Chlorpheniramine Analogues Reverse Chloroquine Resistance in<i>Plasmodium falciparum</i>by Inhibiting PfCRT

Deane, Karen J.; Summers, Robert L.; Lehane, Adele M.; Martin, R. L.; Barrow, Russell A.

doi:10.1021/ml5000228

Cited by 20 publications

(13 citation statements)

References 33 publications

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“…24 Interestingly, chlorpheniramine, which is a structurally similar first-generation antihistamine, has recently been reported to resensitize chloroquine-resistant malaria parasites to chloroquine. 25 Hit compound IOTA0058 was found to be a selective inhibitor of TbrPDEB1, with hPDE4D inhibitory activity outside the measured concentration range (Fig. 1D), although its LE was fairly low ( Table 1).…”

Section: Resultsmentioning

confidence: 95%

Fragment-Based Screening in Tandem with Phenotypic Screening Provides Novel Antiparasitic Hits

Blaazer¹,

Orrling

Shanmugham³

et al. 2015

SLAS Discovery

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Methods to discover biologically active small molecules include target-based and phenotypic screening approaches. One of the main difficulties in drug discovery is elucidating and exploiting the relationship between drug activity at the protein target and disease modification, a phenotypic endpoint. Fragment-based drug discovery is a target-based approach that typically involves the screening of a relatively small number of fragment-like (molecular weight <300) molecules that efficiently cover chemical space. Here, we report a fragment screening on TbrPDEB1, an essential cyclic nucleotide phosphodiesterase (PDE) from Trypanosoma brucei, and human PDE4D, an off-target, in a workflow in which fragment hits and a series of close analogs are subsequently screened for antiparasitic activity in a phenotypic panel. The phenotypic panel contained T. brucei, Trypanosoma cruzi, Leishmania infantum, and Plasmodium falciparum, the causative agents of human African trypanosomiasis (sleeping sickness), Chagas disease, leishmaniasis, and malaria, respectively, as well as MRC-5 human lung cells. This hybrid screening workflow has resulted in the discovery of various benzhydryl ethers with antiprotozoal activity and low toxicity, representing interesting starting points for further antiparasitic optimization.

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Section: Resultsmentioning

confidence: 95%

Fragment-Based Screening in Tandem with Phenotypic Screening Provides Novel Antiparasitic Hits

Blaazer¹,

Orrling

Shanmugham³

et al. 2015

SLAS Discovery

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“…If amantadine hypersensitivity results from the PfCRT-mediated efflux of the drug from the DV, we would expect that inhibitors of PfCRT CQR would reduce this response. We tested this hypothesis by determining the susceptibility of the isogenic lines to amantadine in the absence and presence of verapamil or chlorpheniramine [ 49 ] (another established inhibitor of PfCRT CQR ). These experiments, which included CQ as a control as well as CQ-resistant (Dd2) and CQ-sensitive (3D7) reference strains, entailed using a fluorescence-based method to measure parasite growth in the presence of increasing concentrations of amantadine or CQ.…”

Section: Resultsmentioning

confidence: 99%

Molecular Mechanisms for Drug Hypersensitivity Induced by the Malaria Parasite’s Chloroquine Resistance Transporter

et al. 2016

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Mutations in the Plasmodium falciparum ‘chloroquine resistance transporter’ (PfCRT) confer resistance to chloroquine (CQ) and related antimalarials by enabling the protein to transport these drugs away from their targets within the parasite’s digestive vacuole (DV). However, CQ resistance-conferring isoforms of PfCRT (PfCRTCQR) also render the parasite hypersensitive to a subset of structurally-diverse pharmacons. Moreover, mutations in PfCRTCQR that suppress the parasite’s hypersensitivity to these molecules simultaneously reinstate its sensitivity to CQ and related drugs. We sought to understand these phenomena by characterizing the functions of PfCRTCQR isoforms that cause the parasite to become hypersensitive to the antimalarial quinine or the antiviral amantadine. We achieved this by measuring the abilities of these proteins to transport CQ, quinine, and amantadine when expressed in Xenopus oocytes and complemented this work with assays that detect the drug transport activity of PfCRT in its native environment within the parasite. Here we describe two mechanistic explanations for PfCRT-induced drug hypersensitivity. First, we show that quinine, which normally accumulates inside the DV and therewithin exerts its antimalarial effect, binds extremely tightly to the substrate-binding site of certain isoforms of PfCRTCQR. By doing so it likely blocks the normal physiological function of the protein, which is essential for the parasite’s survival, and the drug thereby gains an additional killing effect. In the second scenario, we show that although amantadine also sequesters within the DV, the parasite’s hypersensitivity to this drug arises from the PfCRTCQR-mediated transport of amantadine from the DV into the cytosol, where it can better access its antimalarial target. In both cases, the mutations that suppress hypersensitivity also abrogate the ability of PfCRTCQR to transport CQ, thus explaining why rescue from hypersensitivity restores the parasite’s sensitivity to this antimalarial. These insights provide a foundation for understanding clinically-relevant observations of inverse drug susceptibilities in the malaria parasite.

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“…3). These were verapamil 15,39 and chlorpheniramine 40 (both partial reversers of CQ resistance in vitro), the quinine dimer 'Q 2 C' (currently the most potent inhibitor of PfCRT Dd2 ) 20 , CQ 15 and saquinavir 38 . Q 2 C was the most potent cis-inhibitor, with half-maximum inhibitory concentrations (IC 50 ) in the nanomolar range.…”

Section: Pfcrt Dd2mentioning

confidence: 99%

The natural function of the malaria parasite’s chloroquine resistance transporter

et al. 2020

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The Plasmodium falciparum chloroquine resistance transporter (PfCRT) is a key contributor to multidrug resistance and is also essential for the survival of the malaria parasite, yet its natural function remains unresolved. We identify host-derived peptides of 4-11 residues, varying in both charge and composition, as the substrates of PfCRT in vitro and in situ, and show that PfCRT does not mediate the non-specific transport of other metabolites and/or ions. We find that drug-resistance-conferring mutations reduce both the peptide transport capacity and substrate range of PfCRT, explaining the impaired fitness of drug-resistant parasites. Our results indicate that PfCRT transports peptides from the lumen of the parasite's digestive vacuole to the cytosol, thereby providing a source of amino acids for parasite metabolism and preventing osmotic stress of this organelle. The resolution of PfCRT's native substrates will aid the development of drugs that target PfCRT and/or restore the efficacy of existing antimalarials.

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Chlorpheniramine Analogues Reverse Chloroquine Resistance inPlasmodium falciparumby Inhibiting PfCRT

Cited by 20 publications

References 33 publications

Fragment-Based Screening in Tandem with Phenotypic Screening Provides Novel Antiparasitic Hits

Fragment-Based Screening in Tandem with Phenotypic Screening Provides Novel Antiparasitic Hits

Molecular Mechanisms for Drug Hypersensitivity Induced by the Malaria Parasite’s Chloroquine Resistance Transporter

The natural function of the malaria parasite’s chloroquine resistance transporter

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