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Tsamesidis, Ioannis, Karine Reybier, Giuseppe Marchetti, Maria Carmina Pau, Patrizia Virdis, Claudio Fozza, Francoise Nepveu, Philip S. Low, Francesco Michelangelo Turrini y Antonella Pantaleo. "Syk Kinase Inhibitors Synergize with Artemisinins by Enhancing Oxidative Stress in Plasmodium falciparum-Parasitized Erythrocytes". Antioxidants 9, n.º 8 (14 de agosto de 2020): 753. http://dx.doi.org/10.3390/antiox9080753.
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Although artemisinin-based combination therapies (ACTs) treat Plasmodium falciparum malaria effectively throughout most of the world, the recent expansion of ACT-resistant strains in some countries of the Greater Mekong Subregion (GMS) further increased the interest in improving the effectiveness of treatment and counteracting resistance. Recognizing that (1) partially denatured hemoglobin containing reactive iron (hemichromes) is generated in parasitized red blood cells (pRBC) by oxidative stress, (2) redox-active hemichromes have the potential to enhance oxidative stress triggered by the parasite and the activation of artemisinin to its pharmaceutically active form, and (3) Syk kinase inhibitors block the release of membrane microparticles containing hemichromes, we hypothesized that increasing hemichrome content in parasitized erythrocytes through the inhibition of Syk kinase might trigger a virtuous cycle involving the activation of artemisinin, the enhancement of oxidative stress elicited by activated artemisinin, and a further increase in hemichrome production. We demonstrate here that artemisinin indeed augments oxidative stress within parasitized RBCs and that Syk kinase inhibitors further increase iron-dependent oxidative stress, synergizing with artemisinin in killing the parasite. We then demonstrate that Syk kinase inhibitors achieve this oxidative enhancement by preventing parasite-induced release of erythrocyte-derived microparticles containing redox-active hemichromes. We also observe that Syk kinase inhibitors do not promote oxidative toxicity to healthy RBCs as they do not produce appreciable amounts of hemichromes. Since some Syk kinase inhibitors can be taken daily with minimal side effects, we propose that Syk kinase inhibitors could evidently contribute to the potentiation of ACTs.
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Marchetti, Giuseppe, Alessandro Dessì, Roberto Dallocchio, Ioannis Tsamesidis, Maria Carmina Pau, Francesco Michelangelo Turrini y Antonella Pantaleo. "Syk Inhibitors: New Computational Insights into Their Intraerythrocytic Action in Plasmodium falciparum Malaria". International Journal of Molecular Sciences 21, n.º 19 (23 de septiembre de 2020): 7009. http://dx.doi.org/10.3390/ijms21197009.
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Resistance to antimalarial drugs has spread rapidly over the past few decades. The WHO recommends artemisinin-based combination therapies for the treatment of uncomplicated malaria, but unfortunately these approaches are losing their efficacy in large areas of Southeast Asia. In 2016, artemisinin resistance was confirmed in 5 countries of the Greater Mekong subregion. We focused our study on Syk inhibitors as antimalarial drugs. The Syk protein is present in human erythrocytes, and the membrane of protein band 3 is its major target following activation by oxidant stress. Tyr phosphorylation of band 3 occurs during P. falciparum growth, leading to the release of microparticles containing hemicromes and structural weakening of the host cell membrane, simplifying merozoite reinfection. Syk inhibitors block these events by interacting with the Syk protein’s catalytic site. We performed in vitro proteomics and in silico studies and compared the results. In vitro studies were based on treatment of the parasite’s cellular cultures with different concentrations of Syk inhibitors, while proteomics studies were focused on the Tyr phosphorylation of band 3 by Syk protein with the same concentrations of drugs. In silico studies were based on different molecular modeling approaches in order to analyze and optimize the ligand–protein interactions and obtain the highest efficacy in vitro. In the presence of Syk inhibitors, we observed a marked decrease of band 3 Tyr phosphorylation according to the increase of the drug’s concentration. Our studies could be useful for the structural optimization of these compounds and for the design of novel Syk inhibitors in the future.
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Kimata-Ariga, Yoko y Rena Morihisa. "Effect of Artemisinin on the Redox System of NADPH/FNR/Ferredoxin from Malaria Parasites". Antioxidants 11, n.º 2 (29 de enero de 2022): 273. http://dx.doi.org/10.3390/antiox11020273.
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FNR and ferredoxin constitute a redox cascade, which provides reducing power in the plastid of malaria parasites. Recently, mutation of ferredoxin (D97Y) was reported to be strongly related to the parasite’s resistance to the front-line antimalarial drug artemisinin. In order to gain insight into the mechanism for the resistance, we studied the effect of dihydroartemisinin (DHA), the active compound of artemisinin, on the redox cascade of NADPH/FNR/ferredoxin in in vitro reconstituted systems. DHA partially inhibited the diaphorase activity of FNR by decreasing the affinity of FNR for NADPH. The activity of the electron transfer from FNR to wild-type or D97Y mutant ferredoxin was not significantly affected by DHA. An in silico docking analysis indicated possible binding of DHA molecule in the binding cavity of 2′5′ADP, a competitive inhibitor for NADPH, on FNR. We previously showed that the D97Y mutant of ferredoxin binds to FNR more strongly than wild-type ferredoxin, and ferredoxin and FNR are generally known to be involved in the oxidative stress response. Thus, these results suggest that ferredoxin is not a direct target of artemisinin, but its mutation may be involved in the protective response against the oxidative stress caused by artemisinin.
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Pratama, Mohammad Rizki Fadhil y Tutus Gusdinar. "BETWEEN ARTEMISININ AND DERIVATIVES WITH NEURAMINIDASE: A DOCKING STUDY INSIGHT". Asian Journal of Pharmaceutical and Clinical Research 10, n.º 8 (1 de agosto de 2017): 304. http://dx.doi.org/10.22159/ajpcr.2017.v10i8.18667.
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Objectives: This study aims to find the relationship between artemisinins and neuraminidase (NA) with molecular docking study and also to determine the most potent NA inhibitor from artemisinin and derivatives.Methods: All ligands were sketched and optimized using Gaussian 03W with Hartree-Fock method basis sets 6-311G. Molecular docking was performed using AutoDock 4.2.3 toward NA in complexes with oseltamivir as co-crystal ligand. The main parameters used were the free energy of binding (ΔG) and dissociation constant (Ki) as affinity marker.Results: Artesunate provided most negative free ΔG and lowest Ki toward NA with −9.55 kcal/mol and 100.66 nM, respectively. Artesunate shows higher affinity than oseltamivir with interactions between artesunate and amino acids at position 246 had important influences on artesunate affinity toward NA from H5N1.Conclusion: In silico molecular docking results indicated that artesunate could be considered as NA inhibitor and should be potential to be developed as anti-influenza particularly to H5N1 with oseltamivir resistance.
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von Bredow, Lukas, Thomas Martin Schäfer, Julian Hogenkamp, Maik Tretbar, Daniel Stopper, Fabian B. Kraft, Julian Schliehe-Diecks et al. "Synthesis, Antiplasmodial, and Antileukemia Activity of Dihydroartemisinin–HDAC Inhibitor Hybrids as Multitarget Drugs". Pharmaceuticals 15, n.º 3 (9 de marzo de 2022): 333. http://dx.doi.org/10.3390/ph15030333.
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Artemisinin-based combination therapies (ACTs) are the gold standard for the treatment of malaria, but the efficacy is threatened by the development of parasite resistance. Histone deacetylase inhibitors (HDACis) are an emerging new class of potential antiplasmodial drugs. In this work, we present the design, synthesis, and biological evaluation of a mini library of dihydroartemisinin–HDACi hybrid molecules. The screening of the hybrid molecules for their activity against selected human HDAC isoforms, asexual blood stage P. falciparum parasites, and a panel of leukemia cell lines delivered important structure–activity relationships. All synthesized compounds demonstrated potent activity against the 3D7 and Dd2 line of P. falciparum with IC50 values in the single-digit nanomolar range. Furthermore, the hybrid (α)-7c displayed improved activity against artemisinin-resistant parasites compared to dihydroartemisinin. The screening of the compounds against five cell lines from different leukemia entities revealed that all hydroxamate-based hybrids (7a–e) and the ortho-aminoanilide 8 exceeded the antiproliferative activity of dihydroartemisinin in four out of five cell lines. Taken together, this series of hybrid molecules represents an excellent starting point toward the development of antimalarial and antileukemia drug leads.
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Lee, Dong-Hwan, Md Hasanuzzaman, Daeho Kwon, Hye-Young Choi, So Myoung Kim, Dong Jin Kim, Dong Ju Kang et al. "10-Phenyltriazoyl Artemisinin is a Novel P-glycoprotein Inhibitor that Suppresses the Overexpression and Function of P-glycoprotein". Current Pharmaceutical Design 24, n.º 46 (26 de abril de 2019): 5590–97. http://dx.doi.org/10.2174/1381612825666190222155700.
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Background: The effect of drugs on ATP-binding cassette transporters, especially permeabilityglycoprotein (P-gp), is an important consideration during new anti-cancer drug development. Objective: In this context, the effects of a newly synthesized artemisinin derivative, 10-(4-phenyl-1H-1,2,3- triazol)-artemisinin (5a), were evaluated on P-gp expression and function. Methods: Reverse transcript polymerase chain reaction and immunoblotting techniques were used to determine the effect of 5a on P-gp expression in LS174T cells. In addition, the ability of 5a to work as either a substrate or an inhibitor of P-gp was investigated through different methods. Results: The results revealed that 5a acts as a novel P-gp inhibitor that dually suppresses the overexpression and function of P-glycoprotein. Co-treatment of LS174T cell line, human colon adenocarcinoma cell line, with 5a and paclitaxel recovered the anticancer effect of paclitaxel by controlling the acquired drug resistance pathway. The overexpression of P-gp induced by rifampin and paclitaxel in a colorectal cell line was suppressed by 5a which could be a novel inhibitory substrate inhibiting the transport of paclitaxel by P-gp. Conclusion: The results revealed that 5a can be classified as a type B P-gp inhibitor (with both substrate and inhibitor activities) with an additional function of suppressing P-gp overexpression. The results might be clinically useful in the development of anticancer drugs against cancers with multidrug resistance.
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Kirkman, Laura A., Wenhu Zhan, Joseph Visone, Alexis Dziedziech, Pradeep K. Singh, Hao Fan, Xinran Tong et al. "Antimalarial proteasome inhibitor reveals collateral sensitivity from intersubunit interactions and fitness cost of resistance". Proceedings of the National Academy of Sciences 115, n.º 29 (2 de julio de 2018): E6863—E6870. http://dx.doi.org/10.1073/pnas.1806109115.
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We describe noncovalent, reversible asparagine ethylenediamine (AsnEDA) inhibitors of the Plasmodium falciparum proteasome (Pf20S) β5 subunit that spare all active subunits of human constitutive and immuno-proteasomes. The compounds are active against erythrocytic, sexual, and liver-stage parasites, against parasites resistant to current antimalarials, and against P. falciparum strains from patients in Africa. The β5 inhibitors synergize with a β2 inhibitor in vitro and in mice and with artemisinin. P. falciparum selected for resistance to an AsnEDA β5 inhibitor surprisingly harbored a point mutation in the noncatalytic β6 subunit. The β6 mutant was resistant to the species-selective Pf20S β5 inhibitor but remained sensitive to the species-nonselective β5 inhibitors bortezomib and carfilzomib. Moreover, resistance to the Pf20S β5 inhibitor was accompanied by increased sensitivity to a Pf20S β2 inhibitor. Finally, the β5 inhibitor-resistant mutant had a fitness cost that was exacerbated by irradiation. Thus, used in combination, multistage-active inhibitors of the Pf20S β5 and β2 subunits afford synergistic antimalarial activity with a potential to delay the emergence of resistance to artemisinins and each other.
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Pulcini, Serena, Henry M. Staines, Jon K. Pittman, Ksenija Slavic, Christian Doerig, Jean Halbert, Rita Tewari et al. "Expression in Yeast Links Field Polymorphisms in PfATP6 to in Vitro Artemisinin Resistance and Identifies New Inhibitor Classes". Journal of Infectious Diseases 208, n.º 3 (18 de abril de 2013): 468–78. http://dx.doi.org/10.1093/infdis/jit171.
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Mustière, Romain, Patrice Vanelle y Nicolas Primas. "Plasmodial Kinase Inhibitors Targeting Malaria: Recent Developments". Molecules 25, n.º 24 (15 de diciembre de 2020): 5949. http://dx.doi.org/10.3390/molecules25245949.
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Recent progress in reducing malaria cases and ensuing deaths is threatened by factors like mutations that induce resistance to artemisinin derivatives. Multiple drugs are currently in clinical trials for malaria treatment, including some with novel mechanisms of action. One of these, MMV390048, is a plasmodial kinase inhibitor. This review lists the recently developed molecules which target plasmodial kinases. A systematic review of the literature was performed using CAPLUS and MEDLINE databases from 2005 to 2020. It covers a total of 60 articles and describes about one hundred compounds targeting 22 plasmodial kinases. This work highlights the strong potential of compounds targeting plasmodial kinases for future drug therapies. However, the majority of the Plasmodium kinome remains to be explored.
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Bao, Changlei, Qian He, Hui Wang, Yanan Sun, Yahang Xu, Yan Pan, Yadan Hu et al. "Artemisinin and Its Derivate Alleviate Pulmonary Hypertension and Vasoconstriction in Rodent Models". Oxidative Medicine and Cellular Longevity 2022 (17 de junio de 2022): 1–21. http://dx.doi.org/10.1155/2022/2782429.
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Background. Pulmonary arterial hypertension (PAH) is a complex pulmonary vasculature disease characterized by progressive obliteration of small pulmonary arteries and persistent increase in pulmonary vascular resistance, resulting in right heart failure and death if left untreated. Artemisinin (ARS) and its derivatives, which are common antimalarial drugs, have been found to possess a broad range of biological effects. Here, we sought to determine the therapeutic benefit and mechanism of ARS and its derivatives treatment in experimental pulmonary hypertension (PH) models. Methods. Isolated perfused/ventilated lung and isometric tension measurements in arteries were performed to test pulmonary vasoconstriction and relaxation. Monocrotaline (MCT) and hypoxia+Su5416 (SuHx) were administered to rats to induce severe PH. Evaluation methods of ARS treatment and its derivatives in animal models include echocardiography, hemodynamics measurement, and histological staining. In vitro, the effect of these drugs on proliferation, viability, and hypoxia-inducible factor 1α (HIF1α) was examined in human pulmonary arterial smooth muscle cells (hPASMCs). Results. ARS treatment attenuated pulmonary vasoconstriction induced by high K+ solution or alveolar hypoxia, decreased pulmonary artery (PA) basal vascular tension, improved acetylcholine- (ACh-) induced endothelial-dependent relaxation, increased endothelial nitric oxide (NO) synthase (eNOS) activity and NO levels, and decreased levels of NAD(P)H oxidase subunits (NOX2 and NOX4) expression, NAD(P)H oxidase activity, and reactive oxygen species (ROS) levels of pulmonary arteries (PAs) in MCT-PH rats. NOS inhibitor, L-NAME, abrogated the effects of ARS on PA constriction and relaxation. Furthermore, chronic application of both ARS and its derivative dihydroartemisinin (DHA) attenuated right ventricular systolic pressure (RVSP), Fulton index (right ventricular hypertrophy), and vascular remodeling of PAs in the two rat PH models. In addition, DHA inhibited proliferation and migration of hypoxia-induced PASMCs. Conclusions. In conclusion, these results indicate that treatment with ARS or DHA can inhibit PA vasoconstriction, PASMC proliferation and migration, and vascular remodeling, as well as improve PA endothelium-dependent relaxation, and eventually attenuate the development and progression of PH. These effects might be achieved by decreasing NAD(P)H oxidase generated ROS production and increasing eNOS activation to release NO in PAs. ARS and its derivatives might have the potential to be novel drugs for the treatment of PH.
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Biosca, Arnau, Miriam Ramírez, Alex Gomez-Gomez, Aritz Lafuente, Valentín Iglesias, Oscar J. Pozo, Santiago Imperial y Xavier Fernàndez-Busquets. "Characterization of Domiphen Bromide as a New Fast-Acting Antiplasmodial Agent Inhibiting the Apicoplastidic Methyl Erythritol Phosphate Pathway". Pharmaceutics 14, n.º 7 (22 de junio de 2022): 1320. http://dx.doi.org/10.3390/pharmaceutics14071320.
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The evolution of resistance by the malaria parasite to artemisinin, the key component of the combination therapy strategies that are at the core of current antimalarial treatments, calls for the urgent identification of new fast-acting antimalarials. The apicoplast organelle is a preferred target of antimalarial drugs because it contains biochemical processes absent from the human host. Fosmidomycin is the only drug in clinical trials targeting the apicoplast, where it inhibits the methyl erythritol phosphate (MEP) pathway. Here, we characterized the antiplasmodial activity of domiphen bromide (DB), another MEP pathway inhibitor with a rapid mode of action that arrests the in vitro growth of Plasmodium falciparum at the early trophozoite stage. Metabolomic analysis of the MEP pathway and Krebs cycle intermediates in 20 µM DB-treated parasites suggested a rapid activation of glycolysis with a concomitant decrease in mitochondrial activity, consistent with a rapid killing of the pathogen. These results present DB as a model compound for the development of new, potentially interesting drugs for future antimalarial combination therapies.
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Malmquist, Nicholas A., Sandeep Sundriyal, Joachim Caron, Patty Chen, Benoit Witkowski, Didier Menard, Rossarin Suwanarusk et al. "Histone Methyltransferase Inhibitors Are Orally Bioavailable, Fast-Acting Molecules with Activity against Different Species Causing Malaria in Humans". Antimicrobial Agents and Chemotherapy 59, n.º 2 (24 de noviembre de 2014): 950–59. http://dx.doi.org/10.1128/aac.04419-14.
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ABSTRACTCurrent antimalarials are under continuous threat due to the relentless development of drug resistance by malaria parasites. We previously reported promisingin vitroparasite-killing activity with the histone methyltransferase inhibitor BIX-01294 and its analogue TM2-115. Here, we further characterize these diaminoquinazolines forin vitroandin vivoefficacy and pharmacokinetic properties to prioritize and direct compound development. BIX-01294 and TM2-115 displayed potentin vitroactivity, with 50% inhibitory concentrations (IC50s) of <50 nM against drug-sensitive laboratory strains and multidrug-resistant field isolates, including artemisinin-refractoryPlasmodium falciparumisolates. Activities againstex vivoclinical isolates of bothP. falciparumandPlasmodium vivaxwere similar, with potencies of 300 to 400 nM. Sexual-stage gametocyte inhibition occurs at micromolar levels; however, mature gametocyte progression to gamete formation is inhibited at submicromolar concentrations. Parasite reduction ratio analysis confirms a high asexual-stage rate of killing. Both compounds examined displayed oral efficacy inin vivomouse models ofPlasmodium bergheiandP. falciparuminfection. The discovery of a rapid and broadly acting antimalarial compound class targeting blood stage infection, including transmission stage parasites, and effective against multiple malaria-causing species reveals the diaminoquinazoline scaffold to be a very promising lead for development into greatly needed novel therapies to control malaria.
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Langlais, David, Regina Cencic, Neda Moradin, James M. Kennedy, Kodjo Ayi, Lauren E. Brown, Ian Crandall et al. "Rocaglates as dual-targeting agents for experimental cerebral malaria". Proceedings of the National Academy of Sciences 115, n.º 10 (20 de febrero de 2018): E2366—E2375. http://dx.doi.org/10.1073/pnas.1713000115.
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Cerebral malaria (CM) is a severe and rapidly progressing complication of infection by Plasmodium parasites that is associated with high rates of mortality and morbidity. Treatment options are currently few, and intervention with artemisinin (Art) has limited efficacy, a problem that is compounded by the emergence of resistance to Art in Plasmodium parasites. Rocaglates are a class of natural products derived from plants of the Aglaia genus that have been shown to interfere with eukaryotic initiation factor 4A (eIF4A), ultimately blocking initiation of protein synthesis. Here, we show that the rocaglate CR-1-31B perturbs association of Plasmodium falciparum eIF4A (PfeIF4A) with RNA. CR-1-31B shows potent prophylactic and therapeutic antiplasmodial activity in vivo in mouse models of infection with Plasmodium berghei (CM) and Plasmodium chabaudi (blood-stage malaria), and can also block replication of different clinical isolates of P. falciparum in human erythrocytes infected ex vivo, including drug-resistant P. falciparum isolates. In vivo, a single dosing of CR-1-31B in P. berghei-infected animals is sufficient to provide protection against lethality. CR-1-31B is shown to dampen expression of the early proinflammatory response in myeloid cells in vitro and dampens the inflammatory response in vivo in P. berghei-infected mice. The dual activity of CR-1-31B as an antiplasmodial and as an inhibitor of the inflammatory response in myeloid cells should prove extremely valuable for therapeutic intervention in human cases of CM.
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Birrell, Geoffrey W., Matthew P. Challis, Amanda De Paoli, Dovile Anderson, Shane M. Devine, Gavin D. Heffernan, David P. Jacobus, Michael D. Edstein, Ghizal Siddiqui y Darren J. Creek. "Multi-omic Characterization of the Mode of Action of a Potent New Antimalarial Compound, JPC-3210, Against Plasmodium falciparum". Molecular & Cellular Proteomics 19, n.º 2 (13 de diciembre de 2019): 308–25. http://dx.doi.org/10.1074/mcp.ra119.001797.
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The increasing incidence of antimalarial drug resistance to the first-line artemisinin combination therapies underpins an urgent need for new antimalarial drugs, ideally with a novel mode of action. The recently developed 2-aminomethylphenol, JPC-3210, (MMV 892646) is an erythrocytic schizonticide with potent in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum lines, low cytotoxicity, potent in vivo efficacy against murine malaria, and favorable preclinical pharmacokinetics including a lengthy plasma elimination half-life. To investigate the impact of JPC-3210 on biochemical pathways within P. falciparum-infected red blood cells, we have applied a “multi-omics” workflow based on high resolution orbitrap mass spectrometry combined with biochemical approaches. Metabolomics, peptidomics and hemoglobin fractionation analyses revealed a perturbation in hemoglobin metabolism following JPC-3210 exposure. The metabolomics data demonstrated a specific depletion of short hemoglobin-derived peptides, peptidomics analysis revealed a depletion of longer hemoglobin-derived peptides, and the hemoglobin fractionation assay demonstrated decreases in hemoglobin, heme and hemozoin levels. To further elucidate the mechanism responsible for inhibition of hemoglobin metabolism, we used in vitro β-hematin polymerization assays and showed JPC-3210 to be an intermediate inhibitor of β-hematin polymerization, about 10-fold less potent then the quinoline antimalarials, such as chloroquine and mefloquine. Further, quantitative proteomics analysis showed that JPC-3210 treatment results in a distinct proteomic signature compared with other known antimalarials. While JPC-3210 clustered closely with mefloquine in the metabolomics and proteomics analyses, a key differentiating signature for JPC-3210 was the significant enrichment of parasite proteins involved in regulation of translation. These studies revealed that the mode of action for JPC-3210 involves inhibition of the hemoglobin digestion pathway and elevation of regulators of protein translation. Importantly, JPC-3210 demonstrated rapid parasite killing kinetics compared with other quinolones, suggesting that JPC-3210 warrants further investigation as a potentially long acting partner drug for malaria treatment.
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Frasse, Philip, Daniel Goldberg y Audrey Odom John. "#23: Investigation of Phosphomannomutase as an Antimalarial Drug Target". Journal of the Pediatric Infectious Diseases Society 10, Supplement_2 (1 de junio de 2021): S10. http://dx.doi.org/10.1093/jpids/piab031.019.
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Abstract Background Malaria continues to pose an enormous economic and global health threat, killing over 200,000 people annually, primarily children under the age of 5. With the constant barrier of antimalarial resistance and the rise of delayed clearance by artemisinin, it is especially important to identify drug/target pairs that rapidly kill parasites. We study targetable metabolic pathways in the malaria parasite, Plasmodium falciparum, to guide such future drug development against this disease. In recent years, we have discovered that a large family of hydrolases, the Haloacid Dehalogenase (HAD) Superfamily of proteins, are implicated in regulating a variety of P. falciparum metabolic pathways, which can lead to dramatic changes in central carbon metabolism and drug resistance. We now turn our attention to a related HAD protein, the putative phosphomannomutase in these parasites, HAD5, responsible for the interconversion of mannose-6-phosphate and mannose-1-phosphate. This is an essential process for all stages of the parasite, and thus has potential as a broad antimalarial target. We examined the role of HAD5 in these parasites, and its potential to be chemically inhibited. Methods Recombinant protein was generated and purified for enzymatic assays to determine HAD5 activity and test inhibitor potency against HAD5 compared to recombinant human orthologs, PMM1 and PMM2. In parallel, CRISPR/Cas9 was used to generate inducible knockdown parasite strains to demonstrate this gene’s essentiality and its role in parasite biology. Parasite growth was measured by flow cytometry and light microscopy. Immunofluorescence analysis (IFA) was used to track the parasite development on a molecular scale. Results Inhibition of HAD5 was achieved in biochemical assays, with an IC50 of 68µM in our most potent compound, representing roughly 10-fold increased potency against the parasite protein compared to human orthologs. In culture, knockdown of HAD5 leads to interrupted egress from and reinvasion into red blood cells, culminating in parasite death. In IFA-visualized parasites, reinvasion-facilitating proteins were no longer anchored to parasite surfaces, accounting for the inhibition of the parasite life cycle. Conclusion In the search for new antimalarial targets, identifying proteins that are essential across multiple parasite life-stages while being distinct from human orthologs is necessary to block parasite transmission, cure symptomatic infection, and minimize off-target effects. HAD5 is an essential protein in malaria parasites that is expressed throughout the parasite’s life cycle, and can be specifically targeted by inhibitors, giving it promise as a future drug target.
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Li, Yitian. "Pyrvinium pamoate can overcome artemisinin’s resistance in anaplastic thyroid cancer". BMC Complementary Medicine and Therapies 21, n.º 1 (28 de mayo de 2021). http://dx.doi.org/10.1186/s12906-021-03332-z.
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Abstract Background Anaplastic thyroid carcinoma is a highly lethal subtype of thyroid cancer without effective therapies. Drug resistance in anaplastic thyroid carcinoma poses a significant problem. Although artemisinin exerts antitumor effects, but its efficacy in anaplastic thyroid carcinoma is unknown. Methods We used RNA sequencing to identify differentially expressed genes. Next, we determined the cause of ART resistance by testing the expression and activity of β-catenin, and enhanced ART activity with a WNT signaling inhibitor. Results Artemisinin suppressed the growth of BHT-101 but not human thyroid anaplastic carcinoma (CAL-62) cells. The mechanism of artemisinin resistance in CAL-62 was associated with the aberrant activation of WNT signaling. Pyrvinium pamoate, an inhibitor of WNT signaling, was used to overcome ART resistance in CAL-62 cells. The combination of artemisinin and pyrvinium pamoate suppressed the growth of CAL-62 cells and induced the apoptosis. Conclusions Our study is the first to prove the efficacy of ART as monotherapy or in combination with PP in the management of anaplastic thyroid cancer, and that the inhibition of WNT signaling may overcome ART resistance.
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Tong, Jie Xin, Sarah E. L. Ang, Esther H. N. Tan y Kevin S. W. Tan. "Viability Screen of LOPAC1280 Reveals Tyrosine Kinase Inhibitor Tyrphostin A9 as a Novel Partner Drug for Artesunate Combinations To Target the Plasmodium falciparum Ring Stage". Antimicrobial Agents and Chemotherapy 63, n.º 4 (4 de febrero de 2019). http://dx.doi.org/10.1128/aac.02389-18.
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ABSTRACT The emergence of artemisinin-resistant Plasmodium falciparum poses a major threat to current frontline artemisinin combination therapies. Artemisinin resistance is widely associated with mutations in the P. falciparum Kelch13 (PfKelch13) propeller region, leading to delayed parasite clearance and increased survival of early-ring-stage parasites. There is therefore a need to discover novel drugs that are effective against artemisinin-resistant P. falciparum. In view of this, our study aimed to identify compounds from the Library of Pharmacologically Active Compounds1280 (LOPAC1280) that could increase the efficacy of artesunate and be used as a potential partner drug for treatment against artemisinin-resistant falciparum malaria. By using a modified ring-stage survival assay, we performed a high-throughput screening of the activities of the 1,280 compounds from the LOPAC library in combination with artesunate against the P. falciparum IPC 5202 field isolate harboring the R539T mutation in the PfKelch13 propeller region. The potencies of the hits against both the IPC 5202 and CamWT_C580Y field isolates were determined through dose-dependent isobologram analyses; CamWT_C580Y has the more prevalent C580Y mutation characteristic of strains with artemisinin resistance. We identified tyrphostin A9 to have synergistic and additive activity against both parasite strains when dosed in combination with artesunate. These findings provide promising novel artesunate combinations that can target the P. falciparum artemisinin-resistant ring stage and insights that may aid in obtaining a better understanding of the mechanism involved in artemisinin resistance.
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Simwela, Nelson V., Barbara H. Stokes, Dana Aghabi, Matt Bogyo, David A. Fidock y Andrew P. Waters. "Plasmodium berghei K13 Mutations Mediate In Vivo Artemisinin Resistance That Is Reversed by Proteasome Inhibition". mBio 11, n.º 6 (10 de noviembre de 2020). http://dx.doi.org/10.1128/mbio.02312-20.
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ABSTRACT The recent emergence of Plasmodium falciparum parasite resistance to the first line antimalarial drug artemisinin is of particular concern. Artemisinin resistance is primarily driven by mutations in the P. falciparum K13 protein, which enhance survival of early ring-stage parasites treated with the artemisinin active metabolite dihydroartemisinin in vitro and associate with delayed parasite clearance in vivo. However, association of K13 mutations with in vivo artemisinin resistance has been problematic due to the absence of a tractable model. Herein, we have employed CRISPR/Cas9 genome editing to engineer selected orthologous P. falciparum K13 mutations into the K13 gene of an artemisinin-sensitive Plasmodium berghei rodent model of malaria. Introduction of the orthologous P. falciparum K13 F446I, M476I, Y493H, and R539T mutations into P. berghei K13 yielded gene-edited parasites with reduced susceptibility to dihydroartemisinin in the standard 24-h in vitro assay and increased survival in an adapted in vitro ring-stage survival assay. Mutant P. berghei K13 parasites also displayed delayed clearance in vivo upon treatment with artesunate and achieved faster recrudescence upon treatment with artemisinin. Orthologous C580Y and I543T mutations could not be introduced into P. berghei, while the equivalents of the M476I and R539T mutations resulted in significant growth defects. Furthermore, a Plasmodium-selective proteasome inhibitor strongly synergized dihydroartemisinin action in these P. berghei K13 mutant lines, providing further evidence that the proteasome can be targeted to overcome artemisinin resistance. Taken together, our findings provide clear experimental evidence for the involvement of K13 polymorphisms in mediating susceptibility to artemisinins in vitro and, most importantly, under in vivo conditions. IMPORTANCE Recent successes in malaria control have been seriously threatened by the emergence of Plasmodium falciparum parasite resistance to the frontline artemisinin drugs in Southeast Asia. P. falciparum artemisinin resistance is associated with mutations in the parasite K13 protein, which associates with a delay in the time required to clear the parasites upon drug treatment. Gene editing technologies have been used to validate the role of several candidate K13 mutations in mediating P. falciparum artemisinin resistance in vitro under laboratory conditions. Nonetheless, the causal role of these mutations under in vivo conditions has been a matter of debate. Here, we have used CRISPR/Cas9 gene editing to introduce K13 mutations associated with artemisinin resistance into the related rodent-infecting parasite, Plasmodium berghei. Phenotyping of these P. berghei K13 mutant parasites provides evidence of their role in mediating artemisinin resistance in vivo, which supports in vitro artemisinin resistance observations. However, we were unable to introduce some of the P. falciparum K13 mutations (C580Y and I543T) into the corresponding amino acid residues, while other introduced mutations (M476I and R539T equivalents) carried pronounced fitness costs. Our study provides evidence of a clear causal role of K13 mutations in modulating susceptibility to artemisinins in vitro and in vivo using the well-characterized P. berghei model. We also show that inhibition of the P. berghei proteasome offsets parasite resistance to artemisinins in these mutant lines.
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Mok, Sachel, Barbara H. Stokes, Nina F. Gnädig, Leila S. Ross, Tomas Yeo, Chanaki Amaratunga, Erik Allman et al. "Artemisinin-resistant K13 mutations rewire Plasmodium falciparum’s intra-erythrocytic metabolic program to enhance survival". Nature Communications 12, n.º 1 (22 de enero de 2021). http://dx.doi.org/10.1038/s41467-020-20805-w.
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AbstractThe emergence and spread of artemisinin resistance, driven by mutations in Plasmodium falciparum K13, has compromised antimalarial efficacy and threatens the global malaria elimination campaign. By applying systems-based quantitative transcriptomics, proteomics, and metabolomics to a panel of isogenic K13 mutant or wild-type P. falciparum lines, we provide evidence that K13 mutations alter multiple aspects of the parasite’s intra-erythrocytic developmental program. These changes impact cell-cycle periodicity, the unfolded protein response, protein degradation, vesicular trafficking, and mitochondrial metabolism. K13-mediated artemisinin resistance in the Cambodian Cam3.II line was reversed by atovaquone, a mitochondrial electron transport chain inhibitor. These results suggest that mitochondrial processes including damage sensing and anti-oxidant properties might augment the ability of mutant K13 to protect P. falciparum against artemisinin action by helping these parasites undergo temporary quiescence and accelerated growth recovery post drug elimination.
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Bouzón-Arnáiz, Inés, Yunuen Avalos-Padilla, Arnau Biosca, Omar Caño-Prades, Lucía Román-Álamo, Javier Valle, David Andreu et al. "The protein aggregation inhibitor YAT2150 has potent antimalarial activity in Plasmodium falciparum in vitro cultures". BMC Biology 20, n.º 1 (22 de octubre de 2022). http://dx.doi.org/10.1186/s12915-022-01374-4.
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Abstract Background By 2016, signs of emergence of Plasmodium falciparum resistance to artemisinin and partner drugs were detected in the Greater Mekong Subregion. Recently, the independent evolution of artemisinin resistance has also been reported in Africa and South America. This alarming scenario calls for the urgent development of new antimalarials with novel modes of action. We investigated the interference with protein aggregation, which is potentially toxic for the cell and occurs abundantly in all Plasmodium stages, as a hitherto unexplored drug target in the pathogen. Results Attempts to exacerbate the P. falciparum proteome’s propensity to aggregation by delivering endogenous aggregative peptides to in vitro cultures of this parasite did not significantly affect their growth. In contrast, protein aggregation inhibitors clearly reduced the pathogen’s viability. One such compound, the bis(styrylpyridinium) salt YAT2150, exhibited potent antiplasmodial activity with an in vitro IC50 of 90 nM for chloroquine- and artemisinin-resistant lines, arresting asexual blood parasites at the trophozoite stage, as well as interfering with the development of both sexual and hepatic forms of Plasmodium. At its IC50, this compound is a powerful inhibitor of the aggregation of the model amyloid β peptide fragment 1-40, and it reduces the amount of aggregated proteins in P. falciparum cultures, suggesting that the underlying antimalarial mechanism consists in a generalized impairment of proteostasis in the pathogen. YAT2150 has an easy, rapid, and inexpensive synthesis, and because it fluoresces when it accumulates in its main localization in the Plasmodium cytosol, it is a theranostic agent. Conclusions Inhibiting protein aggregation in Plasmodium significantly reduces the parasite’s viability in vitro. Since YAT2150 belongs to a novel structural class of antiplasmodials with a mode of action that potentially targets multiple gene products, rapid evolution of resistance to this drug is unlikely to occur, making it a promising compound for the post-artemisinin era.
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Nandi, Deeptashree, Pradeep Singh Cheema, Aakriti Singal, Hina Bharti y Alo Nag. "Artemisinin Mediates Its Tumor-Suppressive Activity in Hepatocellular Carcinoma Through Targeted Inhibition of FoxM1". Frontiers in Oncology 11 (24 de noviembre de 2021). http://dx.doi.org/10.3389/fonc.2021.751271.
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The aberrant up-regulation of the oncogenic transcription factor Forkhead box M1 (FoxM1) is associated with tumor development, progression and metastasis in a myriad of carcinomas, thus establishing it as an attractive target for anticancer drug development. FoxM1 overexpression in hepatocellular carcinoma is reflective of tumor aggressiveness and recurrence, poor prognosis and low survival in patients. In our study, we have identified the antimalarial natural product, Artemisinin, to efficiently curb FoxM1 expression and activity in hepatic cancer cells, thereby exhibiting potential anticancer efficacy. Here, we demonstrated that Artemisinin considerably mitigates FoxM1 transcriptional activity by disrupting its interaction with the promoter region of its downstream targets, thereby suppressing the expression of numerous oncogenic drivers. Augmented level of FoxM1 is implicated in drug resistance of cancer cells, including hepatic tumor cells. Notably, FoxM1 overexpression rendered HCC cells poorly responsive to Artemisinin-mediated cytotoxicity while FoxM1 depletion in resistant liver cancer cells sensitized them to Artemisinin treatment, manifested in lower proliferative and growth index, drop in invasive potential and repressed expression of EMT markers with a concomitantly increased apoptosis. Moreover, Artemisinin, when used in combination with Thiostrepton, an established FoxM1 inhibitor, markedly reduced anchorage-independent growth and displayed more pronounced death in liver cancer cells. We found this effect to be evident even in the resistant HCC cells, thereby putting forth a novel combination therapy for resistant cancer patients. Altogether, our findings provide insight into the pivotal involvement of FoxM1 in the tumor suppressive activities of Artemisinin and shed light on the potential application of Artemisinin for improved therapeutic response, especially in resistant hepatic malignancies. Considering that Artemisinin compounds are in current clinical use with favorable safety profiles, the results from our study will potentiate its utility in juxtaposition with established FoxM1 inhibitors, promoting maximal therapeutic efficacy with minimal adverse effects in liver cancer patients.
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Huang, Zhenghui, Ruoxi Li, Tongke Tang, Dazheng Ling, Manjiong Wang, Dandan Xu, Maoxin Sun et al. "A novel multistage antiplasmodial inhibitor targeting Plasmodium falciparum histone deacetylase 1". Cell Discovery 6, n.º 1 (diciembre de 2020). http://dx.doi.org/10.1038/s41421-020-00215-4.
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AbstractAlthough artemisinin combination therapies have succeeded in reducing the global burden of malaria, multidrug resistance of the deadliest malaria parasite, Plasmodium falciparum, is emerging worldwide. Innovative antimalarial drugs that kill all life-cycle stages of malaria parasites are urgently needed. Here, we report the discovery of the compound JX21108 with broad antiplasmodial activity against multiple life-cycle stages of malaria parasites. JX21108 was developed from chemical optimization of quisinostat, a histone deacetylase inhibitor. We identified P. falciparum histone deacetylase 1 (PfHDAC1), an epigenetic regulator essential for parasite growth and invasion, as a molecular target of JX21108. PfHDAC1 knockdown leads to the downregulation of essential parasite genes, which is highly consistent with the transcriptomic changes induced by JX21108 treatment. Collectively, our data support that PfHDAC1 is a potential drug target for overcoming multidrug resistance and that JX21108 treats malaria and blocks parasite transmission simultaneously.
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Suthram, Niranjan, Siladitya Padhi, Payal Jha, Sunanda Bhattacharyya, Gopalakrishnan Bulusu, Arijit Roy y Mrinal Kanti Bhattacharyya. "Elucidation of DNA Repair Function of PfBlm and Potentiation of Artemisinin Action by a Small-Molecule Inhibitor of RecQ Helicase". mSphere 5, n.º 6 (25 de noviembre de 2020). http://dx.doi.org/10.1128/msphere.00956-20.
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Malaria continues to be a serious threat to humankind not only because of the morbidity and mortality associated with the disease but also due to the huge economic burden that it imparts. Resistance to all available drugs and the unavailability of an effective vaccine cry for an urgent discovery of newer drug targets.
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Enninful, Kweku S., Samuel K. Kwofie, Mark Tetteh-Tsifoanya, Amanda N. L. Lamptey, Georgina Djameh, Samuel Nyarko, Anita Ghansah y Michael D. Wilson. "Targeting the Plasmodium falciparum’s Thymidylate Monophosphate Kinase for the Identification of Novel Antimalarial Natural Compounds". Frontiers in Cellular and Infection Microbiology 12 (25 de mayo de 2022). http://dx.doi.org/10.3389/fcimb.2022.868529.
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Recent reports of resistance to artemisinin-based combination drugs necessitate the need to discover novel antimalarial compounds. The present study was aimed at identifying novel antimalarial compounds from natural product libraries using computational methods. Plasmodium falciparum is highly dependent on the pyrimidine biosynthetic pathway, a de novo pathway responsible for the production of pyrimidines, and the parasite lacks the pyrimidine salvage enzymes. The P. falciparum thymidylate monophosphate kinase (PfTMPK) is an important protein necessary for rapid DNA replication; however, due to its broad substrate specificity, the protein is distinguished from its homologs, making it a suitable drug target. Compounds from AfroDB, a database of natural products originating from Africa, were screened virtually against PfTMPK after filtering the compounds for absorption, distribution, metabolism, excretion, and toxicity (ADMET)-acceptable compounds with FAF-Drugs4. Thirteen hits with lower binding energies than thymidine monophosphate were selected after docking. Among the thirteen compounds, ZINC13374323 and ZINC13365918 with binding energies of −9.4 and −8.9 kcal/mol, respectively, were selected as plausible lead compounds because they exhibited structural properties that ensure proper binding at the active site and inhibitory effect against PfTMPK. ZINC13374323 (also called aurantiamide acetate) is known to exhibit anti-inflammatory and antiviral activities, and ZINC13365918 exhibits antileishmanial activity. Furthermore, aurantiamide acetate, which is commercially available, is a constituent of Artemisia annua, the herb from which artemisinin was derived. The compound also shares interactions with several residues with a potent thymidine analog inhibitor of PfTMPK. The anti-plasmodial activity of aurantiamide acetate was evaluated in vitro, and the mean half-maximal inhibitory concentration (IC50) was 69.33 μM when synchronized P. falciparum 3D7 culture was used as compared to IC50 > 100 μM with asynchronized culture. The significance of our findings within the context of malaria treatment strategies and challenges is discussed.
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de Souza, Guilherme Eduardo, Renata Vieira Bueno, Juliana Oliveira de Souza, Camila Lima Zanini, Fábio Cardoso Cruz, Glaucius Oliva, Rafael Victório Carvalho Guido y Anna Caroline Campos Aguiar. "Antiplasmodial profile of selected compounds from Malaria Box: in vitro evaluation, speed of action and drug combination studies". Malaria Journal 18, n.º 1 (diciembre de 2019). http://dx.doi.org/10.1186/s12936-019-3069-3.
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Abstract Background Artemisinin-based combination therapy (ACT) is used as the first-line treatment of uncomplicated malaria caused by the Plasmodium falciparum parasite and chloroquine-resistant Plasmodium vivax parasites. Evidence of resistance to ACT has been reported in Cambodia, and without new and effective anti-malarial agents, malaria burden and mortality will rise. Methods The used MolPrint 2D fingerprints and the Tanimoto similarity index were used to perform a structural similarity search within the Malaria Box collection to select diverse molecular scaffolds that are different from artesunate. Next, the inhibitory potency against the P. falciparum 3D7 strain (SYBR Green I inhibition assay) and the cytotoxicity against HepG2 cells (MTT and neutral red assays) were evaluated. Then, the speed of action, the combination profile of selected inhibitors with artesunate, and the P. berghei in vivo activity of the best compounds were assessed. Results A set of 11 structurally diverse compounds from the Malaria Box with a similarity threshold of less than 0.05 was selected and compared with artesunate. The in vitro inhibitory activity of each compound confirmed the reported potencies (IC50 values ranging from 0.005 to 1 µM). The cytotoxicity of each selected compound was evaluated and used to calculate the selectivity index (SI values ranging from 15.1 to 6100). Next, both the speed of action and the combination profile of each compound with artesunate was assessed. Acridine, thiazolopyrimidine, quinoxaline, benzimidazole, thiophene, benzodiazepine, isoxazole and pyrimidoindole derivatives showed fast in vitro inhibitory activity of parasite growth, whereas hydrazinobenzimidazole, indenopyridazinone and naphthalenone derivatives were slow-acting in vitro inhibitors. Combinatory profile evaluation indicated that thiazolopyrimidinone and benzodiazepine derivatives have an additive profile, suggesting that the combination of these inhibitors with artesunate is favourable for in vitro inhibitory activity. The remaining compounds showed an antagonistic combinatory profile with artesunate. The collected data indicated that the indenopyridazinone derivative, a bc1 complex inhibitor, had a similar association profile in combination with proguanil when compared to atovaquone combined with proguanil, thereby corroborating the correlation between the molecular target and the combination profile. Lastly, the in vivo activity of the thiazolopyrimidinone and benzodiazepine derivatives were assessed. Both compounds showed oral efficacy at 50 mg/kg in a mouse model of Plasmodium berghei malaria (64% and 40% reduction in parasitaemia on day 5 post-infection, respectively). Conclusions The findings in this paper shed light on the relationship among the speed of action, molecular target and combinatory profile and identified new hits with in vivo activity as candidates for anti-malarial combination therapy.