Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
PLoS One. 2011;6(7):e21237. doi: 10.1371/journal.pone.0021237. Epub 2011 Jul 14.
The Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH) has been considered as a potential molecular target for antimalarials due to this parasite's dependence on glycolysis for energy production. Because the LDH enzymes found in P. vivax, P. malariae and P. ovale (pLDH) all exhibit ∼90% identity to PfLDH, it would be desirable to have new anti-pLDH drugs, particularly ones that are effective against P. falciparum, the most virulent species of human malaria. Our present work used docking studies to select potential inhibitors of pLDH, which were then tested for antimalarial activity against P. falciparum in vitro and P. berghei malaria in mice. A virtual screening in DrugBank for analogs of NADH (an essential cofactor to pLDH) and computational studies were undertaken, and the potential binding of the selected compounds to the PfLDH active site was analyzed using Molegro Virtual Docker software. Fifty compounds were selected based on their similarity to NADH. The compounds with the best binding energies (itraconazole, atorvastatin and posaconazole) were tested against P. falciparum chloroquine-resistant blood parasites. All three compounds proved to be active in two immunoenzymatic assays performed in parallel using monoclonals specific to PfLDH or a histidine rich protein (HRP2). The IC(50) values for each drug in both tests were similar, were lowest for posaconazole (<5 µM) and were 40- and 100-fold less active than chloroquine. The compounds reduced P. berghei parasitemia in treated mice, in comparison to untreated controls; itraconazole was the least active compound. The results of these activity trials confirmed that molecular docking studies are an important strategy for discovering new antimalarial drugs. This approach is more practical and less expensive than discovering novel compounds that require studies on human toxicology, since these compounds are already commercially available and thus approved for human use.
恶性疟原虫乳酸脱氢酶酶（PfLDH）已被认为是抗疟药物的潜在分子靶点，因为这种寄生虫依赖糖酵解产生能量。由于在间日疟原虫、卵形疟原虫和三日疟原虫（pLDH）中发现的 LDH 酶与 PfLDH 具有约 90%的同源性，因此理想情况下是拥有新的抗 pLDH 药物，特别是对恶性疟原虫（最具毒性的人类疟疾寄生虫）有效的药物。我们目前的工作使用对接研究来选择 pLDH 的潜在抑制剂，然后在体外检测这些抑制剂对恶性疟原虫的抗疟活性和在小鼠中的伯氏疟原虫疟疾活性。我们在 DrugBank 中进行了 NADH 类似物（pLDH 的必需辅因子）的虚拟筛选和计算研究，并使用 Molegro Virtual Docker 软件分析了所选化合物与 PfLDH 活性部位的潜在结合。根据与 NADH 的相似性，选择了 50 种化合物。具有最佳结合能的化合物（伊曲康唑、阿托伐他汀和泊沙康唑）用于检测抗氯喹恶性疟原虫血液寄生虫。这三种化合物在平行进行的两种免疫酶测定中均表现出活性，该测定使用针对 PfLDH 或富含组氨酸蛋白（HRP2）的单克隆抗体。在两种测试中，每种药物的 IC50 值都相似，泊沙康唑的最低（<5 μM），比氯喹的活性低 40-100 倍。与未治疗的对照组相比，化合物在治疗的小鼠中降低了伯氏疟原虫的寄生虫血症；伊曲康唑是最不活跃的化合物。这些活性试验的结果证实，分子对接研究是发现新抗疟药物的重要策略。与需要进行人类毒理学研究的新型化合物相比，这种方法更实用且成本更低，因为这些化合物已经在商业上可获得，因此已获准用于人类使用。
