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1.
Dalton Trans ; 53(28): 11903-11913, 2024 Jul 16.
Article in English | MEDLINE | ID: mdl-38953883

ABSTRACT

Monoanionic gold bis(dithiolene) complexes were recently shown to display activity against ovarian cancer cells, Gram-positive bacteria, Candida strains and the rodent malaria parasite, P. berghei. To date, only monoanionic gold(III) bis(dithiolene) complexes with a thiazoline backbone substituted with small alkyl chains have been evaluated for biomedical applications. We now analyzed the influence of the length and the hydrophobicity vs. hydrophilicity of these complexes' alkyl chain on their anticancer and antiplasmodial properties. Isomer analogues of these monoanionic gold(III) bis(dithiolene) complexes, this time with a thiazole backbone, were also investigated in order to assess the influence of the nature of the heterocyclic ligand on their overall chemical and biological properties. In this report we present the total synthesis of four novel monoanionic gold(III) bis(dithiolene) complexes with a long alkyl chain and a polyoxygenated (PEG) chain aiming to improve their solubility and biological properties. Our results showed that the complexes with a PEG chain showed promising anticancer and antiplasmodial activities beside improved solubility, a key parameter in drug discovery and development.


Subject(s)
Antimalarials , Antineoplastic Agents , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/chemical synthesis , Structure-Activity Relationship , Humans , Antimalarials/pharmacology , Antimalarials/chemistry , Antimalarials/chemical synthesis , Gold/chemistry , Gold/pharmacology , Cell Line, Tumor , Drug Screening Assays, Antitumor , Plasmodium falciparum/drug effects , Coordination Complexes/pharmacology , Coordination Complexes/chemistry , Coordination Complexes/chemical synthesis , Organogold Compounds/pharmacology , Organogold Compounds/chemistry , Organogold Compounds/chemical synthesis , Molecular Structure , Parasitic Sensitivity Tests , Cell Proliferation/drug effects , Animals
2.
Int J Mol Sci ; 25(13)2024 Jun 26.
Article in English | MEDLINE | ID: mdl-39000107

ABSTRACT

Even though several new targets (mostly viral infection) for drug repurposing of pyronaridine and artesunate have recently emerged in vitro and in vivo, inter-species pharmacokinetic (PK) data that can extend nonclinical efficacy to humans has not been reported over 30 years of usage. Since extrapolation of animal PK data to those of humans is essential to predict clinical outcomes for drug repurposing, this study aimed to investigate inter-species PK differences in three animal species (hamster, rat, and dog) and to support clinical translation of a fixed-dose combination of pyronaridine and artesunate. PK parameters (e.g., steady-state volume of distribution (Vss), clearance (CL), area under the concentration-time curve (AUC), mean residence time (MRT), etc.) of pyronaridine, artesunate, and dihydroartemisinin (an active metabolite of artesunate) were determined by non-compartmental analysis. In addition, one- or two-compartment PK modeling was performed to support inter-species scaling. The PK models appropriately described the blood concentrations of pyronaridine, artesunate, and dihydroartemisinin in all animal species, and the estimated PK parameters in three species were integrated for inter-species allometric scaling to predict human PKs. The simple allometric equation (Y = a × Wb) well explained the relationship between PK parameters and the actual body weight of animal species. The results from the study could be used as a basis for drug repurposing and support determining the effective dosage regimen for new indications based on in vitro/in vivo efficacy data and predicted human PKs in initial clinical trials.


Subject(s)
Artemisinins , Artesunate , Drug Repositioning , Naphthyridines , Artesunate/pharmacokinetics , Artesunate/pharmacology , Drug Repositioning/methods , Animals , Rats , Dogs , Naphthyridines/pharmacokinetics , Naphthyridines/pharmacology , Artemisinins/pharmacokinetics , Species Specificity , Humans , Models, Biological , Male , Antimalarials/pharmacokinetics , Antimalarials/pharmacology
3.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 36(3): 233-238, 2024 May 23.
Article in Chinese | MEDLINE | ID: mdl-38952307

ABSTRACT

Malaria is an infectious disease that seriously threatens human health. Currently, malaria control mainly depends on antimalarial chemotherapy. However, antimalarial drug resistance is becoming increasingly severe, which poses a great challenge to malaria control, notably treatment of Plasmodium falciparum malaria. To address this challenge, there is a need to facilitate development of novel antimalarial drugs and innovation of treatment strategies, as well as reinforce surveillance and research on antimalarial drug resistance. This article reviews the main categories and use guidelines of current antimalarial agents, summarizes the current status and monitoring methods of antimalarial drug resistance, and proposes the response to antimalarial drug resistance, so as to provide insights into the use of antimalarial drugs and response to antimalarial drug resistance, and contribute to global malaria elimination.


Subject(s)
Antimalarials , Drug Resistance , Malaria , Antimalarials/therapeutic use , Antimalarials/pharmacology , Humans , Malaria/drug therapy , Malaria/prevention & control , Disease Eradication/methods
4.
Parasitol Res ; 123(7): 263, 2024 Jul 08.
Article in English | MEDLINE | ID: mdl-38976068

ABSTRACT

The rapid emergence of drug resistance against the mainstream antimalarial drugs has increased the need for development of novel drugs. Recent approaches have embarked on the repurposing of existing drugs to induce cell death via programmed cell death pathways. However, little is known about the ER stress response and programmed cell death pathways of the malaria parasite. In this study, we treated ex vivo Plasmodium berghei cultures with tunicamycin, 5-fluorouracil, and chloroquine as known stress inducer drugs to probe the transcriptional changes of autophagy and apoptosis-related genes (PbATG5, PbATG8, PbATG12, and PbMCA2). Treatments with 5-fluorouracil and chloroquine resulted in the upregulation of all analyzed markers, yet the levels of PbATG5 and PbATG12 were dramatically higher in chloroquine-treated ex vivo cultures. In contrast, tunicamycin treatment resulted in the downregulation of both PbATG8 and PbATG12, and upregulation of PbMCA2. Our results indicate that the malaria parasite responds to various ER stressors by inducing autophagy- and/or apoptosis-like pathways.


Subject(s)
Antimalarials , Apoptosis , Autophagy , Endoplasmic Reticulum Stress , Plasmodium berghei , Endoplasmic Reticulum Stress/drug effects , Plasmodium berghei/drug effects , Plasmodium berghei/physiology , Apoptosis/drug effects , Antimalarials/pharmacology , Autophagy/drug effects , Animals , Chloroquine/pharmacology , Tunicamycin/pharmacology , Mice
5.
Int J Nanomedicine ; 19: 6777-6809, 2024.
Article in English | MEDLINE | ID: mdl-38983131

ABSTRACT

Chloroquine is a common antimalarial drug and is listed in the World Health Organization Standard List of Essential Medicines because of its safety, low cost and ease of use. Besides its antimalarial property, chloroquine also was used in anti-inflammatory and antivirus, especially in antitumor therapy. A mount of data showed that chloroquine mainly relied on autophagy inhibition to exert its antitumor effects. However, recently, more and more researches have revealed that chloroquine acts through other mechanisms that are autophagy-independent. Nevertheless, the current reviews lacked a comprehensive summary of the antitumor mechanism and combined pharmacotherapy of chloroquine. So here we focused on the antitumor properties of chloroquine, summarized the pharmacological mechanisms of antitumor progression of chloroquine dependent or independent of autophagy inhibition. Moreover, we also discussed the side effects and possible application developments of chloroquine. This review provided a more systematic and cutting-edge knowledge involved in the anti-tumor mechanisms and combined pharmacotherapy of chloroquine in hope of carrying out more in-depth exploration of chloroquine and obtaining more clinical applications.


Subject(s)
Antineoplastic Agents , Autophagy , Chloroquine , Neoplasms , Chloroquine/pharmacology , Chloroquine/therapeutic use , Humans , Neoplasms/drug therapy , Autophagy/drug effects , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Antineoplastic Agents/chemistry , Animals , Antimalarials/pharmacology , Antimalarials/therapeutic use
6.
Biochemistry ; 63(14): 1738-1751, 2024 Jul 16.
Article in English | MEDLINE | ID: mdl-38975628

ABSTRACT

Over the past two decades, the utilization of protein cages has witnessed exponential growth driven by their extensive applications in biotechnology and therapeutics. In the context of the recent Covid-19 pandemic, protein-cage-based scaffolds played a pivotal role in vaccine development. Beyond vaccines, these protein cages have proven valuable in diverse drug delivery applications thanks to their distinctive architecture and structural stability. Among the various types of protein cages, ferritin-based cages have taken the lead in drug delivery applications. This is primarily attributed to their ease of production, exceptional thermal stability, and nontoxic nature. While ferritin-based cages are commonly employed in anticancer drug delivery and contrast agent delivery, their efficacy in malarial drug delivery had not been explored until this study. In this investigation, several antimalarial drugs were encapsulated within horse spleen ferritin, and the binding and loading processes were validated through both experimental and computational techniques. The data unequivocally demonstrate the facile incorporation of antimalarial drugs into ferritin without disrupting its three-dimensional structure. Computational docking and molecular dynamics simulations were employed to pinpoint the precise location of the drug binding site within ferritin. Subsequent efficacy testing on Plasmodium revealed that the developed nanoconjugate, comprising the drug-ferritin conjugate, exhibited significant effectiveness in eradicating the parasite. In conclusion, the findings strongly indicate that ferritin-based carrier systems hold tremendous promise for the future of antimalarial drug delivery, offering high selectivity and limited side effects.


Subject(s)
Antimalarials , Ferritins , Ferritins/chemistry , Ferritins/metabolism , Antimalarials/chemistry , Antimalarials/pharmacology , Animals , Horses , Drug Delivery Systems/methods , Malaria/drug therapy , Molecular Docking Simulation , Molecular Dynamics Simulation , Humans , Spleen/metabolism , Plasmodium falciparum/drug effects
7.
Protein Expr Purif ; 222: 106539, 2024 Oct.
Article in English | MEDLINE | ID: mdl-38960013

ABSTRACT

PF11_0189 is a putative insulin degrading enzyme present in Plasmodium falciparum genome. The catalytic domain of PF11_0189 is about 27 kDa. Substrate specificity study shows PF11_0189 acts upon different types of proteins. The substrate specificity is found to be highest when insulin is used as a substrate. Metal dependency study shows highest dependency of PF11_0189 towards zinc metal for its proteolytic activity. Chelation of zinc metal with EDTA shows complete absence of PF11_0189 activity. Peptide inhibitors, P-70 and P-121 from combinatorial peptide library prepared against PF11_0189 show inhibition with an IC50 value of 4.8 µM and 7.5 µM respectively. A proven natural anti-malarial peptide cyclosporin A shows complete inhibition against PF11_0189 with an IC50 value of 0.75 µM suggesting PF11_0189 as a potential target for peptide inhibitors. The study implicates that PF11_0189 is a zinc metalloprotease involved in catalysis of insulin. The study gives a preliminary insight into the mechanism of complications arising from glucose abnormalities during severe malaria.


Subject(s)
Insulysin , Plasmodium falciparum , Protozoan Proteins , Plasmodium falciparum/enzymology , Plasmodium falciparum/genetics , Insulysin/genetics , Insulysin/chemistry , Insulysin/metabolism , Protozoan Proteins/genetics , Protozoan Proteins/chemistry , Protozoan Proteins/metabolism , Substrate Specificity , Insulin/chemistry , Insulin/metabolism , Insulin/genetics , Zinc/chemistry , Zinc/metabolism , Genome, Protozoan , Recombinant Proteins/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Recombinant Proteins/isolation & purification , Gene Expression , Cloning, Molecular , Antimalarials/chemistry , Antimalarials/pharmacology , Cyclosporine/chemistry , Cyclosporine/pharmacology
8.
Molecules ; 29(13)2024 Jun 24.
Article in English | MEDLINE | ID: mdl-38998949

ABSTRACT

Newly synthesized 7-chloro-4-aminoquinoline-benzimidazole hybrids were characterized by NMR and elemental analysis. Compounds were tested for their effects on the growth of the non-tumor cell line MRC-5 (human fetal lung fibroblasts) and carcinoma (HeLa and CaCo-2), leukemia, and lymphoma (Hut78, THP-1, and HL-60) cell lines. The obtained results, expressed as the concentration at which 50% inhibition of cell growth is achieved (IC50 value), show that the tested compounds affect cell growth differently depending on the cell line and the applied dose (IC50 ranged from 0.2 to >100 µM). Also, the antiplasmodial activity of these hybrids was evaluated against two P. falciparum strains (Pf3D7 and PfDd2). The tested compounds showed potent antiplasmodial activity, against both strains, at nanomolar concentrations. Quantitative structure-activity relationship (QSAR) analysis resulted in predictive models for antiplasmodial activity against the 3D7 strain (R2 = 0.886; Rext2 = 0.937; F = 41.589) and Dd2 strain (R2 = 0.859; Rext2 = 0.878; F = 32.525) of P. falciparum. QSAR models identified the structural features of these favorable effects on antiplasmodial activities.


Subject(s)
Antimalarials , Antineoplastic Agents , Benzimidazoles , Drug Design , Plasmodium falciparum , Quantitative Structure-Activity Relationship , Humans , Benzimidazoles/chemistry , Benzimidazoles/pharmacology , Benzimidazoles/chemical synthesis , Antimalarials/pharmacology , Antimalarials/chemical synthesis , Antimalarials/chemistry , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Plasmodium falciparum/drug effects , Plasmodium falciparum/growth & development , Cell Line, Tumor , Cell Proliferation/drug effects , Quinolines/chemistry , Quinolines/pharmacology , Quinolines/chemical synthesis , Molecular Structure , Aminoquinolines
9.
Sci Rep ; 14(1): 16291, 2024 Jul 15.
Article in English | MEDLINE | ID: mdl-39009685

ABSTRACT

Hard-to-reach communities represent Peru's main challenge for malaria elimination, but information about transmission in these areas is scarce. Here, we assessed Plasmodium vivax (Pv) and P. falciparum (Pf) transmission dynamics, resistance markers, and Pf hrp2/3 deletions in Nueva Jerusalén (NJ), a remote, indigenous community in the Peruvian Amazon with high population mobility. We collected samples from November 2019 to May 2020 by active (ACD) and passive case detection (PCD) in NJ. Parasites were identified with microscopy and PCR. Then, we analyzed a representative set of positive-PCR samples (Pv = 68, Pf = 58) using highly-multiplexed deep sequencing assays (AmpliSeq) and compared NJ parasites with ones from other remote Peruvian areas using population genetics indexes. The ACD intervention did not reduce malaria cases in the short term, and persistent malaria transmission was observed (at least one Pv infection was detected in 96% of the study days). In Nueva Jerusalen, the Pv population had modest genetic diversity (He = 0.27). Pf population had lower diversity (He = 0.08) and presented temporal clustering, one of these clusters linked to an outbreak in February 2020. Moreover, Pv and Pf parasites from NJ exhibited variable levels of differentiation (Pv Fst = 0.07-0.52 and Pf Fst = 0.11-0.58) with parasites from other remote areas. No artemisin resistance mutations but chloroquine (57%) and sulfadoxine-pyrimethamine (35-67%) were detected in NJ's Pf parasites. Moreover, pfhrp2/3 gene deletions were common (32-50% of parasites with one or both genes deleted). The persistent Pv transmission and the detection of a Pf outbreak with parasites genetically distinct from the local ones highlight the need for tailored interventions focusing on mobility patterns and imported infections in remote areas to eliminate malaria in the Peruvian Amazon.


Subject(s)
Malaria, Falciparum , Malaria, Vivax , Plasmodium falciparum , Plasmodium vivax , Protozoan Proteins , Peru/epidemiology , Humans , Plasmodium falciparum/genetics , Plasmodium falciparum/isolation & purification , Plasmodium vivax/genetics , Plasmodium vivax/isolation & purification , Malaria, Falciparum/epidemiology , Malaria, Falciparum/parasitology , Malaria, Falciparum/transmission , Malaria, Vivax/epidemiology , Malaria, Vivax/parasitology , Malaria, Vivax/transmission , Protozoan Proteins/genetics , Female , Male , Child , Adult , Antimalarials/therapeutic use , Antimalarials/pharmacology , Adolescent , Drug Resistance/genetics , Middle Aged , Indigenous Peoples/genetics , Young Adult , Child, Preschool , Genomics/methods , Genetic Variation , Antigens, Protozoan/genetics
10.
PLoS One ; 19(7): e0304337, 2024.
Article in English | MEDLINE | ID: mdl-38968216

ABSTRACT

BACKGROUND: Plasmodium vivax has become the predominant species in the border regions of Thailand. The emergence and spread of antimalarial drug resistance in P. vivax is one of the significant challenges for malaria control. Continuous surveillance of drug resistance is therefore necessary for monitoring the development of drug resistance in the region. This study aims to investigate the prevalence of the mutation in the P. vivax multidrug resistant 1 (Pvmdr1), dihydrofolate reductase (Pvdhfr), and dihydropteroate synthetase (Pvdhps) genes conferred resistance to chloroquine (CQ), pyrimethamine (P) and sulfadoxine (S), respectively. METHOD: 100 P. vivax isolates were obtained between January to May 2023 from a Kanchanaburi province, western Thailand. Nucleotide sequences of Pvmdr1, Pvdhfr, and Pvdhps genes were amplified and sequenced. The frequency of single nucleotide polymorphisms (SNPs)-haplotypes of drug-resistant alleles was assessed. The linkage disequilibrium (LD) tests were also analyzed. RESULTS: In Pvmdr1, T958M, Y976F, and F1076L, mutations were detected in 100%, 21%, and 23% of the isolates, respectively. In Pvdhfr, the quadruple mutant allele (I57R58M61T117) prevailed in 84% of the samples, followed by (L57R58M61T117) in 11%. For Pvdhps, the double mutant allele (G383G553) was detected (48%), followed by the triple mutant allele (G383M512G553) (47%) of the isolates. The most prevalent combination of Pvdhfr (I57R58M61T117) and Pvdhps (G383G553) alleles was sextuple mutated haplotypes (48%). For LD analysis, the association in the SNPs pairs was found between the intragenic and intergenic regions of the Pvdhfr and Pvdhps genes. CONCLUSION: The study has recently updated the high prevalence of three gene mutations associated with CQ and SP resistance. Genetic monitoring is therefore important to intensify in the regions to further assess the spread of drug resistant. Our data also provide evidence on the distribution of drug resistance for the early warning system, thereby threatening P. vivax malaria treatment policy decisions at the national level.


Subject(s)
Antimalarials , Drug Resistance , Malaria, Vivax , Plasmodium vivax , Polymorphism, Single Nucleotide , Plasmodium vivax/genetics , Plasmodium vivax/drug effects , Plasmodium vivax/isolation & purification , Thailand/epidemiology , Drug Resistance/genetics , Humans , Antimalarials/pharmacology , Malaria, Vivax/parasitology , Malaria, Vivax/epidemiology , Malaria, Vivax/drug therapy , Tetrahydrofolate Dehydrogenase/genetics , Linkage Disequilibrium , Mutation , Protozoan Proteins/genetics , Chloroquine/pharmacology , Dihydropteroate Synthase/genetics , Sulfadoxine/pharmacology , Pyrimethamine/pharmacology , Multidrug Resistance-Associated Proteins/genetics , Haplotypes , Male , Female , Adult
11.
Malar J ; 23(1): 205, 2024 Jul 09.
Article in English | MEDLINE | ID: mdl-38982475

ABSTRACT

BACKGROUND: Drug resistance in Plasmodium falciparum is a major threat to malaria control efforts. Pathogen genomic surveillance could be invaluable for monitoring current and emerging parasite drug resistance. METHODS: Data from two decades (2000-2020) of continuous molecular surveillance of P. falciparum parasites from Senegal were retrospectively examined to assess historical changes in malaria drug resistance mutations. Several known drug resistance markers and their surrounding haplotypes were profiled using a combination of single nucleotide polymorphism (SNP) molecular surveillance and whole genome sequence based population genomics. RESULTS: This dataset was used to track temporal changes in drug resistance markers whose timing correspond to historically significant events such as the withdrawal of chloroquine (CQ) and the introduction of sulfadoxine-pyrimethamine (SP) in 2003. Changes in the mutation frequency at Pfcrt K76T and Pfdhps A437G coinciding with the 2014 introduction of seasonal malaria chemoprevention (SMC) in Senegal were observed. In 2014, the frequency of Pfcrt K76T increased while the frequency of Pfdhps A437G declined. Haplotype-based analyses of Pfcrt K76T showed that this rapid increase was due to a recent selective sweep that started after 2014. DISCUSSION (CONCLUSION): The rapid increase in Pfcrt K76T is troubling and could be a sign of emerging amodiaquine (AQ) resistance in Senegal. Emerging AQ resistance may threaten the future clinical efficacy of artesunate-amodiaquine (ASAQ) and AQ-dependent SMC chemoprevention. These results highlight the potential of molecular surveillance for detecting rapid changes in parasite populations and stress the need to monitor the effectiveness of AQ as a partner drug for artemisinin-based combination therapy (ACT) and for chemoprevention.


Subject(s)
Antimalarials , Drug Resistance , Mutation , Plasmodium falciparum , Senegal , Plasmodium falciparum/drug effects , Plasmodium falciparum/genetics , Drug Resistance/genetics , Antimalarials/pharmacology , Antimalarials/therapeutic use , Retrospective Studies , Humans , Malaria, Falciparum/parasitology , Malaria, Falciparum/epidemiology , Polymorphism, Single Nucleotide , Protozoan Proteins/genetics , Haplotypes , Membrane Transport Proteins/genetics
13.
Elife ; 132024 Jul 08.
Article in English | MEDLINE | ID: mdl-38976500

ABSTRACT

New antimalarial drug candidates that act via novel mechanisms are urgently needed to combat malaria drug resistance. Here, we describe the multi-omic chemical validation of Plasmodium M1 alanyl metalloaminopeptidase as an attractive drug target using the selective inhibitor, MIPS2673. MIPS2673 demonstrated potent inhibition of recombinant Plasmodium falciparum (PfA-M1) and Plasmodium vivax (PvA-M1) M1 metalloaminopeptidases, with selectivity over other Plasmodium and human aminopeptidases, and displayed excellent in vitro antimalarial activity with no significant host cytotoxicity. Orthogonal label-free chemoproteomic methods based on thermal stability and limited proteolysis of whole parasite lysates revealed that MIPS2673 solely targets PfA-M1 in parasites, with limited proteolysis also enabling estimation of the binding site on PfA-M1 to within ~5 Å of that determined by X-ray crystallography. Finally, functional investigation by untargeted metabolomics demonstrated that MIPS2673 inhibits the key role of PfA-M1 in haemoglobin digestion. Combined, our unbiased multi-omic target deconvolution methods confirmed the on-target activity of MIPS2673, and validated selective inhibition of M1 alanyl metalloaminopeptidase as a promising antimalarial strategy.


Subject(s)
Antimalarials , Plasmodium falciparum , Plasmodium vivax , Proteomics , Protozoan Proteins , Antimalarials/pharmacology , Antimalarials/chemistry , Plasmodium falciparum/enzymology , Plasmodium falciparum/drug effects , Plasmodium vivax/enzymology , Plasmodium vivax/drug effects , Humans , Protozoan Proteins/metabolism , Protozoan Proteins/antagonists & inhibitors , Protozoan Proteins/chemistry , Proteomics/methods , Aminopeptidases/metabolism , Aminopeptidases/antagonists & inhibitors , Aminopeptidases/chemistry
14.
EMBO Mol Med ; 16(7): 1515-1532, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38862600

ABSTRACT

Parasites, such as the malaria parasite P. falciparum, are critically dependent on host nutrients. Interference with nutrient uptake can lead to parasite death and, therefore, serve as a successful treatment strategy. P. falciparum parasites cannot synthesise cholesterol, and instead source this lipid from the host. Here, we tested whether cholesterol uptake pathways could be 'hijacked' for optimal drug delivery to the intracellular parasite. We found that fluorescent cholesterol analogues were delivered from the extracellular environment to the intracellular parasite. We investigated the uptake and inhibitory effects of conjugate compounds, where proven antimalarial drugs (primaquine and artesunate) were attached to steroids that mimic the structure of cholesterol. These conjugated antimalarial drugs improved the inhibitory effects against multiple parasite lifecycle stages, multiple parasite species, and drug-resistant parasites, whilst also lowering the toxicity to human host cells. Steroids with introduced peroxides also displayed antimalarial activity. These results provide a proof-of-concept that cholesterol mimics can be developed as a drug delivery system against apicomplexan parasites with the potential to improve drug efficacy, increase therapeutic index, and defeat drug resistance.


Subject(s)
Antimalarials , Artesunate , Cholesterol , Plasmodium falciparum , Cholesterol/metabolism , Antimalarials/pharmacology , Antimalarials/therapeutic use , Plasmodium falciparum/drug effects , Plasmodium falciparum/metabolism , Humans , Artesunate/pharmacology , Artesunate/therapeutic use , Primaquine/pharmacology , Primaquine/therapeutic use , Drug Resistance/drug effects , Animals , Malaria, Falciparum/drug therapy , Malaria, Falciparum/parasitology
15.
PLoS Pathog ; 20(6): e1012013, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38870266

ABSTRACT

Plasmodium parasites, the causal agents of malaria, are eukaryotic organisms that obligately undergo sexual recombination within mosquitoes. In low transmission settings, parasites recombine with themselves, and the clonal lineage is propagated rather than broken up by outcrossing. We investigated whether stochastic/neutral factors drive the persistence and abundance of Plasmodium falciparum clonal lineages in Guyana, a country with relatively low malaria transmission, but the only setting in the Americas in which an important artemisinin resistance mutation (pfk13 C580Y) has been observed. We performed whole genome sequencing on 1,727 Plasmodium falciparum samples collected from infected patients across a five-year period (2016-2021). We characterized the relatedness between each pair of monoclonal infections (n = 1,409) through estimation of identity-by-descent (IBD) and also typed each sample for known or candidate drug resistance mutations. A total of 160 multi-isolate clones (mean IBD ≥ 0.90) were circulating in Guyana during the study period, comprising 13 highly related clusters (mean IBD ≥ 0.40). In the five-year study period, we observed a decrease in frequency of a mutation associated with artemisinin partner drug (piperaquine) resistance (pfcrt C350R) and limited co-occurence of pfcrt C350R with duplications of plasmepsin 2/3, an epistatic interaction associated with piperaquine resistance. We additionally observed 61 nonsynonymous substitutions that increased markedly in frequency over the study period as well as a novel pfk13 mutation (G718S). However, P. falciparum clonal dynamics in Guyana appear to be largely driven by stochastic factors, in contrast to other geographic regions, given that clones carrying drug resistance polymorphisms do not demonstrate enhanced persistence or higher abundance than clones carrying polymorphisms of comparable frequency that are unrelated to resistance. The use of multiple artemisinin combination therapies in Guyana may have contributed to the disappearance of the pfk13 C580Y mutation.


Subject(s)
Antimalarials , Drug Resistance , Malaria, Falciparum , Plasmodium falciparum , Plasmodium falciparum/genetics , Plasmodium falciparum/drug effects , Guyana , Malaria, Falciparum/parasitology , Malaria, Falciparum/epidemiology , Malaria, Falciparum/drug therapy , Humans , Antimalarials/pharmacology , Antimalarials/therapeutic use , Drug Resistance/genetics , Artemisinins/pharmacology , Artemisinins/therapeutic use , Mutation , Protozoan Proteins/genetics
16.
Eur J Med Chem ; 275: 116599, 2024 Sep 05.
Article in English | MEDLINE | ID: mdl-38909569

ABSTRACT

The increase in research funding for the development of antimalarials since 2000 has led to a surge of new chemotypes with potent antimalarial activity. High-throughput screens have delivered several thousand new active compounds in several hundred series, including the 4,7-diphenyl-1,4,5,6,7,8-hexahydroquinolines, hereafter termed dihydropyridines (DHPs). We optimized the DHPs for antimalarial activity. Structure-activity relationship studies focusing on the 2-, 3-, 4-, 6-, and 7-positions of the DHP core led to the identification of compounds potent (EC50 < 10 nM) against all strains of P. falciparum tested, including the drug-resistant parasite strains K1, W2, and TM90-C2B. Evaluation of efficacy of several compounds in vivo identified two compounds that reduced parasitemia by >75 % in mice 6 days post-exposure following a single 50 mg/kg oral dose. Resistance acquisition experiments with a selected dihydropyridine led to the identification of a single mutation conveying resistance in the gene encoding for Plasmodium falciparum multi-drug resistance protein 1 (PfMDR1). The same dihydropyridine possessed transmission blocking activity. The DHPs have the potential for the development of novel antimalarial drug candidates.


Subject(s)
Antimalarials , Dihydropyridines , Plasmodium falciparum , Antimalarials/pharmacology , Antimalarials/chemistry , Antimalarials/chemical synthesis , Dihydropyridines/pharmacology , Dihydropyridines/chemistry , Dihydropyridines/chemical synthesis , Structure-Activity Relationship , Plasmodium falciparum/drug effects , Animals , Mice , Stereoisomerism , Parasitic Sensitivity Tests , Molecular Structure , Dose-Response Relationship, Drug , Humans
17.
Eur J Med Chem ; 275: 116621, 2024 Sep 05.
Article in English | MEDLINE | ID: mdl-38944935

ABSTRACT

An optimization of the pyridylpiperazine series against Plasmodium falciparum has been performed, exploring a structure-activity relationship carried out on the toluyl fragment of hit 1, a compound with low micromolar activity against Plasmodium falciparum discovered by high-throughput screening. After confirming the crucial role played by this aryl fragment in the antiplasmodial activity, the replacement of the ortho-methyl substituent of 1 by halogenated ones led to an improvement for four analogs, either in terms of potency, expected pharmacokinetics profile, or both. Further introduction of endocyclic nitrogens in this fragment identified two more optimized compounds, 20 and 23, which are expected to be much more metabolically stable than 1. Additional assessment of the cytotoxicity, Ligand Lipophilic Efficiency, potency against the chloroquine-resistant Dd2 strain and in silico ADMET predictions revealed a satisfactory profile for most compounds, ultimately identifying the four optimized compounds 7, 9, 20 and 23 as promising compounds for further lead optimization of this series against Plasmodium falciparum.


Subject(s)
Antimalarials , Drug Design , Parasitic Sensitivity Tests , Piperazines , Plasmodium falciparum , Antimalarials/pharmacology , Antimalarials/chemical synthesis , Antimalarials/chemistry , Plasmodium falciparum/drug effects , Structure-Activity Relationship , Piperazines/chemistry , Piperazines/pharmacology , Piperazines/chemical synthesis , Humans , Molecular Structure , Dose-Response Relationship, Drug , Animals
18.
J Med Chem ; 67(13): 11401-11420, 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38918002

ABSTRACT

Structure-activity relationship studies of 2,8-disubstituted-1,5-naphthyridines, previously reported as potent inhibitors of Plasmodium falciparum (Pf) phosphatidylinositol-4-kinase ß (PI4K), identified 1,5-naphthyridines with basic groups at 8-position, which retained Plasmodium PI4K inhibitory activity but switched primary mode of action to the host hemoglobin degradation pathway through inhibition of hemozoin formation. These compounds showed minimal off-target inhibitory activity against the human phosphoinositide kinases and MINK1 and MAP4K kinases, which were associated with the teratogenicity and testicular toxicity observed in rats for the PfPI4K inhibitor clinical candidate MMV390048. A representative compound from the series retained activity against field isolates and lab-raised drug-resistant strains of Pf. It was efficacious in the humanized NSG mouse malaria infection model at a single oral dose of 32 mg/kg. This compound was nonteratogenic in the zebrafish embryo model of teratogenicity and has a low predicted human dose, indicating that this series has the potential to deliver a preclinical candidate for malaria.


Subject(s)
1-Phosphatidylinositol 4-Kinase , Antimalarials , Hemeproteins , Naphthyridines , Plasmodium falciparum , Zebrafish , Plasmodium falciparum/drug effects , Animals , Naphthyridines/pharmacology , Naphthyridines/chemistry , Naphthyridines/chemical synthesis , Naphthyridines/therapeutic use , Antimalarials/pharmacology , Antimalarials/chemistry , Antimalarials/chemical synthesis , 1-Phosphatidylinositol 4-Kinase/antagonists & inhibitors , 1-Phosphatidylinositol 4-Kinase/metabolism , Humans , Structure-Activity Relationship , Hemeproteins/antagonists & inhibitors , Hemeproteins/metabolism , Mice , Rats , Malaria, Falciparum/drug therapy , Male , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/chemical synthesis
19.
Int J Mol Sci ; 25(12)2024 Jun 11.
Article in English | MEDLINE | ID: mdl-38928131

ABSTRACT

Chloroquine (CQ) is a 4-aminoquinoline derivative largely employed in the management of malaria. CQ treatment exploits the drug's ability to cross the erythrocyte membrane, inhibiting heme polymerase in malarial trophozoites. Accumulation of CQ prevents the conversion of heme to hemozoin, causing its toxic buildup, thus blocking the survival of Plasmodium parasites. Recently, it has been reported that CQ is able to exert antiviral properties, mainly against HIV and SARS-CoV-2. This renewed interest in CQ treatment has led to the development of new studies which aim to explore its side effects and long-term outcome. Our study focuses on the effects of CQ in non-parasitized red blood cells (RBCs), investigating hemoglobin (Hb) functionality, the anion exchanger 1 (AE1) or band 3 protein, caspase 3 and protein tyrosine phosphatase 1B (PTP-1B) activity, intra and extracellular ATP levels, and the oxidative state of RBCs. Interestingly, CQ influences the functionality of both Hb and AE1, the main RBC proteins, affecting the properties of Hb oxygen affinity by shifting the conformational structure of the molecule towards the R state. The influence of CQ on AE1 flux leads to a rate variation of anion exchange, which begins at a concentration of 2.5 µM and reaches its maximum effect at 20 µM. Moreover, a significant decrease in intra and extracellular ATP levels was observed in RBCs pre-treated with 10 µM CQ vs. erythrocytes under normal conditions. This effect is related to the PTP-1B activity which is reduced in RBCs incubated with CQ. Despite these metabolic alterations to RBCs caused by exposure to CQ, no signs of variations in oxidative state or caspase 3 activation were recorded. Our results highlight the antithetical effects of CQ on the functionality and metabolism of RBCs, and encourage the development of new research to better understand the multiple potentiality of the drug.


Subject(s)
Anion Exchange Protein 1, Erythrocyte , Chloroquine , Erythrocytes , Hemoglobins , Erythrocytes/metabolism , Erythrocytes/drug effects , Erythrocytes/parasitology , Humans , Chloroquine/pharmacology , Hemoglobins/metabolism , Anion Exchange Protein 1, Erythrocyte/metabolism , Adenosine Triphosphate/metabolism , Antimalarials/pharmacology , Caspase 3/metabolism
20.
Article in English | MEDLINE | ID: mdl-38928926

ABSTRACT

Multidrug- and artemisinin-resistant (ART-R) Plasmodium falciparum (Pf) parasites represent a challenge for malaria elimination worldwide. Molecular monitoring in the Kelch domain region (pfk13) gene allows tracking mutations in parasite resistance to artemisinin. The increase in illegal miners in the Roraima Yanomami indigenous land (YIL) could favor ART-R parasites. Thus, this study aimed to investigate ART-R in patients from illegal gold mining areas in the YIL of Roraima, Brazil. A questionnaire was conducted, and blood was collected from 48 patients diagnosed with P. falciparum or mixed malaria (Pf + P. vivax). The DNA was extracted and the pfk13 gene was amplified by PCR. The amplicons were subjected to DNA-Sanger-sequencing and the entire amplified fragment was analyzed. Among the patients, 96% (46) were from illegal mining areas of the YIL. All parasite samples carried the wild-type genotypes/ART-sensitive phenotypes. These data reinforce the continued use of artemisinin-based combination therapies (ACTs) in Roraima, as well as the maintenance of systematic monitoring for early detection of parasite populations resistant to ART, mainly in regions with an intense flow of individuals from mining areas, such as the YIL. This is especially true when the achievement of falciparum malaria elimination in Brazil is planned and expected by 2030.


Subject(s)
Antimalarials , Artemisinins , Drug Resistance , Malaria, Falciparum , Mining , Plasmodium falciparum , Artemisinins/therapeutic use , Artemisinins/pharmacology , Brazil/epidemiology , Plasmodium falciparum/drug effects , Plasmodium falciparum/genetics , Humans , Antimalarials/therapeutic use , Antimalarials/pharmacology , Drug Resistance/genetics , Malaria, Falciparum/drug therapy , Malaria, Falciparum/epidemiology , Malaria, Falciparum/parasitology , Male , Adult , Female , Middle Aged , Young Adult , Adolescent , Genotype
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