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

Neuroprotective Effect of Brivaracetam and Perampanel Combination on Electrographic Seizures and Behavior Anomalies in Pentylenetetrazole-Kindled Mice

Pentylenetetrazole (PTZ)-induced kindling is a broadly used experimental model to study the anticonvulsive potential of new and existing chemical moieties with the aim of discovering drugs hindering seizure progression and associated neurological comorbidities. In the present study, the impact of brivaracetam (BRV) (10 and 20 mg/kg) as monotherapy as well as in combination with 0.25 mg/kg of perampanel (PRP) was investigated on seizure progression with simultaneous electroencephalographic changes in PTZ kindling mouse model. Subsequently, mice were experimentally analyzed for anxiety, cognition, and depression after which their brains were biochemically evaluated for oxidative stress. The outcomes demonstrated that BRV alone delayed the kindling process, but BRV + PRP combination significantly (p < 0.0001) protected the mice from seizures of higher severity and demonstrated an antikindling effect. The PTZ-kindled mice exhibited anxiety, memory impairment, and depression in behavioral tests, which were remarkably less (p < 0.001) in animals treated with drug combination (in a dose-dependent manner) as these mice explored central, illuminated, and exposed zones of open-field test, light/dark box, and elevated plus maze. Moreover, memory impairment was demonstrated by kindled mice, which was significantly (p < 0.001) protected by BRV + PRP as animal's spontaneous alteration, object discrimination, and step-through latencies were increased in various tests employed for the assessment of cognitive abilities. The brains of PTZ-kindled mice had increased malondialdehyde and reduced antioxidant enzymes while treatment with BRV + PRP combination prevented kindling-induced elevation in oxidative markers. The outcomes of this study demonstrate that combining the PRP at low dose augmented the antiseizure properties of BRV as both drugs when administered simultaneously hindered the process of kindling by reducing PTZ-induced excessive electrical activity and oxidative stress in the brain.

Ultrasonic-Assisted Synthesis of Heterocyclic Curcumin Analogs as Antidiabetic, Antibacterial, and Antioxidant Agents Combined with in vitro and in silico Studies

Background

Heterocyclic analogs of curcumin have a wide range of therapeutic potential and the ability to control the activity of a variety of metabolic enzymes.

Methods

1H-NMR and 13C-NMR spectroscopic techniques were used to determine the structures of synthesized compounds. The agar disc diffusion method and α-amylase inhibition assay were used to examine the antibacterial and anti-diabetic potential of the compounds against α-amylase enzyme inhibitory activity, respectively. DPPH-free radical scavenging and lipid peroxidation inhibition assays were used to assess the in vitro antioxidant potential.

Results and Discussion

In this work, nine heterocyclic analogs derived from curcumin precursors under ultrasonic irradiation were synthesized in excellent yields (81.4-93.7%) with improved reaction time. Results of antibacterial activities revealed that compounds 8, and 11 displayed mean inhibition zone of 13.00±0.57, and 19.66±00 mm, respectively, compared to amoxicillin (12.87±1.41 mm) at 500 μg/mL against E. coli, while compounds 8, 11 and 16 displayed mean inhibition zone of 17.67±0.57, 14.33±0.57 and 23.33±00 mm, respectively, compared to amoxicillin (13.75±1.83 mm) at 500 μg/mL against P. aeruginosa. Compound 11 displayed a mean inhibition zone of 11.33±0.57 mm compared to amoxicillin (10.75±1.83 mm) at 500 μg/mL against S. aureus. Compound 11 displayed higher binding affinities of -7.5 and -8.3 Kcal/mol with penicillin-binding proteins (PBPs) and β-lactamases producing bacterial strains, compared to amoxicillin (-7.2 and -7.9 Kcal/mol, respectively), these results are in good agreement with the in vitro antibacterial activities. In vitro antidiabetic potential on α-amylase enzyme revealed that compounds 11 (IC50=7.59 µg/mL) and 16 (IC50=4.08 µg/mL) have higher inhibitory activities than acarbose (IC50=8.0 µg/mL). Compound 8 showed promising antioxidant inhibition efficacy of DPPH (IC50 = 2.44 g/mL) compared to ascorbic acid (IC50=1.24 g/mL), while compound 16 revealed 89.9±20.42% inhibition of peroxide generation showing its potential in reducing the development of lipid peroxides. In silico molecular docking analysis, results are in good agreement with in vitro biological activity. In silico ADMET profiles suggested the adequate oral drug-likeness potential of the compounds without adverse effects.

Conclusion

According to our findings, both biological activities and in silico computational studies results demonstrated that compounds 8, 11, and 16 are promising α-amylase inhibitors and antibacterial agents against E. coli, P. aeruginosa, and S. aureus, whereas compound 8 was found to be a promising antioxidant agent.

QSAR and molecular docking studies of isatin and indole derivatives as SARS 3CLpro inhibitors

The 3C-like protease (3CL^pro), known as the main protease of SARS-COV, plays a vital role in the viral replication cycle and is a critical target for the development of SARS inhibitor. Comparative sequence analysis has shown that the 3CL^pro of two coronaviruses, SARS-CoV-2 and SARS-CoV, show high structural similarity, and several common features are shared among the substrates of 3CL^pro in different coronaviruses. The goal of this study is the development of validated QSAR models by CORAL software and Monte Carlo optimization to predict the inhibitory activity of 81 isatin and indole-based compounds against SARS CoV 3CL^pro. The models were built using a newer objective function optimization of this software, known as the index of ideality correlation (IIC), which provides favorable results. The entire set of molecules was randomly divided into four sets including: active training, passive training, calibration and validation sets. The optimal descriptors were selected from the hybrid model by combining SMILES and hydrogen suppressed graph (HSG) based on the objective function. According to the model interpretation results, eight synthesized compounds were extracted and introduced from the ChEMBL database as good SARS CoV 3CL^pro inhibitor. Also, the activity of the introduced molecules further was supported by docking studies using 3CL^pro of both SARS-COV-1 and SARS-COV-2. Based on the results of ADMET and OPE study, compounds CHEMBL4458417 and CHEMBL4565907 both containing an indole scaffold with the positive values of drug-likeness and the highest drug-score can be introduced as selected leads.

Novel 2-substituted-5-(4-chloro-2-phenoxy)phenyl-1,3,4-oxadiazole derivatives, ligands of GABAA/benzodiazepine receptor complex: Design, synthesis, radioligand binding assay, and pharmacological evaluation

Agonists of Benzodiazepine (BZD) receptor are exhaustively used in the control of muscle spasms, seizure, anxiety, and insomnia. BZDs have some unwanted effects; therefore, the development of new BZD receptor agonists with better efficacy and fewer unwanted effects is one of the subjects of interest. In this study, based on the pharmacophore/receptor model of the BZD binding site of GABA_A receptors, a series of new 2-substituted-5-(4-chloro-2-phenoxy)phenyl-1,3,4-oxadiazole derivatives (6a-f) were designed. Energy minima conformers of the designed compounds and diazepam were well matched in conformational analysis and showed proper interaction with the BZD-binding site of the GABA_A receptor model (α1β2ϒ2) in docking studies. The designed compounds were synthesized in acceptable yield and evaluated for their in vitro affinity to the benzodiazepine receptor of rat brains by radioligand receptor binding assay. The results demonstrated that the affinities of most of the novel compounds were even higher than diazepam. The novel compound 6a with the best affinity in radioligand receptor binding assay (K_i=0.44 nM and IC₅₀= 0.73±0.17 nM) had considerable hypnotic activity and weak anticonvulsant and anxiolytic effects with no negative effect on memory in animal models. Flumazenil as a selective benzodiazepine receptor antagonist was able to prevent hypnotic and anticonvulsant effects of 6a indicating the role of BZD receptors in these effects.

Synthesis of new 2-(5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-ylimino)thiazolidin-4-one derivatives as anti-MRSA and anti-H. pylori agents

In this work, we have synthesized twenty five new 2-(5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-ylimino)thiazolidin-4-one derivatives bearing an aryl or heteroaryl methylene group on position 5 of thiazolidinone and evaluated their antimicrobial activity against Gram-positive and -negative bacteria as well as three metronidazole resistant Helicobacter pylori strains. Most of the compounds were very potent towards tested Gram-positive bacteria and showed an antibacterial efficacy substantially greater than ampicillin as the reference drug. However, no effectiveness was observed for the Gram-negative microorganisms. The compounds 9, 20 and 29 exhibited strong antimicrobial activity against Helicobacter pylori strains (inhibition zone > 30 mm) in 100 μg/disc and (inhibition zone > 20 mm) in 50 μg/disc. Taking these findings together, it seems that these potent antibacterial derivatives could be considered as promising agents for developing new anti-infectious drugs against microorganisms resistant to currently available antibiotics.

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 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.

Repurposing Zileuton as a Depression Drug Using an AI and In Vitro Approach

Repurposing drugs to target M1 macrophages inflammatory response in depression constitutes a bright alternative for commonly used antidepressants. Depression is a significant type of mood disorder, where patients suffer from pathological disturbances associated with a proinflammatory M1 macrophage phenotype. Presently, the most commonly used antidepressants such as Zoloft and Citalopram can reduce inflammation, but suffer from dangerous side effects without offering specificity toward macrophages. We employed a new strategy for drug repurposing based on the integration of RNA-seq analysis and text mining using deep neural networks. Our system employs a Google semantic AI universal encoder to compute sentences embedding. Sentences similarity is calculated using a sorting function to identify drug compounds. Then sentence relevance is computed using a custom-built convolution differential network. Our system highlighted the NRF2 pathway as a critical drug target to reprogram M1 macrophage response toward an anti-inflammatory profile (M2). Using our approach, we were also able to predict that lipoxygenase inhibitor drug zileuton could modulate NRF2 pathway in vitro. Taken together, our results indicate that reorienting zileuton usage to modulate M1 macrophages could be a novel and safer therapeutic option for treating depression.

Thiazole-Bearing 4-Thiazolidinones as New Anticonvulsant Agents

Here, we describe the synthesis and anticonvulsant activity of thiazole-bearing hybrids based on 2-imino-4-thiazolidinone and 2,4-dioxothiazolidine-5-carboxylic acid cores. The structure of target compounds was based on the following: (i) A combination of two thiazole cores; (ii) similarity to ralitolin’s structure; (iii) the compliance with structural requirements for the new anticonvulsants. Target compounds were synthesized via known approaches based on Knoenavegel reaction, alkylation reaction, and one-pot three-component reaction. Anticonvulsant properties of compounds were evaluated in two different models—pentylenetetrazole-induced seizures and maximal electroshock seizure tests. Among the tested compounds 5Z-(3-nitrobenzylidene)-2-(thiazol-2-ylimino)-thiazolidin-4-one Ib, 2-[2,4-dioxo-5-(thiazol-2- ylcarbamoylmethyl)-thiazolidin-3-yl]-N-(2-trifluoromethylphenyl)acetamide IId and (2,4-dioxo-5- (thiazol-2-ylcarbamoylmethylene)-thiazolidin-3-yl)acetic acid ethyl ester IIj showed excellent anticonvulsant activity in both models. The directions of compounds modification based on SAR aspects were discussed. The results of the study provide a basis for further study of the anticonvulsant properties of selected thiazole-thiazolidinones.

Saturated Five-Membered Thiazolidines and Their Derivatives: From Synthesis to Biological Applications

In past decades, interdisciplinary research has been of great interest for scholars. Thiazolidine motifs behave as a bridge between organic synthesis and medicinal chemistry and compel researchers to explore new drug candidates. Thiazolidine motifs are very intriguing heterocyclic five-membered moieties present in diverse natural and bioactive compounds having sulfur at the first position and nitrogen at the third position. The presence of sulfur enhances their pharmacological properties, and, therefore, they are used as vehicles in the synthesis of valuable organic combinations. They show varied biological properties viz. anticancer, anticonvulsant, antimicrobial, anti-inflammatory, neuroprotective, antioxidant activity and so on. This diversity in the biological response makes it a highly prized moiety. Based on literature studies, various synthetic approaches like multicomponent reaction, click reaction, nano-catalysis and green chemistry have been employed to improve their selectivity, purity, product yield and pharmacokinetic activity. In this review article, we have summarized systematic approaches for the synthesis of thiazolidine and its derivatives, along with their pharmacological activity, including advantages of green synthesis, atom economy, cleaner reaction profile and catalyst recovery which will help scientists to probe and stimulate the study of these scaffolds.

Neuro-Behavioral Profile and Toxicity of the Essential Oil of Dorema ammoniacum Gum as an Anti-seizure, Anti-nociceptive, and Hypnotic Agent with Memory-enhancing Properties in D-Galactose Induced Aging Mice

In this study, we focused on the neuro-behavioral profile, toxicity, and possible mechanisms of action of Dorema ammoniacum gum essential oil (DAG-EO). For this purpose, passive avoidance and Y-maze tests were performed to evaluate the potential effect of DAG-EO in the attenuation of memory impairment induced by 49 days administration of D-galactose and acute injection of scopolamine. Anticonvulsant and anti-nociceptive activities of DAG-EO were evaluated in the pentylenetetrazole and ‎maximal electroshock-induced models of seizure and acetic acid-induced writhing tests, respectively. To find the possible mechanism of action, flumazenil and naloxone were used. Furthermore, the possible side effects were determined in the open field, grip strength, and ‎rotarod tests. Our findings supported that 7-day administration of DAG-EO (50 and 100 mg/kg) improves memory impairment induced following administration of D-galactose and scopolamine. It was also revealed that DAG-EO possesses a dose-dependent sedative-hypnotic (100 mg/kg), anticonvulsant (ED50 ≈ 170 mg/kg), and anti-nociceptive (ED50 ≈ 175 mg/kg) activities possibly mediated via directly and/or indirectly modulation of GABAA and opioid receptors. No side effect was observed except muscle relaxation which was less than that of diazepam. The output of this study confirms anti-seizure, anti-nociceptive, sedative-hypnotic, and memory-enhancing properties of DAG-EO by modulation of GABAA receptors.

Novel Group of Imidazole Derivatives as Atypical Selective Cyclooxygenase-2 Inhibitors: Design, Synthesis and Biological Evaluation

In this study, a new series of 5-substituted 1-benzyl-2-(methylsulfonyl)-1-H-imidazole with atypical structure-activity relationship was designed, synthesized, and biological evaluated as selective cyclooxygenase-2 inhibitors. Docking studies revealed that although the pharmacophoric substitute of the compound 5b, methylsulfonyl group, has been directly attached to the central ring, it is in the same direction of the sulfonamide group of Celecoxib, a known selective cyclooxygenase-2 inhibitor. Therefore effective hydrogen binding with Arg513 is established. Also, additional hydrogen binding could form between NH of anilino moiety of the 5b and Arg120. All of the compounds had selective inhibitory activity against cyclooxygenase-2 in micromolar concentrations comparable with the reference, Celecoxibe. Finally, compound 5b with the selectivity index 115 and IC₅₀ of 0.71 µM against cyclooxygenase-2 was the most potent one.