Discovery of small molecule inhibitors of Plasmodium falciparum apicoplast DNA polymerase

Malaria is caused by infection with protozoan parasites of the <i>Plasmodium</i> genus, which is part of the phylum Apicomplexa. Most organisms in this phylum contain a relic plastid called the apicoplast. The apicoplast genome is replicated by a single DNA polymerase (apPOL), which is an attractive target for anti-malarial drugs. We screened small-molecule libraries (206,504 compounds) using a fluorescence-based high-throughput DNA polymerase assay. Dose/response analysis and counter-screening identified 186 specific apPOL inhibitors. Toxicity screening against human HepaRG human cells removed 84 compounds and the remaining were subjected to parasite killing assays using chloroquine resistant <i>P. falciparum</i> parasites. Nine compounds were potent inhibitors of parasite growth and may serve as lead compounds in efforts to discover novel malaria drugs.

疟疾是由顶复门（Apicomplexa）疟原虫属（Plasmodium）的原生动物寄生虫感染引发的疾病。该门类的多数生物体均携带一种被称为顶质体（apicoplast）的残遗质体。顶质体基因组由单一的DNA聚合酶（apPOL）负责复制，该酶是抗疟药物的理想作用靶点。本研究通过基于荧光的高通量DNA聚合酶检测方法，对206504种小分子化合物库进行了筛选。经剂量反应分析与复筛，共鉴定出186种特异性apPOL抑制剂。针对人源HepaRG细胞的毒性筛查剔除了84种化合物，剩余化合物则采用耐氯喹恶性疟原虫（P. falciparum）开展寄生虫杀伤实验。其中9种化合物对寄生虫生长具有强效抑制活性，有望作为先导化合物用于新型抗疟药物的研发。