Genotoxicity assessment of four novel quinazoline-derived trypanocidal agents in the Drosophila wing somatic mutation and recombination test.

Chagas disease, caused by the protozoan Trypanosoma cruzi, has increased in the world due to migration, travelling and climate change; at present, the principal problem is that common trypanocidal agents have resulted in toxic or inconvenient side effects. We tested for genotoxicity in the standard (ST) and high bioactivation (HB) crosses of Drosophila wing somatic mutation and recombination test, four novel trypanocidal agents derived from 2, 4, 6-triaminquinazoline (TAQ): 2,4-diamino-6 nitro-1,3 diazonaftalene (S-1QN2-1), 2,4-diacetamino-6-amino 1,3 diazonaftalene (D-1), N6-(4,methoxybenzyl)quinazoline-2,4,6-triamine (GHPM) and N6-[4-(trifluoromethoxy)benzyl]quinazoline-2,4,6-triamine (GHPMF) at 1.9, 3.9, 7.9 and 15 µM, respectively. Also, high-pressure liquid chromatography (HPLC) analysis was run to determine the remanence of either drug in flare, and Oregon R(R)-flare flies emerged from treated larvae. S-1QN2-1 showed genotoxicity only in the ST cross, increasing the small, large and total spot frequencies at all concentrations and twin spots only at 1.9 µM; D-1 and GHPM showed significant increments of large spots only at 15 µM in the ST cross; GHPMF was not genotoxic at any concentration or either cross. In the mwh clones accumulated distribution frequencies analysis, associated with disrupted cell division, S-1QN2-1 caused alterations in the ST cross at all concentrations but only at 15 µM in the HB cross; D-1 caused alterations at 3.9, 7.9 and 15 µM in the ST cross and at 1.9 and 15 µM in the HB cross; GHPM caused alterations at 7.9 and 15 µM in the ST cross and also at 1.9, 3.9 and 7.9 µM in the HB cross; GHPMF caused those alterations at all concentrations in the ST cross and at 1.9, 3.9 and 7.9 µM in the HB cross. The HPLC results indicated no traces of either agent in the flare and Oregon R(R)-flare flies. We conclude that S-1QN2-1 is clearly genotoxic, D-1 and GHPM have an unclear genotoxicity and GHPMF was not genotoxic; all quinazoline derivatives disrupted cell division. GHPMF is a good candidate to be tested in other genotoxicity and cytotoxic bioassays. The differences in the genotoxic activity of these trypanocidal agents are correlated with differences in their chemical structure.

Evaluation of New Benzimidazole Derivatives as Cysticidal Agents: In Vitro, in Vivo and Docking Studies.

Based on our previous research on cysticidal drugs, we report the synthesis and evaluation of three new benzimidazole derivatives. In these compounds, the amido group was used as a bioisosteric replacement of the ester group. The molecular docking on ß-tubulin revealed that the derivatives interacted through hydrogen bonding with N165, E198 and V236. All compounds showed in vitro activity against Taenia crassiceps cysts. Among them, benzimidazole 3 was found to be the most potent of the series (EC50 0.86 µM). This compound also exhibited the highest probability of binding and the lowest binding free energy score and was therefore selected for in vivo evaluation. Results indicated that the efficacy of compound 3 was comparable to that of the reference drug, albendazole (50.39 vs. 47.16% parasite reduction). Animals treated with compound 3 seemed to tolerate this benzimidazole well, with no changes in behavior, or food and water consumption. These findings are consistent with the in silico prediction results, which indicated low toxicity risks. The pharmacokinetic study showed that the half-life and mean residence time (6.06 and 11.9 h, respectively) were long after oral administration. Together, these results indicate that this new benzimidazole derivative represents a promising structure with cysticidal activity.

Systematic search for benzimidazole compounds and derivatives with antileishmanial effects.

Leishmaniasis is a neglected tropical disease that currently affects 12 million people, and over 1 billion people are at risk of infection. Current chemotherapeutic approaches used to treat this disease are unsatisfactory, and the limitations of these drugs highlight the necessity to develop treatments with improved efficacy and safety. To inform the rational design and development of more efficient therapies, the present study reports a chemoinformatic approach using the ChEMBL database to retrieve benzimidazole as a target scaffold. Our analysis revealed that a limited number of studies had investigated the antileishmanial effects of benzimidazoles. Among this limited number, L. major was the species most commonly used to evaluate the antileishmanial effects of these compounds, whereas L. amazonensis and L. braziliensis were used least often in the reported studies. The antileishmanial activities of benzimidazole derivatives were notably variable, a fact that may depend on the substitution pattern of the scaffold. In addition, we investigated the effects of a benzimidazole derivative on promastigotes and amastigotes of L. infantum and L. amazonensis using a novel fluorometric method. Significant antileishmanial effects were observed on both species, with L. amazonensis being the most sensitive. To the best of our knowledge, this chemoinformatic analysis represents the first attempt to determine the relevance of benzimidazole scaffolds for antileishmanial drug discovery using the ChEMBL database. The present findings will provide relevant information for future structure-activity relationship studies and for the investigation of benzimidazole-derived drugs as potential treatments for leishmaniasis.

Synthesis and biological evaluation of 2-methyl-1H-benzimidazole-5-carbohydrazides derivatives as modifiers of redox homeostasis of Trypanosoma cruzi.

Twelve novel benzimidazole derivatives were synthesized and their in vitro activities against epimastigotes of Trypanosoma cruzi were evaluated. Two derivatives (6 and 7), which have 4-hydroxy-3-methoxyphenyl moiety in their structures, proved to be the most active in inhibiting the parasite growth. Compound 6 showed a trypanocidal activity higher than benznidazole (IC50=5µM and 7.5µM, respectively) and less than nifurtimox (IC50=3.6µM). In addition, the ability of 6 and 7 to modify the redox homeostasis in T cruzi epimastigote was studied; cysteine and glutathione increased in parasites exposed to both compounds, whereas trypanothione only increased with 7 treatment. These results suggest that the decrease in viability of T. cruzi may be attributed to the change in cellular redox balance caused by compound 6 or 7. Furthermore, compounds 6 and 7 showed CC50 values of 160.64 and 160.66µM when tested in mouse macrophage cell line J774 and selectivity indexes (macrophage/parasite) of 32 and 20.1, respectively.

Species-Specific Inactivation of Triosephosphate Isomerase from Trypanosoma brucei: Kinetic and Molecular Dynamics Studies.

Human African Trypanosomiasis (HAT), a disease that provokes 2184 new cases a year in Sub-Saharan Africa, is caused by Trypanosoma brucei. Current treatments are limited, highly toxic, and parasite strains resistant to them are emerging. Therefore, there is an urgency to find new drugs against HAT. In this context, T. brucei depends on glycolysis as the unique source for ATP supply; therefore, the enzyme triosephosphate isomerase (TIM) is an attractive target for drug design. In the present work, three new benzimidazole derivatives were found as TbTIM inactivators (compounds 1, 2 and 3) with an I50 value of 84, 82 and 73 µM, respectively. Kinetic analyses indicated that the three molecules were selective when tested against human TIM (HsTIM) activity. Additionally, to study their binding mode in TbTIM, we performed a 100 ns molecular dynamics simulation of TbTIM-inactivator complexes. Simulations showed that the binding of compounds disturbs the structure of the protein, affecting the conformations of important domains such as loop 6 and loop 8. In addition, the physicochemical and drug-like parameters showed by the three compounds suggest a good oral absorption. In conclusion, these molecules will serve as a guide to design more potent inactivators that could be used to obtain new drugs against HAT.

Synthesis and molecular docking of N'-arylidene-5-(4-chlorophenyl)-1-(3,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carbohydrazides as novel hypoglycemic and antioxidant dual agents.

Herein, the design and synthesis of 10 novel N'-arylidene pyrazole-3-carbohydrazides are described. Compounds were pretended to act as dual agents against diabetes and oxidative stress, two correlated pathologies involved in metabolic syndrome development and progression. The antioxidant capacity was evaluated by means of DPPH and FRAP in vitro assays. It was found that compounds bearing a hydroxyl group at 4-position of the hydrazone moiety are potent antioxidant entities, being compound 3g (a syringaldehyde derivative) the most active compound. In addition, the in vivo hypoglycemic effect of the analogues was determined. With regard to the above, the cinnamaldehyde derivatives showed a scarce biological activity, while the 4-hydroxy analogues showed the higher glycemia reduction at 7h after administration. Interestingly, the most potent antioxidants 3b and 3g also were of the most active compounds in reducing the plasma glucose, reaching 80% of reduction in the case of 3g. Molecular docking binding poses conducted to a plausible interpretation of the biological outcomes and a possible interaction between a hydroxy group and Asn287 of CB1R was proposed as an important feature for enhancing the observed activity.

JVG9, a benzimidazole derivative, alters the surface and cytoskeleton of Trypanosoma cruzi bloodstream trypomastigotes.

Trypanosoma cruzi has a particular cytoskeleton that consists of a subpellicular network of microtubules and actin microfilaments. Therefore, it is an excellent target for the development of new anti-parasitic drugs. Benzimidazole 2-carbamates, a class of well-known broad-spectrum anthelmintics, have been shown to inhibit the in vitro growth of many protozoa. Therefore, to find efficient anti-trypanosomal (trypanocidal) drugs, our group has designed and synthesised several benzimidazole derivatives. One, named JVG9 (5-chloro-1H-benzimidazole-2-thiol), has been found to be effective against T. cruzi bloodstream trypomastigotes under both in vitro and in vivo conditions. Here, we present the in vitro effects observed by laser scanning confocal and scanning electron microscopy on T. cruzi trypomastigotes. Changes in the surface and the distribution of the cytoskeletal proteins are consistent with the hypothesis that the trypanocidal activity of JVG9 involves the cytoskeleton as a target.

Compounds Consisting of Quinazoline, Ibuprofen, and Amino Acids with Cytotoxic and Anti-Inflammatory Effects.

In this research work, a series of 16 quinazoline derivatives bearing ibuprofen and an amino acid were designed as inhibitors of epidermal growth factor receptor tyrosine kinase domain (EGFR-TKD) and cyclooxygenase-2 (COX-2) with the intention of presenting dual action in their biological behavior. The designed compounds were synthesized and assessed for cytotoxicity on epithelial cancer cells lines (AGS, A-431, MCF-7, MDA-MB-231) and epithelial non-tumorigenic cell line (HaCaT). From this evaluation, derivative 6 was observed to exhibit higher cytotoxic potency (IC50) than gefitinib (reference drug) on three cancer cell lines (0.034 µM in A-431, 2.67 µM in MCF-7, and 3.64 µM in AGS) without showing activity on the non-tumorigenic cell line (>100 µM). Furthermore, assessment of EGFR-TKD inhibition by 6 showed a discreet difference compared to gefitinib. Additionally, 6 was used to conduct an in vivo anti-inflammatory assay using the 12-O-tetradecanoylphorbol-3-acetate (TPA) method, and it was shown to be 5 times more potent than ibuprofen. Molecular dynamics studies of EGFR-TKD revealed interactions between compound 6 and M793. On the other hand, one significant interaction was observed for COX-2, involving S531. The RMSD graph indicated that the ligand remained stable in 50 ns.

Effects of an antimalarial quinazoline derivative on human erythrocytes and on cell membrane molecular models.

Plasmodium, the parasite which causes malaria in humans multiplies in the liver and then infects circulating erythrocytes. Thus, the role of the erythrocyte cell membrane in antimalarial drug activity and resistance has key importance. The effects of the antiplasmodial N(6)-(4-methoxybenzyl)quinazoline-2,4,6-triamine (M4), and its inclusion complex (M4/HPßCD) with 2-hydroxypropyl-ß-cyclodextrin (HPßCD) on human erythrocytes and on cell membrane molecular models are herein reported. This work evidences that M4/HPßCD interacts with red cells as follows: a) in scanning electron microscopy (SEM) studies on human erythrocytes induced shape changes at a 10µM concentration; b) in isolated unsealed human erythrocyte membranes (IUM) a concentration as low as 1µM induced sharp DPH fluorescence anisotropy decrease whereas increasing concentrations produced a monotonically decrease of DPH fluorescence lifetime at 37°C; c) X-ray diffraction studies showed that 200µM induced a complete structural perturbation of dimyristoylphosphatidylcholine (DMPC) bilayers whereas no significant effects were detected in dimyristoylphosphatidylethanolamine (DMPE) bilayers, classes of lipids present in the outer and inner monolayers of the human erythrocyte membrane, respectively; d) fluorescence spectroscopy data showed that increasing concentrations of the complex interacted with the deep hydrophobic core of DMPC large unilamellar vesicles (LUV) at 18°C. All these experiments are consistent with the insertion of M4/HPßCD in the outer monolayer of the human erythrocyte membrane; thus, it can be considered a promising and novel antimalarial agent.

Synthesis and antiprotozoal activity of novel 2-{[2-(1H-imidazol-1-yl)ethyl]sulfanyl}-1H-benzimidazole derivatives.

A series of 19 new 2-{[2-(1H-imidazol-1-yl)ethyl]sulfanyl}-1H-benzimidazole derivatives was synthesized starting from the properly substituted 1,2-phenylendiamine. These compounds have hydrogen or methyl at position 1; while hydrogen, chlorine, ethoxy or methoxycarbonyl group is at position 5 and/or 6. The novel compounds were tested against protozoa Trichomonas vaginalis, Giardia intestinalis and Entamoeba histolytica. Experimental evaluations revealed strong activity for all tested compounds, having IC50 values in the nanomolar range, which were even better than metronidazole, the drug of choice for these parasites.

Synthesis and antiprotozoal activity of nitazoxanide-N-methylbenzimidazole hybrids.

A series of a novel hybrid compounds between nitazoxanide and N-methylbenzimidazole were synthesized starting from the corresponding N-methyl-2-nitroanilines. The new hybrid compounds (1-13) were evaluated in vitro against Giardia intestinalis, Entamoeba histolytica, Trichomonas vaginalis. NTZ, MTZ and ABZ were used as drug standards. Experimental evaluations revealed all of the new compounds (1-13) were active and showed strong activity against the three protozoa, particularly with E. histolytica where the IC50 values ranged between 3 and 69 nM. Overall, compounds 2, 5, 7, 8, 9, 11 and 12 stood out with values lower than 87 nM for all three protozoa, comparatively better than the reference drugs.

RCB20, an experimental benzimidazole derivative, affects tubulin expression and induces gross anatomical changes in Taenia crassiceps cysticerci.

Helminth ß-tubulins are the targets of benzimidazole (BZM) carbamate compounds. The specificity of the interactions between such compounds and their in vivo targets depends on the presence of specific amino acid residues in the target molecules. To discover new and effective anthelmintic drugs, we used a medicinal chemistry approach to synthesize a series of BZM derivatives that exploited the BZM moiety as a template. We have previously found that one compound, 2-(trifluoromethyl)-1H-benzimidazole (RCB20), has better in vitro and in vivo activity than albendazole sulfoxide (ABZSO). In the present study, the effect of RCB20 and ABZSO treatment on expression of Taenia crassiceps cysticerci cytoskeletal proteins such as actin, myosin II, and tubulin isoforms was examined. The effects of RCB20 and ABZSO after 11 days treatment of the parasites was evaluated by light, confocal, and electron microscopy, and by immunochemistry and immunohistochemistry. The RCB20-induced effects were more rapid than the ABZSO-induced effects on the parasites. In the RCB20-treated parasites, we observed gross-structural damage at the whole parasite level, particularly in the inner tissues and flame cells. Changes in the expression patterns of the cytoskeletal proteins, as assessed by immunohistochemistry and immunoblotting, revealed that the most important drug-induced effect on the parasites was a reduction in the expression level of tyrosinated α-tubulins. Our research findings suggest that RCB20 treatment affected posttranslational modification of parasite α-tubulin molecules, which involved removal of the α-tubulin carboxy-terminal tyrosine.

Albendazole and its derivative JVG9 induce encystation on Giardia intestinalis trophozoites.

In the present study, we evaluated the effect of an albendazole (ABZ) derivative JVG9 on cultured Giardia intestinalis. To assess the JVG9 effects, we evaluated the tubulin cytoskeleton by confocal microscopy, and we found that the characteristic staining was modified. The scanning electron microscopy images revealed extremely damaged trophozoites and cyst-like cells. The confocal images revealed that this drug triggered the expression of cyst wall protein 1 and encystation. We also found that at low doses, AL triggered the encystation process too.

Synthesis of Quinazolin-2,4,6-triamine Derivatives as Non-purine Xanthine Oxidase Inhibitors and Exploration of Their Toxicological Potential.

In this work, a new set of quinazolin-2,4,6-triamine derivatives were synthesized to explore their potential biological activity as xanthine oxidase (XO) inhibitors, superoxide scavengers and screening of their toxicological profile. Among all the synthesized compounds, B1 exhibited better inhibitory activity against bovine xanthine oxidase (bXO) than allopurinol (IC50 =1.56 µM and IC50 =6.99 µM, respectively). As superoxide scavengers, B1, B2 and B13 exhibited a better effect than allopurinol (97.3 %, 82.1 %, 87.4 % and 69.4 %, respectively). Regarding the toxicological profile, B1 was less cytotoxic than methotrexate on HCT-15 cancer cells. Apoptosis results obtained in cells of female and male mice, showed that B1 and B2 presented a similar behaviour to CrO3 (positive control) with respect to the average frequency to induce apoptosis; while B13 apoptosis induced effect was similar to DMSO and control group. Finally, B1, B2, B13 did not induce genotoxicity in a micronuclei murine model compared to CrO3 .

Antiprotozoal activity of proton-pump inhibitors.

Parasitic diseases are still a major health problem in developing countries. In our effort to find new antiparasitic agents, in this Letter we report the in vitro antiprotozoal activity of omeprazole, lansoprazole, rabeprazole and pantoprazole against Trichomonas vaginalis, Giardia intestinalis and Entamoeba histolytica. Molecular modeling studies were an important tool to highlight the potential antiprotozoal activity of these drugs. Experimental evaluations revealed a strong activity for all compounds tested. Rabeprazole and pantoprazole were the most active compounds, having IC(50) values in the nanomolar range, which were even better than metronidazole, the drug of choice for these parasites.

Studies on 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole/2-hydroxypropyl-ß-cyclodextrin association: Characterization, molecular modeling studies, and in vivo anthelminthic activity.

The purpose of this work is to study the molecular association that occurs between 2-hydroxypropyl-ß-cyclodextrin (HPßCD) and 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB20), an antiparasitic compound recently found by our research group, with poor aqueous solubility. The complex stability constant and stoichiometric ratio determined by phase-solubility diagram and Job's plot provided evidence that HPßCD enhanced water solubility of RCB20 through inclusion complex formation. Two-dimensional ¹H NMR spectroscopy is used to study the molecular arrangement of inclusion complex in solution. These results are further supported using molecular modeling studies. In the solid state, the complexation is confirmed by differential scanning calorimetry, powder X-ray diffraction, and scanning electron microscopy. Finally, RCB20/HPßCD complex has better activity than RCB20 against the adult and muscle larvae phase of Trichinella spiralis.

In Silico Characterization of Masitinib Interaction with SARS-CoV-2 Main Protease.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection continues to be a global health problem. Despite the current implementation of COVID-19 vaccination schedules, identifying effective antiviral drug treatments for this disease continues to be a priority. A recent study showed that masitinib (MST), a tyrosine kinase inhibitor, blocks the proteolytic activity of SARS-CoV-2 main protease (Mpro ). Although MST is a potential candidate for COVID-19 treatment, a comprehensive analysis of its interaction with Mpro has not been done. In this work, we performed molecular dynamics simulations of the MST-Mpro complex crystal structure. The effect of the protonation states of Mpro H163 residue and MST titratable groups were studied. Furthermore, we identified the MST substituents and Mpro mutations that affect the stability of the complex. Our results provide valuable insights into the design of new MST analogs as potential treatments for COVID-19.

Design, Synthesis and Evaluation of 2,4-Diaminoquinazoline Derivatives as Potential Tubulin Polymerization Inhibitors.

Microtubules are highly dynamic polymers composed of α- and ß-tubulin proteins that have been shown to be potential therapeutic targets for the development of anticancer drugs. Currently, a wide variety of chemically diverse agents that bind to ß-tubulin have been reported. Nocodazole (NZ) and colchicine (COL) are well-known tubulin-depolymerizing agents that have close binding sites in the ß-tubulin. In this study, we designed and synthesized a set of nine 2,4-diaminoquinazoline derivatives that could occupy both NZ and COL binding sites. The synthesized compounds were evaluated for their antiproliferative activities against five cancer cell lines (PC-3, HCT-15, MCF-7, MDA-MB-231, and SK-LU-1), a noncancerous one (COS-7), and peripheral blood mononuclear cells (PBMC). The effect of compounds 4 e and 4 i on tubulin organization and polymerization was analyzed on the SK-LU-1 cell line by indirect immunofluorescence, western blotting, and tubulin polymerization assays. Our results demonstrated that both compounds exert their antiproliferative activity by inhibiting tubulin polymerization. Finally, a possible binding pose of 4 i in the NZ/COL binding site was determined by using molecular docking and molecular dynamics (MD) approaches. To our knowledge, this is the first report of non-N-substituted 2,4-diaminoquinazoline derivatives with the ability to inhibit tubulin polymerization.

Synthesis and antiprotozoal activity of novel 1-methylbenzimidazole derivatives.

In this paper are reported the synthesis and antiprotozoal activity in vitro of 24 1-methylbenzimidazole derivatives (13-36) substituted at position 2 with aminocarbonyl, N-methylaminocarbonyl, N,N-dimethylaminocarbonyl, ethoxycarbonyl, 1-hydroxyethyl and acetyl groups, some of them with chlorine atoms at the benzenoid ring. Compounds 13-36 were more active than metronidazole, the choice drug against Giardia intestinalis and most of them against Trichomonas vaginalis. The most active group of compounds for both parasites was that with a 2-ethoxycarbonyl group (16, 22, 28, 34), independently of the substitution pattern at the benzenoid ring.

Synthesis and antiprotozoal activity of some 2-(trifluoromethyl)-1H-benzimidazole bioisosteres.

A series of 2-(trifluoromethyl)-1H-benzimidazole derivatives with various 5- and 6-position bioisosteric substituents (-Cl, -F, -CF3, -CN), namely 1-7, were prepared using a short synthetic route. Each analogue was tested in vitro against the protozoa Giardia intestinalis and Trichomonas vaginalis in comparison with albendazole and metronidazole. Several analogues had IC50 values < 1 microM against both species, which make them significantly more potent than either standard. Compound 4 [2,5(6)-bis(trifluoromethyl)-1H-benzimidazole], was 14 times more active than albendazole against T. vaginalis. This compound (4) also showed moderate antimalarial activity against W2 and D6 strains of Plasmodium falciparum (5.98 and 6.12 microM, respectively). Studying further structure activity relationships through the use of bioisosteric substitution in these benzimidazolic derivatives should provide new leads against protozoal and possibly malarial diseases.