Evaluation of Pyrrolone-Fused Benzosuberene MK2 Inhibitors as Promising Therapeutic Agents for HNSCC: In Vitro Efficacy, In-Vivo Safety, and Pharmacokinetic Profiling

MAPKAPK2/MK2 is well implicated in the progression of Head and Neck Squamous Cell Carcinoma (HNSCC), and potent MK2-inhibitors are required to suppress its activity. Several MK2-inhibitors have been developed in recent years to combat its effects on cancer. However, inadequate solubility, insufficient cellular permeability, systemic toxicity-mediated side effects, and low bioavailability have severely impeded the advancement of MK2-inhibitors to clinical trials. This void necessitates research to develop less toxic and more bioavailable potent MK2-inhibitors in HNSCC. In the present article, we have evaluated the in-vitro efficacy, in-vivo single-dose acute toxicity, and in-vivo pharmacokinetic profiling of recently developed PfBS (pyrrolone-fused benzosuberene) MK2-inhibitor analogues against HNSCC. The PfBS MK2 inhibitor analogues impeded HPV+ and HPV- HNSCC cell proliferation and two-dimensional migration. Moreover, MK2-inhibitors lowered HNSCC cell clonogenic survival in a dose-dependent manner, significantly enhancing radiation-induced cell death via exerting radio-sensitization effects. Furthermore, γ-H2AX immunostaining revealed that PfBS analogues impaired DNA damage repair in HNSCC cells exposed to gamma radiation. In mice, PfBS MK2 inhibitors at 300 mg/kg were well-tolerated without any lethal effects. Pharmacokinetic studies showed that PfBS analogues exhibited rapid absorption (Tmax), adequate plasma concentration above the micromolar level (C0 or Cmax), limited tissue distribution (Vd), and faster elimination from the body (Cl). Overall, this study summarizes in-vitro efficacy, safety, and pharmacokinetics of developed MK2-inhibitors and opens doors for pharmacodynamics and mechanism of action study of most effective leads in HNSCC.

Aminocarbonylation using CO surrogates

Aminocarbonylation reactions play a critical role in the synthesis of amides. Traditional aminocarbonylation processes often rely on carbon monoxide (CO) gas, a highly toxic and challenging reagent to handle. Recent advancements in CO surrogates address these challenges. This review looks at the various CO substitutes used in aminocarbonylation reactions. These include metal carbonyls, acids, formates, chloroform, and others that release CO. Use of CO surrogates not only improves safety but also broadens the substrate scope and operational simplicity of the aminocarbonylation reactions. This review provides a summary of recent progress made in aminocarbonylation reactions using different CO surrogates. We discuss key methodologies, catalytic systems, and mechanistic insights, highlighting the efficiency and versatility of CO surrogates in amide bond formation.

Novel pyrrolone-fused benzosuberene MK2 inhibitors: synthesis, pharmacophore modelling, molecular docking, and anti-cancer efficacy evaluation in HNSCC cells

Head and neck Squamous Cell Carcinoma (HNSCC) is a growing concern worldwide and MAPKAPK2/MK2 (Mitogen-Activated Protein Kinase Activated Protein Kinase 2) is crucially involved in HNSCC progression. Increased disease burden and lacuna of targeted therapies require novel and safe pharmacological inhibitors to suppress the well-explored molecular targets in HNSCC. Here, we used dibromo-substituted benzosuberene synthesized from the mixture of α, β, γ-himachalenes and utilized as a precursor for the synthesis of Pyrrolone-fused benzosuberenes (PfBS) as MK2 inhibitors through aminocarbonylation approach in a single-pot reaction. The devised protocol provides a broad substrate scope, facile recovery, recyclability of Polystyrene-supported palladium (Pd@PS) nanoparticle catalyst, and fewer synthesis steps. In-silico molecular docking, pharmacophore modeling, and ADMET revealed MK2-inhibitory potential and drug-likeliness of PfBS analogues. Surface plasmon resonance (SPR) analysis revealed effective high binding affinity (KD) and kinetics of PfBS analogues with MK2. Additionally, the SPR-mediated in-solution inhibition assay established the MK2-inhibition properties of PfBS analogues through abrogation of MK2-Hsp27 interaction. Further, in-vitro studies validate the findings in HNSCC cells. PfBS analogues exhibited significant anti-proliferative effects on CAL 27 tongue squamous carcinoma cells and were found safe on IEC-6 intestinal epithelial cells. Moreover, immunofluorescence analysis and western-blot assays potentiated, that selected analogues inhibited the inflammatory cytokine TNF-α induced activation of MK2 on cellular and molecular levels in HNSCC cells. In conclusion, this study presents novel MK2-inhibitors and opens the avenue for further pre-clinical and clinical efficacy evaluation of developed PfBS analogues in the treatment of HNSCC.Communicated by Ramaswamy H. Sarma.

Palladium-Catalyzed Aminocarbonylation of Isoquinolines Utilizing Chloroform-COware Chemistry

The carbonyl group forms an integral part of several drug molecules and materials; hence, synthesis of carbonylated compounds remains an intriguing area of research for synthetic and medicinal chemists. Handling toxic CO gas has several limitations; thus, using safe and effective techniques for in or ex situ generation of carbon monoxide from nontoxic and cheap precursors is highly desirable. Among several precursors that have been explored for the generation of CO gas, chloroform can prove to be a promising CO surrogate due to its cost-effectiveness and ready availability. However, the one-pot chloroform-based carbonylation reaction requires strong basic conditions for hydrolysis of chloroform that may affect functional group tolerability of substrates and scale-up reactions. These limitations can be overcome by a two-chamber reactor (COware) that can be utilized for ex situ CO generation through hydrolysis of chloroform in one chamber and facilitating safe carbonylation reactions in another chamber under mild conditions. The versatility of this "Chloroform-COware" technique is explored through palladium-catalyzed aminocarbonylation of medicinally relevant heterocyclic cores, viz., isoquinoline and quinoline.

Catalytic formation of oxalic acid on the partially oxidised greigite Fe3S4(001) surface

Greigite (Fe₃S₄), with its ferredoxin-like 4Fe-4S redox centres, is a naturally occurring mineral capable of acting as a catalyst in the conversion of carbon dioxide (CO₂) into low molecular-weight organic acids (LMWOAs), which are of paramount significance in several soil and plant processes as well as in the chemical industry. In this paper, we report the reaction between CO₂ and water (H₂O) to form oxalic acid (H₂C₂O₄) on the partially oxidised greigite Fe₃S₄(001) surface by means of spin-polarised density functional theory calculations with on-site Coulomb corrections and long-range dispersion interactions (DFT+U-D2). We have calculated the bulk phase of Fe₃S₄ and the two reconstructed Tasker type 3 terminations of its (001) surface, whose properties are in good agreement with available experimental data. We have obtained the relevant phase diagram, showing that the Fe₃S₄(001) surface becomes 62.5% partially oxidised, by replacing S by O atoms, in the presence of water at the typical conditions of calcination [Mitchell et al. Faraday Discuss. 2021, 230, 30-51]. The adsorption and co-adsorption of the reactants on the partially oxidised Fe₃S₄(001) surface are exothermic processes. We have considered three mechanistic pathways to explain the formation of H₂C₂O₄, showing that the coupling of the C-C bond and second protonation are the elementary steps with the largest energy penalty. Our calculations suggest that the partially oxidised Fe₃S₄(001) surface is a mineral phase that can catalyse the formation of H₂C₂O₄ under favourable conditions, which has important implications for natural ecosystems and is a process that can be harnessed for the industrial manufacture of this organic acid.

Plant-based analogues identified as potential inhibitor against tobacco mosaic virus: A biosimulation approach

Benzosuberene compounds with a pyrrolone group adhered to it are compounds extracted from the oils of Cedrus deodara plant, that bear inhibitory capabilities. Tobacco mosaic virus is known to affect crop production every year. The currently known inhibitors against TMV have a weak inhibition effect and also tend to be toxic towards non-target living organisms as well as the environment. Thus, the requirement of non-toxic potent inhibitors is the need of the hour, which led us to test our benzosuberene molecules on the binding site of TMV and check their affinity as well as stability. The non-toxic nature of these molecules has already been experimentally established. Through in-silico analysis involving docking and simulation experiments, we compared the interaction pattern of these ligand molecules with the already present inhibitors. Our investigation proved that the reported ligands (ligands 3, 7, 9, and 17 obtained -177.103, -228.632, -184.134, and - 188.075 kJ/mol binding energies, respectively) interacted with the binding site of TMV much efficiently than the known inhibitors (Ribavirin and Zhao et al. 2020 obtained 121.561 and - 221.393 kJ/mol binding energies, respectively). Moreover, they acquired a stable conformation inside the binding pocket, where a higher number of binding site residues contributed towards interaction. Thus, their structural framework can be optimized for the exploration of their antiviral properties to develop potent botanical viricides against plant virus infection.

Palladium-catalyzed [2 + 2 + 1] annulation: access to chromone fused cyclopentanones with cyclopropenone as the CO source

A variety of chromone fused cyclopentanones are efficiently generated in good to high yields via palladium-catalyzed [2 + 2 + 1] annulation, in which cyclopropenone was utilized for the first time as the sole CO surrogate in the carbonylation process.

Structural based study to identify new potential inhibitors for dual specificity tyrosine-phosphorylation- regulated kinase

Background and Objectives The Dual-specificity tyrosine-phosphorylation regulated kinase-1A (DYRK1A) a serine/threonine kinase that has freshly gained recognition as an essential drug target due to the discovery of its involvement in pathological diseases. The development of new potent inhibitors of DYRK1A would contribute to clarify the molecular mechanisms of associated diseases. It would administer a new lead compound for molecular-targeted protein, which was the primary focus of our study. Methods The library of in-house synthesized pyrrolone-fused benzosuberene (PBS) compounds was docked with DYRK1A receptor. Further, molecular mechanics-Poisson Boltzmann surface area (MM-PBSA) estimations were conducted to confirm our docking outcomes and compared the stability of chosen complexes with the 2C3 (standard molecule) complex. Results This study reports Ligand15, Ligand14, and Ligand11 as potent inhibitors which showed higher ligand efficiency, binding affinity, lipophilic ligand efficiency, and favorable torsion values as compared to 2C3. Conclusion The stated methodologies revealed a unique mechanism of active site binding. The binding interactions within the active site showed that the chosen molecules had notable interactions than the standard molecule, which led to the generation of potential compounds to inhibit DYRK1A.

Carbonylative synthesis of heterocycles involving diverse CO surrogates

Recent advances in the carbonylative synthesis of heterocycles by using diverse CO surrogates as sources of CO are summarized and discussed.

Natural analogues inhibiting selective cyclin-dependent kinase protein isoforms: a computational perspective

Cyclin-dependent kinases (CDKs) are known for their vital role in regulating cell cycle progression through protein-kinase interactions. CDKs also help in regulating transcription and development of the central nervous system. Inhibition of CDKs is a very fundamental approach for drug discovery in areas of different types of cancers, Alzheimer's, and HIV infections. The present research focuses on finding a novel, potent, and specific natural inhibitors of CDK isoforms (CDK2, CDK5, CDK7, CDK9). Molecular docking, molecular dynamics (MD) simulations, and Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) were carried out to get an in-depth understanding of protein-ligand interactions. Based on our molecular docking results, Ligands-3, 5, 14, and 16 were screened among 17 different Pyrrolone-fused benzosuberene compounds as potent and specific inhibitors without any cross-reactivity against different CDK isoforms. Analysis of MD simulations and MM-PBSA studies, revealed the binding energy profiles of all the selected complexes. Our selected ligands performed better than the standard inhibitor (Roscovitine). Ligands-3 and 14 show specificity for CDK7 and Ligands-5 and 16 were specific against CDK9. These ligands are expected to possess lower risk of side effects due to their natural origin. Moreover, the backbone structure of these ligands could also be exploited to develop specific inhibitors against other CDK isoforms.Communicated by Ramaswamy H. Sarma.

Synthesis of α,β-alkynyl ketones via the nickel catalysed carbonylative Sonogashira reaction using oxalic acid as a sustainable C1 source

An efficient and economic nickel-dppb catalyzed, carbonylative Sonogashira cross-coupling reaction was demonstrated to provide rapid access to various α,β-alkynyl ketones from aryl iodides and terminal alkynes using oxalic acid as the ex situ C1 source in a double vial (DV) system. Notably, the role of the ligand in combination with the Ni catalyst for the selective formation of carbonylative Sonogashira products was investigated and supported with control experiments. Yet, no reports are available for carbonylative Sonogashira coupling by using a CO-surrogate under Ni-catalyzed conditions. In this process, for the first time, oxalic acid is used as an ex situ solid, bench stable, easy to handle and efficient CO surrogate in a DV-system for the carbonylative Sonogashira coupling reaction with vast substrate scope.

Chloroform as a CO surrogate: applications and recent developments

The carbonyl moiety is one of the indispensable sub-units in organic synthesis with significant applications in medicinal as well as materials chemistry. Hence the insertion of a carbonyl group via simple and highly efficient routes has been one of the most challenging tasks for organic chemists. Though the direct utilisation of CO gas in carbonylation is the fundamental procedure for the construction of carbonyl compounds, it has certain drawbacks due to its toxic and explosive nature. As a result, the need for cheap and efficient CO surrogates has gained much attention nowadays by which CO gas can be easily generated in situ or ex situ. In this review we discuss the advantages of chloroform as CO surrogate and have surveyed recent carbonylation reactions where chloroform has been used as CO source.

Target identification, screening and in vivo evaluation of pyrrolone-fused benzosuberene compounds against human epilepsy using Zebrafish model of pentylenetetrazol-induced seizures

Pyrrolone-fused benzosuberene (PBS) compounds were semi-synthesized from α,β,γ-Himachalenes extracted from the essential oil of Cedrus deodara following amino-vinyl-bromide substituted benzosuberenes as intermediates. These PBSs compounds classified as an attractive source of therapeutics. The α-isoform of PI3K which is a pivotal modulator of PI3K/AKT/mTOR signaling pathway, responsible for neurological disorders like epilepsy, found as a potential target molecule against these 17 semi-synthesized PBS compounds using in silico ligand-based pharmacophore mapping and target screening. The compounds screened using binding affinities, ADMET properties, and toxicity that were accessed by in silico docking simulations and pharmacokinetics profiling. Ultimately two compounds viz., PBS-8 and PBS-9 were selected for further in vivo evaluation using a zebrafish (Danio rerio) model of pentylenetetrazol (PTZ)-induced clonic convulsions. Additionally, gene expression studies performed for the genes of the PI3K/AKT/mTOR pathway which further validated our results. In conclusion, these findings suggested that PBS-8 is a promising candidate that could bedeveloped as a potential antiepileptic.

Supported Palladium Nanoparticles that Catalyze Aminocarbonylation of Aryl Halides with Amines using Oxalic Acid as a Sustainable CO Source

Polystyrene-supported palladium (Pd@PS) nanoparticles (NPs) have been used to catalyze the aminocarbonylation of aryl halides with amines using oxalic acid as a CO source for the first-time for the synthesis of amides. Furthermore, o-iodoacetophenones participated in amidation and cyclization reactions to give isoindolinones in a single step following a concerted approach. Oxalic acid has been used as a safe, environmentally benign and operationally simple ex situ sustainable CO source under double-layer-vial (DLV) system for different aminocarbonylation reactions. Catalyst stability under a CO environment is a challenging task, however, Pd@PS was found to be recyclable and applicable for a vast substrate scope avoiding regeneration steps. Easy handling of oxalic acid, additive and base-free CO generation, catalyst stability and effortless catalyst separation from the reaction mixture by filtration and introduce of DLV are the added advantages to make the overall process a sustainable approach.

Oxalic/malonic acids as carbon building blocks for benzazole, quinazoline and quinazolinone synthesis

Oxalic/malonic acids as CH/C₂H₃ carbon building blocks for the synthesis of 2-substituted and un-substituted benzazoles, quinazolines and quinazolinones.