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ID: ALA4602638
Journal: Bioorg Med Chem Lett
Title: Propargylglycine-based antimicrobial compounds are targets of TolC-dependent efflux systems in Escherichia coli.
Authors: Roldan BJ, Pajarillo AO, Greenberg JD, Karlinsey JE, Cafiero M, Frawley ER, Peterson LW.
Abstract: A library of novel l-propargylglycine-based compounds were designed and synthesized with the goal of inhibiting the growth of Gram-negative bacteria by targeting LpxC, a highly conserved Gram-negative enzyme which performs an essential step in the lipid A biosynthetic pathway. These compounds were designed with and without a nucleoside and had varying tail structures, which modulate their lipophilicity. The synthetic scheme was improved compared to previous methods: a methyl ester intermediate was converted to a hydroxamic acid, which obviated the need for a THP protecting group and improved the yields and purity of the final compounds. Antimicrobial activity was observed for non-nucleoside compounds containing a phenyl propargyl ether tail (5) or a biphenyl tail (6). An MIC of 16 µg/mL was achieved for 6 in Escherichia coli, but inhibition was only possible in the absence of TolC-mediated efflux. Compound 5 had an initial MIC >160 µg/mL in E. coli. Enhancing outer membrane permeability or eliminating efflux reduced the MIC modestly to 100 µg/mL and 80 µg/mL, respectively. These results highlight the importance of hydrophobicity of this class of compounds in developing LpxC inhibitors, as well as the design challenge of avoiding multidrug efflux activity.
CiteXplore: 31836438