Pemuchiamides A and B, Proline-Rich Linear Lipopeptides, Isolated from a Marine Hormoscilla sp. Cyanobacterium.

Pemuchiamides A and B ( 1 and 2 ) were isolated from a marine Hormoscilla sp. cyanobacterium collected from Pemuchi Beach on Hateruma Island, Japan. Although 1 and 2 existed as a complex mixture of rotamers in chloroform- d , detailed analyses of their 2D NMR and tandem mass spectra revealed their planar structures, respectively. The absolute configurations of 1 and 2 were established via the degradation and derivatization reactions. Pemuchiamide A ( 1 ) exhibited potent growth-inhibitory activity against Trypanosoma brucei rhodesiense , the causative organism of African sleeping sickness, while 2 showed 10-fold weaker activity than 1 . This result indicates that the presence of a hydroxy group at the C-3 position of the 4-aminobutanoic acid moiety negatively affects antitrypanosomal activity.