2-acylamino-5-nitro-1,3-thiazoles: preparation and in vitro bioevaluation against four neglected protozoan parasites.

The 2-acylamino-5-nitro-1,3-thiazole derivatives (1-14) were prepared using a one step reaction. All compounds were tested in vitro against four neglected protozoan parasites (Giardia intestinalis, Trichomonas vaginalis, Leishmania amazonensis and Trypanosoma cruzi). Acetamide (9), valeroylamide (10), benzamide (12), methylcarbamate (13) and ethyloxamate (14) derivatives were the most active compounds against G. intestinalis and T. vaginalis, showing nanomolar inhibition. Compound 13 (IC50=10nM), was 536-times more active than metronidazole, and 121-fold more effective than nitazoxanide against G. intestinalis. Compound 14 was 29-times more active than metronidazole and 6.5-fold more potent than nitazoxanide against T. vaginalis. Ureic derivatives 2, 3 and 5 showed moderate activity against L. amazonensis. None of them were active against T. cruzi. Ligand efficiency indexes analysis revealed higher intrinsic quality of the most active 2-acylamino derivatives than nitazoxanide and metronidazole. In silico toxicity profile was also computed for the most active compounds. A very low in vitro mammalian cytotoxicity was obtained for 13 and 14, showing selectivity indexes (SI) of 246,300 and 141,500, respectively. Nitazoxanide showed an excellent leishmanicidal and trypanocidal effect, repurposing this drug as potential new antikinetoplastid parasite compound.

Synthesis of 2-{2-[(α/ß-naphthalen-1-ylsulfonyl)amino]-1,3-thiazol-4-yl} acetamides with 11ß-hydroxysteroid dehydrogenase inhibition and in combo antidiabetic activities.

Compounds 1-10 were designed using a bioisosteric approach and were prepared using a short synthetic route. The in vitro inhibitory activity of the compounds against 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) was evaluated. Compounds 5 (α-series) and 10 (ß-series) had a moderate inhibitory enzyme activity (55.26% and 67.03% inhibition at 10 µM, respectively) and were as active as BVT.14225 (positive control). Both compounds have a piperidine ring in their structure, but the most active (10) was selected to establish its in vivo antidiabetic effect using a non insulin-dependent diabetes mellitus rat model. The antidiabetic activity of compound 10 was determined at 50 mg/kg single dose in an acute model, and also by short term sub-chronic administration for 5 days. The results indicated a significant decrease of plasma glucose levels, similar than BVT.14225. Additionally, a molecular docking of the most active compounds of each series into the ligand binding pocket of one subunit of human 11ß-HSD1 was performed. In this model the oxygen atom of the sulfonamide make hydrogen bond interactions with the catalytic residues Ser170 and Ala172. We also observed important π-π interactions between the naphthyl group and Tyr177.

Synthesis, in vitro and in silico screening of ethyl 2-(6-substituted benzo[d]thiazol-2-ylamino)-2-oxoacetates as protein-tyrosine phosphatase 1B inhibitors.

The ethyl 2-(6-substituted benzo[d]thiazol-2-ylamino)-2-oxoacetate derivatives (OX 1-9) were prepared using a one-step reaction. The in vitro inhibitory activity of the compounds against protein tyrosine phosphatase 1B (PTP-1B) was evaluated. Compounds OX-(1, 6 and 7) were rapid reversible (mixed-type) inhibitors of PTP-1B with IC(50) values in the low micro-molar range. The most active compounds OX-(1, 6 and 7) were docked into the crystal structure of PTP-1B. Docking results indicate potential hydrogen bond interactions between the oxamate group in all compounds and the catalytic amino acid residues Arg221 and Ser216. The compounds were evaluated for their in vivo hypoglycemic activity, showing significant lowering of plasma glucose concentration in acute normoglycemic model and oral glucose tolerance test similarly at the effect exerted for hypoglycemic drug glibenclamide.

Design, synthesis, and in vitro antiprotozoal, antimycobacterial activities of N-{2-[(7-chloroquinolin-4-yl)amino]ethyl}ureas.

We have synthesized a new series of quinoline tripartite hybrids from chloroquine, ethambutol, and isoxyl drugs, using a short synthetic route. Compounds 1-8 were tested in vitro against five protozoa (Giardia intestinalis, Trichomonas vaginalis,Entamoeba histolytica, Leishmania mexicana and Trypanosoma cruzi) and Mycobacterium tuberculosis. N-(4-Butoxyphenyl)-N'-{2-[(7-chloroquinolin-4-yl)amino]ethyl}urea (6) was the most active compound against all parasites tested. Compound 6 was 670 times more active than metronidazole, against G. intestinalis. It was as active as pentamidine against L. mexicana, and it was twofold more potent than ethambutol and isoxyl versus M. tuberculosis. This compound could be considered as a new broad spectrum antimicrobial agent.

Synthesis and in vitro trichomonicidal, giardicidal and amebicidal activity of N-acetamide(sulfonamide)-2-methyl-4-nitro-1H-imidazoles.

Two new series of imidazole derivatives (acetamides: 1-8 and sulfonamides: 9-15) were synthesized using a short synthetic route. Compound 1 as well as the intermediate 16g were characterized by X-ray crystallography. Imidazole derivatives 1-15 were tested in vitro against three unicellular parasites (Giardia intestinalis, Trichomonas vaginalis and Entamoeba histolytica) in comparison with benznidazole (Bzn) and metronidazole. Compound 1 [N-benzyl-2-(2-methyl-4-nitro-1H-imidazol-1-yl)acetamide] was 2 times more active than Bzn against T. vaginalis and G. intestinalis and it was as active as Bzn against E. histolytica. Sulfonamides showed selective toxicity against E. histolytica over the other parasites. Toxicity assay showed that all compounds are non-cytotoxic against MDCK cell line. The results revealed that compounds 1-15 have antiparasitic bioactivity in the micromolar range against the parasites tested, and could be considered as benznidazole bioisosteres.