ABSTRACT
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
(
w
Bm-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 (IC
50
) (1.02 μM), followed by compound 5 (IC
50
, 2.3 μM) and compound 1 (IC
50
, 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).
w
Bm-LigA thus shows great promise as an antifilarial drug target, and dispiro-cycloalkanone compounds show great promise as antifilarial lead candidates.
摘要
淋巴丝虫与内生共生体
Wolbachia
.消耗
沃尔巴克氏体
会造成线虫发育、繁殖力和存活率的严重缺陷,因此有望成为治疗丝虫病的一种新方法。NAD
+
-依赖性 DNA 连接酶是 DNA 复制、修复和重组过程中必不可少的酶。因此,在本研究中,NAD + 依赖性 DNA 连接酶的抗丝虫药物靶标潜力是研究的重点。
+
-依赖性 DNA 连接酶的抗丝虫药物靶点潜力。
沃尔巴克氏体
共生体的
马来布鲁氏菌
(
w
Bm-LigA)的二螺环烷酮化合物进行了研究。二螺环烷酮能特异性地抑制该酶的缺口闭合和内聚端连接活性,而对人类或 T4 DNA 连接酶没有抑制作用。其抑制方式与 NAD
+
辅助因子的竞争性抑制。对接研究还揭示了这些化合物与目标酶活性位点的相互作用。这些抑制剂对成虫和微丝蚴阶段的
马拉伊蚊
体外
的不利影响,并进一步监测了最具活性的化合物
体内
在鸟类和啮齿动物模型中进行了进一步监测。化合物 1、2 和 5 在体外具有严重的不良影响
在体外
在低浓度下对成虫和微丝蚴的蠕动都有严重的不利影响。化合物 2 是最好的抑制剂,其最低的 50% 抑制浓度(IC
50
)(1.02 μM),其次是化合物 5(IC
50
为 2.3 μM)和化合物 1(IC
50
为 2.9 μM)。这些化合物对成虫和微丝蚴也表现出同样的不利影响
在体内
(
P
0.05)。通过实时定量 PCR 检测,这些化合物还大大减少了狼尾蚴的数量 (
P
0.05)。
w
因此,Bm-LigA 很有希望成为抗丝虫药物的靶点,二螺环烷酮化合物也很有希望成为抗丝虫的候选先导化合物。