1H-1,2,3-triazole tethered mono- and bis-ferrocenylchalcone-β-lactam conjugates: Synthesis and antimalarial evaluation

Exploring antimalarial potential: Conjugating organometallic moieties with organic fragments for enhanced efficacy

In the search for novel ligands with efficacy against various diseases, particularly parasitic diseases, molecular hybridization of organometallic units into biologically active scaffolds has been hailed as an appealing strategy in medicinal chemistry. The conjugation to organometallic fragments can be achieved by an appropriate linker or by directly coordinating the existing drugs to a metal. The success of Ferroquine (FQ, SR97193), an effective chloroquine-ferrocene conjugate currently undergoing the patient-exploratory phase as a combination therapy with the novel triaminopyrimidine ZY-19489 for malaria, has sparked intense interest in organometallic compound drug discovery. We present the evolution of organometallic antimalarial agents over the last decade, focusing on the parent moiety's class and the type of organometallics involved. Four main organometallic antimalarial compounds have been chosen based on conjugated organic moieties: existing antimalarial drugs, other clinical drugs, hybrid drugs, and promising scaffolds of thiosemicarbazones, benzimidazoles, and chalcones, in particular. The presented insights contribute to the ongoing discourse on organometallic compound drug development for malaria diseases.

Novel Benzotriazole-β-lactam Derivatives as Antimalarial Agents: Design, Synthesis, Biological Evaluation and Molecular Docking Studies

Many people around the world suffer from malaria, especially in tropical or subtropical regions. While malaria medications have shown success in treating malaria, there is still a problem with resistance to these drugs. Herein, we designed and synthesized some structurally novel benzotriazole-β-lactams using 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid as a key intermediate. To synthesize the target molecules, the ketene-imine cycloaddition reaction was employed. First, The reaction of 1H-benzo[d][1,2,3]triazole with 2-bromoacetic acid in aqueous sodium hydroxide yielded 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid. Then, the treatment of 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid with tosyl chloride, triethyl amine, and Schiff base provided new β-lactams in good to moderate yields.The formation of all cycloadducts was confirmed by elemental analysis, FT-IR, NMR and mass spectral data. Moreover, X-ray crystallography was used to determine the relative stereochemistry of 4a compound. The in vitro antimalarial activity test was conducted for each compound against P. falciparum K1. The IC50 values ranged from 5.56 to 25.65 μM. A cytotoxicity profile of the compounds at 200 μM final concentration revealed suitable selectivity of the compounds for malaria treatment. Furthermore, the docking study was carried out for each compound into the P. falciparum dihydrofolate reductase enzyme (PfDHFR) binding site to analyze their possible binding orientation in the active site.

Unveiling the anticancer mechanism of 1,2,3-triazole-incorporated thiazole-pyrimidine-isoxazoles: insights from docking and molecular dynamics simulations

Cancer is a major global health concern, and the constant search for novel, selective anticancer compounds with low toxicity is never ending. Nitrogen heterocyclic compounds such as pyrimidine and triazole have been identified as potential candidates for cancer treatment. A novel series of 1,2,3-triazole incorporated thiazole-pyrimidine-isoxazole derivatives 10 (a-j) were designed, synthesized and evaluated for antitumorigenic activities against human breast cancer (MCF-7), human lung cancer (A549) and human prostate (PC3 & DU-145) various cell-lines by employing MTT assay using etoposide as the positive control. The synthesized hybrids yielded decent efficacy, which was further compared with the standard drug. Among all the molecules, 10h revealed the more potent anticancerous activities, having IC50 values ranging from 0.011 ± 0.0017 µM; 0.063 ± 0.0012 µM; 0.017 ± 0.0094 µM and 0.66 ± 0.072 µM with DU145, PC3, A549, and MCF7 cell-lines, respectively. Tubulin, being a major protein involved with diverse biological actions, also serves, as a crucial target for several clinically practiced anticancer drugs, was utilized for docking analyses to evaluate the binding affinity of ligands. Docking results demonstrates that the selected hybrids 10 (g-j) exhibited good binding affinities with protein. Subsequently, drug likeness studies were carried out on the synthesized compounds to evaluate and analyze their drug like properties such as absorption, distribution, metabolism, excretion, and toxicity (ADMET) for toxicity prediction. Based on these analyses, the selected complexes were further employed for molecular dynamic simulations to analyze stability via an exhaustive cumulative 200 nanoseconds simulation. These results suggest that the selected compounds are stable and might serve as potential inhibitors to tubulin complex. In conclusion, we propose these synthesized compounds 10 (g-j) might provide new insights into cancer treatment and have potential for future development.Communicated by Ramaswamy H. Sarma.

Roles of Virtual Screening and Molecular Dynamics Simulations in Discovering and Understanding Antimalarial Drugs

Malaria continues to be a global health threat, with approximately 247 million cases worldwide. Despite therapeutic interventions being available, patient compliance is a problem due to the length of treatment. Moreover, drug-resistant strains have emerged over the years, necessitating urgent identification of novel and more potent treatments. Given that traditional drug discovery often requires a great deal of time and resources, most drug discovery efforts now use computational methods. In silico techniques such as quantitative structure-activity relationship (QSAR), docking, and molecular dynamics (MD) can be used to study protein-ligand interactions and determine the potency and safety profile of a set of candidate compounds to help prioritize those tested using assays and animal models. This paper provides an overview of antimalarial drug discovery and the application of computational methods in identifying candidate inhibitors and elucidating their potential mechanisms of action. We conclude with the continued challenges and future perspectives in the field of antimalarial drug discovery.

Design, synthesis, anticancer evaluation and molecular docking studies of 1,2,3-triazole incorporated 1,3,4-oxadiazole-Triazine derivatives

A new library of 1,2,3-triazole-incorporated 1,3,4-oxadiazole-triazine derivatives (9a-j) was designed, synthesized, and tested in vitro for anticancer activity against PC3 and DU-145 (prostate cancer), A549 (lung cancer), and MCF-7 (breast cancer) cancer cell lines using the MTT assay with etoposide as the control drug. The compounds exhibited remarkable anticancer activity, with IC50 values ranging from 0.16 ± 0.083 μM to 11.8 ± 7.46 μM, whereas the positive control ranged from 1.97 0.45 μM to 3.08 0.135 μM. Compound 9 d with a 4-pyridyl moiety shown exceptional anticancer activity against PC3, A549, MCF-7, and DU-145 cell lines, with IC50 values of 0.17 ± 0.063 μM, 0.19 ± 0.075 μM, 0.51 ± 0.083 μM, and 0.16 ± 0.083 μM, respectively.

Sequential Diimination, Staudinger [2 + 2] Ketene-Imine Cycloaddition, and Ring-Closing Metathesis (RCM) Reactions: In Route to Bis(4-spiro-fused-β-lactams)-Based Macrocycles

Based on sequential organic transformations, that is, diimine formation, Staudinger [2 + 2] ketene-imine cycloaddition, and ring-closing metathesis (RCM) reactions, the synthesis with full structural identification including NMR and HRMS spectral data along with single X-ray diffraction analysis (for anti 7b, anti 8b, syn 9a, and anti 9b) of the first syn/anti bis-4-spiro-β-lactams-based azacrown ethers (7a,b-9a,b) is reported.

Design, Synthesis, and Anticancer Activity Evaluation of Hybrids of Azoles and Barbituric Acids

In order to find new drugs with potent antiproliferative effect, a series of novel barbituric acid derivatives containing azoles at the C-5 position were designed, synthesized, and evaluated for antiproliferative activity against three human cancer cell lines (BEL-7402, MCF-7, and HCT-116) using MTT assay. Several of the synthesized compounds exhibited potent antiproliferative effects. The most promising compound was 5-((1-(4-(trifluoromethyl)phenyl)-1H-1,2,3-triazol-4-yl) methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (3s), which showed considerably high antiproliferative activity in the BEL-7402 cell line, with a half-maximal inhibitory concentration of 4.02 µM and 20.45-fold higher selectivity for BEL-7402 cells than for normal L02 cells. The apoptosis experiment showed that compound 3s induced apoptosis and cell necrosis in a concentration-dependent manner and exert its anti-proliferative activity. Therefore, compound 3s exhibited better therapeutic activity and specificity compared with the positive control 5-fluorouracil.

1,2,3-Triazole β-lactam conjugates as antimicrobial agents

A convenient and efficient synthesis of new triazole β-lactam conjugates using click chemistry is described. β-lactam 15 and 16 were prepared using cycloaddition strategy and propargylated at N-1 to afford compounds 17 and 18. Cu-catalyzed click reaction of these β-lactams 17 and 18 with different aryl azides provided 1,2,3-triazole conjugates 6 and 7, respectively. The products were fully characterized spectroscopically and tested against Gram-(+) and Gram-(-) bacteria. Compound 7a and 7c were found to be most active.

An epigrammatic status of the 'azole'-based antimalarial drugs

The development of multidrug resistance in the malarial parasite has sabotaged majority of the eradication efforts by restraining the inhibition profile of first line as well as second line antimalarial drugs, thus necessitating the development of novel pharmaceutics constructed on appropriate scaffolds with superior potency against the drug-resistant and drug-susceptible Plasmodium parasite. Over the past decades, the infectious malarial parasite has developed resistance against most of the contemporary therapeutics, thus necessitating the rational development of novel approaches principally focused on MDR malaria. This review presents an epigrammatic collation of the epidemiology and the contemporary antimalarial therapeutics based on the 'azole' motif.

Chalcone hybrids and their antimalarial activity

Malaria, one of the most striking, re-emerging infectious diseases caused by the genus Plasmodium, places a huge burden on global healthcare systems. A major challenge in the control and eradication of malaria is the continuous emergence of increasingly widespread drug-resistant malaria, creating an urgent need to develop novel antimalarial agents. Chalcone derivatives are ubiquitous in nature and have become indispensable units in medicinal chemistry applications due to their diverse biological profiles. Many chalcone derivatives demonstrate potential in vitro and in vivo antimalarial activity, so chalcone could be a useful template for the development of novel antimalarial agents. This review covers the recent development of chalcone hybrids as antimalarial agents. The critical aspects of the design and structure-activity relationship of these compounds are also discussed.

Synthesis, characterization and in vitro anticancer activity of thiabendazole-derived 1,2,3-triazole derivatives

Thiabendazolium salts with 1,2,3-triazole motifs were synthesized and characterized; they exhibit good cytotoxic activity.

Design, synthesis, and anti-proliferative evaluation of 1H-1,2,3-triazole grafted tetrahydro-β-carboline-chalcone/ferrocenylchalcone conjugates in estrogen responsive and triple negative breast cancer cells

A series of 1H-1,2,3 triazole grafted tetrahydro-β-carboline-chalcone/ferrocenylchalcone conjugates were synthesized and in vitro evaluated against estrogen responsive (MCF-7) and triple negative (MDA-MB-231) breast cancer cells.

Copper(i)-catalysed azide–alkyne cycloaddition and antiproliferative activity of mono- and bis-1,2,3-triazole derivatives

A series of mono- and bis-1,2,3-triazole derivatives were prepared via the copper(i)-catalysed azide–alkyne cycloaddition between substituted aromatic derivatives, comprising one or two terminal alkyne groups and a selection of aromatic azides.

Computational investigations and molecular dynamics simulations envisioned for potent antioxidant and anticancer drugs using indole-chalcone-triazole hybrids

Cancer, also called malignancy, is a disease which is closely related with the oxidative stress instigated by the overproduction of vulnerable oxygen and nitrogen species. Available drugs are relatively painful and toxic and so are trailing their captivation. Keeping this in mind, we have attempted to reach a novel anti-cancer drug by taking a set of nineteen ligands which are hybrids of Indole-chalcone and triazole. These ligands were allowed to interact with the DNA dodecamer 5'(CGCGAATTCGCG)3' one by one using various docking protocols of Glide. Better docked complexes screened through docking scores and reported activity data were selected and exposed to molecular dynamics run of 20 ns. The dynamical pathways were investigated for each complex comparing the pre- and post- dynamics run. The outcome of the work is discussed in this paper. Among the better hybrids of this series, one of the molecules has shown interesting features, confirming its non-toxic nature and working as intercalator as well minor groove binder, perhaps making it suitable as a potent drug for further pharmacological use.

Current scenario of ferrocene-containing hybrids for antimalarial activity

Hybrid molecules have the potential to enhance the efficacy against both drug-sensitive and drug-resistant organisms, and Ferroquine, a ferrocene hybrid, has demonstrated great potency in clinical trials against both drug-sensitive and drug-resistant malaria. Accordingly, hybridization of ferrocene with other antimalarial pharmacophores represents a promising strategy to develop novel antimalarial candidates. This work attempts to systematically review the recent study of ferrocene hybrids in the design and development of antimalarial agents, and the structure-activity relationship (SAR) is also discussed to provide an insight for rational design of more effective antibacterial candidates.

Combination Therapy Strategies for the Treatment of Malaria

Malaria is a vector- and blood-borne infection that is responsible for a large number of deaths around the world. Most of the currently used antimalarial therapeutics suffer from drug resistance. The other limitations associated with the currently used antimalarial drugs are poor drug bioavailability, drug toxicity, and poor water solubility. Combination therapy is one of the best approaches that is currently used to treat malaria, whereby two or more therapeutic agents are combined. Different combination therapy strategies are used to overcome the aforementioned limitations. This review article reports two strategies of combination therapy; the incorporation of two or more antimalarials into polymer-based carriers and hybrid compounds designed by hybridization of two antimalarial pharmacophores.

Synthesis and Evaluation of the in vitro Antimicrobial Activity of Triazoles, Morpholines and Thiosemicarbazones

BACKGROUND

Microbial infections is a global public health problem. The aim of this work was to synthesize and evaluate the antimicrobial activity of novel triazoles, morpholines and thiosemicarbazones.

METHODS

Compounds were synthesized using 2,4-Dihydroxyacetophenone and 4-hydroxybenzaldehyde as starting materials. The antimicrobial activity of these compounds against bacteria and yeast was evaluated by the broth microdilution method.

RESULTS

The proposed route for synthesis gave high to moderate yields, moreover these compounds were successfully characterized by 1H NMR, 13C NMR and LC-MS. Antimicrobial testing indicated that the thiosemicarbazone and morphine derivatives had the best antimicrobial activity against the microorganisms tested with minimum inhibitory concentrations (MIC) between 0.29 and 5.30 µM. Thiosemicarbazone derivative (12) was able to inhibit the growth of C. tropicalis, with minimum fungicidal concentration (MFC) of 0.55 µM. In addition, this compound was active against E. coli, S. aureus and S. epidermidis, with MIC values ranging from 0.29 to 1.11 µM. Moreover, the morpholine derivative (15) had an MIC value of 0.83 µM against C. albicans and E. coli.

CONCLUSION

We have efficiently synthesized a series of eleven novel triazoles, thiosemicarbazones and morpholine derivatives using 2,4-Dihydroxyacetophenone and 4-hydroxybenzaldehyde as starting materials. Thiosemicarbazone derivative (12) showed promising antifungal and antibacterial activity and these findings suggest that this compound can be used as scaffolds to design new antimicrobial drugs.

Triazole derivatives and their antiplasmodial and antimalarial activities

Malaria, caused by protozoan parasites of the genus Plasmodium especially by the most prevalent parasite Plasmodium falciparum, represents one of the most devastating and common infectious disease globally. Nearly half of the world population is under the risk of being infected, and more than 200 million new clinical cases with around half a million deaths occur annually. Drug therapy is the mainstay of antimalarial therapy, yet current drugs are threatened by the development of resistance, so it's imperative to develop new antimalarials with great potency against both drug-susceptible and drug-resistant malaria. Triazoles, bearing a five-membered heterocyclic ring with three nitrogen atoms, exhibit promising in vitro antiplasmodial and in vivo antimalarial activities. Moreover, several triazole-based drugs have already used in clinics for the treatment of various diseases, demonstrating the excellent pharmaceutical profiles. Therefore, triazole derivatives have the potential for clinical deployment in the control and eradication of malaria. This review covers the recent advances of triazole derivatives especially triazole hybrids as potential antimalarials. The structure-activity relationship is also discussed to provide an insight for rational designs of more efficient antimalarial candidates.

Ferrocene-appended pharmacophores: an exciting approach for modulating the biological potential of organic scaffolds

The present review article describes the recent developments (2014–18) on the synthesis of ferrocene-based pharmacophores with the specific benefits of introducing/replacing organic pharmacophores with the ferrocene core for desired bioactivities.

Insights into the interaction of potent antimicrobial chalcone triazole analogs with human serum albumin: spectroscopy and molecular docking approaches

Mechanistic insights into the interaction of five previously chemically synthesized triazole-linked chalcone analogs (CTs) with human serum albumin (HSA) were sought using various spectroscopic techniques (UV-visible absorption, fluorescence, and circular dichroism) and molecular docking. The fluorescence quenching experiments performed at three different temperatures (288, 298 and 308 K) revealed the static mode of quenching and the binding constants (K_b ∼ 10^6–9) obtained indicated the strong affinity of these analogs for HSA. Furthermore, significant changes in the secondary structure of HSA in the presence of these analogs were also confirmed by far UV-CD spectroscopy. The thermodynamic properties such as the enthalpy change (ΔH°), Gibbs free energy change (ΔG°) and entropy change (ΔS°) revealed that the binding process was spontaneous and exothermic. Theoretical studies, viz., DFT and molecular docking corroborated the experimental results as these five analogs could bind with HSA through hydrogen bonding and hydrophobic interactions. The present study provides useful information regarding the interaction mechanism of these analogs with HSA, which can provide a new avenue to design more potent chalcone triazole analogs for use in the biomedical field.

Mechanistic insights into the interaction of five previously chemically synthesized triazole-linked chalcone analogs with human serum albumin were analyzed using UV-visible absorption, fluorescence quenching, circular dichroism and molecular docking studies.

Synthesis, characterization and antimicrobial evaluation of ferrocene–oxime ether benzyl 1H-1,2,3-triazole hybrids

A series of ferrocene–oxime ether benzyl 1H-1,2,3 triazole hybrids has been synthesized by employing Cu(i) catalyzed azide–alkyne [3+2] cycloaddition reaction and their antibacterial and antifungal activities are reported.

A strategic approach to the synthesis of ferrocene appended chalcone linked triazole allied organosilatranes: Antibacterial, antifungal, antiparasitic and antioxidant studies

A series of ferrocene appended chalcone allied triazole coupled organosilatranes (FCTSa 7-FCTSa 12) were synthesised with the aim of amalgamating the pharmacological action of the constituting moieties into a single molecular scaffold. All the synthesised silatranes were well characterized by various spectroscopic techniques like IR, ¹H NMR, ¹³C NMR and elemental analysis. Organosilatranes were then evaluated for their biological alacrity against bacterial and fungal strains compared with the standard drugs Rifampicin and Amphotericin B respectively. The ferrocene conjugates were found to be only moderately effective against the tested microbes. However, the organosilatranes conceded excellent efficacy against parasite G. lamblia with FCTSa 11 arraying the leading results. On the other hand against another parasite T. vaginalis, FCTSa 8 has emerged as an outstanding composite. Further, Total Antioxidant Assay (TAA) with 2,2'-azino-bis-3-(ethylbenzothiazoline-6-sulphonic acid) revealed FCTSa 10 to be the best claimant for radical scavenging activity. Along these lines, introducing some different substituents in the synthesised hybrids may act as a useful strategy for increasing the biological profile of the drugs.

Malaria, tuberculosis and HIV: what's new? Contribution of the Institut Hospitalo-Universitaire Méditerranée Infection in updated data

The Institut Hospitalo-Universitaire Méditerranée Infection is positioned for the diagnosis, prevention and treatment of the ‘big three’ killer diseases: malaria, tuberculosis and HIV. We implemented the use of new diagnostic samples such as stools and new diagnostic tests such as mass spectrometry for the dual identification of vectors and pathogens. Furthermore, advances in the prevention and treatment of malaria and tuberculosis are reviewed, along with advances in the understanding of the role of microbiota in the resistance to HIV infection. These achievements represent a major step towards a better management of the ‘big three’ diseases worldwide.

Design and synthesis of new triazoles linked to xanthotoxin for potent and highly selective anti-gastric cancer agents

Two series of xanthotoxin-triazole derivatives were designed, synthesized, and studied for their antiproliferative properties. The in vitro cytotoxicity of the compounds in the AGS cancer cell line and the L02 normal cell line was evaluated via MTT assay. Among the synthesized compounds, 9-((1-(4-(trifluoromethyl)phenyl)-1H-1,2,3-triazol-4-yl)methoxy)-7H-furo[3,2-g]chromen-7-one (6p) was found to have the greatest antiproliferative activity against AGS cells (IC₅₀=7.5μM) and showed better activity than the lead compound (xanthotoxin, IC₅₀>100μM) and the reference drug (5-fluorouracil, IC₅₀=29.6μM) did. The IC₅₀ value of 6p in L02 cells was 13.3 times higher than that in the AGS cells. Therefore, the compound exhibited better therapeutic activity and specificity compared with the positive control 5-fluorouracil. Cell cycle analysis revealed that compound 6p inhibited cell growth via the induction of S/G2 phase arrest in AGS cells. Compound 6p was identified as a promising lead compound for the further development and identification of 1,2,3-triazole-based anticancer agents.

Green synthesis and anticancer potential of chalcone linked-1,2,3-triazoles

A series of chalcone linked-1,2,3-triazoles was synthesized via cellulose supported copper nanoparticle catalyzed click reaction in water. The structures of all the compounds were analyzed by IR, NMR and Mass spectral techniques. All the synthesized products were subjected to 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay against a panel of four human cancer cell lines (MCF-7, MIA-Pa-Ca-2, A549, HepG2) to check their anticancer potential. Compound 6h was found to be most active against all the tested cancer cell lines with IC₅₀ values in the range of 4-11 μM and showed better or comparable activity to the reference drug against all the tested cell lines. Cell cycle analysis revealed that compound 6h induces apoptosis and G2/S arrest in MIA-Pa-Ca-2 cells. Compound 6h triggers mitochondrial potential loss in pancreatic cancer MIA-Pa-Ca-2 cells. Further, Compound 6h also triggers caspase-3 and PARP-1 cleavage, which increases in dose dependent manner.

Metal-chloroquine derivatives as possible anti-malarial drugs: evaluation of anti-malarial activity and mode of action

BACKGROUND

Malaria still has significant impacts on the world; particularly in Africa, South America and Asia where spread over several millions of people and is one of the major causes of death. When chloroquine diphosphate (CQDP) lost its efficiency as a first-line anti-malarial drug, this was a major setback in the effective control of malaria. Currently, malaria is treated with a combination of two or more drugs with different modes of action to provide an adequate cure rate and delay the development of resistance. Clearly, a new effective and non-toxic anti-malarial drug is urgently needed.

METHODS

All metal-chloroquine (CQ) and metal-CQDP complexes were synthesized under N(2) using Schlenk techniques. Their interactions with haematin and the inhibition of β-haematin formation were examined, in both aqueous medium and near water/n-octanol interfaces at pH 5. The anti-malarial activities of these metal- CQ and metal-CQDP complexes were evaluated in vitro against two strains, the CQ-susceptible strain (CQS) 3D7 and the CQ-resistant strain (CQR) W2.

RESULTS

The previously synthesized Au(CQ)(Cl) (1), Au(CQ)(TaTg) (2), Pt(CQDP)(2)Cl(2) (3), Pt(CQDP)(2)I(2) (4), Pd(CQ)(2)Cl(2) (5) and the new one Pd(CQDP)(2)I(2) (6) showed better anti-malarial activity than CQ, against the CQS strain; moreover, complexes 2, 3 and 4 were very active against CQR strain. These complexes (1-6) interacted with haem and inhibited β-haematin formation both in aqueous medium and near water/n-octanol interfaces at pH 5 to a greater extent than chloroquine diphosphate (CQDP) and other known metal-based anti-malarial agents.

CONCLUSIONS

The high anti-malarial activity displayed for these metal-CQ and metal-CQDP complexes (1-6) could be attributable to their effective interaction with haem and the inhibition of β-haematin formation in both aqueous medium and near water/n-octanol interfaces at pH 5.

1H-1,2,3-triazole tethered isatin-ferrocene conjugates: Synthesis and in vitro antimalarial evaluation

1H-1,2,3-triazole tethered isatin-ferrocene conjugates were synthesized and evaluated for their antiplasmodial activities against chloroquine-susceptible (3D7) and chloroquine-resistant (W2) strains of Plasmodium falciparum. The conjugates 5f and 5h with an optimum combination of electron-withdrawing halogen substituent at C-5 position of isatin ring and a propyl chain, introduced as linker, proved to be most potent and non-cytotoxic among the series with IC50 values of 3.76 and 4.58 μM against 3D7 and W2 strains, respectively.