scholarly journals Antimalarial Activity of Tulathromycin in a Murine Model of Malaria

2015 ◽  
Vol 59 (6) ◽  
pp. 3672-3674 ◽  
Author(s):  
Nicolas Villarino ◽  
Joshua E. Denny ◽  
Nathan W. Schmidt
Keyword(s):  
Murine Model ◽  
Antimalarial Activity ◽  
Parasite Burden ◽  
Plasmodium Yoelii ◽  
Content Type ◽  
Antimalarial Agents ◽  
Progression Of Disease ◽  
Time Of Infection ◽  
And Control

ABSTRACTThere is an urgent need for new antimalarial agents and strategies to treat and control malaria. This study shows an antiplasmodium effect of tulathromycin in mice infected withPlasmodium yoelii. The administration of tulathromycin around the time of infection prevented the progression of disease in 100% of the animals. In addition, highly parasitized mice treated with tulathromycin showed a decreased parasite burden and cleared the parasite faster than did untreated infected mice.

scholarly journals Antimalarial Activity of Small-Molecule Benzothiazole Hydrazones

2016 ◽  
Vol 60 (7) ◽  
pp. 4217-4228 ◽  
Author(s):  
Souvik Sarkar ◽  
Asim A. Siddiqui ◽  
Shubhra J. Saha ◽  
Rudranil De ◽  
Somnath Mazumder ◽  
...  
Keyword(s):  
Murine Model ◽  
Resistant Strain ◽  
Therapeutic Potential ◽  
Antimalarial Activity ◽  
Hematological Parameters ◽  
Plasmodium Yoelii ◽  
Multiple Drug ◽  
Content Type

ABSTRACTWe synthesized a new series of conjugated hydrazones that were found to be active against malaria parasitein vitro, as well asin vivoin a murine model. These hydrazones concentration-dependently chelated free iron and offered antimalarial activity. Upon screening of the synthesized hydrazones, compound 5f was found to be the most active iron chelator, as well as antiplasmodial. Compound 5f also interacted with free heme (KD[equilibrium dissociation constant] = 1.17 ± 0.8 μM), an iron-containing tetrapyrrole released after hemoglobin digestion by the parasite, and inhibited heme polymerization by parasite lysate. Structure-activity relationship studies indicated that a nitrogen- and sulfur-substituted five-membered aromatic ring present within the benzothiazole hydrazones might be responsible for their antimalarial activity. The dose-dependent antimalarial and heme polymerization inhibitory activities of the lead compound 5f were further validated by following [3H]hypoxanthine incorporation and hemozoin formation in parasite, respectively. It is worth mentioning that compound 5f exhibited antiplasmodial activityin vitroagainst a chloroquine/pyrimethamine-resistant strain ofPlasmodium falciparum(K1). We also evaluatedin vivoantimalarial activity of compound 5f in a murine model where a lethal multiple-drug-resistant strain ofPlasmodium yoeliiwas used to infect Swiss albino mice. Compound 5f significantly suppressed the growth of parasite, and the infected mice experienced longer life spans upon treatment with this compound. Duringin vitroandin vivotoxicity assays, compound 5f showed minimal alteration in biochemical and hematological parameters compared to control. In conclusion, we identified a new class of hydrazone with therapeutic potential against malaria.

scholarly journals Immediate Interferon Gamma Induction Determines Murine Host Compatibility Differences between Toxoplasma gondii and Neospora caninum

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Rachel S. Coombs ◽  
Matthew L. Blank ◽  
Elizabeth D. English ◽  
Yaw Adomako-Ankomah ◽  
Ifeanyi-Chukwu Samuel Urama ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Immune Responses ◽  
Interferon Gamma ◽  
Neospora Caninum ◽  
Ectopic Expression ◽  
Parasite Burden ◽  
Interleukin 12 ◽  
Content Type ◽  
Ifn Γ ◽  
And Control

ABSTRACT Rodents are critical for the transmission of Toxoplasma gondii to the definitive feline host via predation, and this relationship has been extensively studied as a model for immune responses to parasites. Neospora caninum is a closely related coccidian parasite of ruminants and canines but is not naturally transmitted by rodents. We compared mouse innate immune responses to N. caninum and T. gondii and found marked differences in cytokine levels and parasite growth kinetics during the first 24 h postinfection (hpi). N. caninum-infected mice produced significantly higher levels of interleukin-12 (IL-12) and interferon gamma (IFN-γ) by as early as 4 hpi, but the level of IFN-γ was significantly lower or undetectable in T. gondii-infected mice during the first 24 hpi. “Immediate” IFN-γ and IL-12p40 production was not detected in MyD88−/− mice. However, unlike IL-12p40−/− and IFN-γ−/− mice, MyD88−/− mice survived N. caninum infections at the dose used in this study. Serial measures of parasite burden showed that MyD88−/− mice were more susceptible to N. caninum infections than wild-type (WT) mice, and control of parasite burdens correlated with a pulse of serum IFN-γ at 3 to 4 days postinfection in the absence of detectable IL-12. Immediate IFN-γ was partially dependent on the T. gondii mouse profilin receptor Toll-like receptor 11 (TLR11), but the ectopic expression of N. caninum profilin in T. gondii had no impact on early IFN-γ production or parasite proliferation. Our data indicate that T. gondii is capable of evading host detection during the first hours after infection, while N. caninum is not, and this is likely due to the early MyD88-dependent recognition of ligands other than profilin.

scholarly journals Computational Chemogenomics Drug Repositioning Strategy Enables the Discovery of Epirubicin as a New Repurposed Hit for Plasmodium falciparum and P. vivax

2020 ◽  
Vol 64 (9) ◽  
Author(s):  
Letícia Tiburcio Ferreira ◽  
Juliana Rodrigues ◽  
Gustavo Capatti Cassiano ◽  
Tatyana Almeida Tavella ◽  
Kaira Cristina Peralis Tomaz ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
In Silico ◽  
Antimalarial Activity ◽  
Drug Repositioning ◽  
Dna Gyrase ◽  
Plasmodium Yoelii ◽  
Computer Assisted ◽  
Content Type

ABSTRACT Widespread resistance against antimalarial drugs thwarts current efforts for controlling the disease and urges the discovery of new effective treatments. Drug repositioning is increasingly becoming an attractive strategy since it can reduce costs, risks, and time-to-market. Herein, we have used this strategy to identify novel antimalarial hits. We used a comparative in silico chemogenomics approach to select Plasmodium falciparum and Plasmodium vivax proteins as potential drug targets and analyzed them using a computer-assisted drug repositioning pipeline to identify approved drugs with potential antimalarial activity. Among the seven drugs identified as promising antimalarial candidates, the anthracycline epirubicin was selected for further experimental validation. Epirubicin was shown to be potent in vitro against sensitive and multidrug-resistant P. falciparum strains and P. vivax field isolates in the nanomolar range, as well as being effective against an in vivo murine model of Plasmodium yoelii. Transmission-blocking activity was observed for epirubicin in vitro and in vivo. Finally, using yeast-based haploinsufficiency chemical genomic profiling, we aimed to get insights into the mechanism of action of epirubicin. Beyond the target predicted in silico (a DNA gyrase in the apicoplast), functional assays suggested a GlcNac-1-P-transferase (GPT) enzyme as a potential target. Docking calculations predicted the binding mode of epirubicin with DNA gyrase and GPT proteins. Epirubicin is originally an antitumoral agent and presents associated toxicity. However, its antiplasmodial activity against not only P. falciparum but also P. vivax in different stages of the parasite life cycle supports the use of this drug as a scaffold for hit-to-lead optimization in malaria drug discovery.

scholarly journals Evaluation of α,β-Unsaturated Ketones as Antileishmanial Agents

2015 ◽  
Vol 59 (6) ◽  
pp. 3598-3601 ◽  
Author(s):  
Miguel A. Vasquez ◽  
Eva Iniguez ◽  
Umashankar Das ◽  
Stephen M. Beverley ◽  
Linda J. Herrera ◽  
...  
Keyword(s):  
Murine Model ◽  
Mammalian Cells ◽  
Leishmania Major ◽  
Parasite Burden ◽  
Effective Concentration ◽  
Bioluminescent Imaging ◽  
Content Type ◽  
Unsaturated Ketones ◽  
Parasite Replication ◽  
20 Nm

ABSTRACTIn this study, we assessed the antileishmanial activity of 126 α,β-unsaturated ketones. The compounds NC901, NC884, and NC2459 showed high leishmanicidal activity for both the extracellular (50% effective concentration [EC50], 456 nM, 1,122 nM, and 20 nM, respectively) and intracellular (EC50, 1,870 nM, 937 nM, and 625 nM, respectively) forms ofLeishmania majorpropagated in macrophages, with little or no toxicity to mammalian cells. Bioluminescent imaging of parasite replication showed that all three compounds reduced the parasite burden in the murine model, with no apparent toxicity.

scholarly journals Caged Garcinia Xanthones, a Novel Chemical Scaffold with Potent Antimalarial Activity

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Hangjun Ke ◽  
Joanne M. Morrisey ◽  
Shiwei Qu ◽  
Oraphin Chantarasriwong ◽  
Michael W. Mather ◽  
...  
Keyword(s):  
Antimalarial Activity ◽  
Morphological Changes ◽  
Biological Activities ◽  
Hek293 Cells ◽  
Therapeutic Window ◽  
Malaria Parasites ◽  
Content Type ◽  
Lead Compounds ◽  
Antimalarial Agents ◽  
Transport Chain

ABSTRACT Caged Garcinia xanthones (CGXs) constitute a family of natural products that are produced by tropical/subtropical trees of the genus Garcinia. CGXs have a unique chemical architecture, defined by the presence of a caged scaffold at the C ring of a xanthone moiety, and exhibit a broad range of biological activities. Here we show that synthetic CGXs exhibit antimalarial activity against Plasmodium falciparum, the causative parasite of human malaria, at the intraerythrocytic stages. Their activity can be substantially improved by attaching a triphenylphosphonium group at the A ring of the caged xanthone. Specifically, CR135 and CR142 were found to be highly effective antimalarial inhibitors, with 50% effective concentrations as low as ∼10 nM. CGXs affect malaria parasites at multiple intraerythrocytic stages, with mature stages (trophozoites and schizonts) being more vulnerable than immature rings. Within hours of CGX treatment, malaria parasites display distinct morphological changes, significant reduction of parasitemia (the percentage of infected red blood cells), and aberrant mitochondrial fragmentation. CGXs do not, however, target the mitochondrial electron transport chain, the target of the drug atovaquone and several preclinical candidates. CGXs are cytotoxic to human HEK293 cells at the low micromolar level, which results in a therapeutic window of around 150-fold for the lead compounds. In summary, we show that CGXs are potent antimalarial compounds with structures distinct from those of previously reported antimalarial inhibitors. Our results highlight the potential to further develop Garcinia natural product derivatives as novel antimalarial agents.

scholarly journals Depletion of Phagocytic Cells during Nonlethal Plasmodium yoelii Infection Causes Severe Malaria Characterized by Acute Renal Failure in Mice

2016 ◽  
Vol 84 (3) ◽  
pp. 845-855 ◽  
Author(s):  
Mohamad Alaa Terkawi ◽  
Maki Nishimura ◽  
Hidefumi Furuoka ◽  
Yoshifumi Nishikawa
Keyword(s):  
Acute Phase ◽  
Multiorgan Failure ◽  
Parasite Burden ◽  
Renal Tissue ◽  
Plasmodium Yoelii ◽  
Fibrin Deposition ◽  
Phagocytic Cells ◽  
Content Type ◽  
Tubular Necrosis ◽  
Liver And Kidney

In the current study, we examined the effects of depletion of phagocytes on the progression ofPlasmodium yoelii17XNL infection in mice. Strikingly, the depletion of phagocytic cells, including macrophages, with clodronate in the acute phase of infection significantly reduced peripheral parasitemia but increased mortality. Moribund mice displayed severe pathological damage, including coagulative necrosis in liver and thrombi in the glomeruli, fibrin deposition, and tubular necrosis in kidney. The severity of infection was coincident with the increased sequestration of parasitized erythrocytes, the systematic upregulation of inflammation and coagulation, and the disruption of endothelial integrity in the liver and kidney. Aspirin was administered to the mice to minimize the risk of excessive activation of the coagulation response and fibrin deposition in the renal tissue. Interestingly, treatment with aspirin reduced the parasite burden and pathological lesions in the renal tissue and improved survival of phagocyte-depleted mice. Our data imply that the depletion of phagocytic cells, including macrophages, in the acute phase of infection increases the severity of malarial infection, typified by multiorgan failure and high mortality.

scholarly journals Cell Swelling Induced by the Antimalarial KAE609 (Cipargamin) and Other PfATP4-Associated Antimalarials

2018 ◽  
Vol 62 (6) ◽  
Author(s):  
Adelaide S. M. Dennis ◽  
Adele M. Lehane ◽  
Melanie C. Ridgway ◽  
John P. Holleran ◽  
Kiaran Kirk
Keyword(s):  
Malaria Parasite ◽  
Antimalarial Activity ◽  
External Environment ◽  
Osmotic Fragility ◽  
Cell Swelling ◽  
Efflux Transporter ◽  
Extracellular Medium ◽  
Human Malaria Parasite ◽  
Content Type ◽  
Antimalarial Agents

ABSTRACTFor an increasing number of antimalarial agents identified in high-throughput phenotypic screens, there is evidence that they target PfATP4, a putative Na+efflux transporter on the plasma membrane of the human malaria parasitePlasmodium falciparum. For several such “PfATP4-associated” compounds, it has been noted that their addition to parasitized erythrocytes results in cell swelling. Here we show that six structurally diverse PfATP4-associated compounds, including the clinical candidate KAE609 (cipargamin), induce swelling of both isolated blood-stage parasites and intact parasitized erythrocytes. The swelling of isolated parasites is dependent on the presence of Na+in the external environment and may be attributed to the osmotic consequences of Na+uptake. The swelling of the parasitized erythrocyte results in an increase in its osmotic fragility. Countering cell swelling by increasing the osmolarity of the extracellular medium reduces the antiplasmodial efficacy of PfATP4-associated compounds, consistent with cell swelling playing a role in the antimalarial activity of this class of compounds.

scholarly journals Metabolism of Piperaquine to Its Antiplasmodial Metabolites and Their Pharmacokinetic Profiles in Healthy Volunteers

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Huixiang Liu ◽  
Hongchang Zhou ◽  
Tianyu Cai ◽  
Aijuan Yang ◽  
Meitong Zang ◽  
...  
Keyword(s):  
Survival Time ◽  
Antimalarial Activity ◽  
Plasmodium Yoelii ◽  
Comparable Efficacy ◽  
Content Type ◽  
Pharmacokinetic Profiles ◽  
Growth Inhibitory ◽  
Elimination Half

ABSTRACT As a partner antimalarial for artemisinin drug-based combination therapy (ACT), piperaquine (PQ) can be metabolized into two major metabolites, including piperaquine N-oxide (M1) and piperaquine N,N-dioxide (M2). To better understand the antimalarial potency of PQ, the antimalarial activity of the PQ metabolites (M1 and M2) was studied in vitro (in Plasmodium falciparum strains Pf3D7 and PfDd2) and in vivo (in the murine species Plasmodium yoelii) in this study. The recrudescence and survival time of infected mice were also recorded after drug treatment. The pharmacokinetic profiles of PQ and its two metabolites (M1 and M2) were investigated in healthy subjects after oral doses of two widely used ACT regimens, i.e., dihydroartemisinin plus piperaquine phosphate (Duo-Cotecxin) and artemisinin plus piperaquine (Artequick). Remarkable antiplasmodial activity was found for PQ (50% growth-inhibitory concentration [IC50], 4.5 nM against Pf3D7 and 6.9 nM against PfDd2; 90% effective dose [ED90], 1.3 mg/kg of body weight), M1 (IC50, 25.5 nM against Pf3D7 and 38.7 nM against PfDd2; ED90, 1.3 mg/kg), and M2 (IC50, 31.2 nM against Pf3D7 and 33.8 nM against PfDd2; ED90, 2.9 mg/kg). Compared with PQ, M1 showed comparable efficacy in terms of recrudescence and survival time and M2 had relatively weaker antimalarial potency. PQ and its two metabolites displayed a long elimination half-life (∼11 days for PQ, ∼9 days for M1, and ∼4 days for M2), and they accumulated after repeated administrations. The contribution of the two PQ metabolites to the efficacy of piperaquine as a partner drug of ACT for the treatment of malaria should be considered for PQ dose optimization.

Discovery of 3-Cinnamamido-N-Substituted Benzamides as Potential Antimalarial Agents

2020 ◽  
Vol 16 ◽  
Author(s):  
Haicheng Liu ◽  
Yushi Futamura ◽  
Honghai Wu ◽  
Aki Ishiyama ◽  
Taotao Zhang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Antimalarial Activity ◽  
In Vitro Assays ◽  
Compound Library ◽  
Antimalarial Agents ◽  
Phenotypic Screen ◽  
Ic50 Values ◽  
Substituted Benzamides

Background: Malaria is one of the most devastating parasitic diseases, yet the discovery of antimalarial agents remains profoundly challenging. Very few new antimalarials have been developed in the past 50 years, while the emergence of drug-resistance continues to appear. Objective: This study focuses on the discovery, design, synthesis, and antimalarial evaluation of 3-cinnamamido-N-substituted benzamides. Method: In this study, a screening of our compound library was carried out against the multidrug-sensitive Plasmodium falciparum 3D7 strain. Derivatives of the hit were designed, synthesized and tested against P. falciparum 3D7 and the in vivo antimalarial activity of the most active compounds was evaluated using the method of Peters’ 4-day suppressive test. Results: The retrieved hit compound 1 containing a 3-cinnamamido-N-substituted benzamide skeleton showed moderate antimalarial activity (IC50 = 1.20 µM) for the first time. A series of derivatives were then synthesized through a simple four-step workflow, and half of them exhibited slightly better antimalarial effect than the precursor 1 during the subsequent in vitro assays. Additionally, compounds 11, 23, 30 and 31 displayed potent activity with IC50 values of approximately 0.1 µM, and weak cytotoxicity against mammalian cells. However, in vivo antimalarial activity is not effective which might be ascribed to the poor solubility of these compounds. Conclusion: In this study, phenotypic screen of our compound library resulted in the first report of 3-cinnamamide framework with antimalarial activity and 40 derivatives were then designed and synthesized. Subsequent structure-activity studies showed that compounds 11, 23, 30 and 31 exhibited the most potent and selective activity against P. falciparum 3D7 strain with IC50 values around 0.1 µM. Our work herein sets another example of phenotypic screen-based drug discovery, leading to potentially promising candidates of novel antimalarial agents once given further optimization.

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

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