Portobelamides A and B and Caciqueamide, Cytotoxic Peptidic Natural Products from a <i>Caldora</i> sp. Marine Cyanobacterium.
Demirkiran O, Almaliti J, Leão T, Navarro G, Byrum T, Valeriote FA, Gerwick L, Gerwick WH.
Three new compounds, portobelamides A and B (<b>1</b> and <b>2</b>), 3-amino-2-methyl-7-octynoic acid (AMOYA) and hydroxyisovaleric acid (Hiva) containing cyclic depsipeptides, and one long chain lipopeptide caciqueamide (<b>3</b>), were isolated from a field-collection of a <i>Caldora</i> sp. marine cyanobacterium obtained from Panama as part of the Panama International Cooperative Biodiversity Group Program. Their planar structures were elucidated through analysis of 2D NMR and MS data, especially high resolution (HR) MS<sup>2</sup>/MS<sup>3</sup> fragmentation methods. The absolute configurations of compounds <b>1</b> and <b>2</b> were deduced by traditional hydrolysis, derivative formation, and chromatographic analyses compared with standards. Portobelamide A (<b>1</b>) showed good cytotoxicity against H-460 human lung cancer cells (33% survival at 0.9 μM).