Development of new antimalarial endoperoxides and it's antimalarial mechanism

新型抗疟内过氧化物的研制及其抗疟机制

基本信息

批准号：
13672286
负责人：
KIM Hye-sook
金额：
$ 2.3万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Malaria control become more complexes because causal agent Plasmodium falciparum has developed resistance to nearly all available antimalarial drugs. As malaria parasite are increasingly resistance to more common and effective alkaloid drugs, interest in the antimalarial properties of nonalkaloid compounds such as sesquiterpene artemisinin and the related endoperoxides is rapidly growing. The search for novel antimalarial drugs against specific parasite target is thus an urgent task to pursue.Malaria parasites invade human erythrocytes in the erythrocytic stage of infection. While residing in erythrocytes, the parasites depend on hemoglobin as a source of food, digesting it with a series of proteases. Two homologous aspartic proteases called plasmepsin I and II initiate the degradative process by cleaving the native hemoglobin molecule in a highly conserved hinge region. A cysteine protease falcipain-2, and a metalloprotease falcilysin, act further downstream in the pathway to degrade … More hemoglobin to small peptides. Inhibition of these proteases kill parasites in culture and animal model, suggesting that hemoglobin degrading proteases are valid targets for chemotherapy.In this study, we studied development and selection of new antimalarial endopeoxides using about 300 analogs of synthetic endoperoxides. As a results, antimalarial activity of a synthetic endoperoxide, (N-89) was selected using in vitro against Plasmodium falciparum and in vivo against P. bergheii. In vitro N-89 exhibited potent antimalarial activity against chloroquine-sensitive (FCR-3) and chloroquine-resistant (K1) strain, estimated 50% growth inhibitory concentration (IC_<30>) was 28 nM and 26 nM, respectively. In vivo antimalarial activity of the compound was also remarkable, ED_<50> and ED_<90> were 20 mgkg^<-1> and 40 mgkg^<-1>, respectively. Differential effect was found at different developmental stages in vitro. N-89 is more sensitive on early and middle stages parasites and less sensitive on late and schizont stage parasites. The effect was associated with distinct morphological changes. Although late and schizonts stage parasites entered 2^<nd> cycle, their re-invasion was impaired. Consistence with stage-specific effect, inhibition of hemozoin formation is pronounced at mature stage parasites than schizonts. When middle trophozoites stage parasites was incubated with endoperoxide hemoglobin accumulation was found in parasite lysates. An aspartic protease inhibitor of malaria parasite pepstatin A could reverse its hemoglobin accumulation activity, and pepstatin A showed antagonistic effect when combined with N-89. Our results explain antimalarial activity of N-89 may be related to hemoglobin degradation. Less

疟疾控制变得更加复杂，因为致病因子恶性疟原虫已经对几乎所有可用的抗疟药物产生了耐药性。随着疟原虫对更常见和有效的生物碱药物的耐药性日益增强，人们对倍半萜青蒿素和相关内过氧化物等非生物碱化合物的抗疟特性产生了兴趣。因此，寻找针对特定寄生虫靶点的新型抗疟药物是一项紧迫的任务。疟疾寄生虫入侵人类。在感染的红细胞阶段，寄生虫依靠血红蛋白作为食物来源，并用一系列蛋白酶消化它，称为血浆蛋白酶 I 和 II，通过裂解天然血红蛋白来启动降解过程。高度保守的铰链区的分子。金属蛋白酶 falcilysin 在将血红蛋白降解为小肽的途径中发挥作用，抑制这些蛋白酶可杀死培养物和动物模型中的寄生虫，表明血红蛋白降解蛋白酶是化疗的有效靶标。在这项研究中，我们研究了开发和选择。使用约 300 种合成内过氧化物类似物开发新的抗疟内过氧化物。内过氧化物 (N-89) 在体外针对恶性疟原虫，在体内针对伯氏疟原虫，体外 N-89 对氯喹敏感 (FCR-3) 和氯喹耐药 (K1) 菌株表现出有效的抗疟活性，估计该化合物的50％生长抑制浓度(IC_30)分别为28nM和26nM。同样值得注意的是，ED_<50>和ED_<90>分别为20mgkg^<-1>和40mgkg^<-1>，在体外不同发育阶段发现N-89对早期更敏感。和中期寄生虫对晚期和裂殖期寄生虫较不敏感。尽管晚期和裂殖期寄生虫进入第二周期，但其效果与明显的形态变化相关。与阶段特异性效应的一致性，成熟阶段寄生虫对疟原虫色素形成的抑制比裂殖体显着。胃酶抑素 A 可以逆转其血红蛋白积累活性，并且胃酶抑素 A 与 N-89 联合使用时显示出拮抗作用。 N-89 的抗疟活性可能与血红蛋白降解有关。