Derbesiamides A–E, Cyclic Depsipeptides from <i>Pedobesia</i> sp.

Bryopsidales green algae harbor diverse secondary metabolites, yet the family Derbesiaceae remains poorly explored. Herein, we report five cyclic depsipeptides, derbesiamides A–E (1–5), from the green alga Pedobesia sp. The planar structures were established by extensive NMR and HRESI-TOFMS analyses. Absolute configurations of the constituent amino acids were mainly determined by Marfey’s analysis. The configurations of the two threonine residues in 3 were further resolved by partial hydrolysis coupled with LC–MS/MS analysis and comparison with synthetic diastereomeric peptide fragments. These findings expand the chemical diversity of Derbesiaceae and highlight Pedobesia as a source of distinctive metabolites.