Pemuchiamides\nA and B, Proline-Rich Linear Lipopeptides,\nIsolated from a Marine <i>Hormoscilla</i> sp. Cyanobacterium

Pemuchiamides\nA and B (<b>1</b> and <b>2</b>) were\nisolated from a marine <i>Hormoscilla</i> sp. cyanobacterium\ncollected from Pemuchi Beach on Hateruma Island, Japan. Although <b>1</b> and <b>2</b> existed as a complex mixture of rotamers\nin chloroform-<i>d</i>, detailed analyses of their 2D NMR\nand tandem mass spectra revealed their planar structures, respectively.\nThe absolute configurations of <b>1</b> and <b>2</b> were\nestablished via the degradation and derivatization reactions. Pemuchiamide\nA (<b>1</b>) exhibited potent growth-inhibitory activity against <i>Trypanosoma brucei rhodesiense</i>, the causative organism of\nAfrican sleeping sickness, while <b>2</b> showed 10-fold weaker\nactivity than <b>1</b>. This result indicates that the presence\nof a hydroxy group at the C-3 position of the 4-aminobutanoic acid\nmoiety negatively affects antitrypanosomal activity.