Synthesis and biological evaluation of a new class of 4-aminoquinoline–rhodanine hybrid as potent anti-infective agents

Arylidene and amino spacer-linked rhodanine-quinoline hybrids as upgraded antimicrobial agents

Antibiotic resistance associated with various microorganisms such as Gram-positive, Gram-negative, fungal strains, and multidrug-resistant tuberculosis increases the risk of healthcare survival. Preliminary therapeutics becoming ineffective that might lead to noteworthy mortality presents a crucial challenge for the scientific community. Hence, there is an urgent need to develop hybrid compounds as antimicrobial agents by combining two or more bioactive heterocyclic moieties into a single molecular framework with fewer side effects and a unique mode of action. This review highlights the recent advances (2013-2023) in the pharmacology of rhodanine-linked quinoline hybrids as more effective antimicrobial agents. In the drug development process, linker hybrids acquire the top position due to their excellent π-stacking and Van der Waals interaction with the DNA active sites of pathogens. A molecular hybridization strategy has been optimized, indicating that combining these two bioactive moieties with an arylidene and an amino spacer linker increases the antimicrobial potential and reduces drug resistance. Moreover, the structure-activity relationship study is discussed to express the role of various functional groups in improving and decrementing antimicrobial activities for rational drug design. Also, a linker approach may accelerate the development of dynamic antimicrobial agents through molecular hybridization.

Design, synthesis and biological evaluation of 3-substituted-2-thioxothiazolidin-4-one (rhodanine) derivatives as antitubercular agents against Mycobacterium tuberculosis protein tyrosine phosphatase B

Mycobacterium tuberculosis infections still pose a serious threat to human health. Combination therapies are effective medical solutions to the problem. Mycobacterium tuberculosis is an intracellular pathogen that mainly depends on a virulence factor (Mycobacterium tuberculosis protein tyrosine phosphatase B, MptpB) for its survival in the host. Therefore, MptpB inhibitors are potential components of tuberculosis combination treatments. Herein, a new series of MptpB inhibitors bearing a rhodanine group were developed using a structure-based strategy based on the virtual screening hit. The new MptpB inhibitors displayed potent MptpB inhibitory activities and great improvements in cell membrane permeability. The optimal compounds reduced the bacterial burden in a dose-dependent manner in a macrophage infection model, especially, a combination of compound 20 and rifampicin led to a bacterial burden reduction of more than 95%, greater than the reductions achieved with compound 20 or rifampicin alone. This research provides new insights into the rational design of new MptpB inhibitors and verifies that the MptpB inhibitor has a promising potential as a component of tuberculosis treatment.

Spotlight on 4-substituted quinolines as potential anti-infective agents: Journey beyond chloroquine

Continued emerging resistance of pathogens against the clinically approved candidates and their associated limitations continuously demand newer agents having better potency with a more suited safety profile. Quinoline nuclei containing scaffolds of natural and synthetic origin have been documented for diverse types of pharmacological activities, and a number of drugs are clinically approved. In the present review, we unprecedentedly covered the biological potential of 4-substituted quinoline and elaborated a rationale for its special privilege to afford the significant number of approved clinical drugs, particularly against infectious pathogens. Compounds with 4-substituted quinoline are well documented for antimalarial activity, but in the last two decades, they have been extensively explored for activity against cancer, tuberculosis, and several other pathogens including viruses, bacteria, fungi, and other infectious pathogens. In the present study, the anti-infective spectrum of this scaffold is discussed against viruses, mycobacteria, malarial parasites, and fungal and bacterial strains, along with recent updates in this area, with special emphasis on the structure-activity relationship.

Rhodanine derivatives: An insight into the synthetic and medicinal perspectives as antimicrobial and antiviral agents

Rhodanine or 2-Thioxothiazolidin-4-one is a privileged heterocyclic compound offering a wide opportunity for structural modification, lead development, and modification. It is one of the highly decorated scaffolds in the drug discovery process. Rhodanine derivatives possess a plethora of biological activities due to their ability to interact with a diverse range of protein targets, which provide tremendous opportunities to discover new drugs with different modes of action. The most common strategy for developing novel rhodanine derivatives is the introduction of structurally diverse substituents at the C-5 or N-3, or both positions. Since the inception of Epralestat into the market in 1992, the exploration of rhodanine-3-acetic acids has led to the development of novel leads against different biological targets such as MRSA, HHV-6, Mycobacterial tuberculosis, dengue, etc. In the current pandemic era, some rhodanine compounds have been explored against SARS-CoV-2. In recent years, rhodanine and its derivatives have witnessed significant progress in developing new drug leads as potential antimicrobial and antiviral agents. Different synthetic methodologies and recent developments in the medicinal chemistry of rhodanine derivatives, including biological activities, their mechanistic aspects, structure-activity relationships, and in silico findings, have been compiled in the present review. This article will benefit the scientific community and offer perspectives on how these scaffolds as privileged structures might be exploited in the future for rational design and discovery of rhodanine-based bio-active molecules.

Piperonyl-Tethered Rhodanine Derivatives Potently Inhibit Chitinolytic Enzymes of Ostrinia furnacalis

Insect pest chitinases are potential target for developing new insect growth regulators. Piperine was found first to inhibit the insect chitinase (OfChi-h) from Ostrinia furnacalis (Asian corn borer) in this work, except for previously reported OfChtI. Novel piperonyl-tethered rhodanine derivatives 7a-j were rationally designed with piperine as lead and synthesized by introducing a unique rhodanine moiety into the piperine scaffold based on the similar binding cavity of OfChtI and OfChi-h. Compared to piperine, compounds 7a-j showed approximately 100- to 400-fold or 110- to 210-fold higher inhibitory capacity against two chitinases, respectively. Molecular mechanism studies indicated that π interactions are crucial for improving inhibitory activity against two chitinases due to the introduction of the conjugated rhodanine ring. Moreover, compounds 7a-c could dramatically inhibit the growth and development of O. furnacalis larvae by in vivo activity evaluation. This study provides novel piperonyl-tethered rhodanine derivatives inhibiting dual chitinases as insect growth regulator candidates.

Evaluation of xanthene-appended quinoline hybrids as potential leads against antimalarial drug targets

A series of fused heterocycle xanthene-appended quinoline 6a-n was successfully synthesized with regioselectivity and characterized using IR, ¹H NMR, ¹³C NMR, and mass spectral data. Molecular docking was performed to find the binding efficacy of all these newly synthesized compounds towards thirteen antimalarial drug targets. Molecular dynamics simulation was carried out to predict the stability of the ligand-bound complex in a solvent medium. Blind and site-directed docking with compounds 6a-n against 13 drug targets revealed most of the ligands to have a good binding affinity with the targets. Analysis on the basis of binding energy, binding modalities of the ligands, intermolecular interactions, and pharmacophore, we identified only one of the ligand-receptor complexes to provide better results. Molecular dynamic simulation of the selected receptor-ligand complex revealed that the synthesized compound had a better binding affinity with the receptor than the native ligand complex. Further analysis of the synthesized ligand in the laboratory may prove promising results in the search for potential antimalarial drugs.

Synthesis of novel indole-thiazolidinone hybrid structures as promising scaffold with anticancer potential

A series of novel indole-azolidinone hybrids has been synthesized via Knoevenagel reaction of 5-fluoro-3-formyl-1H-indole-2-carboxylic acid methyl ester and some azolidinones differing in heteroatoms in positions 1, 2 and 4. Their anticancer activity in vitro was screened towards MCF-7 (breast cancer), HCT116 (colon cancer), HepG2 (hepatoma), HeLa (cervical cancer), A549 (lung cancer), WM793 (melanoma) and THP-1 (leukemia) cell lines, and a highly active 5-fluoro-3-(4-oxo-2-thioxothiazolidin-5-ylidenemethyl)-1H-indole-2-carboxylic acid methyl ester (3a) was identified and subjected to in-depth investigation of cytotoxicity mechanisms. This compound was found to possess the highest cytotoxic action towards tumor cells comparing with the action of other derivatives (1, 3b, 3c, 3d, 3e). Compound 3a exhibited toxicity toward MCF-7, HCT116, and A549, HepG2 cancer cells, while the non-malignant cells (human keratinocytes of HaCaT line and murine embryonic fibroblasts of Balb/c 3T3 line) possessed moderate sensitivity to it. The compound 3a induced apoptosis in studied tumor cells via caspase 3-, PARP1-, and Bax-dependent mechanisms; however, it did not affect the G1/S transition in HepG2 cells. The compound 3a impaired nuclear DNA in HepG2, HCT116, and MCF-7 cells without intercalating this biomolecule, but much less DNA damage events were induced by 3a in normal Balb/c 3T3 fibroblasts compared with HepG2 carcinoma cells. Thus, 5-fluoro-3-(4-oxo-2-thioxothiazolidin-5-ylidenemethyl)-1H-indole-2-carboxylic acid methyl ester 3a was shown to trigger DNA damage and induce apoptosis of human tumor cells and it might be considered as an anticancer agent perspective for in-depth studies.

5-Arylidene-2-(4-hydroxyphenyl)aminothiazol-4(5H)-ones with selective inhibitory activity against some leukemia cell lines

The data on the pharmacology of 4-thiazolidinones showed that 5-ene-2-(imino)amino-4-thiazolidinones are likely to comprise one of the most promising groups of compounds possessing anticancer properties. A series of 5-arylidene-2-(4-hydroxyphenyl)aminothiazol-4(5H)-ones was designed, synthesized, and studied against 10 leukemia cell lines, including the HL-60, Jurkat, K-562, Dami, KBM-7, and some Ba/F3 cell lines. The structure-activity relationship analysis shows that almost all tested 5-arylidene-2-(4-hydroxyphenyl)aminothiazol-4(5H)-ones were characterized by ІС₅₀ values lower or comparable to that of the control drug chlorambucil. Among the tested compounds, (5Z)-5-(2-methoxybenzylidene)- (12), (5Z)-(2-ethoxybenzylidene)- (21), (5Z)-5-(2-benzyloxybenzylidene)- (25), and (5Z)-5-(2-allyloxybenzylidene)-2-(4-hydroxyphenylamino)thiazol-4(5H)-ones (28) possessed the highest antileukemic activity at submicromolar concentrations (ІС₅₀  = 0.10-0.95 µM).

Molecular Hybridization as a Tool in the Design of Multi-target Directed Drug Candidates for Neurodegenerative Diseases

Neurodegenerative Diseases (NDs) are progressive multifactorial neurological pathologies related to neuronal impairment and functional loss from different brain regions. Currently, no effective treatments are available for any NDs, and this lack of efficacy has been attributed to the multitude of interconnected factors involved in their pathophysiology. In the last two decades, a new approach for the rational design of new drug candidates, also called multitarget-directed ligands (MTDLs) strategy, has emerged and has been used in the design and for the development of a variety of hybrid compounds capable to act simultaneously in diverse biological targets. Based on the polypharmacology concept, this new paradigm has been thought as a more secure and effective way for modulating concomitantly two or more biochemical pathways responsible for the onset and progress of NDs, trying to overcome low therapeutical effectiveness. As a complement to our previous review article (Curr. Med. Chem. 2007, 14 (17), 1829-1852. https://doi.org/10.2174/092986707781058805), herein we aimed to cover the period from 2008 to 2019 and highlight the most recent advances of the exploitation of Molecular Hybridization (MH) as a tool in the rational design of innovative multifunctional drug candidate prototypes for the treatment of NDs, specially focused on AD, PD, HD and ALS.

Design and synthesis of 4-Aminoquinoline-isoindoline-dione-isoniazid triads as potential anti-mycobacterials

A series of 4-aminoquinoline-isoindoline-dione-isoniazid triads were synthesized and assessed for their anti-mycobacterial activities and cytotoxicity. Most of the synthesized compounds exhibited promising activities against the mc²6230 strain of M. tuberculosis with MIC in the range of 5.1-11.9 µM and were non-cytotoxic against Vero cells. The conjugates lacking either isoniazid or quinoline core in their structural framework failed to inhibit the growth of M. tuberculosis; thus, further strengthening the proposed design of triads in the present study.

Development of Novel Glitazones as Antidiabetic Agents: Molecular Design, Synthesis, Evaluation of Glucose Uptake Activity and SAR Studies

Background:

Thiazolidinediones and its bioisostere, namely, rhodanines have become ubiquitous class of heterocyclic compounds in drug design and discovery. In the present study, as part of molecular design, a series of novel glitazones that are feasible to synthesize in our laboratory were subjected to docking studies against PPAR-γ receptor for their selection.

Methods and Results:

As part of the synthesis of selected twelve glitazones, the core moiety, pyridine incorporated rhodanine was synthesized via dithiocarbamate. Later, a series of glitazones were prepared via Knovenageal condensation. In silico docking studies were performed against PPARγ protein (2PRG). The titled compounds were investigated for their cytotoxic activity against 3T3-L1 cells to identify the cytotoxicity window of the glitazones. Further, within the cytotoxicity window, glitazones were screened for glucose uptake activity against L6 cells to assess their possible antidiabetic activity.

Conclusion:

Based on the glucose uptake results, structure activity relationships are drawn for the title compounds.

Prediction of the inhibitory concentrations of chloroquine derivatives using deep neural networks models

In recent years, deep neural networks have begun to receive much attention, which has obvious advantages in feature extraction and modeling. However, in the using of deep neural networks for the QSAR modeling process, the selection of various parameters (number of neurons, hidden layers, transfer functions, data set partitioning, number of iterations, etc.) becomes difficult. Thus, we proposed a new and easy method for optimizing the model and selecting Deep Neural Networks (DNN) parameters through uniform design ideas and orthogonal design methods. By using this approach, 222 chloroquine (CQ) derivatives with half maximal inhibitory concentration values reported in different kinds of literature were selected to establish DNN models and a total number of 128,000 DNN models were built to determine the optimized parameters for selecting the better models. Comparing with linear and Artificial Neural Network (ANN) models, we found that DNN models showed better performance.Communicated by Ramaswamy H. Sarma.

Synthesis and biological evaluation of tryptophan-derived rhodanine derivatives as PTP1B inhibitors and anti-bacterial agents

Several series of novel tryptophan-derived rhodanine derivatives were synthesized and identified as potential competitive PTP1B inhibitors and antibacterial agents. Among the compounds studied, 10b was found to have the best in vitro inhibition activity against PTP1B (IC₅₀ = 0.36 ± 0.02 μM). In addition, the compounds also showed potent inhibition against other PTPs, especially CDC25B. Molecular docking analysis demonstrated that compounds 7c and 10b could occupy both the catalytic site and the adjacent pTyr binding site simultaneously. The compounds also showed higher levels of activity against gram-positive strains, the gram-negative strain Escherichia coli 1924, and multidrug-resistant gram-positive bacterial strains. Compounds 7c, 8c, 9e, 10a, and 10c had comparable or more potent antibacterial activity than the positive controls.

Recent developments with rhodanine as a scaffold for drug discovery

INTRODUCTION

Rhodanines, as one of the 4-thiazolidinones subtypes, are recognized as privileged heterocycles in medicinal chemistry. The main achievements include the development of drug-like molecules with numerous biological activities as well as approved drugs. Among rhodanines, 5-ene-rhodanines are of special interest, and are often claimed as pan assay interference compounds due to Michael acceptor functionality. Areas covered: Herein, the synthetic protocols for rhodanines and their transformation are reviewed. Biological activity is briefly discussed as well as biotargets, mode of actions and optimization directions. Furthermore, the utilization of 5-ene-rhodanines in Michael additions are discussed while both pro and contra arguments have been outlined within medicinal chemistry application. Expert opinion: Rhodanines remain privileged heterocycles in drug discovery. They are accessible building blocks for optimization and transformation into related heterocycles, simplified analogues and fused heterocycles with a thiazolidine framework. Michael acceptor functionality, as well as the thesis about low selectivity towards biotargets of rhodanines, must be confirmed experimentally and it cannot be based on just the presence of conjugated α,β-unsaturated carbonyl. Moreover, the positive aspects of Michael acceptors must be considered as well as their multitarget properties. New criteria for target affinity must be found. In conclusion, rhodanines are generally not problematic per se.

Synthesis, α-glucosidase inhibition and molecular docking studies of novel thiazolidine-2,4-dione or rhodanine derivatives

A series of novel thiazolidine-2,4-dione or rhodanine derivatives (5a-5k, 6a-6k) were synthesized and evaluated for their α-glucosidase inhibitory activity. The majority of compounds exhibited potent inhibitory activity in the range of 5.44 ± 0.13 to 50.45 ± 0.39 μM, when compared to the standard drug acarbose (IC₅₀ = 817.38 ± 6.27 μM). Among the compounds in the series, compounds 5k, 6a, 6b, 6e, 6h and 6k showed potent inhibitory potential with IC₅₀ values of 20.95 ± 0.21, 16.11 ± 0.19, 7.72 ± 0.16, 7.91 ± 0.17, 6.59 ± 0.15 and 5.44 ± 0.13 μM, respectively. Compound 6k (IC₅₀ = 5.44 ± 0.13 μM), containing chloro and rhodanine groups at the 2- and 4-positions of the phenyl ring respectively, was found to be the most active compound that inhibits α-glucosidase activity. Furthermore, molecular docking studies were performed to understand the binding interactions between the molecule and enzyme.

Comprehensive review on various strategies for antimalarial drug discovery

The resistance of malaria parasites to existing drugs carries on growing and progressively limiting our ability to manage this severe disease and finally lead to a massive global health burden. Till now, malaria control has relied upon the traditional quinoline, antifolate and artemisinin compounds. Very few new antimalarials were developed in the past 50 years. Among recent approaches, identification of novel chemotherapeutic targets, exploration of natural products with medicinal significance, covalent bitherapy having a dual mode of action into a single hybrid molecule and malaria vaccine development are explored heavily. The proper execution of these approaches and proper investment from international agencies will accelerate the discovery of drugs that provide new hope for the control or eventual eradication of this global infectious disease. This review explores various strategies for assessment and development of new antimalarial drugs. Current status and scientific value of previous approaches are systematically reviewed and new approaches provide a pragmatic forecast for future developments are introduced as well.

Hybrid molecules: The privileged scaffolds for various pharmaceuticals

The practice of polypharmacology is not a new concept but the approaches which are being adopted for administering the two or more drugs together are varied from time to time. Taking two or more drugs simultaneously, co-formulation of two or more active agents in a single tablet and development of hybrid molecular entities capable to modulate multiple targets are the three popular approaches for multidrug therapy. The simultaneous use of more than one drug for the chemotherapy of a single disease demands a lot of patient compliance. Hence the present form of polypharmacology is gaining popularity in the form of hybrid molecules (multiple ligand approach). From the last 1-2 decades, the synthesis of hybrid molecules by the combination of different biologically relevant moieties has been under constant escalation along with their evaluation as diverse range of pharmacological agents and as potent drugs. This review is focused on the biological potential of hybrid molecules with particular mention of those exhibiting anti-fungal, anti-tuberculosis, anti-malarial, anti-inflammatory and anti-cancer activities. A comparison of the drug potency of the hybrid molecules with their individual counterparts is discussed for quantifying the significance of the concept of molecular hybridisation.

4-Aminoquinoline-hybridization en route towards the development of rationally designed antimalarial agents

Recent developments in 4-aminoquinoline-hybridization, as an attractive strategy for averting and delaying the drug resistance along with improvement in efficacy of new antimalarials, are described.

Quinoline-based antimalarial hybrid compounds

Quinoline-containing compounds, such as quinine and chloroquine, have a long-standing history as potent antimalarial agents. However, the increasing resistance of the Plasmodium parasite against these drugs and the lack of licensed malaria vaccines have forced chemists to develop synthetic strategies toward novel biologically active molecules. A strategy that has attracted considerable attention in current medicinal chemistry is based on the conjugation of two biologically active molecules into one hybrid compound. Since quinolines are considered to be privileged antimalarial building blocks, the synthesis of quinoline-containing antimalarial hybrids has been elaborated extensively in recent years. This review provides a literature overview of antimalarial hybrid molecules containing a quinoline core, covering publications between 2009 and 2014.

New class of methyl tetrazole based hybrid of (Z)-5-benzylidene-2-(piperazin-1-yl)thiazol-4(%H)-one as potent antitubercular agents

In search of potential therapeutics for tuberculosis, we describe here the synthesis and in vitro antitubercular activity of a novel series of thiazolone piperazine tetrazole derivatives. Among all the synthesized derivatives, four compounds (10, 14, 20 and 33) exhibited more potent activity (MIC=3.08, 3.01, 2.62 and 2.51 μM) than ethambutol (MIC=9.78 μM) and pyrazinamide (MIC=101.53 μM) against Mycobacterium tuberculosis. Furthermore, they displayed no toxicity against Vero cells (C1008) and mouse bone marrow derived macrophages (MBMDMϕ). These investigated analogues have emerged as possible lead molecule to enlarge the scope of the study.

Synthesis and biological evaluation of new rhodanine analogues bearing 2-chloroquinoline and benzo[h]quinoline scaffolds as anticancer agents

Several rhodanine derivatives (9-39) were synthesized for evaluation of their potential as anticancer agents. Villsmeier cyclization to synthesize aza-aromatic aldehydes, rhodanine derivatives preparation and Knoevenagel type of condensation between the rhodanines and aza-aromatic aldehydes are key steps used for the synthesis of 31 compounds. In vitro antiproliferative activity of the synthesized rhodanine derivatives (9-39) was studied on a panel of six human tumor cell lines viz. HGC, MNK-74, MCF-7, MDAMB-231, DU-145 and PC-3 cell lines. Some of the compounds were capable of inhibiting the proliferation of cancer cell lines at a micromolar concentration. Six compounds are found to be potent against HGC cell lines; compound 15 is found to be active against HGC - Gastric, MCF7 - Breast Cancer and DU145 - Prostate Cancer cell lines; compound 39 is potent against MNK-74; four compounds are found to be potent against MCF-7 cell lines; three compounds are active against MDAMB-231; nine compounds are found to be potent against DU-145; three compounds are active against PC-3 cell lines. These compounds constitute a promising starting point for the development of novel and more potent anticancer agents in future.

Investigation of Ugi-4CC derived 1H-tetrazol-5-yl-(aryl) methyl piperazinyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid: synthesis, biology and 3D-QSAR analysis

Novel series of 7-piperazinylquinolones with tetrazole derivatives were synthesized and evaluated for their antibacterial activity against various strains of Staphylococcus aureus. All the synthesized compounds showed significant in vitro antibacterial activity against Gram-positive bacteria whereas some compounds displayed moderate activity against Gram-negative bacteria. Among all the synthesized compounds, compounds (6a-c, 6e-g, 6i-k, 6m, 6'f and 6'm) were found to be more effective with MIC ranging from (0.78-3.12 μg/mL) against S. aureus (ATCC-29213) than the control; ciprofloxacin (MIC = 25 μg/mL). Moreover, these analogues displayed no toxicity up to MIC = 0.39 μg/mL against mammalian cell line L-929. Furthermore, to correlate the biological activities of synthesized compounds with their 3D conformation, we attempted 3D-QSAR study.

Discovery of triazine mimetics as potent antileishmanial agents

The World Health Organization has classified the leishmaniasis as a major tropical disease. The discovery of new compounds for leishmaniasis is therefore a pressing concern for the anti-infective research program. We have synthesized 19 compounds of triazine dimers as novel antileishmanial agents. Most of the synthesized derivatives exhibited better activity against intracellular amastigotes (IC50 ranging from 0.77 to 10.32 μM) than the control, pentamidine (IC50 = 13.68 μM), and are not toxic to Vero cells. Compounds 14 and 15 showed significant in vivo inhibition of 74.41% and 62.64%, respectively, in L. donovani/hamster model. Moreover, expansion of Th1-type and suppression of Th2-type immune responses proved that compound 14 stimulates mouse macrophages to prevent the progression of leishmania parasite. The molecular docking studies involving PTR1 protein PDB further validated the concepts involved in the design of these compounds. Among the investigated analogues, compound 14 has emerged as the potential one to enlarge the scope of the study.

Synthesis of 4-aminoquinoline-pyrimidine hybrids as potent antimalarials and their mode of action studies

One of the most viable options to tackle the growing resistance to the antimalarial drugs such as artemisinin is to resort to synthetic drugs. The multi-target strategy involving the use of hybrid drugs has shown promise. In line with this, new hybrids of quinoline with pyrimidine have been synthesized and evaluated for their antiplasmodial activity against both CQ(S) and CQ(R) strains of Plasmodium falciparum. These depicted activity in nanomolar range and were found to bind to heme as well as AT rich pUC18 DNA.

Synthesis and bioevaluation of novel 4-aminoquinoline-tetrazole derivatives as potent antimalarial agents

A series of novel tetrazole derivatives of 4-aminoquinoline were synthesized and screened for their antimalarial activities against both chloroquine-senstive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum as well as for cytotoxicity against VERO cell lines. Most of the synthesized compounds exhibited potent antimalarial activity as compared to chloroquine against K1-strain. Compounds with significant in vitro antimalarial activity were then evaluated for their in vivo efficacy in Swiss mice against Plasmodium yoelii following both intraperitoneal (ip) and oral administration, wherein compounds 20 and 23 each showed in vivo suppression of 99.99% parasitaemia on day 4.