title: Homology modeling of NAD+-dependent DNA ligase of the Wolbachia endosymbiont of Brugia malayi and its drug target potential using dispiro-cycloalkanones.
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 (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.
authors.affiliation: Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Shrivastava
authors.affiliation: Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
authors.forename: Jeetendra K
authors.initials: JK
authors.lastname: Nag
authors.affiliation: Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Pandey
authors.affiliation: Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
authors.forename: Rama Pati
authors.initials: RP
authors.lastname: Tripathi
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Shah
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India.
authors.forename: Mohammad Imran
authors.initials: MI
authors.lastname: Siddiqi
authors.affiliation: Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India shailja_cdri@rediffmail.com.
authors.forename: Shailja
authors.initials: S
authors.lastname: Misra-Bhattacharya
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017178:Brugia malayi / Q000382:microbiology*; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000037:antagonists & inhibitors* / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005369:Filaricides / Q000494:pharmacology*; D005849:Gerbillinae; D007659:Ketones / Q000138:chemical synthesis / Q000494:pharmacology*; D008297:Male; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D051189:Murinae / Q000469:parasitology; D013141:Spiro Compounds / Q000138:chemical synthesis / Q000494:pharmacology*; D013559:Symbiosis; D020577:Wolbachia / Q000187:drug effects* / Q000201:enzymology
chemical_list: D000900:Anti-Bacterial Agents; D005369:Filaricides; D007659:Ketones; D013141:Spiro Compounds; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C120640:DNA ligase (NAD)
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