Comparative chemical and biological hydrolytic stability of homologous esters and isosteres.

Esters are one of the major functional groups present in the structures of prodrugs and bioactive compounds. Their presence is often associated with hydrolytic lability. In this paper, we describe a comparative chemical and biological stability of homologous esters and isosteres in base media as well as in rat plasma and rat liver microsomes. Our results provided evidence for the hydrolytic structure lability relationship and demonstrated that the hydrolytic stability in plasma and liver microsome might depend on carboxylesterase activity. Molecular modelling studies were performed in order to understand the experimental data. Taken together, the data could be useful to design bioactive compounds or prodrugs based on the correct choice of the ester subunit, addressing compounds with higher or lower metabolic lability.

N-Acylhydrazones as drugs.

Over the last two decades, N-acylhydrazone (NAH) has been proven to be a very versatile and promising motif in drug design and medicinal chemistry. Herein, we discuss the current and future challenges in the emergence of bioactive NAH-based scaffolds and to developing strategies to overcome the failures in drug discovery. The NAH-related approved drugs nitrofurazone, nitrofurantoin, carbazochrome, testosterone 17-enanthate 3-benzilic acid hydrazine, nifuroxazide, dantrolene, and azumolene are already used as therapeutics in various countries. PAC-1 is an NAH-based therapeutic agent that entered clinical trials in 2015. Another NAH-derived scaffold, LASSBio-294, is in preclinical trials. This review highlights the detailed comprehensive assessment and therapeutic landscape of bioactive NAH motif scaffolds in preclinical and clinical studies published to date and their promise and associated challenges in current and future drug discovery of NAH-based drugs that will progress to clinical use.

Synthesis, X-ray diffraction study and pharmacological evaluation of 3-amino-4-methylthiophene-2-acylcarbohydrazones.

N-acylhydrazone is an interesting privileged structure that has been used in the molecular design of a myriad of bioactive compounds. In order to identify new antinociceptive drug candidates, we described herein the design, synthesis, X-ray diffraction study and the pharmacological evaluation of a series of 3-amino-4-methylthiophene-2-acylcarbohydrazone derivatives (8a-t). Compounds were prepared in good overall yields through divergent synthesis from a common key intermediate and were characterized by classical spectroscopy methods. X-ray diffraction study was employed for unequivocal determination of the imine double bond stereochemistry. 8a-t were evaluated in vivo through oral administration using the classical writhing test in mice. N-acylhydrazone derivatives 8j and 8l displayed relative potency similar to dipyrone, highlighting them as promising analgesic lead-candidates for further investigation.

Discovery of new orally effective analgesic and anti-inflammatory hybrid furoxanyl N-acylhydrazone derivatives.

We report the design, the synthesis and the biological evaluation of the analgesic and anti-inflammatory activities of furoxanyl N-acylhydrazones (furoxanyl-NAH) by applying molecular hybridization approach. Hybrid compounds with IL-8-release inhibition capabilities were identified. Among them, furoxanyl-NAH, 17, and benzofuroxanyl-derivative, 24, together with furoxanyl-NAH derivative, 31, without IL-8 inhibition displayed both orally analgesic and anti-inflammatory activities. These hybrid derivatives do not have additional LOX- or COX-inhibition activities. For instance, LOX-inhibition by furoxanyl-NAH derivative, 42, emerged as a structural lead to develop new inhibitors. The lack of mutagenicity of the active derivatives 17, 31, and 42, allow us to propose them as candidates for further clinical studies. These results confirmed the success in the exploitation of hybridization strategy for identification of novel N-acylhydrazones (NAH) with optimized activities.

2-Arylpropionic Acid Pyrazolamides as Cannabinoid CB2 Receptor Inverse Agonists Endowed with Anti-Inflammatory Properties.

Among the most recent proposals regarding the mechanism of action of dipyrone, the modulation of cannabinoid receptors CB1 and CB2 appears to be a promising hypothesis. In this context, the present work describes a series of five novel pyrazolamides (7-11) designed as molecular hybrids of dipyrone metabolites and NSAIDs, such as ibuprofen and flurbiprofen. Target compounds were obtained in good overall yields (50-80%) by classical amide coupling between 4-aminoantipyrine and arylacetic or arylpropionic acids, followed in some cases by N-methylation of the amide group. The compounds presented good physicochemical properties in addition to stability to chemical (pH 2 and 7.4) and enzymatic (plasma esterases) hydrolysis and showed medium to high gastrointestinal and BBB permeabilities in the PAMPA assay. When subjected to functional testing on CB1- or CB2-transfected cells, compounds demonstrated an inverse agonist profile on CB2 receptors and the further characterization of compound LASSBio-2265 (11) revealed moderate binding affinity to CB2 receptor (Ki = 16 µM) with an EC50 = 0.36 µM (Emax = 63%). LASSBio-2265 (11) (at 1, 3, and 10 mg/kg p.o.) was investigated in the formalin test in mice and a remarkable analgesic activity in the late inflammatory phase was observed, suggesting it could be promising for the treatment of pain syndromes associated with chronic inflammatory diseases.

The possible molecular evolution of sapoviruses by inter- and intra-genogroup recombination.

Sapporo virus belongs to the genus Sapovirus (family Caliciviridae) and has a non-segmented single-stranded, positive-sense RNA genome. This virus causes acute gastroenteritis in human, porcine and mink hosts. In this study, the complete genome of a Brazilian sapovirus isolate from a child with acute gastroenteritis was determined. A phylogenetic tree was constructed to analyze the genotype of this sapovirus (Sapo_BR-DF01), and possible intra- and inter-genogroups recombination events were evaluated in silico using the RDP3 program. Two inter-genogroup and two intra-genogroup recombination events were newly recognized in this study.

Carbamoyl-N-aryl-imine-urea: a new framework to obtain a putative leishmanicidal drug-candidate.

Leishmaniasis is a neglected parasitic disease, and current treatment includes limitations of toxicity, variable efficacy, high costs and inconvenient doses and treatment schedules. Therefore, new leishmanicidal drugs are still an unquestionable medical need. In this paper we described the design conception of a new framework, the carbamoyl-N-aryl-imine-urea, to obtain putative leishmanicidal drug-candidates. Compounds 9a-e and 10a-e were designed and synthesized and their leishmanicidal activity was studied in comparison to pentamidine, miltefosine and meglumine antimoniate. The conformational profile of the new carbamoyl-N-aryl-imine-urea framework was investigated by X-ray diffraction studies, using compound 9a as a model. The plasma stability of this putative peptide mimetic subunit was studied for compound 10e (LASSBio-1736). Among the congeneric series, LASSBio-1736 was identified as a new antileishmanial drug-candidate, displaying plasma stability, cytotoxicity against amastigote forms of L. amazonensis and L. braziliensis, and leishmanicidal activity in a cutaneous leishmaniasis murine model, without preliminary evidence of hepatic or renal toxicity.

Selective activity against Mycobacteriumtuberculosis of new quinoxaline 1,4-di-N-oxides.

New series of 3-phenylquinoxaline 1,4-di-N-oxide with selective activity against Mycobacterium tuberculosis have been prepared and evaluated. Thirty-four of the seventy tested compounds showed an MIC value less than 0.2 microg/mL, a value on the order of the MIC of rifampicin. Furthermore, 45% of the evaluated derivatives showed a good in vitro activity/toxicity ratio. The most active and selective compounds carry a fluorine atom in the quinoxaline 7-position or in the phenyl substituent para-position. In conclusion, the potency, low cytotoxicity and selectivity of these compounds make them valid lead compounds for synthesizing new analogues, particularly compound 7-methyl-3-(4'-fluoro)phenylquinoxaline-2-carbonitrile 1,4-di-N-oxide (MIC <0.2 microg/mL and SI > 500).

Synthesis, trypanocidal activity and docking studies of novel quinoxaline-N-acylhydrazones, designed as cruzain inhibitors candidates.

In this paper, we report the structural design, synthesis, trypanocidal activity and docking studies of novel quinoxaline-N-acylhydrazone (NAH) derivatives, planned as cruzain inhibitors candidates, a cysteine protease essential for the survival of Trypanosoma cruzi within the host cell. The salicylaldehyde N-acylhydrazones 7a and 8a presented IC(50) values of the same magnitude order than the standard drug nifurtimox (Nfx), when tested in vitro against epimastigote forms of Trypanosoma cruzi (Tulahuen 2 strain) and were non-toxic at the highest assayed doses rendering selectivity indexes (IC(50) (macrophages)/IC(50) (Trypanosoma cruzi)) of >25 for 7a and >20 for 8a, with IC(50) values in macrophages >400 microM.

Homologation: A Versatile Molecular Modification Strategy to Drug Discovery.

Homologation is a concept introduced by Gerhard in 1853 to describe a homologous series in organic chemistry. Since then, the concept has been adapted and used in medicinal chemistry as one of the most important strategies for molecular modification. The homologation types, their influence on physico-chemical properties and molecular conformation are presented and discussed. Its application in lead-identification and lead optimization steps, as well as its impact on pharmacodynamics/pharmacokinetic properties and on protein structure is highlighted from selected examples. • Homologation: definition and types • Homologous series in nature • Comparative physico-chemical and conformational properties • Application in lead-identification and lead-optimization • Impact on pharmacodynamic property • Impact on pharmacokinetic property • Impact on protein structure • Concluding remarks • Acknowledgment • References.

Reduction of cardiac and renal dysfunction by new inhibitor of DPP4 in diabetic rats.

BACKGROUND: Increased mortality due to type 2 diabetes mellitus (T2DM) has been associated with renal and/or cardiovascular dysfunction. Dipeptidyl dipeptidase-4 inhibitors (iDPP-4s) may exert cardioprotective effects through their pleiotropic actions via glucagon-like peptide 1-dependent mechanisms. In this study, the pharmacological profile of a new iDPP-4 (LASSBio-2124) was investigated in rats with cardiac and renal dysfunction induced by T2DM. METHODS: T2DM was induced in rats by 2 weeks of a high-fat diet followed by intravenous injection of streptozotocin. Metabolic disturbance and cardiac, vascular, and renal dysfunction were analyzed in the experimental groups. RESULTS: Sitagliptin and LASSBio-2124 administration after T2DM induction reduced elevated glucose levels to 319.8 ±â€¯13.2 and 279.7 ±â€¯17.8 mg/dL, respectively (p < 0.05). LASSBio-2124 also lowered the cholesterol and triglyceride levels from 76.8 ±â€¯8.0 to 42.7 ±â€¯3.2 mg/dL and from 229.7 ±â€¯25.4 to 100.7 ±â€¯17.1 mg/dL, in diabetic rats. Sitagliptin and LASSBio-2124 reversed the reduction of the plasma insulin level. LASSBio-2124 recovered the increased urinary flow in diabetic animals and reduced 24-h proteinuria from 23.7 ±â€¯1.5 to 13.3 ±â€¯2.8 mg (p < 0.05). It also reduced systolic and diastolic left-ventricular dysfunction in hearts from diabetic rats. CONCLUSION: The effects of LASSBio-2124 were superior to those of sitagliptin in the cardiovascular systems of T2DM rats. This new prototype showed promise for the avoidance of comorbidities in a T2DM experimental model, and thus may constitute an innovative therapeutic agent for the treatment of these conditions in the clinical field in future.

NSAIDs revisited: putative molecular basis of their interactions with peroxisome proliferator-activated gamma receptor (PPARgamma).

This paper describes molecular docking studies of a series of classical NSAIDs with PPARgamma receptor, which has been pointed as a new target for the design of anti-cancer and anti-inflammatory drugs, and has been found to be responsible for some of the already established pharmacological effects observed for marketed drugs. The results show the molecular basis of PPARgamma activation by non-selective COX inhibitors.

Synthesis and structure-activity relationship of 3-phenylquinoxaline 1,4-di-N-oxide derivatives as antimalarial agents.

As a continuation of our research and with the aim of obtaining new antimalarial agents, new series of 3-phenylquinoxaline 1,4-di-N-oxide derivatives have been synthesized following the classical Beirut reaction. Antiplasmodial activity was evaluated in vitro against Plasmodium falciparum by the incorporation of [3H]-hypoxanthine. Cytotoxicity was tested in KB cells by AlamarBlue assay. Twenty-one of the 60 compounds that were assayed against 3D7 (CQ-sensitive) showed enough activity to be also evaluated against K1 (CQ-resistant) strain. Ten of them were shown to be more active than chloroquine in the resistant strain. The most interesting compounds are 7-(methyl or methoxy)-3-(4'-fluoro or chloro)phenylquinoxaline-2-carbonitrile 1,4-di-N-oxides because of their low IC50 and their high SI shown for the K1 strain, making them valid new leads.

Synthesis and anti-platelet activity of novel arylsulfonate--acylhydrazone derivatives, designed as antithrombotic candidates.

In this work, we describe a new class of promising anti-platelet drug candidates with significant antithrombotic activity in vivo. This new series of compounds was structurally planned by modification of known thrombin inhibitors based on the use of acylhydrazone subunit, as a nonpeptide scaffold, and variations at P1 moiety. Three different families of arylsulfonate-acylhydrazone derivatives were designed. The bioassays indicated the first class of derivatives represented by 4f (LASSBio-693) and 4j (LASSBio-743), which were active in inhibiting the platelet aggregation induced by thrombin. The second class represented by compounds 4e (LASSBio-774) and 4h (LASSBio-480) that selectively inhibit the platelet aggregation involving TXA(2) formation. Finally, the third class of derivatives was identified acting as a novel symbiotic agent able to inhibit the platelet aggregation induced by collagen or AA and by thrombin, represented by compounds 4b (LASSBio-694) and 4g (LASSBio-770).

Unexpected reduction of ethyl 3-phenylquinoxaline-2- carboxylate 1,4-di-N-oxide derivatives by amines.

The unexpected tendency of amines and functionalized hydrazines to reduce ethyl 3-phenylquinoxaline-2-carboxylate 1,4-di-N-oxide (1) to afford a quinoxaline 1c and mono-oxide quinoxalines 1a and 1b is described. The experimental conditions were standardized to the use of two equivalents of amine in ethanol under reflux for two hours,with the aim of studying the distinct reductive profiles of the amines and the chemoselectivity of the process. With the exception of hydrazine hydrate, which reduced compound 1 to a 3-phenyl-2-quinoxalinecarbohydrazide derivative, the amines only acted as reducing agents.

Discovery of naphthyl-N-acylhydrazone p38α MAPK inhibitors with in vivo anti-inflammatory and anti-TNF-α activity.

Protein kinases constitute attractive therapeutic targets for development of new prototypes to treat different chronic diseases. Several available drugs, like tinibs, are tyrosine kinase inhibitors; meanwhile, inhibitors of serine/threonine kinases, such as mitogen-activated protein kinase (MAPK), are still trying to overcome some problems in one of the steps of clinical development to become drugs. So, here we reported the synthesis, the in vitro kinase inhibitory profile, docking studies, and the evaluation of anti-inflammatory profile of new naphthyl-N-acylhydrazone derivatives using animal models. Although all tested compounds (3a-d) have been characterized as p38α MAPK inhibitors and have showed in vivo anti-inflammatory action, LASSBio-1824 (3b) presented the best performance as p38α MAPK inhibitor, with IC50  = 4.45 µm, and also demonstrated to be the most promising anti-inflammatory prototype, with good in vivo anti-TNF-α profile after oral administration.

Oxidative imbalance in mice intoxicated by microcystin-LR can be minimized.

Microcystins-LR (MC-LR) is a cyanotoxin produced by cyanobacteria. We evaluated the antioxidant potential of LASSBio-596 (LB-596, inhibitor of phosphodiesterases 4 and 5), per os, and biochemical markers involved in lung and liver injury induced by exposure to sublethal dose of MC-LR. Fifty male Swiss mice received an intraperitoneal injection of 60 µL of saline (CTRL group, n = 20) or a sublethal dose of MC-LR (40 µg/kg, TOX group, n = 20). After 6 h the animals received either saline (TOX and CTRL groups) or LB-596 (50 mg/kg, TOX + LASS group, n = 10) by gavage. At 6 h after exposure, respiratory mechanics was evaluated in 10 CTRL and 10 TOX mice: there was a significant increase of all lung mechanics parameters (static elastance, viscoelastic component of elastance and lung resistive and viscoelastic/inhomogeneous pressures) in TOX compared to CTRL. 8 h after saline or MC-LR administration, i.e., 2 h after treatment with LB-596, blood serum levels of alanine aminotransferase and aspartate aminotransferase, activity of superoxide dismutase, catalase, and content of malondialdehyde and carbonyl in lung and liver, NADPH oxidase 2 and 4 mRNA expressions, dual oxidase enzyme activity and H2O2 generation were analyzed in lung homogenates. All parameters were significantly higher in TOX than in the other groups. There was no significant difference between CTRL and TOX + LASS. MC-LR deteriorated lung and liver functions and induced redox imbalance in them, which was prevented by oral administration of LB-596.

The antithrombotic and haemostatic effects of LASSBio-752: a synthetic, orally active compound in an arterial and venous thrombosis model in rats.

OBJECTIVES: In this work, we further investigated the effect of the compound LASSBio-752 in thrombosis models in rats. METHODS: Arterial and venous thrombosis model, ex-vivo recalcification time and aPTT and PT. KEY FINDINGS: In the venous thrombosis model, oral administration of LASSBio-752 [48.2 mg (100 µmol)/kg] one hour before the thrombus induction decreased thrombus weight by 37 ± 0.2%. Interestingly, the antithrombotic action of this compound [48.2 mg (100 µmol)/kg] occurred at 87.5 ± 2.1% of inhibition after 24 h of administration and showed a lasting activity. When tested on the arterial thrombosis model, after a 1-h interval, there was already an increase in time to total occlusion of 34 ± 2.4 min, but the greatest effect was observed at intervals between 6 and 15 h of administration, when no occlusion of the artery was observed. The antithrombotic effect was reduced after 24 h when the occlusion time was 23.8 ± 2.3 min, close to that of the control, 17.6 ± 2.0 min. We also observed that bleeding was not excessive in any of the intervals tested. CONCLUSIONS: Our results indicate that compound LASSBio-752 is a potential candidate for utilization in the treatment of thromboembolic diseases.

Synthesis, Biological Evaluation and Molecular Docking of New Benzenesulfonylhydrazone as Potential anti-Trypanosoma cruzi Agents.

BACKGROUND: Chagas disease is a public health problem caused by Trypanosoma cruzi. Cruzain is a pharmacological target for designing a new drug against this parasite. Hydrazone and Nacylhydrazone derivatives have been traditionally associated as potential Cruzain inhibitors. Additionally, benzenesulfonyl derivatives show trypanocidal activity. Therefore, in this study, the combination of both structures has been taken into account for drug design. METHODS: Seven benzenesulfonylhydrazone (BS-H) and seven N-propionyl benzenesulfonylhydrazone (BS-NAH) derivatives were synthetized and elucidated by infrared spectroscopy, nuclear magnetic resonance, and elemental analysis. All compounds were evaluated biologically in vitro against two strains of Trypanosoma cruzi (NINOA and INC-5), which are endemic in Mexico, and compared with the reference drugs nifurtimox and benznidazole. In order to gain insight into the putative molecular origin of the trypanocidal properties of these derivatives, docking studies were carried out with Cruzain. RESULTS: Compounds 4 and 6 (BS-H) and 10, 12-14 (BS-NAH) showed the best biological activity against NINOA and INC-5 strains, respectively. Compound 13 was the most potent trypanocidal compound showing a LC50 of 0.06 µM against INC-5 strain. However, compound 4 showed the best activity against both strains (LC50 <30 µM). Theoretical binding modes obtained suggested covalent binding that could explain their biological activity. CONCLUSION: Benzenesulfonyl and N-propionyl benzenesulfonyl hydrazone derivatives are good options for developing new trypanocidal agents. Particularly, compound 4 could be considered a lead compound.

Evaluating the prophylactic potential of the phtalimide derivative LASSBio 552 on allergen-evoked inflammation in rats.

A previous study showed that the novel tetrazolephtalimide derivative LASSBio 552 (2-4-[3-(1H-1,2,3,4-tetraazol-5-yl)propoxy]phenethyl-1,3-isoindolinedione) prevents LTD(4)-evoked tracheal contraction. This led us to examine the putative anti-inflammatory effect of LASSBio 552 in comparison with the leukotriene CysLT(1) receptor antagonist zafirlukast using a model of allergic pleurisy in rats. Treatment with either LASSBio 552 (24-96 micromol/kg, i.p.) or zafirlukast (9-72 micromol/kg, i.p.), 1 h before challenge, inhibited eosinophil and mononuclear cell influx into the pleural cavity 24 h post-challenge, but failed to alter the increased levels of eotaxin, plasma leakage, mast cell degranulation and neutrophil infiltration noted 6 h post-challenge. CD4(+) T cell recruitment 24 h post-challenge was also sensitive to LASSBio 552. This treatment failed to alter cysteinyl leukotriene production at 6 h, but clearly inhibited the phenomenon 24 h and 48 h post-challenge. In in vitro settings LASSBio 552 inhibited allergen-evoked cysteinyl leukotriene generation from isolated mast cells, while histamine release remained unchanged. It also slightly inhibited cysteinyl leukotriene production by eosinophils and mononuclear cells triggered by Ca(+2) ionophore A23187. A leukotriene CysLT(1) receptor transfected cell-based assay revealed that LASSBio 552 did not prevent LTD(4)-evoked Ca(+2) influx, indicating that it was not a leukotriene CysLT(1) receptor antagonist. These findings indicate that LASSBio 552 is able to inhibit eosinophil influx triggered by allergen chalenge in a mechanism at least partially associated with suppression of CD4(+) T cell influx and cysteinyl leukotriene production.