Shrivastava Nidhi, Nag Jeetendra K, Pandey Jyoti, Tripathi Rama Pati, Shah Priyanka, Siddiqi Mohammad Imran, Misra-Bhattacharya Shailja
Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
Antimicrob Agents Chemother. 2015 Jul;59(7):3736-47. doi: 10.1128/AAC.03449-14. Epub 2015 Apr 6.
Lymphatic filarial nematodes maintain a mutualistic relationship with the endosymbiont Wolbachia. Depletion of Wolbachia produces profound defects in nematode development, fertility, and viability and thus has great promise as a novel approach for treating filarial diseases. NAD(+)-dependent DNA ligase is an essential enzyme of DNA replication, repair, and recombination. Therefore, in the present study, the antifilarial drug target potential of the NAD(+)-dependent DNA ligase of the Wolbachia symbiont of Brugia malayi (wBm-LigA) was investigated using dispiro-cycloalkanone compounds. Dispiro-cycloalkanone specifically inhibited the nick-closing and cohesive-end ligation activities of the enzyme without inhibiting human or T4 DNA ligase. The mode of inhibition was competitive with the NAD(+) cofactor. Docking studies also revealed the interaction of these compounds with the active site of the target enzyme. The adverse effects of these inhibitors were observed on adult and microfilarial stages of B. malayi in vitro, and the most active compounds were further monitored in vivo in jirds and mastomys rodent models. Compounds 1, 2, and 5 had severe adverse effects in vitro on the motility of both adult worms and microfilariae at low concentrations. Compound 2 was the best inhibitor, with the lowest 50% inhibitory concentration (IC50) (1.02 μM), followed by compound 5 (IC50, 2.3 μM) and compound 1 (IC50, 2.9 μM). These compounds also exhibited the same adverse effect on adult worms and microfilariae in vivo (P < 0.05). These compounds also tremendously reduced the wolbachial load, as evident by quantitative real-time PCR (P < 0.05). wBm-LigA thus shows great promise as an antifilarial drug target, and dispiro-cycloalkanone compounds show great promise as antifilarial lead candidates.
淋巴丝虫线虫与内共生菌沃尔巴克氏体维持着一种互利共生关系。去除沃尔巴克氏体会导致线虫发育、繁殖力和生存能力出现严重缺陷，因此作为一种治疗丝虫病的新方法具有很大潜力。NAD(+)依赖性DNA连接酶是DNA复制、修复和重组所必需的酶。因此，在本研究中，使用双螺环环烷酮化合物研究了马来布鲁线虫（Brugia malayi）的沃尔巴克氏共生菌（wBm-LigA）的NAD(+)依赖性DNA连接酶作为抗丝虫药物靶点的潜力。双螺环环烷酮特异性抑制该酶的缺口封闭和粘性末端连接活性，而不抑制人或T4 DNA连接酶。抑制模式与NAD(+)辅因子竞争。对接研究还揭示了这些化合物与靶酶活性位点的相互作用。观察到这些抑制剂对体外培养的马来布鲁线虫成虫和微丝蚴阶段有不良影响，并在体内对沙鼠和多乳鼠啮齿动物模型中的最具活性的化合物进行了进一步监测。化合物1、2和5在体外低浓度时对成虫和微丝蚴的运动均有严重不良影响。化合物2是最佳抑制剂，最低半数抑制浓度（IC50）为1.02 μM，其次是化合物5（IC50，2.3 μM）和化合物1（IC50，2.9 μM）。这些化合物在体内对成虫和微丝蚴也表现出相同的不良影响（P < 0.05）。通过定量实时PCR也可明显看出，这些化合物还极大地降低了沃尔巴克氏体载量（P < 0.05）。因此，wBm-LigA作为抗丝虫药物靶点具有很大潜力，双螺环环烷酮化合物作为抗丝虫先导候选物也具有很大潜力。
