A new cyclic depsipeptide, triproamide (<b>1</b>), containing the rare 4-phenylvaline (dolaphenvaline, Dpv) and a β-amino acid, dolamethylleucine (Dml), originally found in dolastatin 16, was isolated from the polar VLC-derived fraction of the extracts prepared from the marine cyanobacterium <i>Symploca hydnoides</i>. Triproamide (<b>1</b>) was isolated along with the known molecule kulokainalide-1 (<b>2</b>), as well as its two new analogues, pemukainalides A (<b>3</b>) and B (<b>4</b>). Their planar structures were elucidated based on extensive NMR and mass spectrometric data. The absolute and relative configurations of the compounds were determined utilizing a combination of Marfey's method, <i>J-</i>based configuration, and chiral-phase HPLC analyses. Kulokainalide-1 (<b>2</b>) and pemukainalide A (<b>3</b>) exhibited cytotoxicity against the MOLT-4 leukemia cell line with IC<sub>50</sub> values of 5.9 and 5.6 μM, respectively.