Kinetic modelling of chloroquine uptake by malaria-infected erythrocytes: Assessment of the factors that may determine drug resistance

doi:10.1016/0006-2952(91)90562-J

Biochemical Pharmacology

Volume 41, Issue 10, 15 May 1991, Pages 1463-1470

https://doi.org/10.1016/0006-2952(91)90562-J Get rights and content

Abstract

The antimalarial chloroquine, by virtue of its weak base properties, concentrates in the acidic compartment(s) of the intraerythrocytic parasite. Drug accumulation is essential for it to exert its pharmacological activity. Drug resistance has been thought to result from insufficient acidification of drug-accumulating organelle(s), (due to weakened proton pump activity and/or proton leak) or to result from the action of the recently suggested active efflux drug pump. In this work we have devised a kinetic model which takes into account the various processes that have been postulated to account for acidification and drug fluxes. Using this model to analyse the time-course of chloroquine uptake and the steady-state levels of drug accumulation, in strains of Plasmodium falciparum which display variable drug resistance, we demonstrate that drug resistance is compatible with the existence of a weakened proton pump in the resistant parasite strains. Consistent with recent molecular studies that show no correlation between the presence of the multidrug efflux pump gene and the phenotypic expression of chloroquine resistance, our analysis fails to detect any such pump activity. We also show that analysis of drug efflux kinetics cannot distinguish between the possible modes of drug resistance.

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Quinoline-resistance reversing agents for the malaria parasite Plasmodium falciparum
2006, Drug Resistance Updates
Resistance to quinoline antimalarials, especially to chloroquine and mefloquine has had a major impact on the treatment of malaria worldwide. In the period since 2000, significant progress has been made in understanding the origins of chloroquine resistance and to a lesser extent mefloquine resistance in Plasmodium falciparum. Chloroquine resistance correlates directly with mutations in the pfcrt gene of the parasite, while changes in another gene, pfmdr1, may also be related to chloroquine resistance in some strains. Mutations in pfcrt do not appear to correlate with mefloquine resistance, but some studies have implicated pfmdr1 in mefloquine resistance. Its involvement however, has not been definitively demonstrated. The protein products of these genes, PfCRT and Pgh-1 are both located in the food vacuole membrane of the parasite. Current evidence suggests that PfCRT is probably a transporter protein. Chloroquine appears to exit the food vacuole via this transporter in resistant PfCRT mutants. Pgh-1 on the other hand, resembles mammalian multi-drug resistance proteins and appears to be involved in expelling hydrophobic drugs from the food vacuole. Resistance reversing agents are believed to act by inhibiting these proteins. The currently known chloroquine- and mefloquine-resistance reversing agents are discussed in this review. This includes a discussion of structure-activity relationships in these compounds and hypotheses on their possible mechanisms of action. The status of current clinical applications is also briefly discussed.
Malagashanine potentiates chloroquine antimalarial activity in drug resistant Plasmodium malaria by modifying both its efflux and influx
2006, Molecular and Biochemical Parasitology
Malagashanine (MG) is the parent compound of the new N_b-C(21) seco-curan alkaloids isolated hitherto from Madagascan Strychnos. On account of its promising chemosensitizing activity against chloroquine (CQ)-resistant Plasmodium falciparum (Pf) strains, we investigated its mechanism of action. One prominent result was the finding that MG significantly increased the accumulation of [³H]-chloroquine in chloroquine resistant (CQR) K1 and FCM29 Pf strains at mid and old trophozoite stages. This effect was concentration-dependent and not observed in chloroquine sensitive (CQS) strains. Comparative monitoring of the release of [³H]-CQ from pre-loaded CQR and CQS Pf strains revealed strong concentration-dependent inhibition of CQ release by MG from the pre-loaded CQR FCM29 strain. We also found that MG substantially inhibited the loss of pre-accumulated CQ in the resistant K1 strain after a washing procedure at 4 °C. On the other hand, we observed that the addition of glucose at the old trophozoite stage induced a rapid increase in CQ accumulation in the CQS 3D7 strain cultured in glucose-free medium, but not in the CQR FCM29 strain. Interestingly, MG considerably increased (>100%) CQ accumulation in the FCM29 strain in a glucose-free medium while the addition of glucose further significantly increased this accumulation. Our study therefore clearly demonstrates that MG prevents CQ efflux from, and stimulates CQ influx into, drug-resistant Pf. Overall, MG appears to be a useful lead for the design and synthesis of more powerful and effective resistance modulators.
Multidrug resistance in parasites: ABC transporters, P-glycoproteins and molecular modelling
2005, International Journal for Parasitology
Parasitic diseases, caused by protozoa, helminths and arthropods, rank among the most important problems in human and veterinary medicine, and in agriculture, leading to debilitating sicknesses and loss of life. In the absence of vaccines and with the general failure of vector eradication programs, drugs are the main line of defence, but the newest drugs are being tracked by the emergence of resistance in parasites, sharing ominous parallels with multidrug resistance in bacterial pathogens. Any of a number of mechanisms will elicit a drug resistance phenotype in parasites, including: active efflux, reduced uptake, target modification, drug modification, drug sequestration, by-pass shunting, or substrate competition. The role of ABC transporters in parasitic multidrug resistance mechanisms is being subjected to more scrutiny, due in part to the established roles of certain ABC transporters in human diseases, and also to an increasing portfolio of ABC transporters from parasite genome sequencing projects. For example, over 100 ABC transporters have been identified in the Escherichia coli genome, but to date only about 65 in all parasitic genomes. Long established laboratory investigations are now being assisted by molecular biology, bioinformatics, and computational modelling, and it is in these areas that the role of ABC transporters in parasitic multidrug resistance mechanisms may be defined and put in perspective with that of other proteins. We discuss ABC transporters in parasites, and conclude with an example of molecular modelling that identifies a new interaction between the structural domains of a parasite P-glycoprotein.
Evidence for activation of endogenous transporters in Xenopus laevis oocytes expressing the Plasmodium falciparum chloroquine resistance transporter, PfCRT
2004, Journal of Biological Chemistry
A large body of genetic, reverse genetic, and epidemiological data has linked chloroquine-resistant malaria to polymorphisms within a gene termed pfcrt in the human malarial parasite Plasmodium falciparum. To investigate the biological function of the chloroquine resistance transporter, PfCRT, as well as its role in chloroquine resistance, we functionally expressed this protein in Xenopus laevis oocytes. Our data show that PfCRT-expressing oocytes exhibit a depolarized resting membrane potential and a higher intracellular pH compared with control oocytes. Pharmacological and electrophysiological studies link the higher intracellular pH to an enhanced amiloride-sensitive H⁺ extrusion and the low membrane potential to an activated nonselective cation conductance. The finding that both properties are independent of each other, together with the fact that they are endogenously present in X. laevis oocytes, supports a model in which PfCRT activates transport systems. Our data suggest that PfCRT plays a role as a direct or indirect activator or modulator of other transporters.
Synthesis and antimalarial evaluation of new 1,4-bis(3-aminopropyl)piperazine derivatives
2003, Bioorganic and Medicinal Chemistry Letters
Citation Excerpt :
Biochemical studies have indicated that CQ-resistant isolates accumulate less drug than their more sensitive counterparts.7 However opinion remains divided upon the mechanistic explanation for this lower accumulation.8,9 Several works suggest that an enhanced CQ efflux by a multidrug-resistance mechanism may be involved.10,11
Synthesis and evaluation of the activity of a new family of 1,4-bis(3-aminopropyl)piperazine derivatives against a chloroquine-resistant strain of Plasmodium falciparum, and as inhibitors of β-hematin formation, are described. The highest antimalarial activities were obtained for compounds displaying the highest predicted vacuolar accumulation ratios and the best potencies as inhibitors of β-hematin formation. The most potent compound displayed an activity 3-fold better than chloroquine for a comparable selectivity index upon MRC-5 cells. Therefore, in this series, the replacement of the 7-chloroquinoline group can constitute a strong rationale for further investigation.
ABC transporters and drug resistance in parasitic protozoa
2003, International Journal of Antimicrobial Agents
Parasitic protozoa are responsible for a wide spectrum of diseases in humans and domestic animals. The main line of defence available against these organisms is chemotherapy. However, the application of chemotherapeutic drugs has resulted in the development of resistance mechanisms, which limit the number of antiprotozoal drugs that are effective in the treatment and control of parasitic diseases. Knowledge about the resistance mechanisms involved may allow the development of new drugs that minimise or circumvent drug resistance or may identify new targets for drug development. This review focuses on the role of protozoal ATP-binding cassette (ABC) transporters in drug resistance. These membrane proteins mediate the ATP-dependent transport of a wide variety of chemotherapeutic drugs away from their targets inside the parasites. The genome sequence of Plasmodium falciparum and Plasmodium yoelii has recently been completed, and the sequencing of other parasitic genomes are now underway. As a result, many new membrane transporters belonging to the ABC superfamily are being discovered. We review the ABC transporters in major parasitic protozoa, including Plasmodium, Leishmania, Trypanosoma and Entamoeba species. Transporters with an established role in drug resistance have been emphasised, but newly discovered transporters with a significant amino acid sequence identity to established ABC drug transporters have also been included.

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Biochemical Pharmacology

Abstract

References (30)

Current concepts and new ideas on the mechanism of action of quinoline-containing antimalarials

Biochem Pharmacol

Lysosomotropic agents

Biochem Pharmacol

Uptake of [³H]chloroquine by drug-sensitive and -resistant strains of the human malarial parasite Plasmodium falciparum

Biochem Pharmacol

Evidence for electrogenic accumulation of mefloquine by malarial parasites

Biochem Pharmacol

Alkalinization of the food vacuole of malaria parasites by quinoline drugs and alkylamines is not correlated with their antimalarial activity

Biochem Pharmacol

Activity of quinoline-containing antimalarials against chloroquine-sensitive and -resistant strains of Plasmodium falciparum in vitro

Trans R Soc Trop Med Hyg

Plasmodium falciparum: cloning by single-erythrocyte micromanipulation and heterogeneity in vitro

Exp Parasitol

Amplification of the multidrug resistance gene in some chloroquine-resistant isolates of P. falciparum

Cell

Antimalarial agents: Mechanism of action

Antimicrob Agents Chemother

Antimalarial agents: Mechanism of chloroquine resistance

Antimicrob Agents Chemother

Reversal of chloroquine resistance in Plasmodium falciparum by verapamil

Science

Reversal of chloroquine resistance in malaria parasite Plasmodium falciparum by desipramine

Science

In vitro reversal of mefloquine and chloroquine resistance in multi-drug resistant Plasmodium falciparum isolates from Thailand

Identification of the acidic compartment of Plasmodium falciparum infected human erythrocytes as the target of the antimalarial drug chloroquine

EMBO J

Antimalarials increase vesicle pH in Plasmodium falciparum

J Cell Biol

Cited by (96)

Quinoline-resistance reversing agents for the malaria parasite Plasmodium falciparum

Malagashanine potentiates chloroquine antimalarial activity in drug resistant Plasmodium malaria by modifying both its efflux and influx

Multidrug resistance in parasites: ABC transporters, P-glycoproteins and molecular modelling

Evidence for activation of endogenous transporters in Xenopus laevis oocytes expressing the Plasmodium falciparum chloroquine resistance transporter, PfCRT

Synthesis and antimalarial evaluation of new 1,4-bis(3-aminopropyl)piperazine derivatives

ABC transporters and drug resistance in parasitic protozoa

Research paperKinetic modelling of chloroquine uptake by malaria-infected erythrocytes: Assessment of the factors that may determine drug resistance

Abstract

Biochem Pharmacol

Biochem Pharmacol

Biochem Pharmacol

Biochem Pharmacol

Biochem Pharmacol

Trans R Soc Trop Med Hyg

Exp Parasitol

Cell

Antimalarial agents: Mechanism of action

Antimicrob Agents Chemother

Antimalarial agents: Mechanism of chloroquine resistance

Antimicrob Agents Chemother

Reversal of chloroquine resistance in Plasmodium falciparum by verapamil

Science

Reversal of chloroquine resistance in malaria parasite Plasmodium falciparum by desipramine

Science

In vitro reversal of mefloquine and chloroquine resistance in multi-drug resistant Plasmodium falciparum isolates from Thailand

Identification of the acidic compartment of Plasmodium falciparum infected human erythrocytes as the target of the antimalarial drug chloroquine

EMBO J

Antimalarials increase vesicle pH in Plasmodium falciparum

J Cell Biol

Research paper
Kinetic modelling of chloroquine uptake by malaria-infected erythrocytes: Assessment of the factors that may determine drug resistance