Synthetic and therapeutic perspectives of nitrogen containing heterocycles as anti-convulsants

Synthesis and Fluorescence Properties of Imidazopyridine-Linked Coumarins via Tandem C(sp2)-H Functionalization/Decarboxylation Reaction

A catalyst-, oxidant-free and green synthetic route for direct access to a series of novel imidazopyridine-linked coumarins has been devised through tandem C(sp2)-H functionalization/decarboxylation reaction in ethyl acetate as a sustainable medium. Moreover, the utilities of ensured products in further organic synthesis were conducted by Suzuki-Miyaura and Sonogashira cross-coupling reactions. The fluorescence characteristics of the produced molecules are appropriate, and the synthesized scaffolds could promisingly garner future attention in clinical diagnostics and bioimaging research.

Pyrazole derivative Z10 ameliorates acute pancreatitis by inhibiting the ERK/Ddt pathway

Acute pancreatitis (AP) can lead to death; however, there is no specific treatment for AP. Screening of drugs for AP treatment is rarely performed. Compounds were screened in a primary pancreatic acinar cell and peritoneal macrophage coculture system. Compounds were used in vitro and in vivo. Compound targets were predicted and validated. Among the 18 nitrogen-containing heterocycles, Z10 was shown to decrease the cerulein plus lipopolysaccharide (CL)-induced secretion of both acinar digestive enzymes and macrophage cytokines. Z10 was also shown to ameliorate CL-induced or sodium taurocholate-induced AP in mice. Proteomics analysis and enzyme linked immunosorbent assay (ELISA) revealed that Z10 decreased the levels of D-dopachrome tautomerase (Ddt) within macrophages and those in the extracellular milieu under CL treatment. Z10 also decreased Ddt expression in AP mice. Moreover, exogenous Ddt induced cytokine and digestive enzyme secretion, which could be inhibited by Z10. Ddt knockdown inhibited CL-induced cytokine secretion. Medium from CL-treated macrophages induced the release of amylase by acinar cells, and Ddt knockdown medium decreased amylase secretion. The target of Z10 was predicted to be ERK2. Z10 increased the thermostability of ERK1/2 but not ERK1 K72A/ERK2 K52A. The docking poses of ERK1 and ERK2 with Z10 were similar. Z10 inhibited ERK1/2 phosphorylation, and Ddt levels and cytokines were regulated by ERK1/2 during AP. Additionally, Z10 could not further inhibit cytokines under ERK1/2 knockdown with CL. Thus, this study revealed that Z10-mediated ERK1/2 inhibition decreased Ddt expression and secretion by macrophages. Ddt inhibition decreased cytokine release and digestive enzyme secretion.

Research Status, Synthesis and Clinical Application of Antiepileptic Drugs

According to the 2017 ILAE's official definition, epilepsy is a slow brain disease state characterized by recurrent episodes. Due to information released by ILAE in 2017, it can be divided into four types, including focal epilepsy, generalized epilepsy, combined generalized, and focal epilepsy, and unknown epilepsy. Since 1989, 24 new antiepileptic drugs have been approved to treat different types of epilepsy. Besides, there are a variety of antiepileptic medications under clinical monitoring. These novel antiepileptic drugs have plenty of advantages. Over the past 33 years, there have been many antiepileptic drugs on the mearket, but no one has been found that can completely cure epilepsy. In this paper, the mentioned drugs were classified according to their targets, and the essential information, and clinical studies of each drug were described. The structure-activity relationship of different chemical structures was summarized. This paper provides help for the follow-up research on epilepsy drugs.

1,2,3-Triazolo[4,5-b]aminoquinolines: Design, synthesis, structure, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity, and molecular docking of novel modified tacrines

An efficient [4 + 2] cyclization protocol to synthesize a series of twelve examples of 1,2,3-triazolo[4,5-b]aminoquinolines (5) as novel structurally modified tacrines was obtained by reacting readily accessible precursors (i.e., 3-alky(aryl)-5-amino-1,2,3-triazole-4-carbonitriles (3)) and selected cycloalkanones (4) of five-, six-, and seven-membered rings. We evaluated the AChE and BChE inhibitory activity of the novel modified tacrines 5, and the compound derivatives from cyclohexanone (4b) showed the best AChE and BChE inhibitory activities. Specifically, 1,2,3-triazolo[4,5-b]aminoquinolines 5bb obtained from 3-methyl-carbonitrile (3b) showed the highest AChE (IC50 = 12.01 μM), while 5ib from 3-sulfonamido-carbonitrile (3i) was the most significant inhibitor for BChE (IC50 = 1.78 μM). In general, the inhibitory potency of compound 5 was weaker than the pure tacrine reference, and our findings may help to design and develop novel anticholinesterase drugs based on modified tacrines.

Design, synthesis, and pharmacological evaluation of [1, 3] dioxolo-chromeno[2,3-b]pyridines as anti-seizure agents

An efficient one-pot three-component reaction for the synthesis of [1,3]dioxolo[4',5':6,7]chromeno[2,3-b]pyridines 4(a-i) has been developed. Synthesis was achieved by reacting sesamol (1), aromatic aldehydes 2(a-i), and 2-aminopropene-1,1,3-tricarbonitrile (3) in the presence of triethylamine at 100 °C under neat reaction condition. Simple operational procedure, broad substrate scope, column chromatography free separations, and high yield of products make it an efficient and largely acceptable synthetic strategy. Synthesized compounds 4(a-i) were further screened for preliminary anticonvulsant activity using MES and scPTZ tests. These analogs were also checked for neurotoxicity and hepatotoxicity. Selected active compounds have been then screened quantitatively to determine ED50 and TD50 values. Analog 4h was found effective in both preclinical seizure models with significant therapeutic/toxicity profile (4h: ED50 = 34.7 mg/kg, MES test; ED50 = 37.9 mg/kg, scPTZ test; TD50 = 308.7 mg/kg). Molecular dynamic simulation for 100 ns of compound 4h-complexed with GABAA receptor revealed good thermodynamic behavior and fairly stable interactions (4h, Docking score =  - 10.94). In conclusion, effective synthetic strategy, significant anticonvulsant activity with good toxicity profile and detailed molecular modeling studies led us to anticipate the emergence of these analogs as valid leads for the development of future effective neurotherapeutic agents.

One-pot double annulations to confer diastereoselective spirooxindolepyrrolothiazoles

A novel four-component reaction in one pot as an atom- and step-economic process was developed to synthesize diastereoselectively spirooxindolepyrrolothiazoles through sequential N,S-acetalation of aldehydes with cysteine and decarboxylative [3 + 2] cycloaddition with olefinic oxindoles. High synthetic efficiency, operational simplification and reaction process economy using EtOH as solvent, and only releasing CO2 and H2O as side products confer this approach favorable in green chemistry metrics analysis.

An Overview of the Biological Evaluation of Selected Nitrogen-Containing Heterocycle Medicinal Chemistry Compounds

Heterocyclic compounds are a class of compounds of natural origin with favorable properties and hence have major pharmaceutical significance. They have an exceptional adroitness favoring their use as diverse smart biomimetics, in addition to possessing an active pharmacophore in a complex structure. This has made them an indispensable motif in the drug discovery field. Heterocyclic compounds are usually classified according to the ring size, type, and the number of heteroatoms present in the ring. Among different heterocyclic ring systems, nitrogen heterocyclic compounds are more abundant in nature. They also have considerable pharmacological significance. This review highlights recent pioneering studies in the biological assessment of nitrogen-containing compounds, namely: triazoles, tetrazoles, imidazole/benzimidazoles, pyrimidines, and quinolines. It explores publications between April 2020 and February 2022 and will benefit researchers in medicinal chemistry and pharmacology. The present work is organized based on the size of the heterocyclic ring.

Overview of Chemistry and Therapeutic Potential of Non-Nitrogen Heterocyclics as Anticonvulsant Agents

Epilepsy is a chronic neurological disorder, characterized by the predisposition of unprovoked seizures affecting the neurobiological, psychological, cognitive, economic, and social wellbeing of the patient. As per the 2019 report by World Health Organization, it affects nearly 80% of the population, which comes from middle to low-income countries. It has been suggested that 70% of such cases can be treated effectively if properly diagnosed. It is one of the most common neurological diseases affecting 50 million people globally. Most of the antiepileptic drugs used in clinical practice are only 60-80% effective in controlling the disease. These drugs suffer from serious drawbacks of non-selectivity and toxicity that limit their clinical usefulness. Hence, there is a need to search for safe, potent, and effective anti-epileptic drugs. One of the emerging strategies to discover and develop selective and non-toxic anticonvulsant molecules focuses on the design of non-nitrogen heterocyclic compounds (NNHC). Drugs such as valproic acid, gabapentin, viagabatrin, fluorofelbamate, tiagabine, progabide, pregabalin, gamma amino butyric acid (GABA), etc. do not contain a nitrogen heterocyclic ring but are as effective anticonvulsants as conventional heterocyclic nitrogen compounds. This review covers the various classes of NNHC which have been developed in the recent past as anticonvulsants along with their chemistry, percentage yield, structure-activity relationship and biological activity. The most potent compound in each series has been identified for comparative studies, for further structural modification and to improve the pharmacokinetic profile. Various optimized synthetic pathways and diverse functionalities other than nitrogen-containing rings discussed in the article may help medicinal chemists to design safe and effective anticonvulsant drugs in near future.

Green Synthesis of New Pyrrolo [1,2-a] quinoxalines as Antiproliferative Agents in GPER-expressing Breast Cancer Cells

4,5-Dihydropyrrolo [1,2-a]quinoxalines are interesting druggable scaffolds, with multifaceted biological properties, including anticancer properties targeting the G protein-coupled estrogen receptor 1 (GPER). In this work, the synthesis and preliminary antiproliferative activity of a small set of new 4,5-dihydropyrrolo[1,2-a]quinoxalines (18-20) and pyrrolo[1,2-a]quinoxalines (21, 22) has been reported, inspired by known antiproliferative agents (G-1, G-15, and G-36). The synthesis of the pyrroloquinoxalinic core was employed following the Pictet–Spengler reaction, using the surfactant p-dodecylbenzene sulphonic acid (p-DBSA), as catalyst. It demonstrated efficiency in the catalysis of the 4-phenylpyrrole [1,2-a] quinoxaline type compound formation in mild solvents such as water, ethanol, and hydroalcoholic solutions. In addition, the reactions proceeded in a short time (between 15 and 120 minutes) at room temperature and with high yields. The in vitro MTT assays showed that the presence of isopropyl groups furnished promising antiproliferative compounds. Although, the acetyl group provided also antiproliferative effects, breaking down its responsibility in the GPER transactivation. Nevertheless, it is possible to conclude that the 4,5-dihydropyrrolo[1,2-a]quinoxalines remain a feasible scaffold to develop anticancer agents against GPER-expressing cells.

Divergent and Regioselective Synthesis of Pyrazolo[1,5-a]pyridines and Imidazo[1,5-a]pyridines

Nitrogenous heterocycles are ubiquitous in pharmaceuticals and drug-like compounds; however, regioselective synthesis has proved challenging. Herein we report our efforts to develop a regioselective method for the synthesis of pyrazolo[1,5-a]pyridines and the serendipitous discovery of a protocol for the regioselective formation of imidazo[1,5-a]pyridines. Together, these transformations allow for the rapid and selective formation of two important heterocyclic motifs from a common intermediate.

Interplay of Acidity and Ionic Liquid Structure on the Outcome of a Heterocyclic Rearrangement Reaction

The study of suitable probe reactions is a powerful tool to investigate the properties of nonconventional solvents such ionic liquids (ILs). In particular, we studied the acid-catalyzed mononuclear rearrangement of heterocycles (MHR) of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant 1,2,3-triazole, in solution of ILs by means of kinetic measurements. We chose as solvents six ILs differing both in the cation and anion, in the presence of five carboxylic and sulfonic acids as catalysts. For a useful comparison, the reaction was also performed in 1,4-dioxane and methanol. In general, the reaction occurs faster in ILs, compared to conventional solvents, according to the weaker solvation interactions operating in the former media. The effect of IL anion and cation on the reactivity and on the acidic strength of the catalysts was analyzed. To this aim, we measured the acidic strength of the sulfonic acids in each IL, estimated by the equilibrium formation constant of each acid with 4-nitroaniline. We found that the trend of reactivity as a function of the IL anion mainly reflects the larger difference in acidic strengths of the catalyst. Conversely, acidic strength spans a narrower range as a function of the IL cation. As a result, other factors come into play, such as the π-π interactions involving aromatic IL cations, substrate, and transition states, leading to a more articulate trend.