Solid-phase synthesis of fusaricidin/li-f class of cyclic lipopeptides: Guanidinylation of resin-bound peptidyl amines

Authors

  • Nina Bionda,

    1. Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL
    2. Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL
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    • Nina Bionda and Jean-Philippe Pitteloud contributed equally to this work

  • Jean-Philippe Pitteloud,

    1. Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL
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    • Nina Bionda and Jean-Philippe Pitteloud contributed equally to this work

  • Jean-Philippe Pitteloud,

    1. Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL
    Search for more papers by this author
    • Nina Bionda and Jean-Philippe Pitteloud contributed equally to this work

  • Predrag Cudic

    Corresponding author
    • Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL
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Correspondence to: Predrag Cudic; e-mail: pcudic@tpims.org

Abstract

Fusaricidins/LI-Fs and related cyclic lipopeptides represent an interesting new class of antibacterial peptides with the potential to meet the challenge of antibiotic resistance in bacteria. Our previous study (Bionda et al. ChemMedChem 2012, 7, 871–882) revealed the significance of the guanidinium group located at the termini of the lipidic tails of these cyclic lipopeptides for their antibacterial activities. Therefore, devising a synthetic strategy that will allow incorporation of guanidinium functionality into their structure is of particular practical importance. Since appropriately protected guanidino fatty acid building blocks are not commercially available, our strategy toward guanidinylated fusaricidin/LI-F analogs include solid-phase synthesis of a cyclic lipopeptide precursor possessing a lipidic tail with a terminal amino group followed by its conversion into corresponding guanidine. To find the optimal method for this conversion, we have examined commonly used guanidinylation reagents under the conditions compatible with standard solid-phase peptide synthesis. Described experimental results demonstrated superiority of N,N′-di-Boc-N″-triflylguanidine in solid-phase preparation of fusaricidin/LI-F class of cyclic lipopeptides. The triflylguanidine reagent gave a single monoguanidinylated product in excellent yield independently of the type of solid-support. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 160–166, 2013.

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