Quaternary ammonium compounds efficiently inhibit Plasmodium falciparum growth in vitro by impairment of choline transport

Abstract

Hemicholinium 3, decamethonium, and decyltrimethylammonium previously have been demonstrated to be efficient inhibitors, with 50% inhibitory concentrations of 4 x 10-6, 10-6, and 7 x 10-7 M, respectively. We show that lengthening of the alkyl chain of decyltrimethylammonium by successive additions of two carbon atoms up to hexadecyltrimethylammonium results in a very low 50% inhibitory concentration of 5 x 10-7 M for dodecyltrimethylammonium. Furthermore, hemicholinium 3 and decamethonium exerted their antiplasmodial activity, regardless of the developmental stage of the parasite, whereas decyltrimethylammonium was particularly lethal for the mature forms. After infected erythrocytes with radioactive choline were supplied, the determination of the water-soluble choline-containing compounds, as well as the assay of choline kinase activity, showed that the specific inhibition of phosphatidylcholine biosynthesis is related to the impairment of choline entry into erythrocytes. Thus, the impairment of the transport of choline, a natural polar head group of phospholipids, appears to be lethal for Plasmodium falciparum in vitro and could be a reasonable approach for a new malaria chemotherapy.The urgent need for new therapeutic approaches to Plasmodium falciparum malaria often has been pointed out (18) because of the resistance of both mosquitoes and parasites to various pesticides and conventional drugs (27). We have shown previously that phospholipid (PL) metabolism could constitute an ideal target for a new chemotherapy (25) because of its magnitude (9, 21, 24, 26) and specificity, because little or no PL biosynthesis occurs in mature mammalian erythrocytes (23). In our previous studies we showed that the lethal effect of quaternary ammonium compounds on P. falciparum in vitro involved the inhibition of phosphatidylcholine (PC) biosynthesis from choline, the natural polar head group of PC (2). Furthermore, we have shown that no alteration in the biosynthesis of the other PL, or of proteins or nucleic acids, occurred. In this study we establish that this inhibition of PC biosynthesis is due to an impairment of choline transport into infected erythrocytes. In addition, we show that the bis-onium compounds act regardless of the developmental stage of the parasite, whereas the monoammonium compound that was tested, decyltrimethylammonium, appears to be most lethal for the maturing parasites (i.e., the schizont form). Obtaining Plasmodium knowlesi-infected erythrocytes. Splenectomized Macaca fasciciilaris monkeys (weight, 3 to 6 kg; Sanofi, Montpellier, France), were infected with cryopreserved (20) P. knowlesi Washington, variant 1 (from G. Mitchell, Guy's Hospital, London). On days 6 to 9, highly infected blood cells were collected and then washed with basic medium (medium B: RPMI 1640 supplemented with 25 mM HEPES [pH 7.4] containing 40 ,uM choline and inositol and 140 FLM serine). Leukocytes were eliminated by passage through a cellulose powder column (CF 11; Whatman, Inc., Clifton, N.J.) (10). After two washes with ...

Inhibition of Plasmodium falciparum Choline Kinase by Hexadecyltrimethylammonium Bromide: a Possible Antimalarial Mechanism

“…This indicates that choline kinase may have a regulatory role in phosphatidylcholine biosynthesis, as its inhibition by HDTAB reduced the production of phosphocholine, which in turn decreased phosphatidylcholine biosynthesis. These results are consistent with the earlier report where a good correlation between the intracellular phosphocholine pool and phosphatidylcholine content had been found by treatment with certain quaternary ammonium compounds (4). Choline kinase has been reported to assist choline transport by its phosphorylation in P. falciparum (29).…”

“…Moreover, PC biosynthesis has been suggested as a realistic target for development of new pharmacophores even against pharmacoresistant strains (1,43). Choline kinase (CK) catalyzes the initial step in the CDP-choline pathway and can be regulatory for PC biosynthesis in various biological systems (42,45), but so far, a regulatory role for CK in malaria parasites has not been reported, although a positive correlation between the intracellular phosphocholine pool and PC content had been found under certain quaternary ammonium compound treatment (4), indicating CK may have the potential to regulate PC biosynthesis in the malaria parasite also. Recently, we have cloned, overexpressed, and characterized Plasmodium falciparum choline kinase (PfCK) (16).…”

Antimicrobial activity of betaine esters, quaternary ammonium amphiphiles which spontaneously hydrolyze into nontoxic components

“…Cationic surfactants are of interest because of their membrane-disruptive and rapid antimicrobial activities (1,17,18). Inclusion in liposomes has been tried in vitro to modify and extend their use (24,30).…”

Antimalarial Herbal Plants in Kupang, Indonesia

“…Berberine is a quartenary alkaloids compound containing quartenary nitrogen in its structure, which has been known to have inhibition activity towards Plasmodium growth by blocking the Colin intracellular transport (Ancelin & Vial, 1986). Colin is required for phospholipid biosynthesis in cellular membrane formation of parasite to cover up the parasitophorous vacuole, cytosol and other subcellular compartments that will consequently inhibit the formation of new parasites.…”