Ulleungpeptins A and B: Antiangiogenic Lipohexapeptides Containing <i>E</i>/<i>Z</i>-Decadienoic Acid Moieties from <i>Streptomyces</i> sp. 13F051

Two new lipopeptides, ulleungpeptins A and B (<b>1</b> and <b>2</b>), were isolated from cultures of <i>Streptomyces</i> sp. 13F051. Spectroscopic analyses revealed that both compounds consist of a 2,4-decadienoic acid moiety conjugated to a hexapeptide incorporating the non-proteinogenic amino acid 3,5-dihydroxyphenylglycines (Dpgs). Detailed NMR studies established that the two compounds differ in the configuration of the double bonds within the 2,4-decadienoic acid moiety. The absolute configurations of the amino acid residues were determined by advanced Marfey's analysis, supported by bioinformatic predictions. Bioactivity evaluation demonstrated that compounds <b>1</b> and <b>2</b> inhibit angiogenesis in HUVEC cells without exhibiting cytotoxicity.