Trypanosoma cruzi killing and immune response boosting by novel phenoxyhydrazine-thiazole against Chagas disease.

Trypanosoma cruzi (T. cruzi) causes Chagas, which is a neglected tropical disease (NTD). WHO estimates that 6 to 7 million people are infected worldwide. Current treatment is done with benznidazole (BZN), which is very toxic and effective only in the acute phase of the disease. In this work, we designed, synthesized, and characterized thirteen new phenoxyhydrazine-thiazole compounds and applied molecular docking and in vitro methods to investigate cell cytotoxicity, trypanocide activity, nitric oxide (NO) production, cell death, and immunomodulation. We observed a higher predicted affinity of the compounds for the squalene synthase and 14-alpha demethylase enzymes of T. cruzi. Moreover, the compounds displayed a higher predicted affinity for human TLR2 and TLR4, were mildly toxic in vitro for most mammalian cell types tested, and LIZ531 (IC50 2.8 µM) was highly toxic for epimastigotes, LIZ311 (IC50 8.6 µM) for trypomastigotes, and LIZ331 (IC50 1.9 µM) for amastigotes. We observed that LIZ311 (IC50 2.5 µM), LIZ431 (IC50 4.1 µM) and LIZ531 (IC50 5 µM) induced 200 µg/mL of NO and JM14 induced NO production in three different concentrations tested. The compound LIZ331 induced the production of TNF and IL-6. LIZ311 induced the secretion of TNF, IFNγ, IL-2, IL-4, IL-10, and IL-17, cell death by apoptosis, decreased acidic compartment formation, and induced changes in the mitochondrial membrane potential. Taken together, LIZ311 is a promising anti-T. cruzi compound is not toxic to mammalian cells and has increased antiparasitic activity and immunomodulatory properties.

In vitro bioevaluation and docking study of dihydrosphingosine and ethambutol analogues against sensitive and multi-drug resistant Mycobacterium tuberculosis.

Tuberculosis remains a major public health problem and one of the top ten causes of death worldwide. The alarming increase in multidrug-resistant and extensively resistant variants (MDR, pre-XDR, and XDR) makes the disease more difficult to treat and control. New drugs that act against MDR/XDR strains are needed for programs to contain this major epidemic. The present study aimed to evaluate new compounds related to dihydro-sphingosine and ethambutol against sensitive and pre-XDR Mycobacterium strains, as well as to characterize the pharmacological activity through in vitro and in silico approaches in mmpL3 protein. Of the 48 compounds analyzed, 11 demonstrated good to moderate activity on sensitive and MDR Mycobacterium tuberculosis (Mtb), with a Minimum Inhibitory Concentration (MIC) ranging from 1.5 to 8 µM. They presented 2 to 14 times greater potency of activity when compared to ethambutol in pre-XDR strain, and demonstrated a selectivity index varying between 2.21 and 82.17. The substance 12b when combined with rifampicin, showed a synergistic effect (FICI = 0.5) on sensitive and MDR Mtb. It has also been shown to have a concentration-dependent intracellular bactericidal effect, and a time-dependent bactericidal effect in M. smegmatis and pre-XDR M. tuberculosis. The binding mode of the compounds in its cavity was identified through molecular docking and using a predicted structural model of mmpL3. Finally, we observed by transmission electron microscopy the induction of damage to the cell wall integrity of M. tuberculosis treated with the substance 12b. With these findings, we demonstrate the potential of a 2-aminoalkanol derivative to be a prototype substance and candidate for further optimization of molecular structure and anti-tubercular activity in preclinical studies.

Synthesis, characterization, antioxidant and antiparasitic activities new naphthyl-thiazole derivatives.

In this work, 13 thiosemicarbazones (1a - m) and 16 thiazoles (2a - p) were obtained, which were properly characterized by spectroscopic and spectrometric techniques. The pharmacokinetic properties obtained in silico revealed that the derivatives are in accordance with the parameters established by lipinski and veber, showing that such compounds have good bioavailability or permeability when administered orally. In assays of antioxidant activity, thiosemicarbazones showed moderate to high antioxidant potential when compared to thiazoles. In addition, they were able to interact with albumin and DNA. Screening assays to assess the toxicity of compounds to mammalian cells revealed that thiosemicarbazones were less toxic when compared to thiazoles. In relation to in vitro antiparasitic activity, thiosemicarbazones and thiazoles showed cytotoxic potential against the parasites Leishmania amazonensis and Trypanosoma cruzi. Among the compounds, 1b, 1j and 2l stood out, showing inhibition potential for the amastigote forms of the two parasites. As for the in vitro antimalarial activity, thiosemicarbazones did not inhibit Plasmodium falciparum growth. In contrast, thiazoles promoted growth inhibition. This study shows in a preliminary way that the synthesized compounds have antiparasitic potential in vitro.

Structural improvement of new thiazolyl-isatin derivatives produces potent and selective trypanocidal and leishmanicidal compounds.

Neglected diseases are a group of transmissible diseases that occur mostly in countries in tropical climates. Among this group, Chagas disease and leishmaniasis stand out, considered threats to global health. Treatment for these diseases is limited. Therefore, there is a need for new therapies against these diseases. In this sense, our proposal consisted of developing two series of compounds, using a molecular hybridization of the heterocyclic isatin and thiazole. The isatin and thiazole ring are important scaffold for several biological disorders, including antiparasitic ones. Herein, thiazolyl-isatin has been synthesized from respective thiosemicarbazone or phenyl-thiosemicarbazone, being some of these new thiazolyl-isatin toxic for trypomastigotes without affecting macrophages viability. From this series, compounds 2e (IC50 = 4.43 µM), 2j (IC50 = 2.05 µM), 2l (IC50 = 4.12 µM) and 2m (1.72 µM) showed the best anti-T. cruzi activity for trypomastigote form presenting a selectivity index higher than Benznidazole (BZN). Compounds 2j, 2l and 2m were able to induce a significantly labelling compatible with necrosis in trypomastigotes. Analysis by scanning electron microscopy showed that T. cruzi trypomastigote cells treated with the compound 2m from IC50 concentrations, promoted changes in the shape, flagella and surface of body causing of the parasite dead. Concerning leishmanicidal evaluation against L. amazonensis and L. infantum, compounds 2l (IC50 = 7.36 and 7.97 µM, respectively) and 2m (6.17 and 6.04 µM, respectively) showed the best activity for promastigote form, besides showed a higher selectivity than Miltefosine. Thus, compounds 2l and 2m showed dual in vitro trypanosomicidal and leishmanicidal activities. A structural activity relationship study showed that thiazolyl-isatin derivatives from phenyl-thiosemicarbazone (2a-m) were, in general, more active than thiazolyl-isatin derivatives from thiosemicarbazone (1a-g). Crystallography studies revealed a different configuration between series 1a-g and 2a-m. The configuration and spatial arrangement divergent between the two sub-series could explain the improved biological activity profile of 2a-m sub-series.

Structural design, synthesis and anti-Trypanosoma cruzi profile of the second generation of 4-thiazolidinones chlorine derivatives.

Chagas disease causes more deaths in the Americas than any other parasitic disease. Initially confined to the American continent, it is increasingly becoming a global health problem. In fact, it is considered to be an "exotic" disease in Europe, being virtually undiagnosed. Benznidazole, the only drug approved for treatment, effectively treats acute-stage Chagas disease, but its effectiveness for treating indeterminate and chronic stages remains uncertain. Previously, our research group demonstrated that 4-thiazolidinones presented anti-T. cruzi activity including in the in vivo assays in mice, making this fragment appealing for drug development. The present work reports the synthesis and anti-T. cruzi activities of a novel series of 4-thiazolidinones derivatives that resulted in an increased anti-T. cruzi activity in comparison to thiosemicarbazones intermediates. Compounds 2c, 2e, and 3a showed potent inhibition of the trypomastigote form of the parasite at low cytotoxicity concentrations in mouse splenocytes. Besides, all the 2c, 2e, and 3a tested concentrations showed no cytotoxic activity on macrophages cell viability. When macrophages were submitted to T. cruzi infection and treated with 2c and 3a, compounds reduced the release of trypomastigote forms. Results also showed that the increased trypanocidal activity induced by 2c and 3a is independent of nitric oxide release. Flow cytometry assay showed that compound 2e was able to induce necrosis and apoptosis in trypomastigotes. Parasites treated with the compounds 2e, 3a, and 3c presented flagellum shortening, retraction and curvature of the parasite body, and extravasation of the internal content. Together, these data revealed a novel series of 4-thiazolidinones fragment-based compounds with potential effects against T. cruzi and lead-like characteristics.

Vaccines for leishmaniasis and the implications of their development for American tegumentary leishmaniasis.

The leishmaniases are a collection of vector-borne parasitic diseases caused by a number of different Leishmania species that are distributed worldwide. Clinical and laboratory research have together revealed several important immune components that control Leishmania infection and indicate the potential of immunization to prevent leishmaniasis. In this review we introduce previous and ongoing experimental research efforts to develop vaccines against Leishmania species. First, second and third generation vaccine strategies that have been proposed to counter cutaneous and visceral leishmaniasis (CL and VL, respectively) are summarized. One of the major bottlenecks in development is the transition from results in animal model studies to humans, and we highlight that although American tegumentary leishmaniasis (ATL; New World CL) can progress to destructive and disfiguring mucosal lesions, most research has been conducted using mouse models and Old World Leishmania species. We conclude that assessment of vaccine candidates in ATL settings therefore appears merited.

Proliferative Effect of Tilapia Fish (Oreochromis niloticus) Lectin on BALB/c Mice Splenocytes.

BACKGROUND: Lectins have been studied in recent years due to their immunomodulatory activities. OBJECTIVE: We purified a lectin named OniL from tilapia fish (Oreochromis niloticus) and here we analyzed the cell proliferation and cytokine production in Balb/c mice splenocytes. METHODS: Cells were stimulated in vitro in 24, 48, 72 hours and 6 days with different concentrations of OniL and Con A. Evaluation of cell proliferation was performed through [3H]-thymidine incorporation, cytokines were investigated using ELISA assay and cell viability assay was performed by investigation of damage through signals of apoptosis and necrosis. RESULTS: OniL did not promote significant cell death, induced high mitogenic activity in relation to control and Con A and stimulated the cells to release high IL-2 and IL-6 cytokines. CONCLUSION: These findings suggest that, like Con A, OniL lectin can be used as a mitogenic agent in immunostimulatory assays.

TLR and NLRP3 inflammasome expression deregulation in macrophages of adult rats subjected to neonatal malnutrition and infected with methicillin-resistant Staphylococcus aureus.

OBJECTIVES: Nutritional aggression in critical periods may lead to epigenetic changes that affect gene expression. The aim of this study was to assess the effect of neonatal malnutrition on the expression of toll-like receptor (TLR)-2, TLR-4, and NLRP3 receptors, caspase-1 enzyme, and interleukin (IL)-1 ß production in macrophages infected with methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) Staphylococcus aureus. METHODS: Wistar rats (N = 24) were divided in two distinct groups: nourished (17% casein) and malnourished (8% casein). Four systems were established after the isolation of mononuclear cells: negative control, positive control, MRSA, and MSSA. The plates were incubated at 37°C for 24 h in humidified atmosphere and 5% carbon dioxide. Tests were performed after this period to analyze the expression of standard recognition receptors, caspase-1 enzyme, and the production of IL-1 ß. Student's t test and analysis of variance were used in the statistical analysis; P < 0.05 was statistically significant. RESULTS: Malnutrition reduced animal growth and the expression of TLR-2, TLR-4, and NLRP3 receptors, the caspase-1 enzyme, and the IL-1 ß levels in macrophages infected with lipopolysaccharides in the present study. However, the interaction between the S. aureus and the macrophages promoted greater gene expression of receptors and enzymes. CONCLUSION: The neonatal malnutrition model compromised the expression of standard recognition receptors, of the caspase-1 enzyme as well as the production of IL-1 ß. However, the S. aureus and neonatal malnutrition combination led to intense transcription of such innate immunity components. Therefore, the deregulation in the expression of TLR and NLRP3 receptors and of the caspase-1 enzyme may induce extensive tissue injury and favor the permanence and spread of these bacteria, especially those that are methicillin resistant.

Synthesis of 4'-(2-ferrocenyl)-2,2':6'2''-terpyridine: characterization and antiprotozoal activity of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes.

A terpyridine ligand Fctpy was reacted with divalent metals (Cu, Co, Mn, Ni and Zn), yielding five complexes of general formula [Metal(Fctpy)2][PF6]2. The structure of Fctpy was determined by single crystal X-ray diffraction studies. The complexes characterized using various spectroscopic techniques suggested an octahedral geometry around the central metal ion. These complexes were screened for their antiamoebic, trypanocidal and antimalarial activities. It was found that, complexes 2 and 3 showed better IC50 values than metronidazole against HM1:IMSS strain of Entamoeba histolytica. A substantial parasitic inhibition was not observed for the trypanocidal activity. However, for the erythrocytic stage of W2 strain of Plasmodium falciparum, the complexes inhibited ß-hematin formation. At the concentration of 10 µg/mL, these complexes did not display toxicity.