title: Antibacterial activity and mechanism of action of a novel anilinouracil-fluoroquinolone hybrid compound.
abstract: The anilinouracils (AUs) such as 6-(3-ethyl-4-methylanilino)uracil (EMAU) are a novel class of gram-positive, selective, bactericidal antibacterials which inhibit pol IIIC, the gram-positive-specific replicative DNA polymerase. We have linked various fluoroquinolones (FQs) to the N-3 position of EMAU to generate a variety of AU-FQ "hybrids" offering the potential for targeting two distinct steps in DNA replication. In this study, the properties of a hybrid, "251D," were compared with those of representative AUs and FQs in a variety of in vitro assays, including pol IIIC and topoisomerase/gyrase enzyme assays, antibacterial, bactericidal, and mammalian cytotoxicity assays. Compound 251D potently inhibited pol IIIC and topoisomerase/gyrase, displayed gram-positive antibacterial potency at least 15 times that of the corresponding AU compound, and as expected, acted selectively on bacterial DNA synthesis. Compound 251D was active against a broad panel of antibiotic-resistant gram-positive pathogens as well as several gram-negative organisms and was also active against both AU- and FQ-resistant gram-positive organisms, demonstrating its capacity for attacking both of its potential targets in the bacterium. 251D also was bactericidal for gram-positive organisms and lacked toxicity in vitro. Although we obtained strains of Staphylococcus aureus resistant to the individual parent compounds, spontaneous resistance to 251D was not observed. We obtained 251D resistance in multiple-passage experiments, but resistance developed at a pace comparable to those for the parent compounds. This class of AU-FQ hybrids provides a promising new pharmacophore with an unusual dual mechanism of action and potent activity against antibiotic-sensitive and -resistant gram-positive pathogens.
authors.affiliation: Microbiotix, Inc., One Innovation Drive, Worcester, MA 01605, USA. mbutler@microbiotix.com
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Butler
authors.forename: William A
authors.initials: WA
authors.lastname: Lamarr
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Foster
authors.forename: Marjorie H
authors.initials: MH
authors.lastname: Barnes
authors.forename: Donna J
authors.initials: DJ
authors.lastname: Skow
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Lyden
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Kustigian
authors.forename: Chengxin
authors.initials: C
authors.lastname: Zhi
authors.forename: Neal C
authors.initials: NC
authors.lastname: Brown
authors.forename: George E
authors.initials: GE
authors.lastname: Wright
authors.forename: Terry L
authors.initials: TL
authors.lastname: Bowlin
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004258:DNA Polymerase III / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D016983:Enterococcus / Q000187:drug effects; D024841:Fluoroquinolones / Q000737:chemistry / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D013210:Staphylococcus / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects; D013329:Structure-Activity Relationship; D059005:Topoisomerase II Inhibitors; D014498:Uracil / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology
chemical_list: C413944:6-(3'-ethyl-4'-methylanilino)uracil; D000814:Aniline Compounds; D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D059005:Topoisomerase II Inhibitors; D014498:Uracil; D004258:DNA Polymerase III