Promising aryl selenoate derivatives as antileishmanial agents and their effects on gene expression.

Leishmaniasis remains one of the main public health problems worldwide, with special incidence in the poorest populations. Selenium and its derivatives can be potent therapeutic options against protozoan parasites. In this work, 17 aryl selenoates were synthesized and screened against three species of Leishmania (Leishmania major, Leishmania amazonensis, and Leishmania infantum). Initial screening in promastigotes showed L. infantum species was more sensitive to selenoderivatives than the others. The lead Se-(2-selenocyanatoethyl) thiophene-2-carboselenoate (16) showed a half-maximal effective concentration of 3.07 µM and a selectivity index > 32.57 against L. infantum promastigotes. It was also the most effective of all 17 compounds, decreasing the infection ratio by 90% in L. infantum-infected macrophages with amastigotes at 10 µM. This aryl selenoate did not produce a hemolytic effect on human red blood cells at the studied doses (10-100 µM). Furthermore, the gene expression of infected murine macrophages related to cell death, the cell cycle, and the selenoprotein synthesis pathway in amastigotes was altered, while no changes were observed in their murine homologs, supporting the specificity of Compound 16 against the parasite. Therefore, this work reveals the possible benefits of selenoate derivatives for the treatment of leishmaniasis.

Novel Pitolisant-Derived Sulfonyl Compounds for Alzheimer Disease.

Alzheimer's disease (AD) is a complex and multifactorial neurodegenerative disorder characterized by cognitive decline, memory loss, behavioral changes, and other neurological symptoms. Considering the urgent need for new AD therapeutics, in the present study we designed, synthesized, and evaluated multitarget compounds structurally inspired by sulfonylureas and pitolisant with the aim of obtaining multitarget ligands for AD treatment. Due to the diversity of chemical scaffolds, a novel strategy has been adopted by merging into one structure moieties displaying H3R antagonism and acetylcholinesterase inhibition. Eight compounds, selected by their binding activity on H3R, showed a moderate ability to inhibit acetylcholinesterase activity in vitro, and two of the compounds (derivatives 2 and 7) were also capable of increasing acetylcholine release in vitro. Among the tested compounds, derivative 2 was identified and selected for further in vivo studies. Compound 2 was able to reverse scopolamine-induced cognitive deficits with results comparable to those of galantamine, a drug used in clinics for treating AD. In addition to its efficacy, this compound showed moderate BBB permeation in vitro. Altogether, these results point out that the fragment-like character of compound 2 leads to an optimal starting point for a plausible medicinal chemistry approach for this novel strategy.

Examination of multiple Trypanosoma cruzi targets in a new drug discovery approach for Chagas disease.

Chagas disease (CD) is a centenarian neglected parasitosis caused by the protozoan Trypanosoma cruzi (T. cruzi). Despite the continuous efforts of many organizations and institutions, CD is still an important human health problem worldwide. A lack of a safe and affordable treatment has led drug discovery programmes to focus, for years, on the search for molecules enabling interference with enzymes that are essential for T. cruzi survival. In this work, the authors want to offer a brief overview of the different validated targets that are involved in diverse parasite pathways: glycolysis, sterol synthesis, the de novo biosynthesis of pyrimidine nucleotides, the degradative processing of peptides and proteins, oxidative stress damage and purine salvage and nucleotide synthesis and metabolism. Their structural aspects, function, active sites, etc. were studied and considered with the aim of defining molecular bases in the search for new effective treatments for CD. This review also compiles, as much as possible, all the inhibitors reported to date against these T. cruzi targets, serving as a reference for future research in this field.

Rational modification of Mannich base-type derivatives as novel antichagasic compounds: Synthesis, in vitro and in vivo evaluation.

The current chemotherapy against Chagas disease is inadequate and insufficient. A series of ten Mannich base-type derivatives have been synthesized to evaluate their in vitro antichagasic activity. After a preliminary screening, compounds 7 and 9 were subjected to in vivo assays in a murine model. Both compounds caused a substantial decrease in parasitemia in the chronic phase, which was an even better result than that of the reference drug benznidazole. In addition, compound 9 also showed better antichagasic activity during the acute phase. Moreover, metabolite excretion, effect on mitochondrial membrane potential and the inhibition of superoxide dismutase (SOD) studies were also performed to identify their possible mechanism of action. Finally, docking studies proposed a binding mode of the Fe-SOD enzyme similar to our previous series, which validated our design strategy. Therefore, the results suggest that these compounds should be considered for further preclinical evaluation as antichagasic agents.

Library of Seleno-Compounds as Novel Agents against Leishmania Species.

The in vitro leishmanicidal activities of a series of 48 recently synthesized selenium derivatives against Leishmania infantum and Leishmania braziliensis parasites were tested using promastigotes and intracellular amastigote forms. The cytotoxicity of the tested compounds for J774.2 macrophage cells was also measured in order to establish their selectivity. Six of the tested compounds (compounds 8, 10, 11, 15, 45, and 48) showed selectivity indexes higher than those of the reference drug, meglumine antimonate (Glucantime), for both Leishmania species; in the case of L. braziliensis, compound 20 was also remarkably selective. Moreover, data on infection rates and amastigote numbers per macrophage showed that compounds 8, 10, 11, 15, 45, and 48 were the most active against both Leishmania species studied. The observed changes in the excretion product profile of parasites treated with these six compounds were also consistent with substantial cytoplasmic alterations. On the other hand, the most active compounds were potent inhibitors of Fe superoxide dismutase (Fe-SOD) in the two parasite species considered, whereas their impact on human CuZn-SOD was low. The high activity, low toxicity, stability, low cost of the starting materials, and straightforward synthesis make these compounds appropriate molecules for the development of affordable antileishmanicidal agents.

In vitro antileishmanial activity and iron superoxide dismutase inhibition of arylamine Mannich base derivatives.

Leishmaniasis is one of the world's most neglected diseases, and it has a worldwide prevalence of 12 million. There are no effective human vaccines for its prevention, and treatment is hampered by outdated drugs. Therefore, research aiming at the development of new therapeutic tools to fight leishmaniasis remains a crucial goal today. With this purpose in mind, we present 20 arylaminoketone derivatives with a very interesting in vitro and in vivo efficacy against Trypanosoma cruzi that have now been studied against promastigote and amastigote forms of Leishmania infantum, Leishmania donovani and Leishmania braziliensis strains. Six out of the 20 Mannich base-type derivatives showed Selectivity Index between 39 and 2337 times higher in the amastigote form than the reference drug glucantime. These six derivatives affected the parasite infectivity rates; the result was lower parasite infectivity rates than glucantime tested at an IC25 dose. In addition, these derivatives were substantially more active against the three Leishmania species tested than glucantime. The mechanism of action of these compounds has been studied, showing a greater alteration in glucose catabolism and leading to greater levels of iron superoxide dismutase inhibition. These molecules could be potential candidates for leishmaniasis chemotherapy.

Design and synthesis of novel quinoxaline derivatives as potential candidates for treatment of multidrug-resistant and latent tuberculosis.

Twenty-four quinoxaline derivatives were evaluated for their antimycobacterial activity using BacTiter-Glo microbial cell viability assay. Five compounds showed MIC values <3.1 µM and IC50 values<1.5 µM in primary screening and therefore, they were moved on for further evaluation. Compounds 21 and 18 stand out, showing MIC values of 1.6 µM and IC50 values of 0.5 and 1.0 µM, respectively. Both compounds were the most potent against three evaluated drug-resistant strains. Moreover, they exhibited intracellular activity in infected macrophages, considering log-reduction and cellular viability. In addition, compounds 16 and 21 were potent against non-replicating Mycobacterium tuberculosis and compound 21 was bactericidal. Therefore, quinoxaline derivatives could be considered for making further advances in the future development of antimycobacterial agents.

Synthesis and biological evaluation of quinoxaline di-N-oxide derivatives with in vitro trypanocidal activity.

We report the synthesis and in vitro activity against Trypanosoma cruzi epimastigotes of 15 novel quinoxaline derivatives. Ten of the derivatives presented IC50 values lower than the reference drugs Nfx and Bzn; four of them standed out with IC50 values lower than 1.5 µM. Moreover, unspecific cytotoxicity and genotoxicity studies are also reported. Compound 14 showed a SI higher than 24, whereas compound 10 was the only one that was negative in the genotoxicity screening.

Synthesis, biological evaluation and structure-activity relationships of new quinoxaline derivatives as anti-Plasmodium falciparum agents.

We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

Flavonoid-quinoxaline Hybrid Compounds as Cathepsin Inhibitors Against Fascioliasis.

Fasciola hepatica is a parasitic trematode that infects livestock animals and humans, causing significant health and economic burdens worldwide. The extensive use of anthelmintic drugs has led to the emergence of resistant parasite strains, posing a threat to treatment success. The complex life cycle of the liver fluke, coupled with limited funding and research interest, have hindered progress in drug discovery. Our group has been working in drug development against this parasite using cathepsin proteases as molecular targets, finding promising compound candidates with in vitro and in vivo efficacy. Here, we evaluated hybrid molecules that combine two chemotypes, chalcones and quinoxaline 1,4-di- N-oxides, previously found to inhibit F. hepatica cathepsin Ls and tested their in vitro activity with the isolated targets and the parasites in culture. These molecules proved to be good cathepsin inhibitors and to kill the juvenile parasites at micromolar concentrations. Also, we performed molecular docking studies to analyze the compounds-cathepsins interface, finding that the best inhibitors interact at the active site cleft and contact the catalytic dyad and residues belonging to the substrate binding pockets. We conclude that the hybrid compounds constitute promising scaffolds for the further development of new fasciolicidal compounds.

New amide derivatives of quinoxaline 1,4-di-N-oxide with leishmanicidal and antiplasmodial activities.

Malaria and leishmaniasis are two of the World's most important tropical parasitic diseases. Continuing with our efforts to identify new compounds active against malaria and leishmaniasis, twelve new 1,4-di-N-oxide quinoxaline derivatives were synthesized and evaluated for their in vitro antimalarial and antileishmanial activity against Plasmodium falciparum FCR-3 strain, Leishmania infantum and Leishmania amazonensis. Their toxicity against VERO cells (normal monkey kidney cells) was also assessed. The results obtained indicate that a cyclopentyl derivative had the best antiplasmodial activity (2.9 µM), while a cyclohexyl derivative (2.5 µM) showed the best activity against L. amazonensis, and a 3-chloropropyl derivative (0.7 µM) showed the best results against L. infantum. All these compounds also have a Cl substituent in the R7 position.

Neglected Zoonotic Diseases: Advances in the Development of Cell-Penetrating and Antimicrobial Peptides against Leishmaniosis and Chagas Disease.

In 2020, the WHO established the road map for neglected tropical diseases 2021-2030, which aims to control and eradicate 20 diseases, including leishmaniosis and Chagas disease. In addition, since 2015, the WHO has been developing a Global Action Plan on Antimicrobial Resistance. In this context, the achievement of innovative strategies as an alternative to replace conventional therapies is a first-order socio-sanitary priority, especially regarding endemic zoonoses in poor regions, such as those caused by Trypanosoma cruzi and Leishmania spp. infections. In this scenario, it is worth highlighting a group of natural peptide molecules (AMPs and CPPs) that are promising strategies for improving therapeutic efficacy against these neglected zoonoses, as they avoid the development of toxicity and resistance of conventional treatments. This review presents the novelties of these peptide molecules and their ability to cross a whole system of cell membranes as well as stimulate host immune defenses or even serve as vectors of molecules. The efforts of the biotechnological sector will make it possible to overcome the limitations of antimicrobial peptides through encapsulation and functionalization methods to obtain approval for these treatments to be used in clinical programs for the eradication of leishmaniosis and Chagas disease.

Antiplasmodial and leishmanicidal activities of 2-cyano-3-(4-phenylpiperazine-1-carboxamido) quinoxaline 1,4-dioxide derivatives.

Malaria and leishmaniasis are two of the World's most important tropical parasitic diseases. Thirteen new 2-cyano-3-(4-phenylpiperazine-1-carboxamido) quinoxaline 1,4-dioxide derivatives (CPCQs) were synthesized and evaluated for their in vitro antimalarial and antileishmanial activity against erythrocytic forms of Plasmodium falciparum and axenic forms of Leishmania infantum. Their toxicity against VERO cells (normal monkey kidney cells) was also assessed. None of the tested compounds was efficient against Plasmodium, but two of them showed good activity against Leishmania. Toxicity on VERO was correlated with leishmanicidal properties.

New quinoxaline derivatives as potential MT1 and MT2 receptor ligands.

Ever since the idea arose that melatonin might promote sleep and resynchronize circadian rhythms, many research groups have centered their efforts on obtaining new melatonin receptor ligands whose pharmacophores include an aliphatic chain of variable length united to an N-alkylamide and a methoxy group (or a bioisostere), linked to a central ring. Substitution of the indole ring found in melatonin with a naphthalene or quinoline ring leads to compounds of similar affinity. The next step in this structural approximation is to introduce a quinoxaline ring (a bioisostere of the quinoline and naphthalene rings) as the central nucleus of future melatoninergic ligands.

Potential of sulfur-selenium isosteric replacement as a strategy for the development of new anti-chagasic drugs.

Current treatment for Chagas disease is based on only two drugs: benznidazole and nifurtimox. Compounds containing sulfur (S) in their structure have shown promising results in vitro and in vivo against Trypanosoma cruzi, the parasite causing Chagas disease. Notably, some reports show that the isosteric replacement of S by selenium (Se) could be an interesting strategy for the development of new compounds for the treatment of Chagas disease. To date, the activity against T. cruzi of three Se- containing groups has been compared with their S counterparts: selenosemicarbazones, selenoquinones, and selenocyanates. More studies are needed to confirm the positive results of Se compounds. Therefore, we have investigated S compounds described in the literature tested against T. cruzi. We focused on those tested in vivo that allowed isosteric replacement to propose their Se counterparts as promising compounds for the future development of new drugs against Chagas disease.

New salicylamide and sulfonamide derivatives of quinoxaline 1,4-di-N-oxide with antileishmanial and antimalarial activities.

Continuing with our efforts to identify new active compounds against malaria and leishmaniasis, 14 new 3-amino-1,4-di-N-oxide quinoxaline-2-carbonitrile derivatives were synthesized and evaluated for their in vitro antimalarial and antileishmanial activity against Plasmodium falciparum Colombian FCR-3 strain and Leishmania amazonensis strain MHOM/BR/76/LTB-012A. Further computational studies were carried out in order to analyze graphic SAR and ADME properties. The results obtained indicate that compounds with one halogenous group substituted in position 6 and 7 provide an efficient approach for further development of antimalarial and antileishmanial agents. In addition, interesting ADME properties were found.

New 1,4-di-N-oxide-quinoxaline-2-ylmethylene isonicotinic acid hydrazide derivatives as anti-Mycobacterium tuberculosis agents.

The increase in the prevalence of drug-resistant tuberculosis cases demonstrates the need of discovering new and promising compounds with antimycobacterial activity. As a continuation of our research and with the aim of identifying new antitubercular drugs candidates, a new series of quinoxaline 1,4-di-N-oxide derivatives containing isoniazid was synthesized and evaluated for in vitro anti-tuberculosis activity against Mycobacterium tuberculosis H37Rv strain. Moreover, various drug-like properties of new compounds were predicted. Taking into account the biological results and the promising drug-likeness profile of these compounds, make them valid leads for further experimental research.

Trypanocidal properties, structure-activity relationship and computational studies of quinoxaline 1,4-di-N-oxide derivatives.

Pyrazole and propenone quinoxaline derivatives were tested against intracellular forms of Leishmania peruviana and Trypanosoma cruzi. Both series were tested for toxicity against proliferative and non-proliferative cells. The pyrazole quinoxaline series was quite inactive against T. cruzi; however, the compound 2,6-dimethyl-3-f-quinoxaline 1,4-dioxide was found to inhibit 50% of Leishmania growth at 8.9 µM, with no impact against proliferative kidney cells and with low toxicity against THP-1 cells and murine macrophages. The compounds belonging to the propenone quinoxaline series were moderately active against T. cruzi. Among these compounds, two were particularly interesting, (2E)-1-(7-fluoro-3-methyl-quinoxalin-2-yl)-3-(3,4,5-trimethoxy-phenyl)-propenone and (2E)-3-(3,4,5-trimethoxy-phenyl)-1-(3,6,7-trimethyl-quinoxalin-2-yl)-propenone. The former possessed selective activity against proliferative cells (cancer and parasites) and was inactive against murine peritoneal macrophages; the latter was active against Leishmania and inactive against the other tested cells. Furthermore, insilico studies showed that both series respected Lipinski's rules and that they confirmed a linear correlation between trypanocidal activities and LogP. Docking studies revealed that compounds of the second series could interact with the poly (ADP-ribose) polymerase protein of Trypanosoma cruzi.

Aryl piperazine and pyrrolidine as antimalarial agents. Synthesis and investigation of structure-activity relationships.

Piperazine and pyrrolidine derivatives were synthesised and evaluated for their capacity to inhibit the growth of Plasmodium falciparum chloroquine-resistant (FCR-3) strain in culture. The combined presence of a hydroxyl group, a propane chain and a fluor were shown to be crucial for the antiplasmodial activity. Five compounds of the aryl-alcohol series inhibited 50% of parasite growth at doses ≤10 µM. The most active compound 1-(4-fluoronaphthyl)-3-[4-(4-nitro-2-trifluoromethylphenyl)piperazin-1-yl] propan-1-ol was almost 20-40 times more active on P. falciparum (IC(50): 0.5 µM) than on tumorogenic and non-tumorogenic cells. In vivo it has a very weak effect; inhibiting 35% of parasite growth only, at 10 mg/kg/day against Plasmodium berghei infected mice without any impact on survival time. In silico molecular docking study and molecular electrostatic potential calculation revealed that this compound bound to the active site of Plasmodium plasmepsin II enzyme.

Studies on log Po/w of quinoxaline di-N-oxides: a comparison of RP-HPLC experimental and predictive approaches.

As reported in our previous papers, a series of quinoxaline-2-carboxamide 1,4-di-N-oxide derivatives were synthesized and studied as anti-tuberculosis agents. Here, the capability of the shake-flask method was studied and the retention time (expressed as log K) of 20 compounds were determined by RP-HPLC analysis. We found that the prediction of log P by the RP-HPLC analysis can result in a high accuracy and can replace the shake-flask method avoiding the experimental problems presented by quinoxaline di-N-oxides. The studied compounds were subjected to the ALOGPS module with the aim of comparing experimental log P(o/w) values and predicted data. Moreover, a preliminary in silico screening of the QSAR relationship was made confirming the influence of reduction peak potential, lipophilicity, H-bond donor capacity and molecular dimension descriptors on anti-tuberculosis activity.