Novel agonists of benzodiazepine receptors: Design, synthesis, binding assay and pharmacological evaluation of 1,2,4-triazolo[1,5-a]pyrimidinone and 3-amino-1,2,4-triazole derivatives

1,2,4-Triazolo-quinazolinones as Effective Antifoulants: Molecular Design, Synthesis, and Biological Evaluation

A series of 1,2,4-triazolo-quinazolinones and 1,2-benzisothiazolone derivatives (S1-S12) were successfully synthesized as environmentally friendly alternatives to copper-based antifouling paints using N-alkylation, cyclocondensation, and one-pot three-component and amide coupling reactions. The monoclinic structure of single-crystal 1,2,4-triazolo-quinazolin-acetic acid (S8) was confirmed by single-crystal X-ray diffraction analysis. All the synthesized molecules were studied for their in silico molecular docking interactions with three target proteins, namely, RbmA, ToxR, and Bap. Following that, the antialgal activity was assessed against two types of marine algae: Chlorella sp. and Chaetoceros curvisetus. The minimal inhibitory concentration and zone of inhibition have been used to evaluate the antibacterial activities of S1-S12 against both marine Gram-positive (Staphylococcus aureus) and Gram-negative (Vibrio parahemolyticus and Vibrio vulnificus) bacteria. Additionally, antifouling studies have been done on all the compounds, and among them, 1,2,4-triazolo-quinazolinyl-acetate (S7), 1,2,4-triazolo-quinazolinyl-acetic acid (S8), 1,2,4-triazolo-quinazolinyl-oxobutanoate (S9), benzo[d]isothiazolyl butanoate (S10), benzo[d]isothiazolyl-acetic acid (S11), and 1,2,4-triazolo-quinazolinyl-acetyl-benzo[d]isothiazolone (S12) exhibited good antialgal, antibacterial, and antifouling activities.

Discovery of selective TYK2 inhibitors: Design, synthesis, in vitro and in silico studies of promising hits with triazolopyrimidinone scaffold

The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway mediates many cytokine and growth factor signals. Tyrosine kinase 2 (TYK2), one of the members of this pathway and the first described member of the JAK family. TYK2 associates with inflammatory and autoimmune diseases, cancer and diabetes. Here, we present novel compounds as selective inhibitors of the canonical kinase domain of TYK2 enzyme. These compounds were rationally designed and synthesized with appropriate reactions. Molecular modeling techniques were used to design and optimize the candidates for TYK2 inhibition and to determine the estimated binding orientations of them inside JAKs. Designed compounds potently inhibited TYK2 with good selectivity against other JAKs as determined by in vitro assays. In order to verify its selectivity properties, compound A8 was tested against 58 human kinases (KinaseProfiler™ assay). The effects of the selected seven compounds on the protein levels of members of the JAK/STAT family were also detected in THP-1 monocytes although the basal level of these proteins is poorly detectable. Therefore, their expression was induced by lipopolysaccharide treatment and compounds A8, A15, A18, and A19 were found to be potent inhibitors of the TYK2 enzyme, (9.7 nM, 6.0 nM, 5.0 nM and 10.3 nM, respectively), and have high selectivity index for the JAK1, JAK2, and JAK3 enzymes. These findings suggest that triazolo[1,5-a]pyrimidinone derivatives may be lead compounds for developing potent TYK2-selective inhibitors targeting enzymes' active site.

Novel Triazole-Containing "Dipeptides": Synthesis, Molecular Docking and Analgesic Activity Studies

Dipeptides of a new structure based on β-triazolalanines and (L)-α-amino acids were synthesized and optimal conditions were developed that ensure both chemical and optical purity of the final products. Molecular docking was carried out and possible intermolecular interactions of dipeptides with potential targets were established. Based on these studies, the analgesic property of chosen dipeptides was studied and it was found that some compounds possess revealed antinociceptive activity in the tail-flick test.

Triazole derivatives as potential xanthine oxidase inhibitors: Design, enzyme inhibition potential, and docking studies

Considerable ingenuity has been shown in the recent years in the discovery of novel xanthine oxidase (XO) inhibitors that fall outside the purine scaffold. The triazole nucleus has been the cornerstone for the development of many enzyme inhibitors for the clinical management of several diseases, where hyperuricemia is one of them. Here, we give a critical overview of significant research on triazole-based XO inhibitors, with respect to their design, synthesis, inhibition potential, toxicity, and docking studies, done till now. Based on these literature findings, we can expect a burst of modifications on triazole-based scaffolds in the near future by targeting XO, which will treat hyperuricemics, that is, painful conditions like gout that at present are hard to deal with.

Hybridization of the effective pharmacophores for treatment of epilepsy: design, synthesis, in vivo anticonvulsant activity, and in silico studies of phenoxyphenyl-1,3,4-oxadiazole-thio-N-phenylacetamid hybrids

BACKGROUND

Epilepsy is a common neurological disorder. The available drugs for this disease only control convulsions in nearly 70% of patients, while bearing many side effects. In this study, a new series of phenoxyphenyl-1,3,4-oxadiazole-thio-N-phenylacetamid hybrids 8a-m was designed, synthesized, and evaluated as potent anticonvulsant agents.

METHODS

Phenoxyphenyl-1,3,4-oxadiazole-thio-N-phenylacetamid derivatives 8a-m were synthesized with well-known chemical reactions and anticonvulsant activity of them was determined by pentylenetetrazole (PTZ) and maximal electroshock (MES) induced seizures in mice. Phenoxyphenyl-1,3,4-oxadiazole-thio-N-phenylacetamid scaffold has the necessary pharmacophores to be a benzodiazepine (BZD) receptor agonist, thus, the most potent anticonvulsant compounds were assayed in vivo and in silico as BZD receptor agonist. Furthermore, in vivo neurotoxicity evaluation and in silico physicochemical, pharmacokinetic, and toxicity study on the most potent compounds were also performed.

RESULTS

Obtained results demonstrated that two compounds among the title new compounds have anticonvulsant activity in PTZ test while all of the new compounds are active in the MES test. The best anticonvulsant activities were obtained with nitro derivatives 8k and 8L. In vivo evaluation of flumazenil effect (a BZD receptor antagonist) on anticonvulsant activity of compound 8k confirmed that this compound is a BZD receptor agonist. The most potent compounds 8k and 8L interacted with the important residues of BZD-binding site of GABA_A receptor. Furthermore, neurotoxicity of the latter compounds was lower than positive control diazepam.

CONCLUSION

According to these results, our designed scaffold can be a valuable lead structure for further structural developments and assessments to obtain a new potent anticonvulsant agent.

Novel spiro[indene-1,2'-quinazolin]-4'(3'H)-one derivatives as potent anticonvulsant agents: One-pot synthesis, in vivo biological evaluation, and molecular docking studies

A new series of spiro[indene-1,2'-quinazolin]-4'(3'H)-one derivatives 4a-m were synthesized via a one-pot method and evaluated for anticonvulsant activities using pentylenetetrazole (PTZ) and maximal electroshock (MES)-induced seizures. Obtained results demonstrated that these compounds have not anticonvulsant activity in PTZ test while are active in the MES test. Among the synthesized compounds, the best anticonvulsant activity was obtained with compound 4h. This compound also was not neurotoxic. Given that the title new compounds have the pharmacophore requirement for benzodiazepine (BZD) receptor agonist, the most potent compound was assayed in vivo and in silico as BZD receptor agonist. After treatment with flumazenil as a standard BZD receptor antagonist, anticonvulsant activity of compound 4h decreased. Therefore, the involvement of BZD receptors in anticonvulsant activity of this compound confirmed. Furthermore, docking study of compound 4h in the BZD-binding site of GABA_A receptor confirmed that this compound interacted with the important residues.

Insights into the molecular mechanism of triazolopyrimidinone derivatives effects on the modulation of α1β2γ2 subtype of GABAA receptor: An in silico approach

Due to the importance of benzodiazepine drugs in clinical practice, such as the treatment of anxiety disorders, depression, and insomnia and the side effects of classical benzodiazepines, the study of new benzodiazepine agonists has received much attentions. In this work, we used in silico methods to explore the molecular mechanism of 1,2,4-triazolo [1,5--a] pyrimidinone derivatives in the modulation of α₁β₂γ₂ subtype of GABA_A receptor. To this aim, molecular docking, molecular dynamics simulation (MD), post-MD analysis, binding free energy calculation, and prediction of ADME properties were performed. Results showed that all new compounds have a better binding affinity for the Benzodiazepine (BZD) site of the receptor than diazepam and compound 4c had the highest affinity among them. Moreover, a good agreement was observed between the calculated ΔG_binding and experimental IC₅₀ values. Also, we noticed that residues in loop regions (particularly loop C and D-F in α₁ and γ₂ subunits, respectively) forming BZD binding site, take part in forming several H-bonds between the agonists and the receptor. Ser205, Thr207, Tyr160, and His102 of α₁ subunit and Thr207 of γ₂ subunit are mainly involved in forming H-bonds. Also, the orientation of agonists in the BZD binding site leads to π-π interactions with hydrophobic residues in loops A-F. Based on the DCCM analysis, the correlated motions in the γ₂ subunit residues are greater than those of α₁ subunit residues. Further, predicted ADME results indicated that all agonists meet the criteria. The triplicate MD simulation showed the reproducibility of the results and strengthened the study. Our results provide a comprehensive insight into the receptor-agonist interactions and clues for designing future BZD agonists.

Recent Developments in the Synthesis of Bicyclic Condensed Pyrimidinones

Abstract:

Functionalized bicyclic pyrimidinones and their derivatives are significant heterocyclic scaffolds being their all-around prevalence in biologically potent compounds. In several attempts to explore the different synthetic methodologies for the construction of bicyclic condensed pyrimidinones, different researchers from all across the globe have reported numerous substantial methods. In the present review, considerable work has been critically compiled on the synthesis of substituted and functionalized bicyclic pyrimidinones from 2000 onwards.

Discovery of 7-alkyloxy- [1,2,4] triazolo[1,5-a] pyrimidine derivatives as selective positive modulators of GABAA1 and GABAA4 receptors with potent antiepileptic activity

A series of 7-alkoxy - [1,2,4] triazolo [1, 5-a] pyrimidine derivatives were designed and synthesized. Maximal electroshock (MES) and pentylenetetrazole (PTZ) tests were utilized to access their anticonvulsant activity. Most of the series of compounds exhibited significant anti-seizure effects. Further studies demonstrated that the anticonvulsant activity of these compounds mainly depended on their allosteric potentiation of GABA_A receptors. Among them, compound 10c was picked for the mechanism study due to its potent activity. The compound is more sensitive to subunit configurations of synaptic α1β2γ2 and extrasynaptic α4β3δ GABA_A receptors, but there were no effects on NMDA receptors and Nav1.2 sodium channels. Meanwhile, 10c acted on the sites of GABA_A receptors distinct from commonly used anticonvulsants benzodiazepines and barbiturates. Furthermore, studies from native neurons demonstrated that compound 10c also potentiated the activity of native GABA_A receptors and reduced action potential firings in cultured cortical neurons. Such structural compounds may lay a foundation for further designing novel antiepileptic molecules.

Triazolopyrimidine Nuclei: Privileged Scaffolds for Developing Antiviral Agents with a Proper Pharmacokinetic Profile

Viruses are a continuing threat to global health. The lack or limited therapeutic armamentarium against some viral infections and increasing drug resistance issues make the search for new antiviral agents urgent. In recent years, a growing literature highlighted the use of triazolopyrimidine (TZP) heterocycles in the development of antiviral agents, with numerous compounds that showed potent antiviral activities against different RNA and DNA viruses. TZP core represents a privileged scaffold for achieving biologically active molecules, thanks to: i) the synthetic feasibility that allows to variously functionalize TZPs in the different positions of the nucleus, ii) the ability of TZP core to establish multiple interactions with the molecular target, and iii) its favorable pharmacokinetic properties. In the present review, after mentioning selected examples of TZP-based compounds with varied biological activities, we will focus on those antivirals that appeared in the literature in the last 10 years. Approaches used for their identification, the hit-to-lead studies, and the emerged structure-activity relationship will be described. A mention of the synthetic methodologies to prepare TZP nuclei will also be given. In addition, their mechanism of action, the binding mode within the biological target, and pharmacokinetic properties will be analyzed, highlighting the strengths and weaknesses of compounds based on the TZP scaffold, which is increasingly used in medicinal chemistry.

Synthesis of 4,6-diphenylpyrimidin-2-ol derivatives as new benzodiazepine receptor ligands

Benzodiazepines (BZDs) have been widely used in neurological disorders such as insomnia, anxiety, and epilepsy. The use of classical BZDs, e.g., diazepam, has been limited due to adverse effects such as interaction with alcohol, ataxia, amnesia, psychological and physical dependence, and tolerance. In the quest for new benzodiazepine agonists with more selectivity and low adverse effects, novel derivatives of 4,6-diphenylpyrimidin-2-ol were designed, synthesized, and evaluated. In this series, compound 2, 4-(2-(benzyloxy)phenyl)-6-(4-fluorophenyl)pyrimidin-2-ol, was the most potent analogue in radioligand binding assay with an IC₅₀ value of 19 nM compared to zolpidem (IC₅₀ = 48 nM), a nonbenzodiazepine central BZD receptor (CBR) agonist. Some compounds with a variety of affinities in radioligand receptor binding assay were selected for in vivo evaluations. Compound 3 (IC₅₀ = 25 nM), which possessed chlorine instead of fluorine in position 4 of the phenyl ring, exhibited an excellent ED₅₀ value in most in vivo tests. Proper sedative-hypnotic effects, potent anticonvulsant activity, appropriate antianxiety effect, and no memory impairment probably served compound 3, a desirable candidate as a benzodiazepine agonist. The pharmacological effects of compound 3 were antagonized by flumazenil, a selective BZD receptor antagonist, confirming the BZD receptors' involvement in the biological effects of the novel ligand.

Rational approaches for the design of various GABA modulators and their clinical progression

GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role in the etiology of several neurological disorders including epilepsy, Alzheimer's disease, Huntington's chorea, migraine, Parkinson's disease, neuropathic pain, and depression. Increase in the GABAergic activity may be achieved through direct agonism at the GABAA receptors, inhibition of enzymatic breakdown of GABA, or by inhibition of the GABA transport proteins (GATs). These functionalities make GABA receptor modulators and GATs attractive drug targets in brain disorders associated with decreased GABA activity. There have been several reports of development of GABA modulators (GABA receptors, GABA transporters, and GABAergic enzyme inhibitors) in the past decade. Therefore, the focus of the present review is to provide an overview on various design strategies and synthetic approaches toward developing GABA modulators. Furthermore, mechanistic insights, structure-activity relationships, and molecular modeling inputs for the biologically active derivatives have also been discussed. Summary of the advances made over the past few years in the clinical translation and development of GABA receptor modulators is also provided. This compilation will be of great interest to the researchers working in the field of neuroscience. From the light of detailed literature, it can be concluded that numerous molecules have displayed significant results and their promising potential, clearly placing them ahead as potential future drug candidates.

Design, synthesis, and preliminary pharmacological evaluation of novel thiazolidinone derivatives as potential benzodiazepine agonists

Thiazolidinones are well-known heterocycles that demonstrate promising biological effects such as anticonvulsant activity. Hybridization of these chemicals with scaffold, which has necessary pharmacophores for binding to the benzodiazepine receptors, can prompt a novel structure possessing extensive anticonvulsant effects. In this study, novel derivatives of thiazolidinone as new benzodiazepine agonists were designed, synthesized, and biologically evaluated. Compound 5h, 4-chloro-2-(2-fluorophenoxy)-N-(4-oxo-2-(p-tolyl)thiazolidin-3-yl)benzamide, exhibited considerable anticonvulsant activity, proper sedative-hypnotic effect, no memory impairment, and no muscle relaxant effect. The pharmacological effects of the designed compounds were antagonized by flumazenil, which confirmed the benzodiazepine receptors' involvement in their biological effects. Based on in silico calculations of ADME properties of our novel compounds, they could be active oral agents potentially. In this study, we designed novel structures by the hybridization of thiazolidinone moiety with scaffold which has necessary pharmacophores for binding to the benzodiazepine receptors. The results are very promising for developing new lead compounds as benzodiazepine agonists possess anticonvulsant effects.

An insight on medicinal attributes of 1,2,4-triazoles

The present review aims to summarize the pharmacological profile of 1,2,4-triazole, one of the emerging privileged scaffold, as antifungal, antibacterial, anticancer, anticonvulsant, antituberculosis, antiviral, antiparasitic, analgesic and anti-inflammatory agents, etc. along with structure-activity relationship. The comprehensive compilation of work carried out in the last decade on 1,2,4-triazole nucleus will provide inevitable scope for researchers for the advancement of novel potential drug candidates having better efficacy and selectivity.

Synthesis of 3,4-dihydroquinolin-2(1H)-one derivatives with anticonvulsant activity and their binding to the GABAA receptor

In this study, a series of 3,4-dihydroquinolin-2(1H)-one derivatives were designed and synthesized using two experimental models, namely maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ), to test the anticonvulsant activity of the target compound in vivo (i.p. in Kunming mice). The neurotoxicity (NT) of the target compound was measured by the rotating rod method (i.p. in Kunming mice). Six compounds with potential activity were selected from the two experimental models to test the 50% effective dose (ED₅₀). In vitro binding experiments with the GABA_A receptor were also performed. The results of the pharmacological experiments showed that compound 7-((5-(pentylthio)-1,3,4-oxadiazol-2-yl)methoxy)-3,4-dihydroquinolin-2(1H)-one (5b) showed the best anticonvulsant activity (MES, ED₅₀ = 10.1 mg/kg; scPTZ, ED₅₀ = 9.3 mg/kg), which was superior to activities shown by carbamazepine and ethosuximide, and it also exhibited the most potent binding affinity to GABA_A receptors (IC₅₀ = 0.12 μM). The GABA content in Wistar rat brains (i.p.) was also investigated, and the results showed that compound 5b may have a certain effect on the GABA system, as it increased the GABA concentration in the brain of rats. Molecular docking was used to study the binding mode of compound 5b and the GABA_A receptor. Compound 5b showed significant interactions with residues at the benzodiazepines binding site on the GABA_A receptor. The physicochemical and pharmacokinetic properties of the target compounds were predicted using Discovery Studio 2019 and ChemBioDraw Ultra 14.0.

Synthesis of 1,3,4-oxadiazole derivatives with anticonvulsant activity and their binding to the GABAA receptor

In this study, a series of 1,3,4-oxadiazole derivatives (5a-s, 10a-s, and 16a-d) were designed and synthesized using maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) models, to test the anticonvulsant activity of the target compounds in vivo. The neurotoxicity (NT) of the target compounds was measured using the rotating rod (ROT) method. Seven compounds with potential activity were selected to test the 50% effective dose (ED₅₀) and 50% toxic dose (TD₅₀). Pharmacological experiments revealed that 6-((5-(pentylthio)-1,3,4-oxadiazol-2-yl)methoxy)-3,4-dihydroquinolin-2(1H)-one (5b) showed the best anticonvulsant activity (MES, ED₅₀ = 8.9 mg/kg; scPTZ, ED₅₀ = 10.2 mg/kg), which was greater than the activities of carbamazepine and ethosuximide. Compound 5b exhibited the most potent binding affinity toward the GABA_A receptor (IC₅₀ = 0.11 μM) in the in vitro binding experiments. Compound 5b displayed significant anxiolytic activity at a low dose (1 mg/kg) in the elevated plus maze (EPM) test. The GABA content in rat brains was also investigated, and the results showed that compound 5b might have affected the GABA system. In our molecular docking experiment, compound 5b showed significant interactions with residues present at the benzodiazepine binding site on the GABA_A receptor. The structure and physicochemical and pharmacokinetic properties of the target compound were predicted using Discovery Studio 2019 and ChemBioDraw Ultra 14.0. Finally we demonstrated that compound 5b mainly acted on GABA_A receptor. Thus the present study has provided potential candidates for further investigation in epilepsy.

An In-Vivo Study on Anticonvulsant, Anxiolytic, and Sedative-Hypnotic Effects of the Polyphenol-Rich Thymus Kotschyanus Extract; Evidence for the Involvement of GABAA Receptors

Antidepressant-like activity of T. kotschyanus has been recently reported by scientists but insufficient attention has been so far devoted to T. kotschyanus, and there is a lack of information on the other neurobehavioral effects and side effects of this species. In the current study, the anticonvulsant, anxiolytic, and sedative-hypnotic, effects of Thymus kotschyanus extract on male NMRI mice were evaluated using pentylenetetrazole, maximal electroshock, elevated plus maze, and pentobarbital-induced sleeping tests. Since phenolic compounds and flavonoids have main roles in pharmacological effects of most plant extracts, the phenolic and flavonoid contents of the extract were measured with Folin-Ciocalteu and AlCl₃ reagents. Acute toxicity, passive avoidance, and open field tests were carried out to assess the toxicity of the extract. To find out the possible mechanism of action, flumazenil as the specific GABA_A receptor antagonist was used. Anticonvulsant and hypnotic effects of the extract were observed at 400 and 600 mg/kg. The extract at the dose of 200 mg/kg revealed significant anxiolytic effects, but it did not show any adverse effects on learning and memory at all the tested doses. Results of this study indicate that Thymus kotschyanus extract has anticonvulsant‎, anxiolytic, and hypnotic effects, which are likely related to the ability of some phenolic compounds to activate α1-containing GABA_A receptors but more experiments still need to be carried out in order to find the exact mechanism, active component, and the toxicity of the Thymus kotschyanus extract.

Synthesis, Antibacterial Activity and Molecular Docking Studies of New Pyrazole Derivatives

Background:

The pyrazole structure is an important heterocyclic structure and plays critical roles in agriculture, industrial and medicine. Furthermore, compounds containing pyrazole are known to exhibit various biological properties such as antibacterial, antifungal, anticancer, antiinflammatory, antidepressant, antipyretic, antiviral, anti-tubercular and anti-HIV activities. Because of these properties, pyrazole molecules have become a very popular topic for organic chemists.

Methods:

A series newly substituted pyrazole molecules were synthesized and characterized. Their antimicrobial activities were investigated by disk diffusion method against some gram positive bacteria and gram negative bacteria.

Results:

The present results indicated that the some test compounds were active in a broad spectrum against important human pathogenic microorganisms. The substituted pyrazoles including carbazone (7a, b) and thiazolidine (8a, b) showed a wide variety of biological activities. The results showed that synthesized pyrazole, compounds 7b and 8b are highly active and more potent in both biological and molecular docking simulation studies.

Conclusion:

The synthesized pyrazole molecules showed moderate antibacterial activities against the tested microorganism compared to antibiotic drug. Some test compounds (7b and 8b) might be used as new antibacterial agents.

Synthesis, structure and biological evaluation of ruthenium(III) complexes of triazolopyrimidines with anticancer properties

Six novel ruthenium(III) complexes of general formula [RuCl₃(L)₃] (1,3,5) and [RuCl₃(H₂O)(L)₂] (2,4,6), where L stands for three different triazolopyrimidine-derived ligands, are reported. The compounds have been structurally characterized (IR, EPR, SCXRD), and their magnetic moments have been determined. The single-crystal X-ray diffraction study revealed a slightly distorted octahedral geometry of the Ru(III) complexes with mer configuration in 1 and 5, and fac configuration in 3. In 2 and 4, three chloride ions are in mer configuration and the two triazolopyrimidines are oriented trans mutually with the water molecule playing the role of the sixth ligand. All complexes have been thoroughly screened for their in vitro cytotoxicity against human breast cancer cell line MCF-7, human cervical cancer cell line HeLa, and L929 murine fibroblast cells, uncovering among others that the most lipophilic complexes 5 and 6, containing the bulky ligand dptp (5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine), display high cytotoxic activity against MCF-7, and HeLa cells. Moreover, it was also revealed that during the interaction of the complexes 1-6 with the cancer MCF-7 cell line, reactive oxygen species are released intracellularly, which could indicate that they are involved in cell apoptosis. Furthermore, extensive studies have been carried out to reveal the mechanism by which complexes 1-6 interact with DNA, albumin, and apotransferrin. The biological studies were complemented by detailed kinetic studies of the hydrolysis of the complexes in the pH range 5-8, to determine the stability of the complexes in solution. Six novel ruthenium(III) complexes with triazolopyrimidine derivatives demonstrated the potential for use as anticancer agents by maintaining the toxic effect on MCF-7 and HeLa cells.

Design, synthesis, and evaluation of anticonvulsant activities of benzoxazole derivatives containing the 1,2,4-triazolone moiety

A novel series of benzoxazole derivatives containing 1,2,4-triazolone (5a-m) was designed. These compounds were synthesized in order to screen their anticonvulsant activities by the maximal electroshock seizure (MES) model and the subcutaneous pentylenetetrazole (sc-PTZ) seizure model in mice. The rotarod test was used to evaluate their neurotoxicities. Most of the compounds showed anti-MES activities at 100 and 300 mg/kg. Compound 5f, which showed potential anticonvulsant activity in the MES model with ED₅₀ values of 22.0 mg/kg, was considered as the most promising one in this study. It exhibited greater safety than that of carbamazepine and valproate regarding neurotoxicity. The efficacy of compound 5f in inhibiting the tonic seizures and death induced by the convulsants 3-mercaptopropionic acid and BIC was also verified. In an enzyme-linked immunosorbent assay, compound 5f and the positive drug phenytoin significantly increased the γ-aminobutyric acid (GABA) level in the mouse brain. Further, pretreatment with an inhibitor of the GABA synthesizing enzyme dramatically raised the ED₅₀ value of 5f in the MES model. These results confirmed that the compound 5f plays its anticonvulsive action via regulating the GABA function in the brain. Also, a docking study of the compound 5f in the benzodiazepine (BZD) binding site of the GABA_A receptor confirmed possible binding of the compound 5f with BZD receptors.

Design, synthesis, in vivo, and in silico evaluation of new coumarin-1,2,4-oxadiazole hybrids as anticonvulsant agents

A novel series of coumarin-1,2,4-oxadiazole hybrids were designed, synthesized, and evaluated as anticonvulsant agents. The title compounds were easily synthesized from reaction of appropriate coumarins and 3-aryl-5-(chloromethyl)-1,2,4-oxadiazole derivatives. In vivo anticonvulsant activity of the synthesized compounds were determined using pentylenetetrazole (PTZ)- and maximal electroshock (MES)-induced seizures confirming that they were more effective against MES test than PTZ test. It should be noted that compounds 3b, 3c, and 3e showed the best activity in MES model which possessed drug-like properties with no neurotoxicity. Anticonvulsant activity of the most potent compound 3b was remarkably reduced after treatment with flumazenil which confirmed the participation of a benzodiazepine mechanism in the anticonvulsant activity. Also, docking study of compound 3b in the BZD-binding site of GABA_A receptor confirmed possible binding of 3b to the BZD receptors.

Recent developments on triazole nucleus in anticonvulsant compounds: a review

Epilepsy is one of the common diseases seriously threatening life and health of human. More than 50 million people are suffering from this condition and anticonvulsant agents are the main treatment. However, side effects and intolerance, and a lack of efficacy limit the application of the current anticonvulsant agents. The search for new anticonvulsant agents with higher efficacy and lower toxicity continues to be the focus and task in medicinal chemistry. Numbers of triazole derivatives as clinical drugs or candidates have been frequently employed for the treatment of various types of diseases, which have proved the importance of this heterocyclic nucleus in drug design and discovery. Recently many endeavours were made to involve the triazole into the anticonvulsants design, which have brought lots of active compounds. This work is an attempt to systematically review the research of triazole derivatives in the design and development of anticonvulsant agents during the past two decades.

Strategies for overcoming tropical disease by ruthenium complexes with purine analog: Application against Leishmania spp. and Trypanosoma cruzi

Tropical diseases currently constitute a major health problem and thus a challenge in the field of drug discovery. The current treatments show serious disadvantages due to cost, toxicity, long therapy duration and resistance, and the use of metal complexes as chemotherapeutic agents against these ailments appears to be a very attractive alternative. Herein, we describe three newly synthesized ruthenium complexes with a bioactive molecule, the purine analogue 5,6,7-trimethyl-1,2,4-triazolo[1,5-a]pyrimidine (tmtp): cis,fac-[RuCl₂(dmso)₃(tmtp)] (1), mer-[RuCl₃(dmso)(H₂O)(tmtp)]·2H₂O (2) and fac,cis-[RuCl₃(H₂O)(tmtp)₂] (3). Their structures were characterized using X-ray and spectroscopic methods (IR, NMR or EPR). The stability of the synthesized complexes 1-3 in various buffered solutions (pH=3-7.4) was monitored using conventional and stopped-flow techniques. The in vitro antiproliferative activity of all ruthenium complexes against promastigote forms of Leishmania spp. (L. infantum, L. braziliensis, and L. donovani) and epimastigote forms of Trypanosoma cruzi was investigated. Notably, the results showed that the activity of 1 against L. brasiliensis was more than three-fold higher than that of glucantime, and 1 showed no appreciable toxicity towards J774.2 macrophages. Additionally, 2 displayed even 141-fold lower toxicity against host cells than glucantime, demonstrating significantly higher selectivity than the reference drug. Therefore, 1 and 2 appear to be excellent candidates for further development as potential drugs for the effective treatment of leishmaniasis and Chagas disease. All novel complexes were also shown to be potent inhibitors of Fe-SOD in the studied species, while their effects on human CuZn-SOD were very low.

Synthesis, Physico-chemical Characterization, Crystal Structure and Influence on Microbial and Tumor Cells of Some Co(II) Complexes with 5,7-Dimethyl-1,2,4-triazolo[1,5-a]pyrimidine

Three complexes, namely [Co(dmtp)₂(OH₂)₄][CoCl₄] (1), [Co(dmtp)₂Cl₂] (2) and [Co(dmtp)₂(OH₂)₄]Cl₂∙2H₂O (3) (dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine), were synthesized and characterized by spectral (IR, UV-Vis-NIR), and magnetic measurements at room temperature, as well as single crystal X-ray diffraction. Complex (1) crystallizes in monoclinic system (space group C2/c), complex (2) adopts an orthorhombic system (space group Pbca), and complex (3) crystallizes in triclinic system (space group P1). Various types of extended hydrogen bonds and π-π interactions provide a supramolecular architecture for all complexes. All species were evaluated for antimicrobial activity towards planktonic and biofilm-embedded microbial cells and influence on HEp-2 cell viability, cellular cycle and gene expression.

Novel 4-thiazolidinone derivatives as agonists of benzodiazepine receptors: Design, synthesis and pharmacological evaluation

A new series of 4-chloro-N-(2-(substitutedphenyl)-4-oxothiazolidin-3-yl)-2-phenoxybenzamide derivatives were designed, synthesized and biologically evaluated as anticonvulsant agents. The designed compounds have the main essential functional groups for binding to the benzodiazepine receptors and 4-thiazolidinone ring as an anticonvulsant pharmacophore. Some of the new synthesized compounds showed considerable anticonvulsant activity in electroshock and pentylenetetrazole-induced lethal convulsion tests. Compound 5i, 4-chloro-N-(2-(4-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-phenoxybenzamide, with the best activity was selected for evaluation of other benzodiazepine pharmacological effects. This compound induced significant sedative-hypnotic activity. However, it does not impair the learning and memory in the experimental condition. Flumazenil was able to antagonize the sedative-hypnotic and anticonvulsant effects of compound 5i indicating that benzodiazepine receptors are highly involved in the pharmacological properties of the novel compounds.

Efficient and regioselective one-step synthesis of 7-aryl-5-methyl- and 5-aryl-7-methyl-2-amino-[1,2,4]triazolo[1,5-a]pyrimidine derivatives

Two facile and efficient one-step procedures for the regioselective synthesis of 7-aryl-5-methyl- and 5-aryl-7-methyl-2-amino-[1,2,4]triazolo[1,5-a]pyrimidines.

The importance of triazole scaffold in the development of anticonvulsant agents

Epilepsy is one of the most important neurological disorders with high prevalence worldwide. Many epileptic patients are not completely treated with available drugs and need multiple therapies. Also, many antiepileptic drugs have shown unwanted side effects and drug interactions. Therefore there are continuing interests to find new anticonvulsant drugs. Triazole ring has been found in the structure of many compounds with diverse biological effects. Due to the success of several triazole-containing drugs that entered the pharmaceutical market as CNS-active drugs, this class of heterocyclic compounds has great importance for discovery and development of new anticonvulsant drugs. In this article, we have tried to summarize the latest efforts which have been made in the design and development of triazole-derived anticonvulsant agents.

Copper supported β-cyclodextrin grafted magnetic nanoparticles as an efficient recyclable catalyst for one-pot synthesis of 1-benzyl-1H-1,2,3-triazoldibenzodiazepinone derivatives via click reaction

Cu immobilized into β-cyclodextrin covalently attached to magnetic nanoparticles (denoted as [Cu@β-CD@SPIONs]) is reported as an efficient and recoverable catalyst for “click” and multicomponent reactions.

The Y137H mutation of VvCYP51 gene confers the reduced sensitivity to tebuconazole in Villosiclava virens

Management of rice false smut disease caused by Villosiclava virens is dependent on demethylation inhibitor (DMI) fungicides. Investigation of molecular mechanisms of resistance is therefore of upmost importance. In this study the gene encoding the target protein for DMI fungicides (VvCYP51) was cloned and investigated. The VvCYP51 gene in the resistant mutant revealed both a change from tyrosine to histidine at position 137 (Y137H) and elevated gene expression compared to the parental isolate. In order to determine which of these mechanisms was responsible for the reduced sensitivity to DMI fungicide tebuconazole, transformants expressing the mutated or the wild type VvCYP51 gene were generated. Transformants carrying the mutated gene were more resistant to tebuconazole compared to control transformants lacking the mutation, but the expression of the VvCYP51 gene was not significantly correlated with EC50 values. The wild type VvCYP51 protein exhibited stronger affinity for tebuconazole compared to the VvCYP51/Y137H in both molecular docking analysis and experimental binding assays. The UV-generated mutant as well as transformants expressing the VvCYP51/Y137H did not exhibit significant fitness penalties based on mycelial growth and spore germination, suggesting that isolates resistant to DMI fungicides based on the Y137H mutation may develop and be competitive in the field.