Synthesis, anticancer activity and mechanism of action of new phthalimido-1,3-thiazole derivatives.

In this work, 22 new compounds were obtained and evaluated for their cytotoxic activity on peripheral blood mononuclear cells (PBMC) and eight different tumor cell lines. All compounds displayed IC50 values above 100 µM when assayed against PBMCs. The cytotoxic assays in tumor cell lines revealed that sub-series of phthalimido-bis-1,3-thiazoles (5a-f) exhibited the best anti-tumor activity profile, presenting viability values below 59 %. As a result, the IC50 value was calculated for compounds 5a-f and 4c, and compounds 5b and 5e were selected for further assays due to their best IC50s. Considering the results presented by the sub-series 5a-f, the importance of the 1,3-thiazole ring in improving the anti-tumor activity was pointed out. Together, the results highlighted the anti-tumor activity of phthalimido-bis-1,3-thiazole derivatives.

2-(phenylthio)ethylidene derivatives as anti-Trypanosoma cruzi compounds: Structural design, synthesis and antiparasitic activity.

Chagas disease is an illness caused by the protozoan parasite Trypanosoma cruzi. The current chemotherapy is based on benznidazole, and, in some countries, Nifurtimox, which is effective in the acute phase of the disease, but its efficacy in the chronic phase remains controversial. It can also cause serious side effects that lead sufferers to abandon treatment. In the present work, is reported the synthesis and trypanocidal activity of new 2-(phenylthio)ethylidene thiosemicarbazones (4-15) and 1,3-thiazoles (16-26). The cyclization of thiosemicarbazones into 1,3-thiazoles presents an improvement in the cytotoxic profile for T. cruzi parasite, denoting selective compounds. Compound 18 was identified as the most promising of all compounds tested, showing an IC50 of 2.6 µM for the trypomastigote form and a non-cytotoxic effect on mouse spleen cells, reaching a selective index of 95.1. Among the 22 compounds tested, six compounds present a better trypanocidal activity, and five compounds have an equipotent activity compared to benznidazole. Flow cytometry and ultrastructural analysis were performed and indicate that compound 18 causes parasite cell death through apoptosis and acts via an autophagic pathway.

Structural design, synthesis and pharmacological evaluation of thiazoles against Trypanosoma cruzi.

Chagas disease is one of the most significant health problems in the American continent. benznidazole (BDZ) and nifurtimox (NFX) are the only drugs approved for treatment and exhibit strong side effects and ineffectiveness in the chronic stage, besides different susceptibility among T. cruzi DTUs (Discrete Typing Units). Therefore, new drugs to treat this disease are necessary. Thiazole compounds have been described as potent trypanocidal agents. Here we report the structural planning, synthesis and anti-T. cruzi evaluation of a new series of 1,3-thiazoles (7-28), which were designed by placing this heterocycle instead of thiazolidin-4-one ring. The synthesis was conducted in an ultrasonic bath with 2-propanol as solvent at room temperature. 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 some cases, methyl at position 5 of the thiazole (compounds 9, 12 and 23) increased trypanocidal property. The exchange of phenyl for pyridinyl heterocycle resulted in increased activity, giving rise to the most potent compound against the trypomasigote form (14, IC50trypo = 0.37 µM). Importantly, these new thiazoles were toxic for trypomastigotes without affecting macrophages and cardiomyoblast viability. The compounds were also evaluated against cruzain, and five of the most active compounds against trypomastigotes (7, 9, 12, 16 and 23) inhibited more than 70% of enzymatic activity at 10 µM, among which compound 7 had an IC50 in the submicromolar range, suggesting a possible mechanism of action. In addition, examination of T. cruzi cell death showed that compound 14 induces apoptosis. We also examined the activity against intracellular parasites, revealing that compound 14 inhibited T. cruzi infection with potency similar to benznidazole. The antiparasitic effect of 14 and benznidazole in combination was also investigated against trypomastigotes and revealed that they have synergistic effects, showing a promising profile for drug combination. Finally, in mice acutely-infected with T. cruzi,14 treatment significanty reduced the blood parasitaemia and had a protective effect on mortality. In conclusion, we report the identification of compounds (7), (12), (15), (23) and (26) with similar trypanocidal activity of benznidazole; compounds (9) and (21) as trypanocidal agents equipotent with BDZ, and compound 14 with potency 28 times better than the reference drug without affecting macrophages and cardiomyoblast viability. Mechanistically, the compounds inhibit cruzain, and 14 induces T. cruzi cell death by an apoptotic process, being considered a good starting point for the development of new anti-Chagas drug candidates.

Desing and synthesis of potent anti-Trypanosoma cruzi agents new thiazoles derivatives which induce apoptotic parasite death.

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.

Antitumor and immunomodulatory activities of thiosemicarbazones and 1,3-Thiazoles in Jurkat and HT-29 cells.

Cancer remains a high incidence and mortality disease, causing around 8.2 million of deaths in the last year. Current chemotherapy needs to be expanded, making research for new drugs a necessary task. Immune system modulation is an emerging concept in cancer cell proliferation control. In fact, there are a number of mechanisms underlying the role immune system plays in tumor cells. In this work, we describe the structural design, synthesis, antitumor and immunomodulatory potential of 31 new 1,3-thiazole and thiosemicarbazone compounds. Cisplatin was used as anticancer drug control. Cytotoxicity against J774A.1 macrophages and antitumor activity against HT-29 and Jurkat cells was determined. These 1,3-thiazole and thiosemicarbazone compounds not only exhibited cytotoxicity in cancer cells, but were able to cause irreversible cancer cell damage by inducing necrosis and apoptosis. In addition, these compounds, especially pyridyl-thiazoles compounds, regulated immune factors such as interleukin 10 and tumor necrosis factor, possible by directing immune system in favor of modulating cancer cell proliferation. By examining their pharmacological activity, we were able to identify new potent and selective anticancer compounds.

Compound profiling and 3D-QSAR studies of hydrazone derivatives with activity against intracellular Trypanosoma cruzi.

Chagas disease is a tropical disease caused by the parasite Trypanosoma cruzi, which is endemic in Central and South America. Few treatments are available with effectiveness limited to the early (acute) stage of disease, significant toxicity and widespread drug resistance. In this work we report the outcome of a HTS-ready assay chemical library screen to identify novel, nontoxic, small-molecule inhibitors of T. cruzi. We have selected 50 compounds that possess hydrazone as a common group. The compounds were screened using recombinant T. cruzi (Tulahuen strain) expressing beta-galactosidase. A 3D quantitative structure-activity relationship (QSAR) analysis was performed using descriptors calculated from comparative molecular field analysis (CoMFA). Our findings show that of the fifty selected hydrazones, compounds LpQM-19, 28 and 31 displayed the highest activity against T. cruzi, leading to a selectivity index (SI) of 20-fold. The 3D-QSAR analysis indicates that a particular electrostatic arrangement, where electron-deficient atoms are aligned along the molecule main axis positively correlates with compound biological activity. These results provide new candidate molecules for the development of treatments against Chagas disease.

Phthalimido-thiazoles as building blocks and their effects on the growth and morphology of Trypanosoma cruzi.

Chagas disease is a parasitic infection caused by protozoan Trypanosoma cruzi that affects approximately 6-7 million people worldwide. Benznidazole is the only drug approved for treatment during the acute and asymptomatic chronic phases; however, its efficacy during the symptomatic chronic phase is controversial. The present work reports the synthesis and anti-T. cruzi activities of a novel series of phthalimido-thiazoles. Some of these compounds showed potent inhibition of the trypomastigote form of the parasite at low cytotoxicity concentrations in spleen cells, and the resulting structure-activity relationships are discussed. We also showed that phthalimido-thiazoles induced ultrastructural alterations on morphology, flagellum shortening, chromatin condensation, mitochondria swelling, reservosomes alterations and endoplasmic reticulum dilation. Together, these data revealed, for the first time, a novel series of phthalimido-thiazoles-structure-based compounds with potential effects against T. cruzi and lead-like characteristics against Chagas disease.

Synthesis and structure-activity relationship study of a new series of antiparasitic aryloxyl thiosemicarbazones inhibiting Trypanosoma cruzi cruzain.

The discovery of new antiparasitic compounds against Trypanosoma cruzi, the etiological agent of Chagas disease, is necessary. Novel aryloxy/aryl thiosemicarbazone-based conformationally constrained analogs of thiosemicarbazones (1) and (2) were developed as potential inhibitors of the T. cruzi protease cruzain, using a rigidification strategy of the iminic bond of (1) and (2). A structure-activity relationship analysis was performed in substituents attached in both aryl and aryloxy rings. This study indicated that apolar substituents or halogen atom substitution at the aryl position improved cruzain inhibition and antiparasitic activity in comparison to unsubstituted thiosemicarbazone. Two of these compounds displayed potent inhibitory antiparasitic activity by inhibiting cruzain and consequently were able to reduce the parasite burden in infected cells and cause parasite cell death through necrosis. In conclusion, we demonstrated that conformational restriction is a valuable strategy in the development of antiparasitic thiosemicarbazones.

Design, synthesis and structure-activity relationship of phthalimides endowed with dual antiproliferative and immunomodulatory activities.

The present work reports the synthesis and evaluation of the antitumour and immunomodulatory properties of new phthalimides derivatives designed to explore molecular hybridization and bioisosterism approaches between thalidomide, thiosemicarbazone, thiazolidinone and thiazole series. Twenty-seven new molecules were assessed for their immunosuppressive effect toward TNFα, IFNγ, IL-2 and IL-6 production and antiproliferative activity. The best activity profile was observed for the (6a-f) series, which presents phthalyl and thiazolidinone groups.

2-Pyridyl thiazoles as novel anti-Trypanosoma cruzi agents: structural design, synthesis and pharmacological evaluation.

The present work reports on the synthesis, anti-Trypanosoma cruzi activities and docking studies of a novel series of 2-(pyridin-2-yl)-1,3-thiazoles derived from 2-pyridine thiosemicarbazone. The majority of these compounds are potent cruzain inhibitors and showed excellent inhibition on the trypomastigote form of the parasite, and the resulting structure-activity relationships are discussed. Together, these data present a novel series of thiazolyl hydrazones with potential effects against Chagas disease and they could be important leads in continuing development against Chagas disease.