Design, Synthesis, Antimalarial Activity and Docking Study of 7-Chloro-4- (2-(substituted benzylidene)hydrazineyl)quinolines

Experimental and computational evaluation of anti-malarial and antioxidant potential of transition metal (II) complexes with tridentate schiff base derived from pyrrolopyrimidine

In the twenty-first century, we are experiencing persistent waves of diverse pathogen variations, contributing significantly to global illness and death rates. Within this varied spectrum of illnesses, malaria and oxidative damage emerge as prominent obstacles that have persistently affected human health. The motivation for exploring the antioxidant potential of transition metal (II) complexes with tridentate Schiff base ligands is driven by the need for effective treatments against malaria and oxidative stress-related conditions. Both malaria and oxidative damage are significant global health concerns. Transition metal complexes can potentially offer enhanced anti-malarial and antioxidant activities, providing a dual benefit. To explore the aforementioned facts and examine the therapeutic potential, the previously synthesized pyrrolopyrimidinehydrazide-3-chlorobenzaldehyde, such as HPPHmCB ligand(1)andtheirMn(II),Fe(II),Co(II),Ni(II), Pd(II),Cu(II),Zn(II),Cd(II),Hg(II)complexes(2-10) of benzaldehydes and pyrrolopyrimidinehydrazide were proposed for in vitro anti-malarial and antioxidant investigation. These compounds were assessed for their anti-malarial efficacy against Plasmodium falciparum using a micro assay protocol, with IC50 values indicating the concentration required to inhibit parasite maturation by 50%. The Hg(II) complex displays pronounced antimalarial activity with an IC50 value of 1.98 ± 0.08 µM, closely aligning with the efficacy of quinine, whereas Zn(II), Cu(II), Pd(II) complexes demonstrates most significant anti-malarial activity, with IC50 values close to the reference compound quinine. The antioxidant activity of the compounds was evaluated using the DPPH assay, with several metal complexes such as Cu(II)and Zn(II) showing strong potential in neutralizing oxidative stress. Furthermore, molecular docking simulations were conducted to explore the binding interactions of the compounds with PfNDH2, providing insights into their pharmacological potential. The study also examined the electronic properties, solubility, and potential hepatotoxicity of the compounds. The findings suggest that the metal complexes could be promising candidates for further development as anti-malarial agents, offering enhanced potency compared to the base compound.

Drug Repurposing: A Leading Strategy for New Threats and Targets

Less than 6% of rare illnesses have an appropriate treatment option. Repurposed medications for new indications are a cost-effective and time-saving strategy that results in excellent success rates, which may significantly lower the risk associated with therapeutic development for rare illnesses. It is becoming a realistic alternative to repurposing "conventional" medications to treat joint and rare diseases considering the significant failure rates, high expenses, and sluggish stride of innovative medication advancement. This is due to delisted compounds, cheaper research fees, and faster development time frames. Repurposed drug competitors have been developed using strategic decisions based on data analysis, interpretation, and investigational approaches, but technical and regulatory restrictions must also be considered. Combining experimental and computational methodologies generates innovative new medicinal applications. It is a one-of-a-kind strategy for repurposing human-safe pharmaceuticals to treat uncommon and difficult-to-treat ailments. It is a very effective method for discovering and creating novel medications. Several pharmaceutical firms have developed novel therapies by repositioning old medications. Repurposing drugs is practical, cost-effective, and speedy and generally involves lower risks when compared to developing a new drug from the beginning.

Exploring diverse frontiers: Advancements of bioactive 4-aminoquinoline-based molecular hybrids in targeted therapeutics and beyond

Amongst heterocyclic compounds, quinoline and its derivatives are advantaged scaffolds that appear as a significant assembly motif for developing new drug entities. Aminoquinoline moiety has gained significant attention among researchers in the 21stcentury. Considering the biological and pharmaceutical importance of aminoquinoline derivatives, herein, we review the recent developments (since 2019) in various biological activities of the 4-aminoquinoline scaffold hybridized with diverse heterocyclic moieties such as quinoline, pyridine, pyrimidine, triazine, dioxine, piperazine, pyrazoline, piperidine, imidazole, indole, oxadiazole, carbazole, dioxole, thiazole, benzothiazole, pyrazole, phthalimide, adamantane, benzochromene, and pyridinone. Moreover, by gaining knowledge about SARs, structural insights, and molecular targets, this review may help medicinal chemists design cost-effective, selective, safe, and more potent 4-aminoquinoline hybrids for diverse biological activities.

Synthesis, antileishmanial, antimalarial evaluation and molecular docking study of some hydrazine-coupled pyrazole derivatives

Pyrazole-bearing compounds are known for their diverse pharmacological effects including potent antileishmanial and antimalarial activities. Herein, some hydrazine-coupled pyrazoles were successfully synthesized and their structures were verified by employing elemental microanalysis, FTIR, and 1H NMR techniques. The in vitro antileishmanial and in vivo antimalarial activities of the synthesized pyrazole derivatives (9-15) were evaluated against Leishmania aethiopica clinical isolate and Plasmodium berghei infected mice, respectively. The result revealed that compound 13 displayed superior antipromastigote activity (IC50 = 0.018) that was 174- and 2.6-fold more active than the standard drugs miltefosine (IC50 = 3.130) and amphotericin B deoxycholate (IC50 = 0.047). The molecular docking study conducted on Lm-PTR1, complexed with Trimethoprim was acquired from the Protein Data Bank (PDB ID:2bfm), justified the better antileishmanial activity of compound 13. Furthermore, the target compounds 14 and 15 elicited better inhibition effects against Plasmodium berghei with 70.2% and 90.4% suppression, respectively. In conclusion, the hydrazine-coupled pyrazole derivatives may be considered potential pharmacophores for the preparation of safe and effective antileishmanial and antimalarial agents.

Identification of starvation-mimetic bioactive phytocomponent from Withania somnifera using in-silico molecular modelling and flow cytometry-based analysis for the management of malaria

Multidrug resistance episodes in malaria increased from 3.9% to 20% from 2015 to 2019. Synchronizing the clinical manifestation in chronological sequence led to a unique impression on glucose demand (increased up to 100-fold) by the parasite-infected RBCs. Hence, restriction in the glucose uptake to parasite-infected RBCs could be an alternative approach to conquer the global burden of malaria to a greater extent. A C28 steroidal lactone Withaferin A (WS-3) isolated from Withania somnifera leave extract shows better thermodynamically stable interactions with the glucose transporters (GLUT-1 and PfHT) to standard drugs metformin and lopinavir. MD simulations for a trajectory period of 100 ns reflect stable interactions with the interactive amino acid residues such as Pro141, Gln161, Gln282, Gln283, Trp388, Phe389, and Phe40, Asn48, Phe85, His168, Gln169, Asn311 which potentiating inhibitory activity of WS-3 against GLUT-1 and PfHT respectively. WS-3 was non-hemotoxic (%hemolysis <5%) for a high concentration of up to 1 mg/ml in the physiological milieu. However, the %hemolysis significantly increased up to 30.55 ± 0.929% in a parasitophorous simulated environment (pH 5.0). Increased hemolysis of WS-3 could be due to the production of ROS in an acidic environment. Further, the inhibitory activity of WS-3 against both glucose transporters was supported with flow cytometry-based analysis of parasite-infected RBCs. Results show that WS-3 has low mean fluorescence intensities for both target proteins compared to conventional drugs, suggesting a potential sugar transporter inhibitor against GLUT-1 and PfHT for managing malaria. Communicated by Ramaswamy H. Sarma.

Recent developments in antimalarial activities of 4-aminoquinoline derivatives

Malaria is the fifth most lethal parasitic infection in the world. Antimalarial medications have played a crucial role in preventing and eradicating malaria. Numerous heterocyclic moieties have been incorporated into the creation of effective antimalarial drugs. The 4-aminoquinoline moiety is favoured in antimalarial drug discovery due to the diverse biological applications of its derivative. Since the 1960s, 4-aminoquinoline has been an important antimalarial drug due to its low toxicity, high tolerability, and rapid absorption after administration. This review focused on the antimalarial efficacy of the 4-aminoquinoline moiety hybridised with various heterocyclic scaffolds developed by scientists since 2018 against diverse Plasmodium clones. It could aid in the future development of more effective antimalarial agents.

7-Chloroquinolinehydrazones as First-in-Class Anticancer Experimental Drugs in the NCI-60 Screen among Different Investigated Series of Aryl, Quinoline, Pyridine, Benzothiazole and Imidazolehydrazones

In the context of a continuously increasing global cancer risk, the search for new effective and affordable anticancer drugs remains a constant demand. This study describes chemical experimental drugs able to destroy cancer cells by arresting their growth. New hydrazones with quinoline, pyridine, benzothiazole and imidazole moieties have been synthesized and evaluated for their cytotoxic potential against 60 cancer cell lines. 7-Chloroquinolinehydrazones were the most active in the current study and exhibited good cytotoxic activity with submicromolar GI₅₀ values on a large panel of cell lines from nine tumor types (leukemia, non-small cell lung cancer, colon cancer, CNS cancer, melanoma, ovarian cancer, renal cancer, prostate cancer and breast cancer). This study provided consistent structure-activity relationships in this series of experimental antitumor compounds.

Drug Repurposing: An Effective Tool in Modern Drug Discovery

Drug repurposing is using an existing drug for a new treatment that was not indicated before. It has received immense attention during the COVID-19 pandemic emergency. Drug repurposing has become the need of time to fasten the drug discovery process and find quicker solutions to the over-exerted healthcare scenario and drug needs. Drug repurposing involves identifying the drug, evaluating its efficiency using preclinical models, and proceeding to phase II clinical trials. Identification of the drug candidate can be made through computational and experimental approaches. This approach usually utilizes public databases for drugs. Data from primary and translational research, clinical trials, anecdotal reports regarding off-label uses, and other published human data information available are included. Using artificial intelligence algorithms and other bioinformatics tools, investigators systematically try to identify the interaction between drugs and protein targets. It can be combined with genetic data, clinical analysis, structure (molecular docking), pathways, signatures, targets, phenotypes, binding assays, and artificial intelligence to get an optimum outcome in repurposing. This article describes the strategies involved in drug repurposing and enlists a series of repurposed drugs and their indications.

Multi-target molecular dynamic simulations reveal glutathione-S-transferase as the most favorable drug target of knipholone in Plasmodium falciparum

Knipholone is an antiplasmodial phytocompound obtained from the roots of Kniphofia foliosa. Despite several available studies, the molecular drug targets of knipholone in P. falciparum remained unknown. Nowadays, in silico techniques are widely used to study the molecular interactions between compounds and proteins as they provide results quickly with high precision and accuracy. In this study, we aim to identify the potential molecular drug targets of knipholone in P. falciparum. We selected 10 proteins of P. falciparum with unique metabolic functions and we found that knipholone showed better binding affinity than the native ligands of 6 proteins. Out of the 6 proteins, knipholone showed better enzyme inhibitory potential than the native ligands of 4 proteins. We carried out a 100 ns MD simulations for knipholone and the native ligands of four proteins and this was followed by binding free energy calculations. In each step, the performance of knipholone was compared to the native ligands of the proteins. Knipholone outperformed the native ligand of Glutathione-S-Transferase (1OKT) at crucial computational studies as evidence from the lower protein-ligand root mean square deviation value, protein root mean square fluctuation value, and protein-ligand binding free energies. The ligand properties of knipholone provide additional evidence for its stability and it maintains adequate protein-ligand contacts during the entire simulation. The density functional theory study also supported the stability of knipholone at the active binding site of 1OKT. From the studied proteins, we conclude that Glutathione-S-Transferase is the most favorable drug target for knipholone in P. falciparum.Communicated by Ramaswamy H. Sarma.

Recent advances in functionalized quinoline scaffolds and hybrids-Exceptional pharmacophore in therapeutic medicine

Quinoline is one of the most common nitrogen-containing heterocycles owing to its fascinating pharmacological properties and synthetic value in organic and pharmaceutical chemistry. Functionalization of this moiety at different positions has allowed for varying pharmacological activities of its derivative. Several publications over the last few decades have specified various methods of synthesis. This includes classical methods of synthesizing the primary quinoline derivatives and efficient methods that reduce reaction time with increased yield employing procedures that fulfill one of the twelve green chemistry principles, "safer solvent". The metal nanoparticle-catalyzed reaction also serves as a potent and effective technique for the synthesis of quinoline with excellent atom efficiency. The primary focus of this review is to highlight the routes to synthesizing functionalized quinoline derivatives, including hybrids that have moieties with predetermined activities bound to the quinoline moiety which are of interest in synthesizing drug candidates with dual modes of action, overcoming toxicity, and resistance amongst others. This was achieved using updated literature, stating the biological activities and mechanisms through which these compounds administer relief. The ADMET studies and Structure-Activity Relationship (SAR) of novel derivatives were also highlighted to explore the drug-likeness of the quinoline-hybrids and the influence of substituent characteristics and position on the biological activity of the compounds.

Combating Lassa Fever in West African Sub-Region: Progress, Challenges, and Future Perspectives

Lassa fever (LF) is a rodent-borne disease that threatens human health in the sub-region of West Africa where the zoonotic host of Lassa virus (LASV) is predominant. Currently, treatment options for LF are limited and since no preventive vaccine is approved for its infectivity, there is a high mortality rate in endemic areas. This narrative review explores the transmission, pathogenicity of LASV, advances, and challenges of different treatment options. Our findings indicate that genetic diversity among the different strains of LASV and their ability to circumvent the immune system poses a critical challenge to the development of LASV vaccines/therapeutics. Thus, understanding the biochemistry, physiology and genetic polymorphism of LASV, mechanism of evading host immunity are essential for development of effective LASV vaccines/therapeutics to combat this lethal viral disease. The LASV nucleoprotein (NP) is a novel target for therapeutics as it functions significantly in several aspects of the viral life cycle. Consequently, LASV NP inhibitors could be employed as effective therapeutics as they will potentially inhibit LASV replication. Effective preventive control measures, vaccine development, target validation, and repurposing of existing drugs, such as ribavirin, using activity or in silico-based and computational bioinformatics, would aid in the development of novel drugs for LF management.

In silico screening of phytopolyphenolics for the identification of bioactive compounds as novel protease inhibitors effective against SARS-CoV-2

Due to the unavailability specific drugs or vaccines (FDA approved) that can cure COVID-19, the development of potent antiviral drug candidates/therapeutic molecules against COVID-19 is urgently required. This study was aimed at in silico screening and study of polyphenolic phytochemical compounds in a rational way by virtual screening, molecular docking and molecular dynamics studies against SARS-CoV-2 main protease (Mpro) and papain-like protease (PLpro) enzymes. The objective of the study was to identify plant-derived polyphenolic compounds and/or flavonoid molecules as possible antiviral agents with protease inhibitory potential against SARS-CoV-2. In this study, we report plant-derived polyphenolic compounds (including flavonoids) as novel protease inhibitors against SARS-CoV-2. From virtual docking and molecular docking study, 31 polyphenolic compounds were identified as active antiviral molecules possessing well-defined binding affinity with acceptable ADMET, toxicity and lead-like or drug-like properties. Six polyphenolic compounds, namely, enterodiol, taxifolin, eriodictyol, leucopelargonidin, morin and myricetin were found to exhibit remarkable binding affinities against the proteases with taxifolin and morin exhibiting the highest binding affinity toward Mpro and PLpro respectively. Molecular dynamics simulation studies of these compounds in complex with the proteases showed that the binding of the compounds is characterized by structural perturbations of the proteases suggesting their antiviral activities. These compounds can therefore be investigated further by in vivo and in vitro techniques to assess their potential efficacy against SARS-CoV-2 and thus serve as the starting point for the development of potent antiviral agents against the deadly COVID-19.

Phytocompounds as potential inhibitors of SARS-CoV-2 Mpro and PLpro through computational studies

The inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) and papain-like protease (PLpro) prevents viral multiplications; these viral enzymes have been recognized as one of the most favorable targets for drug discovery against SARS-CoV-2. In the present study, we screened 225 phytocompounds present in 28 different Indian spices to identify compounds as potential inhibitors of SARS-CoV-2 Mpro and PLpro. Molecular docking, molecular dynamics simulation, molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding free energy calculations, and absorption, distribution, metabolism, excretion and toxicity (ADMET) studies were done. Based on binding affinity, dynamics behavior, and binding free energies, the present study identifies pentaoxahexacyclo-dotriacontanonaen-trihydroxybenzoate derivative (PDT), rutin, and dihyroxy-oxan-phenyl-chromen-4-one derivative (DOC), luteolin-7-glucoside-4'-neohesperidoside as promising inhibitors of SARS-CoV-2 Mpro and PLpro, respectively.

Identification of bioactive molecules from Triphala (Ayurvedic herbal formulation) as potential inhibitors of SARS-CoV-2 main protease (Mpro) through computational investigations

Severe acute respiratory syndrome coronavirus disease (SARS-CoV-2) induced coronavirus disease 2019 (COVID-19) pandemic is the present worldwide health emergency. The global scientific community faces a significant challenge in developing targeted therapies to combat the SARS-CoV-2 infection. Computational approaches have been critical for identifying potential SARS-CoV-2 inhibitors in the face of limited resources and in this time of crisis. Main protease (M^pro) is an intriguing drug target because it processes the polyproteins required for SARS-CoV-2 replication. The application of Ayurvedic knowledge from traditional Indian systems of medicine may be a promising strategy to develop potential inhibitor for different target proteins of SARS-CoV-2. With this endeavor, we docked bioactive molecules from Triphala, an Ayurvedic formulation, against M^pro followed by molecular dynamics (MD) simulation (100 ns) to investigate their inhibitory potential against SARS-CoV-2. The top four best docked molecules (terflavin A, chebulagic acid, chebulinic acid, and corilagin) were selected for MD simulation study and the results obtained were compared to native ligand X77. From docking and MD simulation studies, the selected molecules showed promising binding affinity with the formation of stable complexes at the active binding pocket of M^pro and exhibited negative binding energy during MM-PBSA calculations, indication their strong binding affinity with the target protein. The identified bioactive molecules were further analyzed for drug-likeness by Lipinski's filter, ADMET and toxicity studies. Computational (in silico) investigations identified terflavin A, chebulagic acid, chebulinic acid, and corilagin from Triphala formulation as promising inhibitors of SARS-CoV-2 M^pro, suggesting experimental (in vitro/in vivo) studies to further explore their inhibitory mechanisms.

Repurposing of phytomedicine-derived bioactive compounds with promising anti-SARS-CoV-2 potential: Molecular docking, MD simulation and drug-likeness/ADMET studies

In view of the potential of traditional plant-based remedies (or phytomedicines) in the management of COVID-19, the present investigation was aimed at finding novel anti-SARS-CoV-2 molecules by in silico screening of bioactive phytochemicals (database) using computational methods and drug repurposing approach. A total of 160 compounds belonging to various phytochemical classes (flavonoids, limonoids, saponins, triterpenoids, steroids etc.) were selected (as initial hits) and screened against three specific therapeutic targets (Mpro/3CLpro, PLpro and RdRp) of SARS-CoV-2 by docking, molecular dynamics simulation and drug-likeness/ADMET studies. From our studies, six phytochemicals were identified as notable ant-SARS-CoV-2 agents (best hit molecules) with promising inhibitory effects effective against protease (Mpro and PLpro) and polymerase (RdRp) enzymes. These compounds are namely, ginsenoside Rg2, saikosaponin A, somniferine, betulinic acid, soyasapogenol C and azadirachtin A. On the basis of binding modes and dynamics studies of protein-ligand intercations, ginsenoside Rg2, saikosaponin A, somniferine were found to be the most potent (in silico) inhibitors potentially active against Mpro, PLpro and RdRp, respectively. The present investigation can be directed towards further experimental studies in order to confirm the anti-SARS-CoV-2 efficacy along with toxicities of identified phytomolecules.