title: Biological evaluation of benzothiazole ethyl urea inhibitors of bacterial type II topoisomerases.
abstract: The type II topoisomerases DNA gyrase (GyrA/GyrB) and topoisomerase IV (ParC/ParE) are well-validated targets for antibacterial drug discovery. Because of their structural and functional homology, these enzymes are amenable to dual targeting by a single ligand. In this study, two novel benzothiazole ethyl urea-based small molecules, designated compound A and compound B, were evaluated for their biochemical, antibacterial, and pharmacokinetic properties. The two compounds inhibited the ATPase activity of GyrB and ParE with 50% inhibitory concentrations of <0.1 μg/ml. Prevention of DNA supercoiling by DNA gyrase was also observed. Both compounds potently inhibited the growth of a range of bacterial organisms, including staphylococci, streptococci, enterococci, Clostridium difficile, and selected Gram-negative respiratory pathogens. MIC90s against clinical isolates ranged from 0.015 μg/ml for Streptococcus pneumoniae to 0.25 μg/ml for Staphylococcus aureus. No cross-resistance with common drug resistance phenotypes was observed. In addition, no synergistic or antagonistic interactions between compound A or compound B and other antibiotics, including the topoisomerase inhibitors novobiocin and levofloxacin, were detected in checkerboard experiments. The frequencies of spontaneous resistance for S. aureus were <2.3 × 10(-10) with compound A and <5.8 × 10(-11) with compound B at concentrations equivalent to 8× the MICs. These values indicate a multitargeting mechanism of action. The pharmacokinetic properties of both compounds were profiled in rats. Following intravenous administration, compound B showed approximately 3-fold improvement over compound A in terms of both clearance and the area under the concentration-time curve. The measured oral bioavailability of compound B was 47.7%.
authors.affiliation: Biota Europe Ltd., Begbroke, Oxfordshire, United Kingdom.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Stokes
authors.forename: Helena B
authors.initials: HB
authors.lastname: Thomaides-Brears
authors.forename: Stephanie
authors.initials: S
authors.lastname: Barker
authors.forename: James M
authors.initials: JM
authors.lastname: Bennett
authors.forename: Joanne
authors.initials: J
authors.lastname: Berry
authors.forename: Ian
authors.initials: I
authors.lastname: Collins
authors.forename: Lloyd G
authors.initials: LG
authors.lastname: Czaplewski
authors.forename: Vicki
authors.initials: V
authors.lastname: Gamble
authors.forename: Paul
authors.initials: P
authors.lastname: Lancett
authors.forename: Alastair
authors.initials: A
authors.lastname: Logan
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lunniss
authors.forename: Hilary
authors.initials: H
authors.lastname: Peasley
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Pommier
authors.forename: Daniel
authors.initials: D
authors.lastname: Price
authors.forename: Carol
authors.initials: C
authors.lastname: Smee
authors.forename: David J
authors.initials: DJ
authors.lastname: Haydon
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D052160:Benzothiazoles / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D027101:DNA Topoisomerase IV / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D056945:Hep G2 Cells; D006801:Humans; D000067596:Interleukin-33; D007378:Interleukins; D064704:Levofloxacin / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests; D009675:Novobiocin / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D059003:Topoisomerase Inhibitors / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D052160:Benzothiazoles; C506535:Il33 protein, mouse; D000067596:Interleukin-33; D007378:Interleukins; D011994:Recombinant Proteins; D059003:Topoisomerase Inhibitors; D009675:Novobiocin; D064704:Levofloxacin; D014508:Urea; D000251:Adenosine Triphosphatases; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II
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