Trypanosoma Cruzi Epimastigotes Research Articles

In Vitro Identification of Phosphorylation Sites on TcPolβ by Protein Kinases TcCK1, TcCK2, TcAUK1, and TcPKC1 and Effect of Phorbol Ester on Activation by TcPKC of TcPolβ in Trypanosoma cruzi Epimastigotes.

Chagas disease is caused by the single-flagellated protozoan Trypanosoma cruzi, which affects several million people worldwide. Understanding the signal transduction pathways involved in this parasite's growth, adaptation, and differentiation is crucial. Understanding the basic mechanisms of signal transduction in T. cruzi could help to develop new drugs to treat the disease caused by these protozoa. In the present work, we have demonstrated that Fetal Calf Serum (FCS) can quickly increase the levels of both phosphorylated and unphosphorylated forms of T. cruzi DNA polymerase beta (TcPolβ) in tissue-cultured trypomastigotes. The in vitro phosphorylation sites on TcPolβ by protein kinases TcCK1, TcCK2, TcAUK1, and TcPKC1 have been identified by Mass Spectrometry (MS) analysis and with antibodies against phosphor Ser-Thr-Tyr. MS analysis indicated that these protein kinases can phosphorylate Ser and Thr residues on several sites on TcPolβ. Unexpectedly, it was found that TcCK1 and TcPKC1 can phosphorylate a different Tyr residue on TcPolβ. By using a specific anti-phosphor Tyr monoclonal antibody, it was determined that TcCK1 can be in vitro autophosphorylated on Tyr residues. In vitro and in vivo studies showed that phorbol 12-myristate 13-acetate (PMA) can activate the PKC to stimulate the TcPolβ phosphorylation and enzymatic activity in T. cruzi epimastigotes.

Organometallic N‐acylhydrazones of 5‐nitrofuran and 5‐nitrothiophene based: Synthesis, electrochemical, antiparasitic evaluation, and computational study

In searching for new therapeutic agents for treating American trypanosomiasis and Human African trypanosomiasis, four nitroheterocyclic acylhydrazones of general formulae [R1‐CH=N‐NH‐C(O)‐(5‐C4H2X)] (where R1 = ferrocenyl or cyrhetrenyl, and X = O or S) have been synthesized and characterized by spectroscopic techniques. Comparative studies of their stability by 1H‐NMR and UV–Vis experiments were reported. Single‐crystal X‐ray diffraction confirmed the molecular structures of NF‐1 and NT‐2. Their X‐ray crystal structures reveal that both adopt an E‐configuration on the C=N moiety. Regarding the ‐NH‐C(O)‐ bond, the structure of NF‐1 confirmed a trans conformation, while NT‐2 exhibited a cis‐amide conformation. The cyclic voltammetry and electron spin resonance (ESR) experiments were conducted to study the electrochemical behavior of N‐acylhydrazones. The antiparasitic activities of compounds against Trypanosoma cruzi (epimastigotes) and Trypanosoma brucei (trypomastigotes) revealed that cyrhetrenyl complexes were more effective than their ferrocenyl analogs. The cyrhetrenyl derivative NT‐2 (EC50 = 2.25 μM) showed activity against T. brucei comparable to the standard drug nifurtimox (Nfx, EC50 = 3.56 μM). The ferrocenyl compound NT‐1 (>200 μM) was at least two times less cytotoxic than the Nfx (88.7 μM) against the L6 rat skeletal myoblast cell line and exhibited a selectivity like Nfx toward T. brucei. Density functional theory (DFT) calculations were utilized as an approximation to explain the impact of organometallic and heterocyclic rings on antiparasitic activities. This study supported the experimental results, confirming that the cyrhetrenyl fragment in N‐acylhydrazone derivatives plays a significant role in the antitrypanosomal activity, which can be attributed to an increase in positive charge on the metal.

Non-histone protein methylation in Trypanosoma cruzi epimastigotes.

Post-translational methylation of proteins, which occurs in arginines and lysines, modulates several biological processes at different levels of cell signaling. Recently, methylation has been demonstrated in the regulation beyond histones, for example, in the dynamics of protein-protein and protein-nucleic acid interactions. However, the presence and role of non-histone methylation in Trypanosoma cruzi, the etiologic agent of Chagas disease, has not yet been elucidated. Here, we applied mass spectrometry-based-proteomics (LC-MS/MS) to profile the methylproteome of T. cruzi epimastigotes, describing a total of 1252 methyl sites in 824 proteins. Functional enrichment and protein-protein interaction analysis show that protein methylation impacts important biological processes of the parasite, such as translation, RNA and DNA binding, amino acid, and carbohydrate metabolism. In addition, 171 of the methylated proteins were previously reported to bear phosphorylation sites in T. cruzi, including flagellar proteins and RNA binding proteins, indicating that there may be an interplay between these different modifications in non-histone proteins. Our results show that a broad spectrum of functions is affected by methylation in T. cruzi, indicating its potential to impact important processes in the biology of the parasite and other trypanosomes.

Transcriptomic analysis of the adaptation to prolonged starvation of the insect-dwelling Trypanosoma cruzi epimastigotes.

Trypanosoma cruzi is a digenetic unicellular parasite that alternates between a blood-sucking insect and a mammalian, host causing Chagas disease or American trypanosomiasis. In the insect gut, the parasite differentiates from the non-replicative trypomastigote forms that arrive upon blood ingestion to the non-infective replicative epimastigote forms. Epimastigotes develop into infective non-replicative metacyclic trypomastigotes in the rectum and are delivered via the feces. In addition to these parasite stages, transitional forms have been reported. The insect-feeding behavior, characterized by few meals of large blood amounts followed by long periods of starvation, impacts the parasite population density and differentiation, increasing the transitional forms while diminishing both epimastigotes and metacyclic trypomastigotes. To understand the molecular changes caused by nutritional restrictions in the insect host, mid-exponentially growing axenic epimastigotes were cultured for more than 30 days without nutrient supplementation (prolonged starvation). We found that the parasite population in the stationary phase maintains a long period characterized by a total RNA content three times smaller than that of exponentially growing epimastigotes and a distinctive transcriptomic profile. Among the transcriptomic changes induced by nutrient restriction, we found differentially expressed genes related to managing protein quality or content, the reported switch from glucose to amino acid consumption, redox challenge, and surface proteins. The contractile vacuole and reservosomes appeared as cellular components enriched when ontology term overrepresentation analysis was carried out, highlighting the roles of these organelles in starving conditions possibly related to their functions in regulating cell volume and osmoregulation as well as metabolic homeostasis. Consistent with the quiescent status derived from nutrient restriction, genes related to DNA metabolism are regulated during the stationary phase. In addition, we observed differentially expressed genes related to the unique parasite mitochondria. Finally, our study identifies gene expression changes that characterize transitional parasite forms enriched by nutrient restriction. The analysis of the here-disclosed regulated genes and metabolic pathways aims to contribute to the understanding of the molecular changes that this unicellular parasite undergoes in the insect vector.

Bulbiferamide, an Antitrypanosomal Hexapeptide Cyclized via an N-Acylindole Linkage from a Marine Obligate Microbulbifer.

UV absorption spectroscopy-guided fractionation of the culture extract of a marine obligate bacterium of the genus Microbulbifer yielded a novel cyclic hexapeptide, bulbiferamide (1). NMR spectroscopic and mass spectrometric analyses revealed the structure of 1 to be a cyclic tetrapeptide appending a ureido-bridged two amino acid unit. Notably, Trp is a junction residue, forming on one hand a very rare N-aminoacylated indole linkage for cyclization and on the other hand connecting the ureido-containing tail structure, which is an unprecedented way of configuring peptides. The component amino acids were determined to be l by the advanced Marfey's method. Compound 1 displayed growth inhibitory activity against Trypanosoma cruzi epimastigotes with an IC50 value of 4.1 μM, comparable to the currently approved drug benznidazole, while it was not cytotoxic to P388 murine leukemia cells at 100 μM.

Biological activities of 1,4-naphthoquinones derivatives against T. cruzi and L. amazonensis

Introduction: Chagas disease and Leishmaniasis are neglected diseases caused bythe Trypanosoma cruzi and kentoplastid parasites Leishmania spp. Parasitic diseasescause great impact on social and economic, affecting millions of people in the worldand represent a major global health problem. In the search for new alternatives for thetreatment of Leishmaniasis and Chagas disease, strategies have been used to discovernew active molecules, because there is an urgent need for the development of newdrugs. In this scenario, 1,4-naphthoquinones have shown notable activity in thecontext of neglected diseases. Aim: To synthesis of 1,4-naphthoquinones derivativesand evaluated these compounds against Trypanosoma cruzi epimastigotes, Leishmaniapromastigotes (Leishmania amazonensis) and cytotoxicity to LLCMK2 cells.Results: Nine 1,4-naphthoquinones derivatives were synthesized using 2-Bromo-1,4-naphthoquinone (1), 1,4-Naphthoquinone (5) and 2-Hydroxi-1,4-naphthoquinone(9) as starting material. Derivative 6a exhibited excellent trypanocidal activity,IC50 of 0.25 ± 0.02 μM, superior potency compared with the reference drug Benznidazol.Besides, these compounds displayed low activity against promastigote from L.amazonensis. Conclusion: The results indicate that compound 6a may have potentialfor agent against Chagas disease.

Consumption of Galactose by Trypanosoma cruzi Epimastigotes Generates Resistance against Oxidative Stress.

In this study, we demonstrate that Trypanosoma cruzi epimastigotes previously grown in LIT medium supplemented with 20 mM galactose and exposed to sub-lethal concentrations of hydrogen peroxide (100 μM) showed two-fold and five-fold viability when compared to epimastigotes grown in LIT medium supplemented with two different glucose concentrations (20 mM and 1.5 mM), respectively. Similar results were obtained when exposing epimastigotes from all treatments to methylene blue 30 μM. Additionally, through differential centrifugation and the selective permeabilization of cellular membranes with digitonin, we found that phosphoglucomutase activity (a key enzyme in galactose metabolism) occurs predominantly within the cytosolic compartment. Furthermore, after partially permeabilizing epimastigotes with digitonin (0.025 mg × mg−1 of protein), intact glycosomes treated with 20 mM galactose released a higher hexose phosphate concentration to the cytosol in the form of glucose-1-phosphate, when compared to intact glycosomes treated with 20 mM glucose, which predominantly released glucose-6-phosphate. These results shine a light on T. cruzi’s galactose metabolism and its interplay with mechanisms that enable resistance to oxidative stress.

Oxonitrogenated Derivatives of Eremophilans and Eudesmans: Antiproliferative and Anti-Trypanosoma cruzi Activity.

Cancer is one of the most important causes of death worldwide. Solid tumors represent the vast majority of cancers (>90%), and the chemotherapeutic agents used for their treatment are still characterized by variable efficacy and toxicity. Sesquiterpenes are a group of natural compounds that have shown a wide range of biological activities, including cytotoxic and antiparasitic activity, among others. The antiproliferative activity of natural sesquiterpenes, tessaric acid, ilicic acid, and ilicic alcohol and their semisynthetic derivatives against HeLa, T-47D, WiDr, A549, HBL-100, and SW1573 cell lines were evaluated. The effect of the compounds on Trypanosoma cruzi epimastigotes was also assessed. The selectivity index was calculated using murine splenocytes. Derivatives 13 and 15 were the most antiproliferative compounds, with GI50 values ranging between 5.3 (±0.32) and 14 (±0.90) μM, in all cell lines tested. The presence of 1,2,3-triazole groups in derivatives 15–19 led to improvements in activity compared to those corresponding to the starting natural product (3), with GI50 values ranging between 12 (±1.5) and 17 (±1.1) μM and 16 being the most active compound. In relation to the anti-T. cruzi activity, derivatives 7 and 16 obtained from tessaric acid and ilicic acid were among the most active and selective compounds with IC50 values of 9.3 and 8.8 µM (SI = 8.0 and 9.4), respectively.

In Vitro, In Vivo, and In Silico Studies of Cumanin Diacetate as a Potential Drug against Trypanosoma cruzi Infection.

The sesquiterpene lactones cumanin, helenalin, and hymenin and their semisynthetic derivatives were evaluated against Trypanosoma cruzi epimastigotes. The cytotoxicity of the compounds was evaluated on murine splenocytes. Cumanin diacetate was one of the most active and selective compounds [IC50 = 3.20 ± 0.52 μg/mL, selectivity index (SI) = 26.0]. This sesquiterpene lactone was selected for its evaluation on trypomastigote and amastigote forms of the parasite. The diacetylated derivative of cumanin showed moderate activity on trypomastigotes (IC50 = 32.4 ± 5.8 μg/mL). However, this compound was able to efficiently inhibit parasite replication with an IC50 value of 2.2 ± 0.05 μg/mL against the amastigote forms. Cumanin diacetate showed selectivity against the intracellular forms of Trypanosoma cruzi with an SI value of 52.7. This cumanin analogue was also active on an in vivo model of Chagas disease, leading to a reduction in the parasitemia levels in comparison with nontreated animals. Histopathological analysis of skeletal muscular tissues from treated mice showed only focal interstitial lymphocyte inflammatory infiltrates with slight myocyte necrosis; in contrast, nontreated animals showed severe lymphocyte inflammatory infiltrates with necrosis of the myocytes. A molecular docking study of cumanin and its derivatives on trypanothione reductase from T. cruzi (TcTR) was performed. The results of ΔG docking achieved let the identification of diacetylated and O-alkylated derivatives of cumanin as good inhibitors of TcTR. Cumanin diacetate could be considered a potential candidate for further studies for the development of new therapies against Chagas disease.

Calcium Signaling Involves Na+/H+ Exchanger and IP3 Receptor Activation in T. cruzi Epimastigotes

The calcium ion (Ca2+) plays a fundamental role in the metabolism and cell physiology of eukaryotic cells. In general, increases in cytosolic Ca2+ may come from both of the extracellular environment through specific channels and/or calcium release from intracellular stores. The mechanism by which the ion calcium (Ca2+) is released from intracellular stores in higher eukaryotes is well known; however, in lower eukaryotes is still a subject of study. In the present work, it was elucidated that Trypanosoma cruzi epimastigotes can release Ca2+ from intracellular stores in response to high osmolarity, in a process involving a protein kinase-regulated Na+/H+ exchanger present in the acidocalsisomes of the parasite. In addition, we demonstrated that epimastigote membranes are able to release Ca2+ in response to exogenous activators of both inositol 1,4,5-triphosphate (IP3) and Ryanodine receptors. Furthermore, we also summarize the involvement of calcium-related signaling pathways in biochemical and morphological changes triggered by hyperosmotic stress in T. cruzi epimastigotes.

Trypanocidal Activity of Traditional Antiparasitic Medicinal Plants from the Amazon

Pharmacognosy Research,2021,13,4,227-232.DOI:10.5530/pres.13.4.15Published:October 2021Type:Original ArticleAuthors:María-Helena Arias, Gustavo A. Vallejo, and Giovanny Garavito Author(s) affiliations:María-Helena Arias1, Gustavo A. Vallejo2, Giovanny Garavito1,* 1Universidad Nacional de Colombia, Sede Bogotá, Facultad de Ciencias, Departamento de Farmacia, Grupo de Investigación FaMeTra (Farmacología de la Medicina Tradicional y Popular); Carrera 30 45-03, Bogotá D.C. 111321, COLOMBIA. 2Laboratorio de Investigación en Parasitología Tropical, Facultad de Ciencias, Universidad del Tolima, Ibagué, COLOMBIA. Abstract:Background: Neglected Infectious Diseases control is an urgent need in endemic areas, but it’s not a priority in the commercial interests of the pharmaceutical industry. Chagas disease (caused by Trypanosoma cruzi) is the parasitic disease of greatest impact in Latin America. Medicinal plants continue to be an affordable front-line option in endemic areas. Thus, we aimed to advance in the pharmacological evaluation of four medicinal plants traditionally used in the Amazon against parasitic infections. Materials and Methods: The plants were collected in the Amazon region of Colombia. The dry plant material was submitted to water percolation extraction. Extracts were tested in vitro against Trypanosoma cruzi (epimastigotes), and cytotoxicity was assessed against HepG2 and MRC5 cells. Finally, the general profile of metabolites present in the extracts was studied by thin-layer chromatography. Results: In vitro, against T. cruzi, extracts of Ambelania duckei and Curarea toxicofera shows concentration- dependent inhibition (IC50 of 221+/-29 and 50+/-5 μg/mL respectively), comparable with benznidazole (IC50: 0.7 μg/mL); while Abuta grandifolia and Aspidosperma excelsum exhibited IC50’s > 500 μg/mL. All extracts showed no cytotoxicity against HepG2 and MRC5 cells. Yields of extraction were between 3.2 and 9.5% and preliminary phytochemical profile showed flavonoids and steroids in all extracts. Conclusion: Promising plants, traditionally used to treat other protozoan infections, could be assessed against T. cruzi. C. toxicofera exhibits good activity against epimastigotes of T. cruzi, being a species that can reasonably be considered for bioassay-guided antitrypanosomal fractionation. Keywords:Chagas disease, cytotoxicity, Medicinal plants, Neglected Infectious Diseases, Trypanocidal agents, Trypanosoma cruziView:PDF (407.9 KB)

Antiprotozoal Compounds from Urolepis hecatantha (Asteraceae).

The dewaxed dichloromethane extract of Urolepis hecatantha and the compounds isolated from it were tested for their in vitro activity on Trypanosoma cruzi epimastigotes and Leishmania infantum promastigotes. The extract of U. hecatantha showed activity against both parasites with IC50 values of 7 µg/mL and 31 µg/mL, respectively. Fractionation of the dichloromethane extract led to the isolation of euparin, jaceidin, santhemoidin C, and eucannabinolide. The sesquiterpene lactones eucannabinolide and santhemoidin C were active on T. cruzi with IC50 values of 10 ± 2 µM (4.2 µg/mL) and 18 ± 3 µM (7.6 µg/mL), respectively. Euparin and santhemoidin C were the most active on L. infantum with IC50 values of 18 ± 4 µM (3.9 µg/mL) and 19 ± 4 µM (8.0 µg/mL), respectively. Eucannabinolide has also shown drug-like pharmacokinetic and toxicity properties.

Proteomic changes in Trypanosoma cruzi epimastigotes treated with the proapoptotic compound PAC-1

Apoptosis is a highly regulated process of cell death in metazoans. Therefore, understanding the biochemical changes associated with apoptosis-like death in Trypanosoma cruzi is key to drug development. PAC-1 was recently shown to induce apoptosis in T. cruzi; with this as motivation, we used quantitative proteomics to unveil alterations of PAC-1-treated versus untreated epimastigotes. The PAC-1 treatment reduced the abundance of putative vesicle-associated membrane protein, putative eukaryotic translation initiation factor 1 eIF1, coatomer subunit beta, putative amastin, and a putative cytoskeleton-associated protein. Apoptosis-like signaling also increases the abundance of proteins associated with actin cytoskeleton remodeling, cell polarization, apoptotic signaling, phosphorylation, methylation, ergosterol biosynthesis, vacuolar proteins associated with autophagy, and flagellum motility. We shortlist seventeen protein targets for possible use in chemotherapy for Chagas disease. Almost all differentially abundant proteins belong to a family of proteins previously associated with apoptosis in metazoans, suggesting that the apoptotic pathway's key functions have been preserved from trypanosomatids and metazoans. SignificanceApproximately 8 million people worldwide are infected with Trypanosoma cruzi. The treatment of Chagas disease comprises drugs with severe side effects, thus limiting their application. Thus, developing new pharmaceutical solutions is relevant, and several molecules targeting apoptosis are therapeutically efficient for parasitic, cardiac, and neurological diseases. Apoptotic processes lead to specific morphological features that have been previously observed in T. cruzi. Here, we investigate changes in epimastigotes' proteomic profile treated with the proapoptotic compound PAC-1, providing data concerning the regulation of both metabolic and cellular processes in nonmetazoan apoptotic cells. We shortlist seventeen protein target candidates for use in chemotherapy for Chagas disease.

Mitochondrial behavior during nuclear and mitochondrial DNA repair in Trypanosoma cruzi epimastigotes

Different genotoxic agents can lead to DNA single- and double-strand breaks, base modification and oxidation. As most living organisms, Trypanosoma cruzi is subjected to oxidative stress during its life cycle; thus, DNA repair is essential for parasite survival and establishment of infection. The mitochondrion plays important roles beyond the production of ATP. For example, it is a source of signaling molecules, such as the superoxide anion and H2O2. Since T. cruzi has only one mitochondrion, the integrity of this organelle is pivotal for parasite viability. H2O2 and methyl methanesulfonate cause DNA lesions in T. cruzi that are repaired by different DNA repair pathways. Herein, we evaluate mitochondrial involvement during the repair of nuclear and mitochondrial DNA in T. cruzi epimastigotes incubated with these two genotoxic agents under conditions that induce repairable DNA damage. Overall, in both treatments, an increase in oxygen consumption rates and in mitochondrial H2O2 release was observed, as well as maintenance of ATP levels compared to control. Interestingly, these changes coincided with DNA repair kinetics, suggesting the importance of the mitochondrion for this energy-consuming process.

Trypanocidal Activity of Four Sesquiterpene Lactones Isolated from Asteraceae Species.

The sesquiterpene lactones eupatoriopicrin, estafietin, eupahakonenin B and minimolide have been isolated from Argentinean Astearaceae species and have been found to be active against Trypanosoma cruzi epimastigotes. The aim of this work was to evaluate the activity of these compounds by analyzing their effect against the stages of the parasites that are infective for the human. Even more interesting, we aimed to determine the effect of the most active and selective compound on an in vivo model of T. cruzi infection. Eupatoriopicrin was the most active against amastigotes and tripomastigotes (IC50 = 2.3 µg/mL, and 7.2 µg/mL, respectively) and displayed a high selectivity index. This compound was selected to study on an in vivo model of T. cruzi infection. The administration of 1 mg/kg/day of eupatoriopicrin for five consecutive days to infected mice produced a significant reduction in the parasitaemia levels in comparison with non-treated animals (area under parasitaemia curves 4.48 vs. 30.47, respectively). Skeletal muscular tissues from eupatopicrin-treated mice displayed only focal and interstitial lymphocyte inflammatory infiltrates and small areas of necrotic; by contrast, skeletal tissues from T. cruzi infected mice treated with the vehicle showed severe lymphocyte inflammatory infiltrates with necrosis of the adjacent myocytes. The results indicate that eupatoriopicrin could be considered a promising candidate for the development of new therapeutic agents for Chagas disease.

In vitro and in silico evaluations of new aryloxy-1,4-naphthoquinones as anti-Trypanosoma cruzi agents

In the search for new therapeutic alternatives for Chagas disease, a series of six aryloxy -naphthoquinone derivatives were synthesized and evaluated in vitro against Trypanosoma cruzi epimastigotes of the Tulahuen 2, INC-5, and NINOA strains. The compounds 3d and 4a showed better or similar trypanosomicidal activity than the reference drug nifurtimox. In addition, 3d and 4a also elicited better trypanosomicidal activity than nifurtimox against T. cruzi bloodstream trypomastigotes. On the other hand, 3b showed the highest selective indexes (SI values between 44 and 500, in the three T. cruzi strains). Finally, molecular docking studies suggested that these compounds could be potential trypanothione reductase inhibitors. Therefore, based on these new results, we validated that the aryloxy-naphthoquinone scaffold is essential to obtain more selective cytotoxic and trypanosomicidal compounds.

Isolation, Biochemical Characterization and Antiparasitic Activity of BmatTX-IV, A Basic Lys49-Phospholipase A2 from the Venom of Bothrops mattogrossensis from Paraguay.

Functional and structural diversity of proteins of snake venoms is coupled with a wide repertoire of pharmacological effects. Snake venoms are targets of studies linked to searching molecules with biotechnological potential. A homologue phospholipase A2 (BmatTX-IV) was obtained using two chromatographic techniques. Mass spectrometry and two-dimensional gel electrophoresis were used to determine the molecular mass and isoelectric point, respectively. By means of Edman degradation chemistry, it was possible to obtain the partial sequence of amino acids that comprise the isolated toxin. Trypanocidal, leishmanicidal and cytoxic activity against Trypanosoma cruzi, Leishmania infantum and murine fibrobasts was determinated. Combination of both chromatographic steps used in this study demonstrated efficacy to obtain the PLA2-Lys49. BmatTX-IV showed molecular mass and isoelectric point of 13.55 kDa and 9.3, respectively. Amino acid sequence of N-terminal region (51 residues) shows the presence of Lys49 residue at position 49, a distinctive trait of enzymatically inactive PLA2. Bothrops mattogrossensis snake venom showed IC50 values of 11.9 μg/mL against Leishmania infantum promastigotes and of 13.8 μg/mL against Trypanosoma cruzi epimastigotes, respectively. On the other hand, the venom showed a high cytotoxic activity (IC50 value of 16.7 μg/mL) against murine fibroblasts, whereas the BmatTX-IV showed IC50 value of 81.2 μg/mL. Physicochemical and biological characterization of snake venoms components is critically important, since these complex mixtures provide a source of molecules with antiparasitic potential, making further studies necessary to identify and characterize components with higher efficacy and selectivity.

Novel [1,2,3]triazolo[1,5-a]pyridine derivatives are trypanocidal by sterol biosynthesis pathway alteration.

Aim: To study a new series of [1,2,3]triazolo[1,5-α]pyridine derivatives as trypanocidal agents because current antichagasic pharmacologic therapy is only partially effective. Materials & methods: The effect of the series upon Trypanosoma cruzi epimastigotes and murine macrophages viability, cell cycle, cell death and on the metabolites of the sterol biosynthesis pathway was measured; also, docking in 14α-demethylase was analyzed. Results: Compound 16 inhibits 14α-demethylase producing an imbalance in the cholesterol/ergosterol synthesis pathway, as suggested by a metabolic control and theoretical docking analysis. Consequently, it prevented cell proliferation, stopping the cellular cycle at the G2/M phase, inducing cell death. Conclusion: Although the exact cell death mechanism remained elusive, this series can be used for the further rational design of novel antiparasitic molecules.

Synthesis, 2D-QSAR Studies and Biological Evaluation of Quinazoline Derivatives as Potent Anti-Trypanosoma cruzi Agents

Chagas disease affects about 7 million people worldwide. Only two drugs are currently available for the treatment for this parasite disease, namely, benznidazol (Bzn) and nifurtimox (Nfx). Both drugs have limited curative power in the chronic phase of the disease. Therefore, continuous research is an urgent need so as to discover novel therapeutic alternatives. The development of safer and more efficient therapeutic anti-T. cruzi drugs continues to be a major goal in trypanocidal chemotherapy. Synthesis, 2D-QSAR and drug-like physicochemical properties of a set of quinazolinone and quinazoline derivatives were studied as trypanocidal agents. All compounds were screened in vitro against Trypanosoma cruzi (Tulahuen strain, Tul 2 stock) epimastigotes and bloodstream trypomastigotes. Out of 34 compounds synthesized and tested, six compounds (5a, 5b, 9b, 9h, 13f and 13p) displayed significant activity against both epimastigotes and tripomastigotes, without exerting toxicity on Vero cells. The antiprotozoal activity of these quinazolinone and quinazoline derivatives represents an interesting starting point for a medicinal chemistry program aiming at the development of novel chemotherapies for Chagas disease.

In vitro activity of steroidal dendrimers on Trypanosoma cruzi epimastigote form with PAMAM dendrons modified by “click” chemistry

The increasing use of dendrimers shows promise for the treatment of inflammatory diseases, Chagas disease and other conditions such as cancer. In this study, the activity of 1st and 2nd generation dendrimers over T. cruzi in the epimastigote stage was tested. Dendrimers were derived from α-ethynylestradiol (EE) modified with PAMAM-type dendrons through a triazole ring. The activity of each compound was evaluated in five doses (from 1.3 to 20 µmol/mL) by flow cytometry, including benznidazole (Bz) as positive control. The findings show that an equivalent concentration of 14.8 µmol/mL of 2nd generation (G) dendrimer is 8 times more effective than Bz at 24 h, and it maintains its superiority at 48 h with an IC50 = 1.25 ± 0.19 µmol/mL. A TUNEL assay showed that dendrimers induce cell death in T. cruzi epimastigotes mostly via apoptosis, unlike Bz, which induces death via necrosis in more than 50% of cells.