New (arylalkyl)azole derivatives showing anticonvulsant effects could have VGSC and/or GABAAR affinity according to molecular modeling studies

New Ester-Containing Azole Derivatives With Potent Anti-Candida Effects: Synthesis, Antifungal Susceptibility, Cytotoxicity, and Molecular Modeling Studies

Mortalities due to mycoses have dramatically increased with the emergence of drug-resistant strains and growing immune-compromised populations globally. Azole antifungals have been the first choice against fungal infections of a wide spectrum and several azole derivatives with ester function were reported for their potentially promising and favorable activity against Candida spp. In this study, we designed and synthesized a series of 1-(aryl)-2-(1H-imidazol-1-yl/1H-1,2,4-triazol-1-yl)ethyl esters, and tested them against seven reference Candida strains using EUCAST reference microdilution method. Among the series, 6a, 6d, and 6g proved highly potent in vitro compared to fluconazole; especially against Candida albicans and Candida tropicalis with minimum inhibitor concentration (MIC) values as low as 0.125 and 0.06 mg/L, respectively, although their activities against Candida krusei and Candida glabrata remained limited. The compounds also showed minimal toxicity to murine fibroblasts according to the in vitro cytotoxicity tests. Molecular modeling predicted 6g as an orally available druglike compound according to all parameters and CYP51 inhibition as the likely mechanism for their antifungal effects. The study underpins the promise of azoles with ester functionality as a potential scaffold for small-molecule antifungal drug design.

Azoles containing naphthalene with activity against Gram-positive bacteria: in vitro studies and in silico predictions for flavohemoglobin inhibition

Azoles are first-line drugs used in fungal infections. Topical antifungals, such as miconazole and econazole, are known to be active against Gram-positive bacteria, which was reported to result from bacterial flavohemoglobin (flavoHb) inhibition. Dual antibacterial/antifungal action is believed to have benefits for antimicrobial chemotherapy. In this study, we tested antibacterial effects of an in-house library of naphthalene-bearing azoles, some of which were reported as potent antifungals, in an attempt to find dual-acting hits. Several potent derivatives were obtained against the Gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus. 9 was active at a minimum inhibitor concentration (MIC) less than 1 µg/ml against E. faecalis and S. aureus, and 10 against S. aureus. 16 was also potent against E. faecalis and S. aureus (MIC = 1 and 2 µg/ml, respectively). Six more were active against S. aureus with MIC ≤ 4 µg/ml. In vitro cytotoxicity studies showed that the active compounds were safe for healthy cells within their MIC ranges. According to the calculated descriptors, the library was found within the drug-like chemical space and free of pan-assay interference compounds (PAINS). Molecular docking studies suggested that the compounds might be bacterial flavohemoglobin (flavoHb) inhibitors and the azole and naphthalene rings were important pharmacophores, which was further supported by pharmacophore modeling study. As a result, the current study presents several non-toxic azole derivatives with antibacterial effects. In addition to their previously reported antifungal properties, they could set a promising starting point for the future design of dual acting antimicrobials. Communicated by Ramaswamy H. Sarma.

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.

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.

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.

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.

p-Trifluoroacetophenone Oxime Ester Derivatives: Synthesis, Antimicrobial and Cytotoxic Evaluation and Molecular Modeling Studies

Background:

Azole antifungals are among the first-line drugs clinically used for the treatment of systemic candidiasis, a deadly type of fungal infection that threatens mostly immunecompromised and hospitalized patients. Some azole derivatives were also reported to have antiproliferative effects on cancer cells.

Objective:

In this study, 1-(4-trifluoromethylphenyl)-2-(1H-imidazol-1-yl)ethanone (3), its oxime (4), and a series of its novel oxime ester derivatives (5a-v) were synthesized and tested for their in vitro antimicrobial activities against certain ATCC standard strains of Candida sp. fungi and bacteria. The compounds were also tested for their cytotoxic effects against mouse fibroblast and human neuroblastoma cell lines. Molecular modeling studies were performed to provide insights into their possible mechanisms for antifungal and antibacterial actions.

Methods:

The compounds were synthesized by the reaction of various oximes with acyl chlorides. Antimicrobial activity of the compounds was determined according to the broth microdilution method. For the determination of cytotoxic effect, we used MTS assay. Molecular docking and QM/MM studies were performed to predict the binding mechanisms of the active compounds in the catalytic site of C. albicans CYP51 (CACYP51) and S. aureus flavohemoglobin (SAFH), the latter of which was created via homology modeling.

Results:

5d, 5l, and 5t showed moderate antifungal activity against C. albicans, while 3, 5c, and 5r showed significant antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Most of the compounds showed approximately 40-50% inhibition against the human neuroblastoma cells at 100 µM. In this line, 3 was the most potent with an IC50 value of 82.18 μM followed by 5a, 5o, and 5t. 3 and 5a were highly selective to the neuroblastoma cells. Molecular modelling results supported the hypothesis that our compounds were inhibitors of CAYP51 and SAFH.

Conclusion:

This study supports that oxime ester derivatives may be used for the development of new antimicrobial and cytotoxic agents.

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.

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

BACKGROUND

Currently available antiepileptic drugs offer limited symptomatic treatment and fail to cure more than 30% of the epileptic seizures. (Arylalkyl)azoles are a class of anticonvulsants including nafimidone and loreclezole. Here, we report the design and synthesis of new (arylalkyl)azoles in N-[1-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethylidene]hydroxylamine ester structure, their anticonvulsant screening and in silico prediction studies of their pharmacokinetic properties.

METHODS

The title compounds were synthesized according to the Steglich esterification of N-[1-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethylidene]hydroxylamine with various carboxylic acids. Anticonvulsant identification and quantification tests were performed in mice by the Epilepsy Therapy Screening Program (ETSP) of the National Institutes of Health (NIH) using 6Hz psychomotor, maximal electroshock (MES), and rotorod tests. Their physicochemical and pharmacokinetic properties were calculated using QikProp.

RESULTS

Most of the compounds showed protection against 6Hz- and/or MES-induced seizures. 4a, 4b, and 4g were active at 100mg/kg, 4g was active in both tests without neurotoxicity. According to the QikProp calculations the title compounds were druglike and had some favourable properties such as high membrane permeability and oral absorptivity.

CONCLUSION

Anticonvulsant screening of a set N-[1-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethylidene]hydroxylamine esters yielded some active derivatives in 6Hz and MES test. Especially, 4g emerged as a promising compound with activity at 100mg/kg and no toxicity. The compounds were predicted to be drug like and have good pharmacokinetic properties except hERG inhibition, which needs to be addressed in further optimization studies.