AbstractPrimaquine (PQ) is an essential antimalarial drug but despite being developed over 70 years ago, its mode of action is unclear. Here, we demonstrate that hydroxylated-PQ metabolites (OH-PQm) are responsible for efficacy against liver and sexual transmission stages of Plasmodium falciparum. The antimalarial activity of PQ against liver stages depends on host CYP2D6 status, whilst OH-PQm display direct, CYP2D6-independent, activity. PQ requires hepatic metabolism to exert activity against gametocyte stages. OH-PQm exert modest antimalarial efficacy against parasite gametocytes; however, potency is enhanced ca.1000 fold in the presence of cytochrome P450 NADPH:oxidoreductase (CPR) from the liver and bone marrow. Enhancement of OH-PQm efficacy is due to the direct reduction of quinoneimine metabolites by CPR with the concomitant and excessive generation of H2O2, leading to parasite killing. This detailed understanding of the mechanism paves the way to rationally re-designed 8-aminoquinolines with improved pharmacological profiles.
摘要:
盐酸伯氨喹(PQ)是一种重要的
抗疟药,但尽管已经开发了70多年,其作用方式仍不清楚。在这里,我们证明羟基化的PQ代谢物(OH-PQm)对
疟原虫的肝和性传播阶段的疗效负责。PQ对肝阶段的抗疟活性取决于宿主CYP2D6状态,而OH-PQm显示出直接的、独立于CYP2D6的活性。PQ需要肝代谢才能对配子体阶段产生活性。OH-PQm对疟原虫配子体的抗疟功效较小,但在肝和骨髓的细胞色素P450
NADPH:氧化还原酶(CPR)的存在下,其效力增强约1000倍。OH-PQm功效的增强是由于CPR对醌
亚胺代谢物的直接还原,同时产生大量的H
2O
2,导致疟原虫死亡。这种机制的详细理解为有理重设计具有改进药理特性的
8-氨基喹啉铺平了道路。