Pipestelides A-C: cyclodepsipeptides from the Pacific marine sponge Pipestela candelabra.

ABSTRACT

Pipestelides A-C (2-4) are three new NRPS-PKS hybrid macrolides containing uncommon moieties, isolated from the Pacific marine sponge Pipestela candelabra. Their structures were elucidated on the basis of spectroscopic data. These cyclodepsipeptides appear to be biosynthetically related to jaspamide (aka jasplakinolide) (1) by chemical modification of the building blocks of the polyketide or peptide chains. Pipestelides A-C (2-4) contain a bromotyrosine [3-amino-3-(bromo-4-hydroxyphenyl)propanoic acid] unit, a polypropionate with a Z double bond, and a 2-hydroxyquinolinone, respectively. Revised chemical shift assignments are provided for the co-isolated known jasplakinolide C(a) (5). In addition, compounds 2 and 3 exhibited cytotoxic activities in the micromolar range.