부산대학교 도서관

ABSTRACTChloroquine (CQ) has been the mainstay of malaria treatment for more than 60 years. However, the emergence and spread of CQ resistance now restrict its use to only a few areas where malaria is endemic. The aim of the present study was to investigate whether a novel combination of a CQ-like moiety and an imipramine-like pharmacophore can reverse CQ resistance ex vivo. Between March to October 2011 and January to September 2013, two “reversed chloroquine” (RCQ) compounds (PL69 and PL106) were tested against multidrug-resistant field isolates of Plasmodium falciparum(n= 41) and Plasmodium vivax(n= 45) in Papua, Indonesia, using a modified ex vivoschizont maturation assay. The RCQ compounds showed high efficacy against both CQ-resistant P. falciparumand P. vivaxfield isolates. For P. falciparum, the median 50% inhibitory concentrations (IC50s) were 23.2 nM for PL69 and 26.6 nM for PL106, compared to 79.4 nM for unmodified CQ (P< 0.001 and P= 0.036, respectively). The corresponding values for P. vivaxwere 19.0, 60.0, and 60.9 nM (P< 0.001 and P= 0.018, respectively). There was a significant correlation between IC50s of CQ and PL69 (Spearman's rank correlation coefficient [rs] = 0.727, P< 0.001) and PL106 (rs= 0.830, P< 0.001) in P. vivaxbut not in P. falciparum. Both RCQs were equally active against the ring and trophozoite stages of P. falciparum, but in P. vivax, PL69 and PL106 showed less potent activity against trophozoite stages (median IC50s, 130.2 and 172.5 nM) compared to ring stages (median IC50s, 17.6 and 91.3 nM). RCQ compounds have enhanced ex vivoactivity against CQ-resistant clinical isolates of P. falciparumand P. vivax, suggesting the potential use of reversal agents in antimalarial drug development. Interspecies differences in RCQ compound activity may indicate differences in CQ pharmacokinetics between the two Plasmodiumspecies.