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JACS Au Mar 2024Malaria is one of the most widespread diseases worldwide. Besides a growing number of people potentially threatened by malaria, the consistent emergence of resistance...
Malaria is one of the most widespread diseases worldwide. Besides a growing number of people potentially threatened by malaria, the consistent emergence of resistance against established antimalarial pharmaceuticals leads to an urge toward new antimalarial drugs. Hybridization of two chemically diverse compounds into a new bioactive product is a successful concept to improve the properties of a hybrid drug relative to the parent compounds and also to overcome multidrug resistance. 1,2,3-Triazoles are a significant pharmacophore system among nitrogen-containing heterocycles with various applications, such as antiviral, antimalarial, antibacterial, and anticancer agents. Several marketed drugs possess these versatile moieties, which are used in a wide range of medical indications. While the synthesis of hybrid compounds containing a 1,2,3-triazole unit was described using Cu- and Ru-catalyzed azide-alkyne cycloaddition, an alternative metal-free pathway has never been reported for the synthesis of antimalarial hybrids. However, a metal-free pathway is a green method that allows toxic and expensive metals to be replaced with an organocatalyst. Herein, we present the synthesis of new artemisinin-triazole antimalarial hybrids a facile Ramachary-Bressy-Wang organocatalyzed azide-carbonyl [3 + 2] cycloaddition (organo-click) reaction. The prepared new hybrid compounds are highly potent against chloroquine (CQ)-resistant and multi-drug-resistant strains (IC (Dd2) down to 2.1 nM; IC (K1) down to 1.8 nM) compared to CQ (IC (Dd2) = 165.3 nM; IC (K1) = 302.8 nM). Moreover, the most potent hybrid drug was more efficacious in suppressing parasitemia and extending animal survival in -infected mice (up to 100% animal survival and up to 40 days of survival time) than the reference drug artemisinin, illustrating the potential of the hybridization concept as an alternative and powerful drug-discovery approach.
PubMed: 38559731
DOI: 10.1021/jacsau.3c00716 -
Nucleic Acids Research Jun 2024Gametocyte development of the Plasmodium parasite is a key step for transmission of the parasite. Male and female gametocytes are produced from a subpopulation of...
Gametocyte development of the Plasmodium parasite is a key step for transmission of the parasite. Male and female gametocytes are produced from a subpopulation of asexual blood-stage parasites, but the mechanisms that regulate the differentiation of sexual stages are still under investigation. In this study, we investigated the role of PbARID, a putative subunit of a SWI/SNF chromatin remodeling complex, in transcriptional regulation during the gametocyte development of P. berghei. PbARID expression starts in early gametocytes before the manifestation of male and female-specific features, and disruption of its gene results in the complete loss of gametocytes with detectable male features and the production of abnormal female gametocytes. ChIP-seq analysis of PbARID showed that it forms a complex with gSNF2, an ATPase subunit of the SWI/SNF chromatin remodeling complex, associating with the male cis-regulatory element, TGTCT. Further ChIP-seq of PbARID in gsnf2-knockout parasites revealed an association of PbARID with another cis-regulatory element, TGCACA. RIME and DNA-binding assays suggested that HDP1 is the transcription factor that recruits PbARID to the TGCACA motif. Our results indicated that PbARID could function in two chromatin remodeling events and paly essential roles in both male and female gametocyte development.
Topics: Animals; Female; Male; Mice; Chromatin Assembly and Disassembly; Plasmodium berghei; Protozoan Proteins; Transcription Factors; Genotype; Sequence Analysis, RNA; Chromatin; Amino Acid Sequence; Sequence Analysis, Protein; Phylogeny; Transcriptome; Genome, Protozoan
PubMed: 38554111
DOI: 10.1093/nar/gkae207 -
Microorganisms Feb 2024Membranolytic molecules constitute the first line of innate immune defense against pathogenic microorganisms. sporozoites are potentially exposed to these cytotoxic...
Membranolytic molecules constitute the first line of innate immune defense against pathogenic microorganisms. sporozoites are potentially exposed to these cytotoxic molecules in the hemolymph and salivary glands of mosquitoes, as well as in the skin, blood, and liver of the mammalian host. Here, we show that sporozoites are resistant to bacteriolytic concentration of cecropin B, a cationic amphipathic antimicrobial insect peptide. Intriguingly, anti-tumoral cell-penetrating peptides derived from the anti-apoptotic protein AAC11 killed and sporozoites. Using dynamic imaging, we demonstrated that the most cytotoxic peptide, called RT39, did not significantly inhibit the sporozoite motility until the occurrence of a fast permeabilization of the parasite membrane by the peptide. Concomitantly, the cytosolic fluorescent protein constitutively expressed by sporozoites leaked from the treated parasite body while To-Pro 3 and FITC-labeled RT39 internalized, respectively, binding to the nucleic acids and membranes of sporozoites. This led to an increase in the parasite granularity as assessed by flow cytometry. Most permeabilization events started at the parasite's posterior end, resulting in the appearance of a fluorescent dot in the anterior part of sporozoites. Understanding and exploiting the susceptibility of sporozoites and other plasmodial stages to membranolytic molecules might foster strategies to eliminate the parasite and block its transmission.
PubMed: 38543531
DOI: 10.3390/microorganisms12030480 -
Memorias Do Instituto Oswaldo Cruz 2024Malaria is an infectious disease caused by protozoan parasites belonging to the genus Plasmodium. Human-to-human transmission depends on a mosquito vector; thus, the...
BACKGROUND
Malaria is an infectious disease caused by protozoan parasites belonging to the genus Plasmodium. Human-to-human transmission depends on a mosquito vector; thus, the interruption of parasite transmission from humans to mosquitoes is an important approach in the fight against malaria. The parasite stages infectious to mosquitoes are the gametocytes, sexual stages that are ingested by the vector during a blood meal and transform into male and female gametes in the midgut. Immunity against sexual stage antigens expressed by gametocytes, gametes, and the zygote formed after fertilisation can interrupt the parasite sexual cycle in the mosquito. This transmission blocking immunity is mediated by specific antibodies ingested during the mosquito blood feed, inhibiting the parasite development in the midgut. Merozoite thrombospondin related anonymous protein (MTRAP) is a merozoite and gametocyte surface protein essential for gamete egress from erythrocytes and for parasite transmission to mosquitoes.
OBJECTIVES
Here, we evaluated the potential of the P. berghei MTRAP to elicit antibodies with the ability to inhibit gamete fertilisation in vitro.
METHODS
We expressed a soluble recombinant PbMTRAP and used it to immunise BALB/c mice. The transmission blocking activity of the anti-rPbMTRAP antibodies was tested through in vivo challenge experiments followed by in vitro conversion assays.
FINDINGS
Immunisations with the rPbMTRAP induced a strong antibody response and the antibodies recognised the native protein by Western Blot and IFA. Anti-rPbMTRAP present in the blood stream of immunised mice partially inhibited gamete conversion into ookinetes.
CONCLUSION
Our results indicate that antibodies to PbMTRAP may reduce but are not sufficient to completely block transmission.
Topics: Male; Female; Humans; Animals; Mice; Protozoan Proteins; Plasmodium berghei; Merozoites; Malaria; Culicidae
PubMed: 38537036
DOI: 10.1590/0074-02760230217 -
PLoS Neglected Tropical Diseases Mar 2024Pharmacophores such as hydroxyethylamine (HEA) and phthalimide (PHT) have been identified as potential synthons for the development of compounds against various...
Pharmacophores such as hydroxyethylamine (HEA) and phthalimide (PHT) have been identified as potential synthons for the development of compounds against various parasitic infections. In order to further advance our progress, we conducted an experiment utilising a collection of PHT and HEA derivatives through phenotypic screening against a diverse set of protist parasites. This approach led to the identification of a number of compounds that exhibited significant effects on the survival of Entamoeba histolytica, Trypanosoma brucei, and multiple life-cycle stages of Leishmania spp. The Leishmania hits were pursued due to the pressing necessity to expand our repertoire of reliable, cost-effective, and efficient medications for the treatment of leishmaniases. Antileishmanials must possess the essential capability to efficiently penetrate the host cells and their compartments in the disease context, to effectively eliminate the intracellular parasite. Hence, we performed a study to assess the effectiveness of eradicating L. infantum intracellular amastigotes in a model of macrophage infection. Among eleven L. infantum growth inhibitors with low-micromolar potency, PHT-39, which carries a trifluoromethyl substitution, demonstrated the highest efficacy in the intramacrophage assay, with an EC50 of 1.2 +/- 3.2 μM. Cytotoxicity testing of PHT-39 in HepG2 cells indicated a promising selectivity of over 90-fold. A chemogenomic profiling approach was conducted using an orthology-based method to elucidate the mode of action of PHT-39. This genome-wide RNA interference library of T. brucei identified sensitivity determinants for PHT-39, which included a P-type ATPase that is crucial for the uptake of miltefosine and amphotericin, strongly indicating a shared route for cellular entry. Notwithstanding the favourable properties and demonstrated efficacy in the Plasmodium berghei infection model, PHT-39 was unable to eradicate L. major infection in a murine infection model of cutaneous leishmaniasis. Currently, PHT-39 is undergoing derivatization to optimize its pharmacological characteristics.
Topics: Humans; Animals; Mice; Antiprotozoal Agents; Leishmania; Amphotericin B; Leishmaniasis, Cutaneous; Phthalimides; Leishmania infantum
PubMed: 38527083
DOI: 10.1371/journal.pntd.0012050 -
PloS One 2024Novel and highly sensitive point-of-care malaria diagnostic and surveillance tools that are rapid and affordable are urgently needed to support malaria control and...
BACKGROUND
Novel and highly sensitive point-of-care malaria diagnostic and surveillance tools that are rapid and affordable are urgently needed to support malaria control and elimination.
METHODS
We demonstrated the potential of near-infrared spectroscopy (NIRS) technique to detect malaria parasites both, in vitro, using dilutions of infected red blood cells obtained from Plasmodium falciparum cultures and in vivo, in mice infected with P. berghei using blood spotted on slides and non-invasively, by simply scanning various body areas (e.g., feet, groin and ears). The spectra were analysed using machine learning to develop predictive models for infection.
FINDINGS
Using NIRS spectra of in vitro cultures and machine learning algorithms, we successfully detected low densities (<10-7 parasites/μL) of P. falciparum parasites with a sensitivity of 96% (n = 1041), a specificity of 93% (n = 130) and an accuracy of 96% (n = 1171) and differentiated ring, trophozoite and schizont stages with an accuracy of 98% (n = 820). Furthermore, when the feet of mice infected with P. berghei with parasitaemia ≥3% were scanned non-invasively, the sensitivity and specificity of NIRS were 94% (n = 66) and 86% (n = 342), respectively.
INTERPRETATION
These data highlights the potential of NIRS technique as rapid, non-invasive and affordable tool for surveillance of malaria cases. Further work to determine the potential of NIRS to detect malaria in symptomatic and asymptomatic malaria cases in the field is recommended including its capacity to guide current malaria elimination strategies.
Topics: Animals; Mice; Spectroscopy, Near-Infrared; Parasites; Malaria, Falciparum; Malaria; Plasmodium falciparum; Machine Learning; Sensitivity and Specificity
PubMed: 38527002
DOI: 10.1371/journal.pone.0289232 -
BMC Complementary Medicine and Therapies Mar 2024The potent antiplasmodial activity of 1-hydroxy-5,6,7-trimethoxyxanthone (HTX), isolated from Mammea siamensis T. Anders. flowers, has previously been demonstrated in...
BACKGROUND
The potent antiplasmodial activity of 1-hydroxy-5,6,7-trimethoxyxanthone (HTX), isolated from Mammea siamensis T. Anders. flowers, has previously been demonstrated in vitro. However, its in vivo activity has not been reported. Therefore, this study aimed to investigate the antimalarial activity and acute toxicity of HTX in a mouse model and to evaluate the pharmacokinetic profile of HTX following a single intraperitoneal administration.
METHODS
The in vivo antimalarial activity of HTX was evaluated using a 4-day suppressive test. Mice were intraperitoneally injected with Plasmodium berghei ANKA strain and given HTX daily for 4 days. To detect acute toxicity, mice received a single dose of HTX and were observed for 14 days. Additionally, the biochemical parameters of the liver and kidney functions as well as the histopathology of liver and kidney tissues were examined. HTX pharmacokinetics after intraperitoneal administration was also investigated in a mouse model. Liquid chromatography triple quadrupole mass spectrometry was used to quantify plasma HTX and calculate pharmacokinetic parameters with the PKSolver software.
RESULTS
HTX at 10 mg/kg body weight significantly suppressed parasitemia in malaria-infected mice by 74.26%. Mice treated with 3 mg/kg HTX showed 46.88% suppression, whereas mice treated with 1 mg/kg displayed 34.56% suppression. Additionally, no symptoms of acute toxicity were observed in the HTX-treated groups. There were no significant alterations in the biochemical parameters of the liver and kidney functions and no histological changes in liver or kidney tissues. Following intraperitoneal HTX administration, the pharmacokinetic profile exhibited a maximum concentration (C) of 94.02 ng/mL, time to attain C (T) of 0.5 h, mean resident time of 14.80 h, and elimination half-life of 13.88 h.
CONCLUSIONS
HTX has in vivo antimalarial properties against P. berghei infection. Acute toxicity studies of HTX did not show behavioral changes or mortality. The median lethal dose was greater than 50 mg/kg body weight. Pharmacokinetic studies showed that HTX has a long elimination half-life; hence, shortening the duration of malaria treatment may be required to minimize toxicity.
Topics: Mice; Animals; Antimalarials; Mammea; Plant Extracts; Malaria; Flowers; Body Weight
PubMed: 38521901
DOI: 10.1186/s12906-024-04427-z -
Heliyon Mar 2024Artemisinin-based combinations (ACTs) are World Health Organization-recommended treatment for malaria. Artemether (A) and lumefantrine (LUM) were the first co-formulated...
Artemisinin-based combinations (ACTs) are World Health Organization-recommended treatment for malaria. Artemether (A) and lumefantrine (LUM) were the first co-formulated ACT and first-line treatment for malaria globally, artemether is dihydroartemisinin's (DHA's) prodrug. Artemisinins and LUM face low aqueous solubility while artemisinin has low bioavailability and short half-life thus requiring continuous dosage to maintain adequate therapeutic drug-plasma concentration. This study aimed at improving ACTs limitations by nano-formulating DHA-LUM using solid lipid nanoparticles (SLNs) as nanocarrier. SLNs were prepared by modified solvent extraction method based on water-in-oil-in-water double emulsion. Mean particle size, polydispersity index and zeta potential were 308.4 nm, 0.29 and -16.0 mV respectively. Nanoencapsulation efficiencies and drug loading of DHA and LUM were 93.9%, 33.7%, 11.9%, and 24.10% respectively. Nanoparticles were spherically shaped and drugs followed Kors-Peppas release model, steadily released for over 72 h. DHA-LUM-SLNs were 31% more efficacious than conventional oral doses in clearing from infected Swiss albino mice.
PubMed: 38501019
DOI: 10.1016/j.heliyon.2024.e26868 -
Trends in Parasitology Apr 2024Du, Ren, et al. recently showed in a Plasmodium berghei ANKA (PbA) experimental malaria model that phosphatase of regenerating liver 2 (PRL2) regulates neutrophil...
Du, Ren, et al. recently showed in a Plasmodium berghei ANKA (PbA) experimental malaria model that phosphatase of regenerating liver 2 (PRL2) regulates neutrophil extracellular traps (NETs) in severe malaria (SM)-related acute lung injury (ALI). PRL2 deficiency caused SM with ALI in a mouse model by increasing NETs in pulmonary tissue; hydroxychloroquine (HCQ) may ameliorate this.
Topics: Animals; Mice; Extracellular Traps; Neutrophils; Lung; Malaria; Acute Lung Injury
PubMed: 38485580
DOI: 10.1016/j.pt.2024.03.001 -
MBio Apr 2024Remodeling the erythrocyte membrane and skeleton by the malarial parasite is closely associated with intraerythrocytic development. However, the mechanisms underlying...
UNLABELLED
Remodeling the erythrocyte membrane and skeleton by the malarial parasite is closely associated with intraerythrocytic development. However, the mechanisms underlying this association remain unclear. In this study, we present evidence that erythrocytic α-spectrin, but not β-spectrin, was dynamically ubiquitinated and progressively degraded during the intraerythrocytic development of from the ring to the schizont stage. We further observed an upregulated expression of phosphatidylinositol 3-kinase (PfPI3K) in the infected red blood cells during the intraerythrocytic development of the parasite. The data indicated that PfPI3K phosphorylated and activated erythrocytic ubiquitin-protein ligase, leading to increased α-spectrin ubiquitination and degradation during development. We further revealed that inhibition of the activity of PfPI3K impaired development and infectivity in mice. These findings collectively unveil an important mechanism of PfPI3K-ubiquitin-mediated degradation of α-spectrin during the intraerythrocytic development of species. Proteins in the PfPI3K regulatory pathway are novel targets for effective treatment of severe malaria.
IMPORTANCE
is the causative agent of severe malaria that causes millions of deaths globally. The parasite invades human red blood cells and induces a cascade of alterations in erythrocytes for development and proliferation. Remodeling the host erythrocytic cytoskeleton is a necessary process during parasitization, but its regulatory mechanisms remain to be elucidated. In this study, we observed that erythrocytic α-spectrin is selectively degraded after invasion, while β-spectrin remained intact. We found that the α-spectrin chain was profoundly ubiquitinated by E3 ubiquitin ligase and degraded by the 26S proteasome. E3 ubiquitin ligase activity was regulated by phosphatidylinositol 3-kinase (PfPI3K) signaling. Additionally, blocking the PfPI3K-ubiquitin-proteasome pathway in -infected red blood cells reduced parasite proliferation and infectivity. This study deepens our understanding of the regulatory mechanisms of host and malarial parasite interactions and paves the way for the exploration of novel antimalarial drugs.
Topics: Humans; Animals; Mice; Plasmodium falciparum; Spectrin; Erythrocytes; Malaria, Falciparum; Ubiquitin; Phosphatidylinositol 3-Kinase; Ubiquitin-Protein Ligases
PubMed: 38470053
DOI: 10.1128/mbio.03510-23