Abstract
            
               Plasmodium falciparum heat shock protein 70 (PfHsp70-1) is thought to play an essential role in parasite survival and virulence in the human host, making it a potential antimalarial drug target. A malate dehydrogenase based aggregation suppression assay was adapted for the screening of small molecule modulators of Hsp70. A number of small molecules of natural (marine prenylated alkaloids and terrestrial plant naphthoquinones) and related synthetic origin were screened for their effects on the protein aggregation suppression activity of purified recombinant PfHsp70-1. Five compounds (malonganenone A-C, lapachol and bromo-β-lapachona) were found to inhibit the chaperone activity of PfHsp70-1 in a concentration dependent manner, with lapachol preferentially inhibiting PfHsp70-1 compared to another control Hsp70. Using growth inhibition assays on P. falciparum infected erythrocytes, all of the compounds, except for malonganenone B, were found to inhibit parasite growth with IC50 values in the low micromolar range. Overall, this study has identified two novel classes of small molecule inhibitors of PfHsp70-1, one representing a new class of antiplasmodial compounds (malonganenones). In addition to demonstrating the validity of PfHsp70-1 as a possible drug target, the compounds reported in this study will be potentially useful as molecular probes for fundamental studies on Hsp70 chaperone function.
 
                                    摘要
            
               恶性疟原虫热休克蛋白 70(PfHsp70-1)被认为在寄生虫在人类宿主中的存活和毒力方面发挥着重要作用,因此成为潜在的
抗疟药物靶标。为了筛选 Hsp70 的小分子调节剂,对基于
苹果酸脱氢酶的聚集抑制试验进行了改良。筛选了一些天然小分子(海洋前烯
生物碱和陆生植物
萘醌)和相关合成小分子对纯化
重组 PfHsp70-1 蛋白聚集抑制活性的影响。结果发现,五种化合物(丙龙烯酮 A-C、
拉帕酚和
溴-β-
拉帕酚那)以浓度依赖性方式抑制 PfHsp70-1 的伴侣蛋白活性,与另一种对照 Hsp70 相比,
拉帕酚那优先抑制 PfHsp70-1。通过对恶性疟原虫感染的红细胞进行生长抑制试验,发现除
丙二醛烯酮 B 外,所有化合物都能抑制寄生虫的生长,其 IC50 值在低微摩尔范围内。总之,这项研究发现了两类新型的 PfHsp70-1 小分子
抑制剂,其中一类代表了一类新的抗寄生虫化合物(malonganenones)。除了证明 PfHsp70-1 是一个可能的药物靶点之外,本研究中报告的化合物还可能成为 Hsp70 伴侣功能基础研究的分子探针。