Trypomastigote Forms Research Articles

FAZ27 cooperates with FLAM3 and ClpGM6 to maintain cell morphology in Trypanosoma brucei.

The human parasite Trypanosoma brucei transitions from the trypomastigote form to the epimastigote form in the insect vector by repositioning its mitochondrial genome and flagellum-associated cytoskeleton. The molecular mechanisms underlying such changes in cell morphology remain elusive, but recent works demonstrated the involvement of three flagellar proteins, FLAM3, ClpGM6 and KIN-E, in this process by controlling the elongation of the flagellum attachment zone (FAZ). In this report, we identified a FAZ flagellum domain-localizing protein named FAZ27 and characterized its role in cell morphogenesis. Depletion of FAZ27 in the trypomastigote form caused major morphological changes and repositioning of the mitochondrial genome and flagellum-associated cytoskeleton, generating epimastigote-like cells. Furthermore, proximity biotinylation and co-immunoprecipitation identified FLAM3 and ClpGM6 as FAZ27-interacting proteins, and analyses of their functional interplay revealed an interdependency for assembly into the FAZ flagellum domain. Finally, we showed that assembly of FAZ27 occurred proximally, identical to the assembly pattern of other FAZ sub-domain proteins. Taken together, these results demonstrate a crucial role for the FAZ flagellum domain in controlling cell morphogenesis and suggest a coordinated assembly of all the FAZ sub-domains at the proximal end of the FAZ.

Interaction of dicentrinone, an antitrypanosomal aporphine alkaloid isolated from Ocotea puberula (Lauraceae), in cell membrane models at the air-water interface

In the present work, the oxoaporphine alkaloid dicentrinone was isolated, for the first time, from leaves of Ocotea puberula (Lauraceae). This alkaloid exhibited antiparasitic activity against trypomastigote forms of Trypanosoma cruzi (IC50 of 16.4 ± 1.7 μM), similar to the positive control benznidazole (IC50 of 18.7 ± 4.1 μM), reduced mammalian cytotoxicity (CC50 > 200 μM), and a selectivity index (SI) higher than 12. These results were correlated with the effects observed using cellular membrane models, represented by 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), in Langmuir monolayers. Dicentrinone was incorporated in the films, submitted to lateral compression, and characterized by tensiometry. As observed in compression-decompression and time-stability curves, dicentrinone expanded the lipid monolayers, decreased the compressional modulus of the film, and reduced the stability of the monolayer. Brewster Angle Microscopy and interfacial Infrared Spectroscopy showed that dicentrinone causes the monolayers to be segregated in phases, and to increase the number of gauche/trans conformers ratio for the lipid acyl methylene groups, indicating configurational disorder. As a result, dicentrinone caused a disturbance in the cell membrane models, altering the physicochemical properties of the lipid surface such as thermodynamic, rheological, morphological, and structural aspects. These results can be useful to understand the interactions between dicentrinone and lipid biological surfaces at the molecular level.

Antichagasic effect of hemocyanin derived from antimicrobial peptides of penaeus monodon shrimp

Trypanosoma cruzi, the etiological agent of Chagas disease, is responsible for the infection of millions of people worldwide and it is a public health problem, without an effective cure. Four fragments with antimicrobial potential from the hemocyanin of Penaeus monodon shrimp were identified using a computer software AMPA. The present study aimed to evaluate the antichagasic effect of these four peptides (Hmc364-382, Hmc666-678, Hmc185-197 and Hmc476-498). The peptides were tested against the epimastigote, trypomastigote and amastigote forms of Trypanosoma cruzi Y strain (benznidazole-resistant strain) and cytotoxicity in mammalian cells was evaluated against LLC-MK2 lineage cells. Two fragments (Hmc364-382, Hmc666-678) showed activity against the epimastigote and trypomastigote forms and their selectivity index (SI) was calculated. The Hmc364-382 peptide was considered the most promising (SI > 50) one and it was used for further studies, using flow cytometry analyses with specific molecular probes and scanning electron microscopy (SEM). Hmc364-382 was able to induce cell death in T. cruzi through necrosis, observed by loss of membrane integrity in flow cytometry analyses and pore formation in SEM. Overall, Hmc364-382 open perspectives to the development of new antichagasic agents.

Synthesis and trypanocidal activity of novel pyridinyl-1,3,4-thiadiazole derivatives

Herein, we present the design, synthesis and trypanocidal evaluation of sixteen new 1,3,4-thiadiazole derivatives from N-aminobenzyl or N-arylhydrazone series. All derivatives were assayed against the trypomastigote form of Trypanosoma cruzi, showing IC50 values ranging from 3 to 226 μM, and a better trypanocidal profile was demonstrated for the 1,3,4-thiadiazole-N-arylhydrazones (3a-g). In this series, the 2-pyridinyl fragment bound to the imine subunit of the hydrazine moiety presented pharmacophoric behavior for trypanocidal activity. Compounds 2a, 11a and 3e presented remarkable activity and excellent selectivity indexes. Compound 2a was also active against the intracellular amastigote form of T. cruzi. Moreover, its corresponding hydrochloride, compound 11a, showed the most promising profile, producing phenotypic changes similar to those caused by posaconazole, a well-known inhibitor of sterol biosynthesis. Thus, 1,3,4-thiadiazole derivative 11a could be considered a good prototype for the development of new drug candidates for Chagas disease therapy.

Wasp venom peptide as a new antichagasic agent

Chagas disease is caused by Trypanosoma cruzi and affects approximately 10 million people a year worldwide. The only two treatment options, benznidazole and nifurtimox, have low efficacy and high toxicity towards human cells. Mastoporan peptide (MP) a small cationic AMP from the venom of the wasp Polybia paulista has been reported as a potent trypanocidal agent. Thus, we evaluated the antichagasic effect of another AMP from the venom of the same wasp Polybia paulista, polybia-CP (ILGTILGLLSKL-NH2), and investigated its mechanism of action against different stages of the trypanosomal cells life cycle. Polybia-CP was tested against the epimastigote, trypomastigote and amastigote forms of the T. cruzi Y strain (benznidazole-resistant strain) and inhibited the development of these forms. We also assessed the selectivity of the AMP against mammalian cells by exposing LLC-MK2 cells to polybia-CP, the peptide presented a high selectivity index (>106). The mechanism of action of polybia-CP on trypanosomal cells was investigated by flow cytometry, scanning electron microscopy (SEM) and enzymatic assays with T. cruzi GAPDH (tcGAPDH), enzyme that catalyzes the sixth step of glycolysis. Polybia-CP induced phosphatidylserine exposure, it also increased the formation of reactive species of oxigen (ROS) and reduced the transmembrane mitochondrial potential. Polybia-CP also led to cell shrinkage, evidencing apoptotic cell death. We did not observe the inhibition of tcGAPDH or autophagy induction. Altogether, polybia-CP has shown the features of a promising template for the development of new antichagasic agents.

Improving the drug-likeness of inspiring natural products - evaluation of the antiparasitic activity against Trypanosoma cruzi through semi-synthetic and simplified analogues of licarin A

Neolignan licarin A (1) was isolated from leaves of Nectandra oppositifolia (Lauraceae) and displayed activity against trypomastigote forms of the etiologic agent of American trypanosomiasis, Trypanosoma cruzi. Aiming for the establishment of SAR, five different compounds (1a – 1e) were prepared and tested against T. cruzi. The 2-allyl derivative of licarin A (1d) exhibited higher activity against trypomastigotes of T. cruzi (IC50 = 5.0 μM and SI = 9.0), while its heterocyclic derivative 1e displayed IC50 of 10.5 μM and reduced toxicity against NCTC cells (SI > 19.0). However, these compounds presented limited oral bioavailability estimation (<85%, Papp <1.0 × 10−6 cm/s) in parallel artificial membrane permeability assays (PAMPA) due to excessive lipophilicity. Based on these results, different simplified structures of licarin A were designed: vanillin (2), vanillyl alcohol (3), isoeugenol (4), and eugenol (5), as well as its corresponding methyl (a), acetyl (b), O-allyl (c), and C-allyl (d) analogues. Vanillin (2) and its acetyl derivative (2b) displayed expressive activity against intracellular amastigotes of T. cruzi with IC50 values of 5.5 and 5.6 μM, respectively, and reduced toxicity against NCTC cells (CC50 > 200 μM). In addition, these simplified analogues showed a better permeability profile (Papp > 1.0 × 10−6 cm/s) on PAMPA models, resulting in improved drug-likeness. Vanillyl alcohol acetyl derivative (3b) and isoeugenol methyl derivative (4a) displayed activity against the extracellular forms of T. cruzi (trypomastigotes) with IC50 values of 5.1 and 8.8 μM respectively. Based on these results, compounds with higher selectivity index against extracellular forms of the parasite (1d, 1e, 3d, and 4a) were selected for a mechanism of action study. After a short incubation period (1 h) all compounds increased the reactive oxygen species (ROS) levels of trypomastigotes, suggesting cellular oxidative stress. The ATP levels were increased after two hours of incubation, possibly involving a high energy expenditure of the parasite to control the homeostasis. Except for compound 4a, all compounds induced hyperpolarization of mitochondrial membrane potential, demonstrating a mitochondrial imbalance. Considering the unique mitochondria apparatus of T. cruzi and the lethal alterations induced by structurally based on licarin A, these compounds are interesting hits for future drug discovery studies in Chagas disease.

Trypanosoma cruzi-Infected Human Macrophages Shed Proinflammatory Extracellular Vesicles That Enhance Host-Cell Invasion via Toll-Like Receptor 2.

Extracellular vesicles (EVs) shed by trypomastigote forms of Trypanosoma cruzi have the ability to interact with host tissues, increase invasion, and modulate the host innate response. In this study, EVs shed from T. cruzi or T.cruzi-infected macrophages were investigated as immunomodulatory agents during the initial steps of infection. Initially, by scanning electron microscopy and nanoparticle tracking analysis, we determined that T. cruzi-infected macrophages release higher numbers of EVs (50–300 nm) as compared to non-infected cells. Using Toll-like-receptor 2 (TLR2)-transfected CHO cells, we observed that pre-incubation of these host cells with parasite-derived EVs led to an increase in the percentage of infected cells. In addition, EVs from parasite or T.cruzi-infected macrophages or not were able to elicit translocation of NF-κB by interacting with TLR2, and as a consequence, to alter the EVs the gene expression of proinflammatory cytokines (TNF-α, IL-6, and IL-1β), and STAT-1 and STAT-3 signaling pathways. By proteomic analysis, we observed highly significant changes in the protein composition between non-infected and infected host cell-derived EVs. Thus, we observed the potential of EVs derived from T. cruzi during infection to maintain the inflammatory response in the host.

Knocking Down TcNTPDase-1 Gene Reduces in vitro Infectivity of Trypanosoma cruzi.

Ecto-Nucleoside Triphosphate Diphosphohydrolases are enzymes that hydrolyze tri- and/or diphosphate nucleosides. Evidences pointed out to their participation in Trypanosoma cruzi virulence, infectivity, and purine acquisition. In this study, recombinant T. cruzi knocking out or overexpressing the TcNTPDase-1 gene were built, and the role of TcNTPDase-1 in the in vitro interaction with VERO cells was investigated. Results show that epimastigote forms of hemi-knockout parasites showed about 50% lower level of TcNTPDase-1 gene expression when compared to the wild type, while the T. cruzi overexpressing this gene reach 20 times higher gene expression. In trypomastigote forms, the same decreasing in TcNTPDase-1 gene expression was observed to the hemi-knockout parasites. The in vitro infection assays showed a reduction to 51.6 and 59.9% at the adhesion and to 25.2 and 26.4% at the endocytic indexes to the parasites knockout to one or other allele (Hygro and Neo hemi-knockouts), respectively. In contrast, the infection assays with T. cruzi overexpressing TcNTPDase-1 from the WT or Neo hemi-knockout parasites showed an opposite result, with the increasing to 287.7 and 271.1% at the adhesion and to 220.4 and 186.7% at the endocytic indexes, respectively. The parasitic load estimated in infected VERO cells by quantitative real time PCR corroborated these findings. Taken together, the partial silencing and overexpression of the TcNTPDase-1 gene generated viable parasites with low and high infectivity rates, respectively, corroborating that the enzyme encoded for this gene plays an important role to the T. cruzi infectivity.

Nuclear export of replication protein A in the nonreplicative infective forms of Trypanosomacruzi.

Replication protein A (RPA), a heterotrimeric complex, is the major single-stranded DNA binding protein in eukaryotes. Recently, we characterized RPA from Trypanosomacruzi, showing that it is involved in DNA replication and DNA damage response in this organism. Better efficiency in differentiation from epimastigote to metacyclic trypomastigote forms was observed in TcRPA-2 subunit heterozygous knockout cells, suggesting that RPA is involved in this process. Here, we show that RPA cellular localization changes during the T.cruzi life cycle, with RPA being detected only in the cytoplasm of the metacyclic and bloodstream trypomastigotes. We also identify a nuclear export signal (NES) in the trypanosomatid RPA-2 subunit. Mutations in the negatively charged residues of RPA-2 NES impair the differentiation process, suggesting that RPA exportation affects parasite differentiation into infective forms.

Anti-Trypanosoma cruzi Activity and Molecular Docking Studies of 1Hpyrazolo[ 3, 4-b]pyridine Derivatives

Background: Untargeted studies led to the development of some pyrazolopyridine derivatives for the antiparasitic profile, particularly the derivatives containing the structural carbohydrazide subunit. In this work, we proceeded in the biological screening of 27 N’- (substitutedphenylmethylene)- 4-carbohydrazide-3-methyl-1-phenyl-1H-pyrazolo[3, 4-b]pyridine derivatives against T. cruzi as well as the cytotoxic evaluation. To obtain more information about the trypanocidal activity of this class of compounds, we carried out molecular docking simulations to get an insight into putative targets in T. cruzi. Methods: The assays were evaluated against both trypomastigote and amastigote forms of T. cruzi and cytotoxicity assays on LLCMK2 cells. The predominant conformational compounds were analyzed and molecular docking simulations performed. Results: The results from trypanocidal activity screening of this series showed that just the compounds with phenyl group at C-6 position exhibited activity and the N’-4-hydroxyphenylmethylene derivative presented the best profile against both trypomastigote and amastigote forms of T. cruzi. Docking simulation results showed that this compound has a binding affinity with both CYP51 and cruzain targets of T. cruzi. Conclusion: Our results indicate that the hydroxyl substituent at the N’-substituted-phenylmethylene moiety and the phenyl ring at C-6 of 1H-pyrazolo[3,4-b]pyridine system are relevant for the trypanocidal activity of this class of compounds. Also, docking simulations showed that activity presented can be related to more than one target of the parasite.

Natural Infection by Trypanosoma cruzi in a Dog from Bahia State - Northeast of Brazil

Background: Chagas Disease (CD) is a parasitic anthropozoonosis caused by the Trypanosoma cruzi (T. cruzi), a protozoan transmitted by insects from the Reduviidae family. Several species of wild and domestic animals, humans included, are susceptible, developing acute clinical signals (myocarditis and cardiac arrhythmias) or chronic signals (drop on the performance and syncope) of the disease. In Brazil, the disease in dogs shows variable indexes of occurrence. The present paper describes the natural infection by T. cruzi in a canine living in the city of Barra, in the state of Bahia, Brazil, a region classified as high risk of vulnerability for the CD in the northeast of Brazil.Case: A 9-year-old male dog, non-specific breed, was referred to the clinic the Veterinary Clinic for Small Animals, at the Veterinary Medical Teaching Hospital), at the Federal University of the West of Bahia. Its owner reported the presence of bloody secretion in the penile region. During the physical exam it was possible to observe an increase in the volume of the penis base. All of the animal’s physiological parameters were within normal levels. Blood samples and cytological laminas from the lesioned area were collected and sent to the Laboratory of Veterinary Clinical Pathology in the same institution. The cytological exam showed monomorphic population of great round cells with a round nucleus, condensed chromatin and one to two prominent nucleolus, abundant and slightly basophilic cytoplasm, with multiple stippled vacuoles, thus confirming a Transmissible venereal tumor (TVT) case. With the blood exam one observed a thrombocytopenia, neutrophilia with a deviation on the left and the presence of a trypomastigote form of Trypanosoma sp. in the blood smears. A complete blood sample was sent to the Laboratory of Pathology and Molecular Biology from the Fiocruz-BA (Oswaldo Cruz Foundation in the State of Bahia), being identified by the PCR technique, T. cruzi.Discussion: During the complete blood count, specifically using the blood smear, the microscopic visualization of the trypomastigote form of the Trypanosoma sp., a hemoparasite of filiform aspect, with undulating membrane over the whole body and free flagellum, confirming a case of trypanosomiasis. Such diagnostics had not been considered up to this moment, as the animal did not present any clinic symptomatology that indicated the pathological condition. The high levels of parasitemia presented by the animal, confirmed by the presence of the protozoan in the blood smear, probably indicate the acute phase of the infection, period in which the multiplication and development of the agent is higher, consequently allowing the visualization of the hemoparasite in the lamina. Although the TVT had proved to be the main derogatory factor of sanity and wellbeing of the animal, one calls the attention in this case for the trypanosomiasis, a zoonosis that causes great risk to the sole health, highlighting that the canine species is taken as an important reservoir of T. cruzi, relevant for the maintenance and interaction among the domestic and wild cycles of the Chagas Disease. This is the first report of a canine naturally infected by T. cruzi in the west Region of the State of Bahia. It is, thus, important to emphasize its significance once dogs can be reservoirs of the protozoan, acting in their life cycle and epidemiological chain of the Chagas Disease, enabling the infection of triatomines and humans. Future studies should be done with the purpose of determining the predominance of the agent in the region of the city of Barra, in the State of Bahia.

Morphometric and morphological characterization of Trypanosoma sp. (Kinetoplastea: Trypanosomatidae) hemoparasite of Crested Eagle, Morphnus guianensis in the Brazilian Amazon.

Morphnus guianensis is a species belonging to the Accipitridae family classified as almost threatened by the International Union for Conservation of Nature (IUCN). Trypanosomes are flagellated protozoa that carry out their life cycle in the circulatory system of vertebrate hosts and within the digestive tract of invertebrate hosts. This study recorded Trypanosoma sp. parasitizing M. guianensis in the Brazilian Amazon, providing data related to the morphology and morphometry of the trypomastigote forms of peripheral blood of this bird. The mean values of the measured morphological regions were used to compare morphometric similarity with morphotypes described for Trypanosoma sp. through the Bray-Curtis method and, after statistical analysis, the dendrogram was generated from the morphological similarities with a similarity greater than 95% with T. paddae described for different hosts in different geographical regions.

Design, Synthesis and In Vitro Trypanocidal and Leishmanicidal Activities of 2‐(2‐Arylidene)hydrazono‐4‐oxothiazolidine‐5‐acetic Acid Derivatives

AbstractTrypanosomatids are protozoan parasites responsible for leishmaniasis, Chagas disease and sleeping sickness. The design of new antitrypanosomatid drugs with trypanosomicidal and leishmanicidal activities is an effective perspective. The thiazolidinone ring is an important scaffold for several biological disorders. Herein, 4‐oxothiazolidine‐5‐acetic acids (1 a‐1 w) have been synthesized from respective thiosemicarbazone and maleic anhydride. Some of these 4‐oxothiazolidine‐5‐acetic acids were toxic for trypomastigotes without affecting macrophages viability. From this series, compounds 1 e (IC50=10 μM), 1 u (IC50=8.94 μM), 1 g (IC50=5.65 μM) and 1 w (14.06 μM) showed the best anti‐T. cruzi activity for trypomastigote form, while 1 e, 1 u and 1 g showed SI higher than benznidazole (BZD). Similarly, against epimastigote the compound 1 q (IC50epi= 4.70 μM) has been found more selective and most active than benznidazole. However, evaluation against T. cruzi revealed that most of the active compounds have a low inhibition profile and weak leishmanicidal activity. In silico data suggests a good drug‐likeness profile, high chemical stability and demonstrate the use of these compounds in the designing of new anti‐T. cruzi and anti‐Leishmanial drugs.

Trypanocidal Mechanism of Action and in silico Studies of p-Coumaric Acid Derivatives.

Trypanosoma species are responsible for chronic and systemic infections in millions of people around the world, compromising life quality, and family and government budgets. This group of diseases is classified as neglected and causes thousands of deaths each year. In the present study, the trypanocidal effect of a set of 12 ester derivatives of the p-coumaric acid was tested. Of the test derivatives, pentyl p-coumarate (7) (5.16 ± 1.28 μM; 61.63 ± 28.59 μM) presented the best respective trypanocidal activities against both epimastigote and trypomastigote forms. Flow cytometry analysis revealed an increase in the percentage of 7-AAD labeled cells, an increase in reactive oxygen species, and a loss of mitochondrial membrane potential; indicating cell death by necrosis. This mechanism was confirmed by scanning electron microscopy, noting the loss of cellular integrity. Molecular docking data indicated that of the chemical compounds tested, compound 7 potentially acts through two mechanisms of action, whether by links with aldo-keto reductases (AKR) or by comprising cruzain (CZ) which is one of the key Trypanosoma cruzi development enzymes. The results indicate that for both enzymes, van der Waals interactions between ligand and receptors favor binding and hydrophobic interactions with the phenolic and aliphatic parts of the ligand. The study demonstrates that p-coumarate derivatives are promising molecules for developing new prototypes with antiprotozoal activity.

Exoproteome profiling of Trypanosoma cruzi during amastigogenesis early stages.

Chagas disease is caused by the protozoan Trypanosoma cruzi, affecting around 8 million people worldwide. After host cell invasion, the infective trypomastigote form remains 2–4 hours inside acidic phagolysosomes to differentiate into replicative amastigote form. In vitro acidic-pH-induced axenic amastigogenesis was used here to study this step of the parasite life cycle. After three hours of trypomastigote incubation in amastigogenesis promoting acidic medium (pH 5.0) or control physiological pH (7.4) medium samples were subjected to three rounds of centrifugation followed by ultrafiltration of the supernatants. The resulting exoproteome samples were trypsin digested and analysed by nano flow liquid chromatography coupled to tandem mass spectrometry. Computational protein identification searches yielded 271 and 483 protein groups in the exoproteome at pH 7.4 and pH 5.0, respectively, with 180 common proteins between both conditions. The total amount and diversity of proteins released by parasites almost doubled upon acidic incubation compared to control. Overall, 76.5% of proteins were predicted to be secreted by classical or non-classical pathways and 35.1% of these proteins have predicted transmembrane domains. Classical secretory pathway analysis showed an increased number of mucins and mucin-associated surface proteins after acidic incubation. However, the number of released trans-sialidases and surface GP63 peptidases was higher at pH 7.4. Trans-sialidases and mucins are anchored to the membrane and exhibit an enzyme-substrate relationship. In general, mucins are glycoproteins with immunomodulatory functions in Chagas disease, present mainly in the epimastigote and trypomastigote surfaces and could be enzymatically cleaved and released in the phagolysosome during amastigogenesis. Moreover, evidence for flagella discard during amastigogenesis are addressed. This study provides the first comparative analysis of the exoproteome during amastigogenesis, and the presented data evidence the dynamism of its profile in response to acidic pH-induced differentiation.

Novel nitroimidazole derivatives evaluated for their trypanocidal, cytotoxic, and genotoxic activities

The current treatment of Chagas disease is based on the use of two drugs, nifurtimox (Nfx) and benznidazole (Bnz), both of which present limited efficacy in the chronic stage of the disease and toxic side effects. Thus, the discovery of novel compounds is urgently required. Herein, we report the successful synthesis of 4-nitroimidazole analogs of Bnz via nucleophilic aromatic substitution or cycloaddition reactions. The analogs were biologically evaluated, and compound 4 (4-cyclopropyl-1-(1-methyl-4-nitro-1H-imidazole-5-yl)-1H-1,2,3-triazole) was identified as the most potent against both the trypomastigote (IC50 = 5.4 μM) and amastigote (IC50 = 12.0 μM) forms of T. cruzi, showing activity in the same range as Bnz (IC50 = 8.8 and 8.7 μM, respectively). The cytotoxic and genotoxic activities of compounds 5, 4 and 11 were assessed. These three compounds were cytotoxic and genotoxic to RAW and HepG2 cells and mutagenic to Salmonella enterica strains. However, 4 exhibited toxic effects only at concentrations higher than those needed for trypanocidal activity. Molecular docking of 4 showed the importance of the size and π-π interactions between the nitroimidazole and the cofactor (flavin mononucleotide) of T.cruzi-nitroreductase (TcNTR). Moreover, the residues His503 and Tyr545 are relevant for binding to TcNTR. Our design strategy was capable of generating novel and active Bnz analogs.

(±)-Licarin A and its semi-synthetic derivatives: In vitro and in silico evaluation of trypanocidal and schistosomicidal activities

This paper reports the synthesis of (±)-licarin A 1, a dihydrobenzofuran neolignan, resultant of an oxidative coupling reaction of isoeugenol and horseradish peroxidase (HRP) enzyme. Following, three semi-synthetic derivatives from this compound were obtained: benzylated (±)-licarin A 2, methylated (±)-licarin A 3 and acetylated (±)-licarin A 4. After structural elucidation and assignment by Nuclear Magnetic Resonance of 1H, 13C and DEPT, all compounds were evaluated in vitro against Trypomastigote forms of Trypanosoma cruzi (T. cruzi), the etiologic agent of Chagas disease, and Schistosoma mansoni (S. mansoni) worms, the etiologic agent of schistosomiasis. Compound (4) was the most active against S. mansoni adult worms, displaying worm viability reduction at 25 µM and mortality of all worms at 100 and 200 µM within 24 h. Compound 1 was the second most active, showing worm viability reduction at 50 µM and mortality of 25% and 100% of worms in 24h at concentrations of 100 and 200 µM, respectively. In addition, theoretical calculations aiming at finding molecular properties that showed the correlation for schistosomicidal and trypanocidal activities of (±)-licarin A and three of its semi-synthetic derivatives were also performed.

In Vitro Trypanocidal and Antibacterial Activities of Essential Oils from Four Species of the Family Annonaceae.

The objective of this study was to evaluate the chemical composition, and the trypanocidal and antibacterial activities of the essential oils from four species of Annonaceae: Bocageopsis multiflora (Mart.) R.E.Fr., Duguetia quitarensis Benth., Fusaea longifolia (Aubl.) Saff., and Guatteria punctata (Aubl.) R.A.Howard. The chemical composition of the essential oils from the aerial parts yielded 23, 20, 21 and 23 constituents, respectively, which were identified by GC/MS. The trypanocidal activity was evaluated against the amastigote and trypomastigote forms of T. cruzi. The antibacterial activity was evaluated by the microdilution method against enterohemorrhagic Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, Streptococcus pyogenes, and methicillin-resistant Staphylococcus aureus. The results of trypanocidal activity showed that the essential oils of the four species were active at the tested concentrations, with G. punctata essential oil being the most active, with IC50 =0.029 μg/mL, and selectivity index (SI)=32, being 34 times more active than the reference drug benznidazole. All EOs showed strong antibacterial activity (minimum inhibitory concentrations of 4.68-37.5 μg/mL) against strains of S. mutans.

Organometallic Gold(III) Complexes with Tridentate Halogen‐Substituted Thiosemicarbazones: Effects of Halogenation on Cytotoxicity and Anti‐Parasitic Activity

Chemical properties and biological activity of Au(III) compounds obtained from dichlorido[2‐(dimethylaminomethyl)phenyl‐C1,N]gold(III), [Au(damp‐C1,N)Cl2], and halogenated, potentially tridentate thiosemicarbazones have been studied. The results of this work show that the complexation of the halogenated thiosemicarbazones with Au(III) enhances their stability against hydrolysis and retains or enhances their anti‐parasitic activity. Fluorination in the periphery of the ligands has expectedly no influence on the structural chemistry of the obtained Au(III) complexes, but modulates their biological behaviour. Best results with a remarkably high selectivity index for the trypomastigote form of Trypanosoma cruzi were obtained with the complex containing the ligand, which presents a 3,5‐fluorine substitution in meta‐position of an aromatic ring, [Au(dampH)(L‐3,5‐F)]Cl.

Antichagasic effect of violacein from Chromobacterium violaceum

Violacein (VIO), a bacterial pigment produced by Chromobacterium violaceum, was examined to evaluate the antichagasic activity and its action mechanism against Trypanosoma cruzi Y strain. Violacein was tested against the epimastigote, trypomastigote and amastigote forms of T. cruzi Y strain (benznidazole-resistant strain). VIO inhibited all T. cruzi developmental forms, including amastigotes, which is implicated in the burden of infection in the chronic phase of Chagas disease (CD). VIO induced cell death in T. cruzi through apoptosis, as determined by flow cytometry analyses with specific molecular probes and morphological alterations, such as involvement of reactive oxygen species and changes in mitochondrial membrane potential and cell shrinkage. The results suggest antichagasic activity of VIO against T. cruzi Y strain with apoptotic involvement. The treatment of CD has limited efficacy and side effects that restrict patient tolerability and compliance. The VIO molecule could be used as a model for therapeutic alternatives for this disease.