New Cyclic Peptides from the Indonesian Sponge Theonella swinhoei

Three new cyclic peptides, barangamides B, C, and D and a new depsipeptide, theonellapeptolide IIe as well as known theonellapeptolides Ia, Id, Ie, IId have been isolated from the sponge Theonella swinhoei collected in Baranglompo Island, Indonesia. The structures of barangamides were elucidated by interpretation of NMR data and application of Marfeyʹs method. The structure of theonellapeptolide IIe, a mixture of several conformers showing complex NMR spectra, was determined by MS analysis of a ring-opened product and by chemical reaction. Some of the theonellapeptolides showed mild immunosuppressive activity, while barangamide A was inactive.