Violacein-Induced Chaperone System Collapse Underlies Multistage Antiplasmodial Activity.
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ABSTRACT:
SUBMITTER: Tavella TA
PROVIDER: S-EPMC8042658 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundViolacein is a deep violet compound that is produced by a number of bacterial species. It is synthesized from tryptophan by a pathway that involves the sequential action of 5 different enzymes (encoded by genes vioA to vioE). Violacein has antibacterial, antiparasitic, and antiviral activities, and also has the potential of inducing apoptosis in certain cancer cells.ResultsHere, we describe the construction of a series of plasmids harboring the complete or partial violacein biosynthesis operon and their use to enable production of violacein and deoxyviolacein in E.coli. We performed in vitro assays to determine the biological activity of these compounds against Plasmodium, Trypanosoma, and mammalian cells. We found that, while deoxyviolacein has a lower activity against parasites than violacein, its toxicity to mammalian cells is insignificant compared to that of violacein.ConclusionsWe constructed E. coli strains capable of producing biologically active violacein and related compounds, and propose that deoxyviolacein might be a useful starting compound for the development of antiparasite drugs.
| S-EPMC5896143 | biostudies-literature
Project description:The discovery and development of multistage antimalarial drugs targeting intra-erythrocytic asexual and sexual Plasmodium falciparum parasites is of utmost importance to achieve the ambitious goal of malaria elimination. Here, we report the validation of naphthylisoquinoline (NIQ) alkaloids and their synthetic analogues as multistage active antimalarial drug candidates. A total of 30 compounds were tested, of which 17 exhibited IC50 values <1 μM against drug-sensitive P. falciparum parasites (NF54 strain); 15 of these retained activity against a panel of drug-resistant strains. These compounds showed low in vitro cytotoxicity against HepG2 cells, with selectivity indices of >10. The tested compounds showed activity in vitro against both early- and late-stage P. falciparum gametocytes while blocking male gamete formation (>70% inhibition of exflagellation at 2 μM). Additionally, five selected compounds were found to have good solubility (≥170 μM in PBS at pH 6.5), while metabolic stability towards human, mouse, and rat microsomes ranged from >90% to >7% after 30 min. Dioncophylline C (2a) emerged as a front runner from the study, displaying activity against both asexual parasites and gametocytes, a lack of cross-resistance to chloroquine, good solubility, and microsomal stability. Overall, this is the first report on the multistage activity of NIQs and their synthetic analogues including gametocytocidal and gametocidal effects induced by this class of compounds.
| S-EPMC7270141 | biostudies-literature
Project description:Although 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.
| S-EPMC7733455 | biostudies-literature
Project description:It is now generally recognised that different modes of programmed cell death (PCD) are intimately linked to the cancerous process. However, the mechanism of PCD involved in cancer chemoprevention is much less clear and may be different between types of chemopreventive agents and tumour cell types involved. Therefore, from a pharmacological view, it is crucial during the earlier steps of drug development to define the cellular specificity of the candidate as well as its capacity to bypass dysfunctional tumoral signalling pathways providing insensitivity to death stimuli. Studying the cytotoxic effects of violacein, an antibiotic dihydro-indolone synthesised by an Amazon river Chromobacterium, we observed that death induced in CD34(+)/c-Kit(+)/P-glycoprotein(+)/MRP1(+) TF1 leukaemia progenitor cells is not mediated by apoptosis and/or autophagy, since biomarkers of both types of cell death were not significantly affected by this compound. To clarify the working mechanism of violacein, we performed kinome profiling using peptide arrays to yield comprehensive descriptions of cellular kinase activities. Pro-death activity of violacein is actually carried out by inhibition of calpain and DAPK1 and activation of PKA, AKT and PDK, followed by structural changes caused by endoplasmic reticulum stress and Golgi apparatus collapse, leading to cellular demise. Our results demonstrate that violacein induces kinome reprogramming, overcoming death signaling dysfunctions of intrinsically resistant human leukaemia cells.
| S-EPMC3469566 | biostudies-literature
Project description:The Ca(2+)-permeable cation channel transient receptor potential melastatin 2 (TRPM2) plays a key role in pathogen-evoked phagocyte activation, postischemic neuronal apoptosis, and glucose-evoked insulin secretion, by linking these cellular responses to oxidative stress. TRPM2 channels are coactivated by binding of intracellular ADP ribose and Ca(2+) to distinct cytosolically accessible sites on the channels. These ligands likely regulate the activation gate, conserved in the voltage-gated cation channel superfamily, that comprises a helix bundle formed by the intracellular ends of transmembrane helix six of each subunit. For several K(+) and TRPM family channels, activation gate opening requires the presence of phosphatidylinositol-bisphosphate (PIP(2)) in the inner membrane leaflet. Most TRPM family channels inactivate upon prolonged stimulation in inside-out patches; this "rundown" is due to PIP(2) depletion. TRPM2 currents also run down within minutes, but the molecular mechanism of this process is unknown. Here we report that high-affinity PIP(2) binding regulates Ca(2+) sensitivity of TRPM2 activation. Nevertheless, TRPM2 inactivation is not due to PIP(2) depletion; rather, it is state dependent, sensitive to permeating ions, and can be completely prevented by mutations in the extracellular selectivity filter. Introduction of two negative charges plus a single-residue insertion, to mimic the filter sequence of TRPM5, results in TRPM2 channels that maintain unabated maximal activity for over 1 h, and display altered permeation properties but intact ADP ribose/Ca(2+)-dependent gating. Thus, upon prolonged stimulation, the TRPM2 selectivity filter undergoes a conformational change reminiscent of that accompanying C-type inactivation of voltage-gated K(+) channels. The noninactivating TRPM2 variant will be invaluable for gating studies.
| S-EPMC3421201 | biostudies-literature
Project description:Malaria remains one of the major health concerns due to the resistance of Plasmodium species toward the existing drugs warranting an urgent need for new antimalarials. Thymol derivatives were known to exhibit enhanced antimicrobial activities; however, no reports were found against Plasmodium spp. In the present study, the antiplasmodial activity of thymol derivatives was evaluated against chloroquine-sensitive (NF-54) and -resistant (K1) strains of Plasmodium falciparum. Among the thymol derivatives tested, 4-chlorothymol showed potential activity against sensitive and resistant strains of P. falciparum. 4-Chlorothymol was found to increase the reactive oxygen species and reactive nitrogen species level. Furthermore, 4-chlorothymol could perturb the redox balance by modulating the enzyme activity of GST and GR. 4-Chlorothymol also showed synergy with chloroquine against chloroquine-resistant P. falciparum. 4-Chlorothymol was found to significantly suppress the parasitemia and increase the mean survival time in in vivo assays. Interestingly, in in vivo assay, 4-chlorothymol in combination with chloroquine showed higher chemosuppression as well as enhanced mean survival time at a much lower concentration as compared to individual doses of chloroquine and 4-chlorothymol. These observations clearly indicate the potential use of 4-chlorothymol as an antimalarial agent, which may also be effective in combination with the existing antiplasmodial drugs against chloroquine-resistant P. falciparum infection. In vitro cytotoxicity/hemolytic assay evidently suggests that 4-chlorothymol is safe for further exploration of its therapeutic properties.
| S-EPMC7988344 | biostudies-literature
Project description:Ribozymes must fold into compact, native structures to function properly in the cell. The first step in forming the RNA tertiary structure is the neutralization of the phosphate charge by cations, followed by collapse of the unfolded molecules into more compact structures. The specificity of the collapse transition determines the structures of the folding intermediates and the folding time to the native state. However, the forces that enable specific collapse in RNA are not understood. Using time-resolved SAXS, we report that upon addition of 5 mM Mg(2+) to the Azoarcus group I ribozyme up to 80% of chains form compact structures in less than 1 ms. In 1 mM Mg(2+), the collapse transition produces extended structures that slowly approach the folded state, while > or = 1.5 mM Mg(2+) leads to an ensemble of random coils that fold with multistage kinetics. Increased flexibility of molecules in the intermediate ensemble correlates with a Mg(2+)-dependent increase in the fast folding population and a previously unobserved crossover in the collapse kinetics. Partial denaturation of the unfolded RNA with urea also increases the fraction of chains following the fast-folding pathway. These results demonstrate that the preferred collapse mechanism depends on the extent of Mg(2+)-dependent charge neutralization and that non-native interactions within the unfolded ensemble contribute to the heterogeneity of the ribozyme folding pathways at the very earliest stages of tertiary structure formation.
| S-EPMC2918669 | biostudies-literature
Project description:BackgroundNew classes of anti-malarial drugs are needed to control the alarming Plasmodium falciparum resistance toward current anti-malarial therapy. The ethnopharmacological approach allows the discovery of original chemical structures from the vegetable biodiversity. Previous studies led to the selection of a bisbenzylisoquinoline, called cepharanthine and isolated from a Cambodian plant: Stephania rotunda. Cepharanthine could exert a mechanism of action different from commonly used drugs. Potential plasmodial targets are reported here.MethodsTo study the mechanism of action of cepharanthine, a combined approach using phenotypic and transcriptomic techniques was undertaken.ResultsCepharanthine blocked P. falciparum development in ring stage. On a culture of synchronized ring stage, the comparisons of expression profiles showed that the samples treated with 5 ?M of cepharanthine (IC90) were significantly closer to the initial controls than to the final ones. After a two-way ANOVA (p-value?<?0.05) on the microarray results, 1,141 probes among 9,722 presented a significant differential expression.A gene ontology analysis showed that the Maurer's clefts seem particularly down-regulated by cepharanthine. The analysis of metabolic pathways showed an impact on cell-cell interactions (cytoadherence and rosetting), glycolysis and isoprenoid pathways. Organellar functions, more particularly constituted by apicoplast and mitochondrion, are targeted too.ConclusionThe blockage at the ring stage by cepharanthine is described for the first time. Transcriptomic approach confirmed that cepharanthine might have a potential innovative antiplasmodial mechanism of action. Thus, cepharanthine might play an ongoing role in the progress on anti-malarial drug discovery efforts.
| S-EPMC4152577 | biostudies-literature
Project description:A series of [(aryl)arylsufanylmethyl]pyridines (AASMP) have been synthesized. These compounds inhibited hemozoin formation, formed complexes (K(D) = 12 to 20 muM) with free heme (ferriprotoporphyrin IX) at a pH close to the pH of the parasite food vacuole, and exhibited antimalarial activity in vitro. The inhibition of hemozoin formation may develop oxidative stress in Plasmodium falciparum due to the accumulation of free heme. Interestingly, AASMP developed oxidative stress in the parasite, as evident from the decreased level of glutathione and increased formation of lipid peroxide, H(2)O(2), and hydroxyl radical (.OH) in P. falciparum. AASMP also caused mitochondrial dysfunction by decreasing mitochondrial potential (DeltaPsim) in malaria parasite, as measured by both flow cytometry and fluorescence microscopy. Furthermore, the generation of .OH may be mainly responsible for the antimalarial effect of AASMP since .OH scavengers such as mannitol, as well as spin trap alpha-phenyl-n-tertbutylnitrone, significantly protected P. falciparum from AASMP-mediated growth inhibition. Cytotoxicity testing of the active compounds showed selective activity against malaria parasite with selectivity indices greater than 100. AASMP also exhibited profound antimalarial activity in vivo against chloroquine resistant P. yoelii. Thus, AASMP represents a novel class of antimalarial.
| S-EPMC2224759 | biostudies-literature
Project description:Malaria is one of the most dangerous infectious diseases. Because the causative Plasmodium parasites have developed resistances against virtually all established antimalarial drugs, novel antiplasmodial agents are required. In order to target plasmodial kinases, novel N-unsubstituted bisindolylcyclobutenediones were designed as analogs to the kinase inhibitory bisindolylmaleimides. Molecular docking experiments produced favorable poses of the unsubstituted bisindolylcyclobutenedione in the ATP binding pocket of various plasmodial protein kinases. The synthesis of the title compounds was accomplished by sequential Friedel-Crafts acylation procedures. In vitro screening of the new compounds against transgenic NF54-luc P. falciparum parasites revealed a set of derivatives with submicromolar activity, of which some displayed a reasonable selectivity profile against a human cell line. Although the molecular docking studies suggested the plasmodial protein kinase PfGSK-3 as the putative biological target, the title compounds failed to inhibit the isolated enzyme in vitro. As selective submicromolar antiplasmodial agents, the N-unsubstituted bisindolylcyclobutenediones are promising starting structures in the search for antimalarial drugs, albeit for a rational development, the biological target addressed by these compounds has yet to be identified.
| S-EPMC8402075 | biostudies-literature