Synthesis and anticonvulsant screening of 1,2,4-triazole derivatives

Development of new chiral 1,2,4-triazole-3-thiones and 1,3,4-thiadiazoles with promising in vivo anticonvulsant activity targeting GABAergic system and voltage-gated sodium channels (VGSCs)

Antiepileptic drugs (AEDs) are used in the treatment of epilepsy, a neurodegenerative disease characterized by recurrent and untriggered seizures that aim to prevent seizures as a symptomatic treatment. However, they still have significant side effects as well as drug resistance. In recent years, especially 1,3,4-thiadiazoles and 1,2,4-triazoles have attracted attention in preclinical and clinical studies as important drug candidates owing to their anticonvulsant properties. Therefore, in this study, which was conducted to discover AED candidate molecules with reduced side effects at low doses, a series of chiral 2,5-disubstituted-1,3,4-thiadiazoles (4a-d) and 4,5-disubstituted-1,2,4-triazole-3 thiones (5a-d) were designed and synthesized starting from l-phenylalanine ethyl ester hydrochloride. The anticonvulsant activities of the new chiral compounds were assessed in several animal seizure models in mice and rats for initial (phase I) screening after their chemical structures including the configuration of the chiral center were elucidated using spectroscopic methods and elemental analysis. First, all chiral compounds were pre-screened using acute seizure tests induced electrically (maximal electroshock test, 6 Hz psychomotor seizure model) and induced chemically (subcutaneous metrazol seizure model) in mice and also their neurotoxicity (TOX) was determined in the rotorad assay. Two of the tested compounds were used for quantitative testing, and (S)-(+)5-[1-(4-fluorobenzamido)-2-phenylethyl]-4-(4-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (5b) and (S)-(+)-(5-[1-(4-fluorobenzamido)-2-phenylethyl]-4-(4-methoxyphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (5c) emerged as the most promising anticonvulsant drug candidates and also showed low neurotoxicity. The antiepileptogenic potential of these compounds was determined using a chronic seizure induced electrically corneal kindled mouse model. Furthermore, all chiral compounds were tested for their neuroprotective effect against excitotoxic kainic acid (KA) and N-methyl-d-aspartate (NMDA) induced in vitro neuroprotection assay using an organotypic hippocampal slice culture. The KA-induced neuroprotection assay results revealed that compounds 5b and 5c, which are the leading compounds for anticonvulsant activity, also had the strongest neuroprotective effects with IC50 values of 103.30 ± 1.14 and 113.40 ± 1.20 μM respectively. Molecular docking studies conducted to investigate the molecular binding mechanism of the tested compounds on the GABAA receptor showed that compound 5b exhibits a strong affinity to the benzodiazepine (BZD) binding site on GABA. It also revealed that the NaV1.3 binding interactions were consistent with the experimental data and the reported binding mode of the ICA121431 inhibitor. This suggests that compound 5b has a high affinity for these specific binding sites, indicating its potential as a ligand for modulating GABAA and NaV1.3 receptor activity. Furthermore, the ADME properties displayed that all the physicochemical and pharmacological parameters of the compounds stayed within the specified limits and revealed a high bioavailability profile.

Chromenone: An emerging scaffold in anti-Alzheimer drug discovery

Alzheimer's disease (AD) presents a growing global health concern. In recent decades, natural and synthetic chromenone have emerged as promising drug candidates due to their multi-target potential. Natural chromenone, quercetin, scopoletin, esculetin, coumestrol, umbelliferone, bergapten, and methoxsalen (xanthotoxin), and synthetic chromenone hybrids comprising structures like acridine, 4-aminophenyl, 3-arylcoumarins, quinoline, 1,3,4-oxadiazole, 1,2,3-triazole, and tacrine, have been explored for their potential to combat AD. Key reactions used for synthesis of chromenone hybrids include Perkin and Pechmann condensation. The activity of chromenone hybrids has been reported against several drug targets, including AChE, BuChE, BACE-1, and MAO-A/B. This review comprehensively explores natural, semisynthetic, and synthetic chromenone, elucidating their synthetic routes, possible mode of action/drug targets and structure-activity relationships (SAR). The acquired knowledge provides valuable insights for the development of new chromenone hybrids against AD.

Azoles display promising anticonvulsant effects through possible PPAR-α activation

Azoles such as nafimidone, denzimol and loreclezole are known for their clinical efficacy against epilepsy, and loreclezole acts by potentiating γ-aminobutyric acid (GABA)-ergic currents. In the current study, we report a series of azole derivatives in alcohol ester and oxime ester structure showing promising anticonvulsant effects in 6 Hz and maximal electro shock (MES) models with minimal toxicity. The most promising of the series, 5f, was active in both 6 Hz and MES tests with a median effective dose (ED50) of 118.92 mg/kg in 6 Hz test and a median toxic dose (TD50) twice as high in mice. The compounds were predicted druglike and blood-brain barrier (BBB) penetrant in silico. Contrary to what was expected, the compounds showed no in vitro affinity to GABAA receptors (GABAARs) in radioligand binding assays; however, they were found structurally similar to peroxisome proliferator-activated receptors alpha (PPAR-α) agonists and predicted to show high affinity and agonist-like binding to PPAR-α in molecular docking studies. As a result, 5f emerged as a safe azole anticonvulsant with a wide therapeutic window and possible action through PPAR-α activation.

Design, Synthesis and Anticonvulsant Activity of Cinnamoyl Derivatives of 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1-(2H)-one Oxime

BACKGROUND

Epilepsy continues to be a significant global health problem and the search for new drugs for its treatment remains an urgent task. 5-HT2 and GABAA-receptors are among promising biotargets for the search for new anticonvulsants.

METHODS

New potential 5-HT2 and GABAA ligands in the series of substituted cinnamoyl derivatives of 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1-(2H)-one oxime were designed using pharmacophore model and molecular docking analysis. The synthesis of new compounds was carried out from 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1(2H)-one oxime and substituted cinnamoyl chlorides. The anticonvulsant activity of new substances has been established using the maximal electroshock seizure test.

RESULTS

Several synthesized substituted cinnamoyl derivatives of 3,4,6,7,8,9-hexahydrodibenzo [b,d]furan-1-(2H)-one oxime significantly reduced the severity of convulsive manifestations and completely prevented the death of animals after MES. The structure-activity relationship was investigated. The most effective compound was found to be GIZH-348 (1g) (3,4,6,7,8,9-hexahydrodibenzo[ b,d]furan-1(2Н)-one О-(4-chlorophenyl)acryloyl)oxime) at the doses of 10-20 mg/kg.

CONCLUSION

Molecular and pharmacophore modelling methods allowed us to create a new group of substituted cinnamoyl derivatives of 3,4,6,7,8,9-hexahydrodibenzo[b,d]furan-1-(2H)-one oxime with anticonvulsant activity.

Azole derivatives inhibit wildtype butyrylcholinesterase and its common mutants

Azoles, which have been used for antifungal chemotherapy for decades, have recently been of interest for their efficacy against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). There is little known about the potential of azoles against BChE, however there is none regarding their inhibitory effects against mutants of BChE. In the current study, an azole library of 1-aryl-2-(1H-imidazol-1-yl)ethanol/ethanone oxime esters were tested against AChE and BChE, which yielded derivates more potent than the positive control, galantamine, against both isoforms. Kinetic analyses were performed for wildtype and mutant (A328F and A328Y) inhibition for the two most potent BChE inhibitors, pivalic and 3-bezoylpropanoic acid esters of 2-(1H-imidazol-1-yl)-1-(2-naphthyl)ethanol, which were found to have great affinity to the wildtype and mutant BChE types with Ki values as low as 0.173 ± 0.012 µM. The compounds were identified to show linear competitive or mixed type inhibition. Molecular modeling confirmed these kinetic data and provided further insights regarding molecular basis of BChE inhibition by the active derivatives. Thus, current study suggests new azole derivatives with promising cholinesterase inhibitory effects and reveals the first set of information to promote our understanding for the inhibitory behavior of this class against the mutant BChE forms.

Synthesis and Biological Evaluation of Coumarin Triazoles as Dual Inhibitors of Cholinesterases and β-Secretase

Coumarin is a naturally occurring bioactive pharmacophore with wide occurrence among central nervous system (CNS)-active small molecules. 8-Acetylcoumarin, one of the natural coumarins, is a mild inhibitor of cholinesterases and β-secretase, which are vital targets of Alzheimer's disease. Herein, we synthesized a series of coumarin-triazole hybrids as potential multitargeted drug ligands (MTDLs) with better activity profiles. The coumarin-triazole hybrids occupy the cholinesterase active site gorge from the peripheral to the catalytic anionic site. The most active analogue, 10b, belonging to the 8-acetylcoumarin core, inhibits acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-secretase-1 (BACE-1) with IC₅₀ values of 2.57, 3.26, and 10.65 μM, respectively. The hybrid, 10b, crosses the blood-brain barrier via passive diffusion and inhibits the self-aggregation of amyloid-β monomers. The molecular dynamic simulation study reveals the strong interaction of 10b with three enzymes and forming stable complexes. Overall, the results warrant a detailed preclinical investigation of the coumarin-triazole hybrids.

Discovery of Pongol, the Furanoflavonoid, as an Inhibitor of CDK7/Cyclin H/MAT1 and Its Preliminary Structure-Activity Relationship

Natural products have been a great source of leads for cancer drug discovery. The cyclin-dependent kinases (CDKs) play a vital role in the initiation and progression of cancer. The CDK-activating kinase, CDK7/cyclin H/MAT1, has recently gained tremendous attention in targeted cancer drug discovery. Herein, we screened a small library of pure natural products in an ADP-Glo CDK7/H kinase assay that yielded a series of furano- and naphthoflavonoids among actives. Pongol (SBN-88), the hydroxy-substituted furanoflavonoid, inhibits CDK7/H as well as CDK9/T1 with IC₅₀ values of 0.93 and 0.83 μM, respectively, and >20-fold selectivity over CDK2/E1 (IC₅₀ > 20 μM). The molecular docking and molecular dynamics simulation revealed that the presence of phenolic -OH in pongol is vital for kinase inhibition, as its absence resulted in a significant loss in activity (e.g., lanceolatin B). The prime MM-GBSA calculations revealed the presence of strong lipophilic and H-bonding interactions of pongol with CDKs.

Monoamine oxidase A and B inhibitory activities of 3,5-diphenyl-1,2,4-triazole substituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives

Monoamine oxidase (EC 1.4.3.4, MAO) is a flavin adenine dinucleotide-containing flavoenzyme located on the outer mitochondrial membrane and catalyzes the oxidative deamination of monoaminergic neurotransmitters and dietary amines. MAO exists in humans as two isoenzymes, hMAO-A and hMAO-B, which are distinguished by their tertiary structures, preferred substrates and inhibitors, and selective inhibition of these isoenzymes are used in the treatment of different diseases such as Alzheimer's, Parkinson's and depression. In the present study, we report the design, synthesis and characterization of 3,5-diphenyl-1,2,4-triazole substituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives as novel and selective inhibitors of hMAO-B. Twenty one compounds (38, 39a-h, 41a-d, 42a-h) were screened for their inhibitory activity against hMAO-A and hMAO-B by using in vitro Amplex Red® reagent based fluorometric method and all compounds were found to be as selective h-MAO-B inhibitors to a different degree. The compound 42e and 42h displayed the highest inhibitory activity against hMAO-B with IC₅₀ values of 2.51 and 2.81 µM, respectively, and more than 25-fold selectivity towards inhibition of hMAO-B. A further kinetic evaluation of the most potent derivative (42e) was also performed and a mixed mode of inhibition of hMAO-B by the compound 42e was determined (K_i = 0,26 µM). According to our findings the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole emerged as a promising scaffold for the development of novel and selective hMAO-B inhibitors.

Design, synthesis and biological evaluation of naphthalene-derived (arylalkyl)azoles containing heterocyclic linkers as new anticonvulsants: A comprehensive in silico, in vitro, and in vivo study

In continuation of our research to find strong and safe anticonvulsant agents, a number of (arylalkyl)azoles (AAAs) containing naphthylthiazole and naphthyloxazole scaffolds were designed and synthesized. The in vivo anticonvulsant evaluations in BALB/c mice revealed that some of them had significant anticonvulsant activity in both maximal electroshock (MES) and pentylenetetrazole (PTZ) models of epilepsy. The best profile of activity was observed with compounds containing imidazole and triazole rings (C1, C6, G1, and G6). In particular, imidazolylmethyl-thiazole C1 with median effective dose (ED₅₀)= 7.9 mg/kg in the MES test, ED₅₀= 27.9 mg/kg in PTZ test, and without any sign of neurotoxicity (in the rotarod test, 100 mg/kg) was the most promising compound. The patch-clamp recording was performed to study the mechanism of action of the representative compound C1 on hippocampal dentate gyrus (DG) cells. The results did not confirm any modulatory effect of C1 on the voltage-gated ion channels (VGICs) or GABA_A agonism, but suggested a significant reduction of excitatory postsynaptic currents (EPSCs) frequency on hippocampal DG neurons. Sub-acute toxicity studies revealed that administration of the most active compounds (C1, C6, G1, and G6) at 100 mg/kg bw/day for two weeks did not result in any mortality or significant toxicity as evaluated by assessment of biochemical markers such as lipid peroxidation, intracellular glutathione, total antioxidant capacity, histopathological changes, and mitochondrial functions. Other pharmacological aspects of compounds including mechanistic and ADME properties were investigated computationally and/or experimentally. Molecular docking on the NMDA and AMPA targets suggested that the introduction of the heterocyclic ring in the middle of AAAs significantly affects the affinity of the compounds. The obtained results totally demonstrated that the prototype compound C1 can be considered as a new lead for the development of anticonvulsant agents.

Kravtsov V, Melnic E, Petrou A, Glamočlija J, Soković M, Carazo A, Mladěnka P, Poroikov V, Geronikaki A, Macaev FZ. Chromenol Derivatives as Novel Antifungal Agents: Synthesis, In Silico and In Vitro Evaluation

Herein we report the synthesis of some new 1H-1,2,4-triazole functionalized chromenols (3a-3n) via tandem reactions of 1-(alkyl/aryl)-2-(1H-1,2,4-triazole-1-yl) with salicylic aldehydes and the evaluation of their antifungal activity. In silico prediction of biological activity with computer program PASS indicate that the compounds have a high novelty compared to the known antifungal agents. We did not find any close analog among the over 580,000 pharmaceutical agents in the Cortellis Drug Discovery Intelligence database at the similarity cutoff of 70%. The evaluation of antifungal activity in vitro revealed that the highest activity was exhibited by compound 3k, followed by 3n. Their MIC values for different fungi were 22.1-184.2 and 71.3-199.8 µM, respectively. Twelve from fourteen tested compounds were more active than the reference drugs ketoconazole and bifonazole. The most sensitive fungus appeared to be Trichoderma viride, while Aspergillus fumigatus was the most resistant one. It was found that the presence of the 2-(tert-butyl)-2H-chromen-2-ol substituent on the 4th position of the triazole ring is very beneficial for antifungal activity. Molecular docking studies on C. albicans sterol 14α-demethylase (CYP51) and DNA topoisomerase IV were used to predict the mechanism of antifungal activities. According to the docking results, the inhibition of CYP51 is a putative mechanism of antifungal activity of the novel chromenol derivatives. We also showed that most active compounds have a low cytotoxicity, which allows us to consider them promising antifungal agents for the subsequent testing activity in in vivo assays.

Triazolo Based-Thiadiazole Derivatives. Synthesis, Biological Evaluation and Molecular Docking Studies

The goal of this research is to investigate the antimicrobial activity of nineteen previously synthesized 3,6-disubstituted-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole derivatives. The compounds were tested against a panel of three Gram-positive and three Gram-negative bacteria, three resistant strains, and six fungi. Minimal inhibitory, bactericidal, and fungicidal concentrations were determined by a microdilution method. All of the compounds showed antibacterial activity that was more potent than both reference drugs, ampicillin and streptomycin, against all bacteria tested. Similarly, they were also more active against resistant bacterial strains. The antifungal activity of the compounds was up to 80-fold higher than ketoconazole and from 3 to 40 times higher than bifonazole, both of which were used as reference drugs. The most active compounds (2, 3, 6, 7, and 19) were tested for their inhibition of P. aeruginosa biofilm formation. Among them, compound 3 showed significantly higher antibiofilm activity and appeared to be equipotent with ampicillin. The prediction of the probable mechanism by docking on antibacterial targets revealed that E. coli MurB is the most suitable enzyme, while docking studies on antifungal targets indicated a probable involvement of CYP51 in the mechanism of antifungal activity. Finally, the toxicity testing in human cells confirmed their low toxicity both in cancerous cell line MCF7 and non-cancerous cell line HK-2.

In vivo- and in silico-driven identification of novel synthetic quinoxalines as anticonvulsants and AMPA inhibitors

The lack of effective therapies for epileptic patients and the potentially harmful consequences of untreated seizure incidents have made epileptic disorders in humans a major health concern. Therefore, new and more potent anticonvulsant drugs are continually sought after, to combat epilepsy. On the basis of the pharmacophoric structural specifications of effective α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonists with an efficient anticonvulsant activity, the present work reports the design and synthesis of two novel sets of quinoxaline derivatives. The anticonvulsant activity of the synthesized compounds was evaluated in vivo according to the pentylenetetrazol-induced seizure protocol, and the results were compared with those of perampanel as a reference drug. Among the synthesized compounds, 24, 28, 32, and 33 showed promising activities with ED₅₀ values of 37.50, 23.02, 29.16, and 23.86 mg/kg, respectively. Docking studies of these compounds suggested that AMPA binding could be the mechanism of action of these derivatives. Overall, the pharmacophore-based structural optimization, in vivo and in silico docking, and druglikeness studies indicated that the designed compounds could serve as promising candidates for the development of effective anticonvulsant agents with good pharmacokinetic profiles.

Antibacterial azole derivatives: Antibacterial activity, cytotoxicity, and in silico mechanistic studies

Azole antifungal drugs are commonly used in antifungal chemotherapy. Antibacterial effects of some topical antifungals, such as miconazole and econazole, have lately been revealed, which suggests a promising venue in antimicrobial chemotherapy. In this study, we tested an in-house azole collection with antifungal properties for their antibacterial activity to identify dual-acting hits using the broth microdilution method. The in vitro screen yielded a number of potent derivatives against gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus. Compound 73's minimum inhibitory concentration (MIC) value less than 1 μg/ml against S. aureus; however, none of the compounds showed noteworthy activity against methicillin-resistant S. aureus (MRSA). All the active compounds were found safe at their MIC values against the healthy fibroblast cells in the in vitro cytotoxicity test. Molecular docking studies of the most active compounds using a set of docking programs with flavohemoglobin (flavoHb) structure, the proposed target of the azole antifungals with antibacterial activity, presented striking similarities regarding the binding modes and interactions between the tested compounds and the antifungal drugs with crystallographic data. In addition to being noncytotoxic, the library was predicted to be drug-like and free of pan-assay interference compounds (PAINS). As a result, the current study revealed several potential azole derivatives with both antifungal and antibacterial activities. Inhibition of bacterial flavoHb was suggested as a possible mechanism of action for the title compounds.

Discovery of potent α-glucosidase inhibitors through structure-based virtual screening of an in-house azole collection

Diabetes mellitus, a chronic disorder characterized by hyperglycemia, is considered a pandemic of modern times. α-Glucosidase inhibitors emerged as a promising class of antidiabetic drugs with better tolerability compared with its alternatives. Azoles, although widely preferred in drug design, have scarcely been investigated for their potential against α-glucosidase. In this study, we evaluated α-glucosidase inhibitory effects 20 azole derivatives selected out of an in-house collection via structure-based virtual screening (VS) with consensus scoring approach. Seven compounds were identified with better IC₅₀ values than acarbose (IC₅₀  = 68.18 ± 1.01 µM), a well-known α-glucosidase inhibitor drug, which meant 35% success for our VS methodology. Compound 52, 54, 56, 59, and 81 proved highly potent with IC₅₀ values in the range of 40-60 µM. According to the enzyme kinetics study, four of them were competitive, 56 was non-competitive inhibitor. Structure-activity relationships, quantum mechanical, and docking analyses showed that azole rings at ionized state may be key to the potency observed for the active compounds and modifications to shift the balance between the neutral and ionized states further to the latter could yield more potent derivatives.

Synthesis, Characterization and Bioassay of Novel Substituted 1-(3-(1,3-Thiazol-2-yl)phenyl)-5-oxopyrrolidines

Thiazole derivatives attract the attention of scientists both in the field of organic synthesis and bioactivity research due to their high biological activity. In the present study, thiazole ring was obtained by the interaction of 1-(4-(bromoacetyl)phenyl)-5-oxopyrrolidine-3-carboxylic acid with thiocarbamide or benzenecarbothioamide, as well as tioureido acid. A series of substituted 1-(3-(1,3-thiazol-2-yl)phenyl)-5-oxopyrrolidines with pyrrolidinone, thiazole, pyrrole, 1,2,4-triazole, oxadiazole and benzimidazole heterocyclic fragments were synthesized and their antibacterial properties were evaluated against Gram-positive strains of Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Gram-negative Pseudomonas aeruginosa, Escherichia coli and Salmonella enterica enteritidis. The vast majority of compounds exhibited between twofold and 16-fold increased antibacterial effect against the test-cultures when compared with Oxytetracycline.

Antifungal screening and in silico mechanistic studies of an in-house azole library

Systemic Candida infections pose a serious public health problem with high morbidity and mortality. C. albicans is the major pathogen identified in candidiasis; however, non-albicans Candida spp. with antifungal resistance are now more prevalent. Azoles are first-choice antifungal drugs for candidiasis; however, they are ineffective for certain infections caused by the resistant strains. Azoles block ergosterol synthesis by inhibiting fungal CYP51, which leads to disruption of fungal membrane permeability. In this study, we screened for antifungal activity of an in-house azole library of 65 compounds to identify hit matter followed by a molecular modeling study for their CYP51 inhibition mechanism. Antifungal susceptibility tests against standard Candida spp. including C. albicans revealed derivatives 12 and 13 as highly active. Furthermore, they showed potent antibiofilm activity as well as neglectable cytotoxicity in a mouse fibroblast assay. According to molecular docking studies, 12 and 13 have the necessary binding characteristics for effective inhibition of CYP51. Finally, molecular dynamics simulations of the C. albicans CYP51 (CACYP51) homology model's catalytic site complexed with 13 were stable demonstrating excellent binding.