode complex II, and they display low toxicity in mammalian cells and vertebrate organisms. Although a big number of benzamides were tested against C. elegans in high-throughput screens, bioisosteres of the amide moiety were not represented in the chemical space examined. We thus identified an opportunity for the design, synthesis and evaluation of novel compounds, using bioisosteric replacements of the amide group present in benzamides. The compound Wact-11 was used as the reference scaffold to prepare a set of bioisosteres to be evaluated against C. elegans. Eight types of amide replacement were selected, including ester, thioamide, selenoamide, sulfonamide, alkyl thio- and oxo-amides, urea and triazole. The results allowed us to perform a structure-activity relationship, highlighting the relevance of the amide group for nematicide activity. Experimental evidence was complemented with in silico structural studies over a C. elegans complex II model as a molecular target of benzamides. Importantly, compound Wact-11 was active against the flatworm Echinococcus granulosus, suggesting a previously unreported pan-anthelmintic potential for benzamides.

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The compound (E)-2-cyano-N,3-diphenylacrylamide (JMPR-01) was structurally developed using bioisosteric modifications of a hybrid prototype as formed from fragments of indomethacin and paracetamol. Initially, in vitro assays were performed to determine cell viability (in macrophage cultures), and its ability to modulate the synthesis of nitrite and cytokines (IL-1ß and TNFα) in non-cytotoxic concentrations. In vivo, anti-inflammatory activity was explored using the CFA-induced paw edema and zymosan-induced peritonitis models. To investigate possible molecular targets, molecular docking was performed with the following crystallographic structures: LT-A4-H, PDE4B, COX-2, 5-LOX, and iNOS. As results, we observed a significant reduction in the production of nitrite and IL-1ß at all concentrations used, and also for TNFα with JMPR-01 at 50 and 25 µM. The anti-edematogenic activity of JMPR-01 (100 mg/kg) was significant, reducing edema at 2-6 h, similar to the dexamethasone control. In induced peritonitis, JMPR-01 reduced leukocyte migration by 61.8, 68.5, and 90.5% at respective doses of 5, 10, and 50 mg/kg. In silico, JMPR-01 presented satisfactory coupling; mainly with LT-A4-H, PDE4B, and iNOS. These preliminary results demonstrate the strong potential of JMPR-01 to become a drug for the treatment of inflammatory diseases.

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Considering the emergence of antifungal resistance on Sporothrix brasiliensis, we aimed to assess new benzylidene-carbonyl compounds against feline-borne S. brasiliensis isolates. The compounds were designed as bioisosteres from previously reported benzylidene-ketones generating the p-coumaric (1), cinnamic (2), p-methoxycinnamic (3) and caffeic acid (4) analogues. The corresponding compounds were tested against feline isolates of S. brasiliensis with sensitivity (n = 4) and resistance (n = 5) to itraconazole (ITZ), following the M38-A2 protocol (CLSI, Reference method for broth dilution antifungal susceptibility testing of filamentous fungi M38-A2 Guideline, 2008). Eleven analogues showed activity against all fungal strains with minimum inhibitory concentrations (MIC) ≤1 mg/ml (1a-d, 2e, 3b, 3e, 4, 4a and 5e) and fungicidal concentrations (MFC) ≤1 mg/ml (1b, 1d, 3e and 4a), whereas 3 was the less active with both MIC and MFC values above 1 mg/ml. Compound 3e (4-methoxy-N-butylcinnamamide) was the most potent (MICrange 0.08-0.16 mg/ml; MFCrange 0.32-0.64 mg/ml) from the set, suggesting a different role of the substituents in ester and amide derivatives. The designed compounds proved to be important prototypes with improved drug-likeness to achieve compounds with higher activity against ITZ-resistant S. brasiliensis.

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β-defensins are antimicrobial peptides presenting in vertebrate animals. They participate in innate immunity, but little is known about them in reptiles, including snakes. Although several β-defensin genes were described in Brazilian snakes, their function is still unknown. The peptide sequence from these genes was deduced, and synthetic peptides (with approximately 40 amino acids and derived peptides) were tested against pathogenic bacteria and fungi using microbroth dilution assays. The linear peptides, derived from β-defensins, were designed applying the bioisosterism strategy. The linear β-defensins were more active against Escherichia coli, Micrococcus luteus, Citrobacter freundii, and Staphylococcus aureus. The derived peptides (7–14 mer) showed antibacterial activity against those bacteria and on Klebsiella pneumoniae. Nonetheless, they did not present activity against Candida albicans, Cryptococcus neoformans, Trychophyton rubrum, and Aspergillus fumigatus showing that the cysteine substitution to serine is deleterious to antifungal properties. Tryptophan residue showed to be necessary to improve antibacterial activity. Even though the studied snake β-defensins do not have high antimicrobial activity, they proved to be attractive as template molecules for the development of antibiotics.

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ß-defensins are antimicrobial peptides presenting in vertebrate animals. They participate in innate immunity, but little is known about them in reptiles, including snakes. Although several ß-defensin genes were described in Brazilian snakes, their function is still unknown. The peptide sequence from these genes was deduced, and synthetic peptides (with approximately 40 amino acids and derived peptides) were tested against pathogenic bacteria and fungi using microbroth dilution assays. The linear peptides, derived from ß-defensins, were designed applying the bioisosterism strategy. The linear ß-defensins were more active against Escherichia coli, Micrococcus luteus, Citrobacter freundii, and Staphylococcus aureus. The derived peptides (7-14 mer) showed antibacterial activity against those bacteria and on Klebsiella pneumoniae. Nonetheless, they did not present activity against Candida albicans, Cryptococcus neoformans, Trychophyton rubrum, and Aspergillus fumigatus showing that the cysteine substitution to serine is deleterious to antifungal properties. Tryptophan residue showed to be necessary to improve antibacterial activity. Even though the studied snake ß-defensins do not have high antimicrobial activity, they proved to be attractive as template molecules for the development of antibiotics.

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A series of 3-substituted-7-aminoalcoxy-coumarin was designed and evaluated as cholinesterase inhibitors and antioxidants. All compounds were effective in inhibiting AChE with potencies in the nanomolar range. The 3-(4-(dimethylamino)phenyl)-7-aminoethoxy-coumarin (6a) was considered a hit, showing good AChE inhibition potency (IC50 = 20 nM) and selectivity (IC50 BuChE/AChE = 354), quite similar to the reference drug donepezil (IC50 = 6 nM; IC50 BuChE/AChE = 365), also presenting antioxidant properties, low citotoxicity and good-predicted ADMET properties. The mode of action (mixed-type) and SAR analysis for this series of compounds were described by means of kinetic and molecular modeling evaluations.

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Using bioisosterism as a medicinal chemistry tool, 16 3,5-diaryl-isoxazole analogues of the tetrahydrofuran neolignans veraguensin, grandisin and machilin G were synthesized via 1,3-dipolar cycloaddition reactions, with yields from 43% to 90%. Antitrypanosomatid activities were evaluated against Trypanosoma cruzi, Leishmania (L.) amazonensis and Leishmania (V.) braziliensis. All compounds were selective for the Leishmania genus and inactive against T. cruzi. Isoxazole analogues showed a standard activity on both promastigotes of L. amazonensis and L. braziliensis. The most active compounds were 15, 16 and 19 with IC50 values of 2.0, 3.3 and 9.5 µM against L. amazonensis and IC50 values of 1.2, 2.1 and 6.4 µM on L. braziliensis, respectively. All compounds were noncytotoxic, showing lower cytotoxicity (>250 µM) than pentamidine (78.9 µM). Regarding the structure-activity relationship (SAR), the methylenedioxy group was essential to antileishmanial activity against promastigotes. Replacement of the tetrahydrofuran nucleus by an isoxazole core improved the antileishmanial activity.

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Capsaicin is a substance produced by Capsicum peppers with extensive biological activity reported in the literature. Among these studies, it was suggested that the anti-tumor activity is related to modulation of the Transient Potential Receptor Vanilloid (TRPV) channels. Capsaicin is known to bind with very high affinity to TRPV1 (IC50 ≈ 7 nM), triggering the burning sensation followed by analgesia. However, recent studies have suggested that the pro-apoptotic effects of capsaicin are TRPV6-mediated. Herein we report the development of a novel inhibitor of the TRPV6 using two different strategies for compounds design. We generated a series of direct and chimeric capsaicinoids based on the literature compounds, capsaicin, and cis-22a. These analogs were probed against HEK-hTRPV6 and the hits were further optimized. Based on the previous SAR and chemical optimization, we found 56h, named MRC-130, a derivative that remarkably inhibited TRPV6 in the nanomolar range (IC50 = 83 ± 4 nM), possess high selectivity and stability in vitro, and lesser hERG inhibition compared to the reference compound, cis-22a. It is expected that these new molecules would contribute significantly to the study on the TRPV6 function and its role in tumor pathophysiology

Capsaicina é uma substância produzida por pimentas do gênero Capsicum com extensa atividade biológica relatada na literatura. Entre esses estudos, sugeriu-se que a atividade antitumoral esteja relacionada à modulação dos canais TRPV (do inglês, Transient Potential Receptor Vanilloid). Sabe-se que a capsaicina se liga com altíssima afinidade ao TRPV1 (IC50 ≈ 7 nM), desencadeando a sensação de queimação seguida de analgesia. No entanto, estudos recentes sugeriram que os efeitos pró-apoptóticos da capsaicina são mediados pelo TRPV6. Visando o exposto, este trabalho relata o desenvolvimento de um novo inibidor do TRPV6 usando duas estratégias diferentes para o planejamento dos compostos. Geramos séries de capsaicinoides diretos e quiméricos com base nos compostos da literatura, capsaicina e cis-22a. Esses análogos foram analisados contra HEK-hTRPV6 e os análogos mais promissores foram otimizados. Com base na REA e em otimizações químicas anteriores, encontramos 56h, chamado MRC-130, um derivado que inibiu notavelmente o TRPV6 na faixa nanomolar (IC50 = 83 ± 4 nM), possui alta seletividade e estabilidade in vitro e menor inibição de hERG em comparação com o composto de referência, cis-22a. Espera-se que essas novas moléculas contribuam significativamente para o estudo da função do TRPV6 e seu papel na fisiopatologia tumoral

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As neoplasias malignas, doenças mundialmente conhecidas como câncer, possuem um dos tratamentos mais onerosos, tóxicos e de baixa seletividade na terapêutica atual. Adicionalmente, o contínuo crescimento da incidência da doença também representa em uma grande problemática. Os produtos de origem natural se apresentam como alternativas para o tratamento de diversas doenças, incluindo o câncer. A capsaicina, produto natural proveniente das pimentas do gênero Capsicum, apresenta propriedades antineoplásicas, portanto, pode ser utilizada como protótipo para obtenção de análogos. Quatro séries foram planejadas e sintetizadas, obtendo-se compostos ureídicos e tioureídicos. A estratégia sintética se baseou na reação da piperonilamina ou vanililamina com isocianatos ou isotiocianatos, ligados a substituintes aromáticos ou alquílicos. Vinte e sete análogos foram sintetizados com rendimentos variando entre 22 a 90 %. Todos os compostos apresentaram aspecto sólido variando a cor de branco a levemente amarelados. Para a caracterização das substâncias obtidas foram utilizados dados de RMN 1H e 13C, ponto de fusão e a determinação de pureza foi realizada mediante HPLC. Todos os compostos foram submetidos a ensaios de avaliação da atividade citotóxica por redução do MTT contra linhagens de células cancerígenas e células sadias. Os compostos RPF652, RPF 512 - 514) apresentaram atividade comparável ou superior ao protótipo com valores de IC50 na faixa de micromolar. Os resultados apontados pela modelagem molecular indicam que descritores eletrônicos como Ehomo e Elumo podem estar associados à atividade do composto, ClogP (3,92) pode favorecer melhor permeabilidade na membrana celular, e o maior número de sítios de acepção de ligação de hidrogênio podem corroborar com a citotoxidade em linhagem A2058. Particularmente, o análogo RPF652 apresentou atividade pronunciada com valores de IC50 de 55, 67, e 87 µM contra as células A2058, SK-MEL 25, e U87, respectivamente, o que representa atividade de superior à capsaicina. Como uma tendência o composto RPF652 causou parada no ciclo de linhagem B-RAF B16F10 não levando a célula à morte. Porém esta linhagem não apresenta mutação no códon V600E. Em contraponto, o análogo RPF652 apresentou maior potência contra linhagem V600EB-RAF A2058 mutada, indicando possível seletividade em linhagens que apresentam a mutação no códon V600E da proteína B-RAF. Ademais, novos esforços devem ser concentrados no análogo RPF652 para melhor elucidação mecanística de sua atividade

Malignant neoplasms have one of the most expensive, non-selective and toxic treatment of present times. This situation, combined with the rising incidence rate, represents a major problem for humanity. The use of natural products can be an alternative for treatment of several diseases, including cancer. Capsaicin is a natural product derived from Capsicum peppers, with reported anticancer activity and can be used as prototype for the design of new molecules with remarkable activity. Capsaicin analogues were designed and synthesized in four series of derivatives, replacing the prototype amide bond with urea and thiourea functions. The synthetic approach builds the urea/ thiourea scaffold using the reaction of piperonyl/ vanilyl amine with alkyl and aryl isocyanides/ isothiocyanides. Twenty-seven new compounds were obtained with yields from 22 to 90 %, and were fully characterized using 1H and 13C NMR, the purity was determined by melting point and HPLC. All of the obtained compounds were evaluated in MTT cytotoxic assays against different cancer cell-lines (B16F10, A2058, SK-MEL 25 and U-87), and compared with healthy human cells (T75). Additionally, the most active compound was submitted to a cell cycle arrest assay. The thiourea derivative RPF652 was the most active compound, and the urea derivatives RPF512, RPF513 and RPF514 showed good micromolar IC50 values. This results, when correlated with several in silico-calculated properties for the obtained molecules, suggests that ClogP, Ehomo, Elumo and the number of hydrogen-bond acception sites may be correlated to the anticancer activity reported. RPF652 especially, showed IC50 values with superior activity and better selectivity index when compared with capsaicin. The cell-cycle assay of RPF652 showed significant arrest in V600E-codon B-RAF non-mutated cell lines (B16F10) without killing it. V600E-codon B-RAF mutated cells A2058, were significantly more sensitive to the compound. These findings may suggest some insights about the mechanism of action and targets of this compounds

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A tuberculose (TB) é considerada uma das principais doenças infecciosas e apresenta fatores críticos como a relação com o HIV/AIDS, tratamento longo e a resistência a múltiplos fármacos. A enzima di-hidrofolato redutase das micobactérias (mtDHFR) é um alvo pouco explorado e apresenta grande potencial para o desenvolvimento de novos fármacos contra TB. Estudos preliminares obtiveram fragmentos com baixa afinidade à mtDHFR, entretanto com potencial para otimização. Com isso, o fragmento foi usado como protótipo para a proposição de 22 análogos. Os compostos foram planejados utilizando informações sobre ligantes e a estrutura tridimensional de mtDHFR, além do biososterismo como estratégia norteadora. Os ensaios de docking molecular com a mtDHFR revelaram que os análogos propostos tiveram escores interessantes e, além disso, a inserção de substituintes demonstrou favorecer a ligação à enzima, o que corroborou o planejamento. Com isso, sintetizou-se 22 análogos planejados e o protótipo MB872, por meio de protocolos de alquilação, hidrólise e cicloadição 1,3 dipolar para os compostos com anéis triazol e tetrazol. Os compostos foram obtidos com rendimentos de bom a ótimo (60 ~ 90%) e suas estruturas foram elucidadas por RMN 1H e 13C. Os resultados do ensaio de inibição enzimática corroboraram com os dados de docking, uma vez que a presença do grupo carboxílico revelou ser importante para a atividade. Além disso, alguns dos compostos revelaram atividades interessantes, entre 8 a 40 µM, sendo que o mais ativo apresentou IC50 de 7 µM. Ensaios de cinética enzimática com o análogo mais ativo indicou uma inibição não competitiva com o substrato natural da enzima, uma vez que os valores de Km se mantiveram constantes, enquanto Vmax decaiu (0,22 µM e 0,43 - 0,34 ΔFU/min, respectivamente). Os análogos sintetizados foram mandados para ensaio in vitro para avaliar a atividade frente a micobactéria

Tuberculosis (TB) is an important infectious disease and presents critical factors such as the relationship with HIV / AIDS, long treatment and resistance to multiple drugs. The enzyme dihydrofolate reductase from mycobacteria (mtDHFR) is a poorly explored and presents great potential to be a target for new drugs against TB. Preliminary studies have obtained fragments with low affinity to mtDHFR, but with potential to become lead compounds. Therefore, the fragment was used as a prototype for 22 analogues proposed in this work. The compounds were designed using bioisosterism, information about ligands and the three-dimensional structure of mtDHFR. Molecular docking assays with mtDHFR revealed satisfactory scores for anlogues. Furthermore, the insertion of substituents seemed to increase the affinity with the enzyme. Thereby, twenty two analogues and prototype were synthesized using alkylation, hydrolysiss and 1,3-dipolar cycloaddition methods. The compounds were obtained in good yields (60 ~ 90%) and their structures were elucidated with 1H and 13C NMR spectroscopy. The enzymatic affinity assay corroborates docking results, because the presence of carboxyl group showed to be important for the activity. Furthermore, some of the compounds revealead interesting activities, ranging 8 to 40 µM. The most active showed IC50 of 7 µM and enzyme kinetics assays indicated noncompetitive inhibition with natural enzyme substrate. The synthesized analogs were sent for in vitro assay to assess mycobacteria activity

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Chagas disease, caused by the kinetoplastid protozoan parasite Trypanosoma cruzi, remains a relevant cause of illness and premature death and it is estimated that 6 million to 7 million people are infected worldwide. Although chemotherapy options are limited presenting serious problems, such as low efficacy and high toxicity. T. cruzi is susceptible to thiazoles, making this class of compounds appealing for drug development. Previously, thiazoles resulted in an increase in anti-T. cruzi activity in comparison to thiosemicarbazones. Here, we report the structural planning, synthesis and anti-T. cruzi evaluation of new thiazoles derivatives (3a-m and 4a-m), designed from molecular hybridization associated with non-classical bioisosterism. By varying substituents attached to the phenyl and thiazole rings, substituents were observed to retain, enhance or greatly increase their anti-T. cruzi activity, in comparison to the corresponding thiosemicarbazones. In most cases, electron-withdrawing substituents, such as bromine, 3,4-dichloro and nitro groups, greatly increased antiparasitic activity. Specifically, new thiazoles were identified that inhibit the epimastigote proliferation and were toxic for trypomastigotes without affecting macrophages viability. These compounds were also evaluated against cruzain. However, inhibition of this enzyme was not observed, suggesting that the compounds work through another mechanism. In addition, examination of T. cruzi cell death showed that these molecules induce apoptosis. In conclusion, except for compounds 3h and 3k, all thiazoles derivatives evaluated exhibited higher cytotoxic activity against the trypomastigote forms than the reference medicament benznidazole, without affecting macrophages viability. Compounds 4d and 4k were highlights, CC50 = 1.2 e 1.6 µM, respectively. Mechanistically, these compounds do not inhibit the cruzain, but induce T. cruzi cell death by an apoptotic process, being considered a good starting point for the development of new anti-Chagas drug candidates.

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A series of semicarbazone, thiosemicarbazone, and aminoguanidine derivatives were synthesized and tested as antitrypanosomal agents. The theoretical NMR of the compounds was calculated using molecular modeling techniques (density functional theory (DFT) calculations) and confirmed the formation of the compounds. The ability to inhibit cruzain and Trypanosoma cruzi epimastigote replication was evaluated. Cruzain inhibition ranged between 70 and 75% (100 µM), and IC50 values observed in epimastigote forms of T. cruzi ranged from 20 to 140 µM. Furthermore, the compounds did not present cytotoxicity at concentrations up to 50 and 250 µM in MTT tests. Molecular modeling studies were conducted using DFT method (B3LYP functional and the basis set 6-311G(d,p)) to understand the activity of the compounds, corroborating the observed cruzain inhibitory activity. In docking studies, the obtained analogs showed good complementarity with cruzain active site. In addition, docking results are in accordance with the susceptibility of these analogs to nucleophilic attack of the catalytic Cys25. Taken together, this study shows that this class of compounds can be used as a prototype in the identification of new antichagasic drugs.

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Chagas disease, caused by Trypanosoma cruzi, is a parasitosis that predominates in Latin America. It is estimated that 25 million people are under the risk of infection and, in 2008, more than 10 thousand deaths were registered. The only two drugs available in the therapeutics, nifurtimox and benznidazole, showed to be more effective in the acute phase of the disease. However, there is no standard treatment protocol effective for the chronic phase. Nitrofurazone (NF), an antimicrobial drug, has activity against T. cruzi, although being toxic. Considering the need for new antichagasic drugs, the existence of promising new therapeutic targets, as 14α-sterol demethylase and cruzain, and employing the bioisosterism and molecular hybridization approaches, four novel compounds were synthesized, characterized by melting point range, elemental analysis, IR and NMR spectroscopy. The compounds were tested against T. cruzi amastigotes in infected U2OS cells. All compounds showed selectivity towards T. cruzi and showed trypanomicidal activity in low micromolar range. The compound 3 showed potency similar to benznidazole, but lower efficacy. These results highlight the importance of the 1,2,4-triazole, thiosemicarbazonic and nitro group moieties for designing new efficient compounds, potentially for the chronic phase of Chagas disease.

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A novel class of benzo[d][1,3]dioxol-5-ylmethyl alkyl/aryl amide and ester analogues of capsaicin were designed, synthesized, and evaluated for their cytotoxic activity against human and murine cancer cell lines (B16F10, SK-MEL-28, NCI-H1299, NCI-H460, SK-BR-3, and MDA-MB-231) and human lung fibroblasts (MRC-5). Three compounds (5f, 6c, and 6e) selectively inhibited the growth of aggressive cancer cells in the micromolar (µM) range. Furthermore, an exploratory data analysis pointed at the topological and electronic molecular properties as responsible for the discrimination process regarding the set of investigated compounds. The findings suggest that the applied designing strategy, besides providing more potent analogues, indicates the aryl amides and esters as well as the alkyl esters as interesting scaffolds to design and develop novel anticancer agents.

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