- Development of Single-Stranded DNA Bisintercalating Inhibitors of Primase DnaG as Antibiotics
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Many essential enzymes in bacteria remain promising potential targets of antibacterial agents. In this study, we discovered that dequalinium, a topical antibacterial agent, is an inhibitor of Staphylococcus aureus primase DnaG (SaDnaG) with low-micromolar minimum inhibitory concentrations against several S. aureus strains, including methicillin-resistant bacteria. Mechanistic studies of dequalinium and a series of nine of its synthesized analogues revealed that these compounds are single-stranded DNA bisintercalators that penetrate a bacterium by compromising its membrane. The best compound of this series likely interacts with DnaG directly, inhibits both staphylococcal cell growth and biofilm formation, and displays no significant hemolytic activity or toxicity to mammalian cells. This compound is an excellent lead for further development of a novel anti-staphylococcal therapeutic.
- Green, Keith D.,Punetha, Ankita,Chandrika, Nishad Thamban,Hou, Caixia,Garneau-Tsodikova, Sylvie,Tsodikov, Oleg V.
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- Synthesis and quantitative structure-activity relationship of a novel series of small conductance Ca2+-activated K+ channel blockers related to dequalinium
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The synthesis, pharmacological testing, and quantitative structure- activity relationship studies of a novel series of bisquinolinium small conductance Ca2+-activated K+ channel blockers (23) related to dequalinium are described. In this series, two quinolinium rings are linked via the 4- position to an α,ω-diamino alkylene chain and the ring N atom is quaternized with a methyl or benzyl group. The exocyclic N atom can be replaced by 0, S, or CH2 but with some loss of potency. The quinoline groups do not have to be quaternized for blocking activity, as long as they are basic enough to be protonated at the site of action. For the quaternary compounds, there is considerable steric tolerance for the group R attached to the ring N atom of the quinoline; a benzyl group gave the optimum potency in this series. Moreover, and in contrast to previously reported results for dequalinium analogues, there is no correlation of activity with N1 charge or E(HOMO). On the other hand, a good correlation was obtained between the blocking potency of the compounds and E(LUMO) [pEMR = 1.16(±0.26)E(LUMO) + 5.33(±1.29) (n = 11, r = 0.83, s = 0.243)]. It has been possible to combine this equation with the previously reported E(LUMO) correlation for a series of dequalinium analogues to include all the compounds of both series [pEMR = 1.17(±0.15)E(LUMO) + 5.33(±0.76) (n = 24, r = 0.85, s = 0.249)]. A possible physical meaning for the E(LUMO) correlation based upon the principle of maximum hardness is discussed.
- Galanakis,Davis,Ganellin,Dunn
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