Design, synthesis and bioevaluation of 1,2,3,9-tetrahydropyrrolo[2,1-b]quinazoline-1-carboxylic acid derivatives as potent neuroprotective agents

Lead optimization based design, synthesis, and pharmacological evaluation of quinazoline derivatives as multi-targeting agents for Alzheimer's disease treatment

The complexity and multifaceted nature of Alzheimer's disease (AD) have driven us to further explore quinazoline scaffolds as multi-targeting agents for AD treatment. The lead optimization strategy was utilized in designing of new series of derivatives (AK-1 to AK-14) followed by synthesis, characterization, and pharmacological evaluation against human cholinesterase's (hChE) and β-secretase (hBACE-1) enzymes. Amongst them, compounds AK-1, AK-2, and AK-3 showed good and significant inhibitory activity against both hAChE and hBACE-1 enzymes with favorable permeation across the blood-brain barrier. The most active compound AK-2 revealed significant propidium iodide (PI) displacement from the AChE-PAS region and was non-neurotoxic against SH-SY5Y cell lines. The lead molecule (AK-2) also showed Aβ aggregation inhibition in a self- and AChE-induced Aβ aggregation, Thioflavin-T assay. Further, compound AK-2 significantly ameliorated Aβ-induced cognitive deficits in the Aβ-induced Morris water maze rat model and demonstrated a significant rescue in eye phenotype in the Aꞵ-phenotypic drosophila model of AD. Ex-vivo immunohistochemistry (IHC) analysis on hippocampal rat brains showed reduced Aβ and BACE-1 protein levels. Compound AK-2 suggested good oral absorption via pharmacokinetic studies and displayed a good and stable ligand-protein interaction in in-silico molecular modeling analysis. Thus, the compound AK-2 can be regarded as a lead molecule and should be investigated further for the treatment of AD.

Practical Three-Component Regioselective Synthesis of Drug-Like 3-Aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines as Potential Non-Covalent Multi-Targeting Inhibitors To Combat Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are one of the prominent health challenges facing contemporary society, and many efforts have been made to overcome and (or) control it. In this research paper, we described a practical one-pot two-step three-component reaction between 3,4-dihydronaphthalen-1(2H)-one (1), aryl(or heteroaryl)glyoxal monohydrates (2a-h), and hydrazine monohydrate (NH2NH2•H2O) for the regioselective preparation of some 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnoline derivatives (3a-h). After synthesis and characterization of the mentioned cinnolines (3a-h), the in silico multi-targeting inhibitory properties of these heterocyclic scaffolds have been investigated upon various Homo sapiens-type enzymes, including hMAO-A, hMAO-B, hAChE, hBChE, hBACE-1, hBACE-2, hNQO-1, hNQO-2, hnNOS, hiNOS, hPARP-1, hPARP-2, hLRRK-2(G2019S), hGSK-3β, hp38α MAPK, hJNK-3, hOGA, hNMDA receptor, hnSMase-2, hIDO-1, hCOMT, hLIMK-1, hLIMK-2, hRIPK-1, hUCH-L1, hPARK-7, and hDHODH, which have confirmed their functions and roles in the neurodegenerative diseases (NDs), based on molecular docking studies, and the obtained results were compared with a wide range of approved drugs and well-known (with IC50, EC50, etc.) compounds. In addition, in silico ADMET prediction analysis was performed to examine the prospective drug properties of the synthesized heterocyclic compounds (3a-h). The obtained results from the molecular docking studies and ADMET-related data demonstrated that these series of 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines (3a-h), especially hit ones, can really be turned into the potent core of new drugs for the treatment of neurodegenerative diseases (NDs), and/or due to the having some reactionable locations, they are able to have further organic reactions (such as cross-coupling reactions), and expansion of these compounds (for example, with using other types of aryl(or heteroaryl)glyoxal monohydrates) makes a new avenue for designing novel and efficient drugs for this purpose.

Design, Synthesis, and Biological Evaluation of Pierardine Derivatives as Novel Brain-Penetrant and In Vivo Potent NMDAR-GluN2B Antagonists for Ischemic Stroke Treatment

A series of structurally novel GluN2B NMDAR antagonists were designed, synthesized, and biologically evaluated as anti-stroke therapeutics by optimizing the chemical structure of Pierardine, the active ingredient of traditional Chinese medicine Dendrobium aphyllum (Roxb.) C. E. Fischer identified via in silico screening. The systematic structure-activity relationship study led to the discovery of 58 with promising NMDAR-GluN2B binding affinity and antagonistic activity. Of the two enantiomers, S-58 exhibited significant inhibition (IC50 = 74.01 ± 12.03 nM) against a GluN1/GluN2B receptor-mediated current in a patch clamp assay. In addition, it displayed favorable specificity over other subtypes and off-target receptors. In vivo, S-58 exerted therapeutic efficacy comparable to that of the approved GluN2B NMDAR antagonist ifenprodil and excellent safety profiles. In addition to the attractive in vitro and in vivo potency, S-58 exhibited excellent brain exposure. In light of these merits, S-58 has been advanced to further preclinical investigation as a potential anti-stroke candidate.

Discovery of novel tryptamine derivatives as GluN2B subunit-containing NMDA receptor antagonists via pharmacophore-merging strategy with orally available therapeutic effect of cerebral ischemia

A series of tryptamine derivatives has been designed and synthesized as novel GluN2B subunit-containing NMDA receptor (GluN2B-NMDAR) antagonists, which could simultaneously manifest the receptor-ligand interactions of representative GluN2B-NMDAR antagonists ifenprodil (1) and EVT-101 (3). In the present study, the neuroprotective potential of these compounds was explored through chemical synthesis and pharmacological characterization. Compound Z25 with significantly better neuroprotective activity than the positive control drug (percentage of protection: 55.8 ± 0.6% vs. 41.0 ± 2.7%) was considered to be an effective antagonist of the human GluN2B-NMDA receptor. Judging from in vitro pharmacological profiling, Z25 could downregulate NMDA-induced increased intracellular Ca²⁺ concentration, and Z25 could also upregulate NMDA-induced decreased intracellular p-ERK 1/2 expression, which suggested that Z25 is an antagonist of the GluN2B-NMDA receptor. Furthermore, the in vitro preliminary evaluation of the drug-like properties of compound Z25 showed remarkable plasma stability. Based on in vivo pharmacokinetic and pharmacodynamic studies in C57 mice, compound Z25 exhibited a relatively short half-life and a low F value (3.12 ± 0.01%), while administration of Z25 substantially improved the cognitive performance of mice in a series of tests of cerebral ischemic injury. Overall, these results support the further development of compound Z25 as a potential lead compound to treat the cerebral ischemic injury by antagonizing GluN2B-NMDA receptor.

Transition-metal-catalyzed synthesis of quinazolines: A review

Quinazolines are a class of nitrogen-containing heterocyclic compounds with broad-spectrum of pharmacological activities. Transition-metal-catalyzed reactions have emerged as reliable and indispensable tools for the synthesis of pharmaceuticals. These reactions provide new entries into pharmaceutical ingredients of continuously increasing complexity, and catalysis with these metals has streamlined the synthesis of several marketed drugs. The last few decades have witnessed a tremendous outburst of transition-metal-catalyzed reactions for the construction of quinazoline scaffolds. In this review, the progress achieved in the synthesis of quinazolines under transition metal-catalyzed conditions are summarized and reports from 2010 to date are covered. This is presented along with the mechanistic insights of each representative methodology. The advantages, limitations, and future perspectives of synthesis of quinazolines through such reactions are also discussed.

Polyphosphoric acid-promoted one-pot synthesis and neuroprotective effects of flavanones against NMDA-induced injury in PC12 cells

We report herein an efficient polyphosphoric acid (PPA) promoted one-pot protocol for the synthesis of flavanone derivatives from 2-hydroxyacetophenones and benzaldehydes. A variety of flavanones were produced in moderate to excellent yields and evaluated for their neuroprotective effects against N-methyl-d-aspartate (NMDA)-induced excitotoxicity in PC12 cells. Derivatives bearing electron-donating groups exhibited better neuroprotective activity. Compound 3m demonstrated the best protective potency and reversed the intracellular calcium (Ca²⁺) influx caused by NMDA, suggesting that flavanones protected the PC12 cells against NMDA-induced neurotoxicity via inhibition of Ca²⁺ overload.

Synthesis of pyrimidine-containing alkaloids

This review deals with the synthesis of naturally occurring alkaloids containing partially or completely saturated pyrimidine nuclei. The interest in these compounds is associated with their structural diversity, high biological activity and toxicity. The review is divided into four parts, each of which describes a number of synthetic methodologies toward structurally different naturally occurring alkaloids containing saturated cyclic six-membered amidine, guanidine, aminal and urea (thiourea) moieties, respectively. The development of various synthetic strategies for the preparation of these compounds has remarkably increased during the past few decades. This is primarily due to the fact that some of these compounds are isolated only in limited quantities, which makes it practically impossible to study their full structural characteristics and biological activity.

Discovery of novel brain-penetrant GluN2B NMDAR antagonists via pharmacophore-merging strategy as anti-stroke therapeutic agents

In this work, a novel structural series of brain-penetrant GluN2B NMDAR antagonists were designed, synthesized and biologically evaluated as anti-stroke therapeutic agents via merging the structures of NBP and known GluN2B ligands. Approximately half of them exhibited superior neuroprotective activity to NBP against NMDA-induced neurotoxicity in hippocampal neurons at 10 μM, and compound 45e and 45f exerted equipotent activity to ifenprodil, an approved GluN2B- selective NMDAR antagonist. In particular, 45e, with the most potent neuroprotective activity throughout this series, displayed dramatically enhanced activity (K_i = 3.26 nM) compared to ifenprodil (K_i = 14.80 nM) in Radioligand Competitive Binding Assay, and remarkable inhibition (IC₅₀ = 79.32 nM) against GluN1/GluN2B receptor-mediated current in Patch Clamp Assay. Meanwhile, 45e and its enantiomers exhibited low inhibition rate against the current mediated by other investigated receptors at the concentration of 10 μM, indicating their favorable selectivity for GluN1/GluN2B. In the rat model of middle cerebral artery ischemia (MCAO), 45e exerted comparable therapeutic efficacy to ifenprodil at the same dosage. In addition to the attractive in vitro and in vivo potency, 45e displayed a favorable bioavailability (F = 63.37%) and an excellent brain exposure. In further repeated dose toxicity experiments, compound 45e demonstrated an acceptable safety profile. With the above merits, 45e is worthy of further functional investigation as a novel anti-stroke therapeutic agent.

Therapeutic potential of quinazoline derivatives for Alzheimer's disease: A comprehensive review

Quinazolines are considered as a promising class of bioactive heterocyclic compounds with broad properties. Particularly, the quinazoline scaffold has an impressive role in the design and synthesis of new CNS-active drugs. The drug-like properties and pharmacological characteristics of quinazoline could lead to different drugs with various targets. Among CNS disorders, Alzheimer's disease (AD) is a progressive neurodegenerative disorder with memory loss, cognitive decline and language dysfunction. AD is a complex and multifactorial disease therefore, the need for finding multi-target drugs against this devastative disease is urgent. A literature survey revealed that quinazoline derivatives have diverse therapeutic potential for AD as modulators/inhibitors of β-amyloid, tau protein, cholinesterases, monoamine oxidases, and phosphodiesterases as well as other protective effects. Thus, we describe here the most relevant and recent studies about anti-AD agents with quinazoline structure which can further aid the development and discovery of new anti-AD agents.

Repurposing of cefpodoxime proxetil as potent neuroprotective agent through computational prediction and in vitro validation

In recent reports, NR2B-NMDA receptor antagonists showed more research value because of its strong targeting ability and less side effects potential. In 2016, EVT-101 was reported to bind in an almost entirely new binding region of this target. Whether strikingly different binding modes can improve targeting and reduce side effects is worth studying. In our preliminary work, we explored the binding patterns of ifenprodil and EVT-101, found the key amino acids and summarized the pharmacophores, hoping to find such antagonists that target the two binding modes simultaneously. In this study, we developed a scalable virtual screening workflow in the FDA-approved drugs library to identify novel NR2B-NMDAR antagonists based on the combination of two pharmacophores. Cefpodoxime proxetil (5) was identified as the hit compound, and it was found for the first time that 5 might have neuroprotective activity as a NR2B-NMDAR antagonist. This result interested us to make further study, the ligand-receptor interactions modeled by molecular docking studies showed that the compound could perfectly merge both the pharmacophore characteristics of ifenprodil and EVT-101 at the binding cavity between the ATDs of GluN1 and GluN2B. The accuracy of molecular docking results and binding stability of ligand-receptor complexes were validated through 100 ns molecular dynamics simulation and binding free energy calculation. Afterwards, MTT assay (49.8%±0.1%, 5 μM) on NMDA injured SH-SY5Y cells and evidence of the effect on attenuating Ca2+ influx induced by NMDA were applied to validate the computational results, further investigation showed that 5 could suppress the NR2B upregulation induced by NMDA. [Formula: see text] Communicated by Ramaswamy H. Sarma.

Novel pyrrolo[2,1-c][1,4]benzodiazepine-3,11-dione (PBD) derivatives as selective HDAC6 inhibitors to suppress tumor metastasis and invasion in vitro and in vivo

Selective inhibition of histone deacetylase 6 (HDAC6) has been emerged as a promising approach to cancer treatment. As a pivotal strategy for drug discovery,molecular hybridization was introduced in this study and a series of pyrrolo[2,1-c][1,4] benzodiazepine-3,11-diones (PBDs) based hydroxamic acids was rationally designed and synthesizedas novel selective HDAC6 inhibitors. Preliminary in vitro enzyme inhibition assay and structure-activity relationship (SAR) discussion confirmed our design strategy and met the expectation. Several of the compounds showed high potent against HDAC6 enzyme in vitro, and compound A7 with a long aliphatic linker was revealed to have the similar activity as the positive control tubastatin A. Further in vitro characterization of A7 demonstrates the metastasis inhibitory potency in MDA-MB-231 cell line and western blotting showed that A7 could induce the upregulation of Ac-α-tubulin, but not induce the excessive acetylation of histone H3, which indicated that the compound had HDAC6 targeting effect in MDA-MB-231 cells. In vivo study revealed that compound A7 has satisfactory inhibitory effects onliver and lung metastasis of breast cancer in mice. Molecular docking released that A7 could fit well with the receptor and interact with some key residues, which lays a foundation for further structural modifications to elucidate the interaction mode between compounds and target protein. This pharmacological investigation workflow provided a reasonable and reference methodto examine the pharmacological effects of inhibiting HDAC6 with a single molecule, either in vitro or in vivo. All of these results suggested that A7 is a promising lead compound that could lead to the further development of novel selective HDAC6 inhibitors for the treatment of tumor metastasis.

Design, synthesis and biological evaluation of 1-benzyl-5-oxopyrrolidine-2-carboximidamide derivatives as novel neuroprotective agents

A series of 1-benzyl-5-oxopyrrolidine-2-carboximidamide derivatives were designed and synthesized. Their protective activities against N-methyl-d-aspartic acid (NMDA)-induced cytotoxicity were investigated in vitro. All of the compounds exhibited neuroprotective activities, especially 12k, which showed higher potency than reference compound 1 (ifenprodil). Further investigation showed that 12k could attenuate Ca²⁺ influx and suppress the NR2B upregulation induced by NMDA. The docking results indicated that 12k could fit well into binding site of 1 in the NR2B-NMDA receptor. Additionally, 12k exhibited excellent metabolic stability. Furthermore, the results of behavioral tests showed that compound 12k could significantly improve learning and memory in vivo. These results suggested that 12k is a promising neuroprotective drug candidate and that the NR2B-NMDA receptor is a potential target of 12k.