Similar structure-activity relationships of quinoline derivatives for antiprion and antimalarial effects

Prion diseases are invariably fatal neurodegenerative diseases, in which the infectious agent consists of PrP(Sc), a pathogenic misfolded isoform of the normal cellular prion protein (PrP(C)). Until now, no pharmacological options exist for these novel pathogens. Here we describe the screening of a series of polyquinolines and quinolines linked to a large variety of terminal groups for their ability to cure a persistently prion infected cell line (ScN2a). Several compounds showed antiprion activity in the nanomolar range. The most active molecule, named 42, had a half-effective concentration (EC50) for antiprion activity of 50 nM. In a library of quinoline derivatives we were able to identify several structure-activity relationships (SAR). Remarkably, antiprion SAR in ScN2a cells were similar to antimalarial SAR in a cell model of malaria, particularly for the sulfonamide quinoline derivatives, suggesting that some molecular targets of antiprion and antimalarial substances overlap.

Novel N-(4-Piperidinyl)benzamide Antimalarials with Mammalian Protein Farnesyltransferase Inhibitory Activity

Protein farnesyltransferase of Plasmodium falciparum is a potential target in the treatment of malaria for which increased drug resistance is observed. The design, synthesis and evaluation of a series of N-(4-piperidinyl)benzamides is reported. The most potent compounds showed in vitro activity against the parasite at submicromolar concentrations.

Synthesis and antimalarial evaluation of new N1-(7-chloro-4-quinolyl)-1,4-bis(3-aminopropyl)piperazine derivatives

Synthesis and evaluation of the activity of new N(1)-(7-chloro-4-quinolyl)-1,4-bis(3-aminopropyl)piperazine derivatives against a chloroquine-resistant strain of Plasmodium falciparum are described. Selectivity indices were improved for two compounds versus the lead 1, the bis-cyclopropylmethyl derivative, thus increasing the therapeutic interest of our family. As our previous studies conducted on the mode of action of our compounds made us hypothesize the existence of original mechanisms and/or original targets, terminal amino derivatives can be considered as promising tools further mechanistical studies, as probes for affinity chromatography.

Design, synthesis and antimalarial activity of a glyoxylylhydrazone library

Synthesis of a new family of quinolylhydrazone derivatives and evaluation of their activity against a chloroquine-resistant strain of Plasmodium falciparum are described. The best compound displayed an activity 6-fold higher than chloroquine. None of the active compounds were found to inhibit beta-hematin formation in vitro in the same range as chloroquine and five among them displayed lower calculated vacuolar accumulation ratios, suggesting the implication of a different mechanism of action.

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

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 beta-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 beta-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.

Synthesis and in vitro and in vivo antimalarial activity of N1-(7-chloro-4-quinolyl)-1,4-bis(3-aminopropyl)piperazine derivatives

Three series of monoquinolines consisting of a 1,4-bis(3-aminopropyl)piperazine linker and a large variety of terminal groups were synthesized. Our aim was to prove that in related bisquinoline, it is the second quinoline moiety that is responsible for cytotoxicity and that it is not an absolute requirement for overcoming resistance to chloroquine (CQ). Eleven compounds displayed a higher selectivity index (ratio CC50/IC50 activity) than CQ, and one of them cured mice infected by Plasmodium berghei.

Parallel synthesis and anti-malarial activity of a sulfonamide library

Solution-phase synthesis and evaluation of a library of 31 sulfonamides as inhibitors of a chloroquine-resistant strain of Plasmodium falciparum are described. The most potent compound displayed an activity 100-fold better than chloroquine. Experiments using a fluorescent sulfonamide derivative suggest that their site of action inside the parasite is different to that of chloroquine.