Pandangolide 1a, a metabolite of the sponge-associated fungus Cladosporium sp., and the absolute stereochemistry of pandangolide 1 and iso-cladospolide B

Fractionation of the ethyl acetate extract of a Cladosporium sp., isolated from the Red Sea sponge Niphates rowi, yielded a new hexaketide, pandangolide 1a (1), together with its known diastereomer pandangolide 1 (2) and the known iso-cladospolide B (3). The structures of the compounds were determined by 1D and 2D NMR techniques and mass spectrometric data. The absolute configurations of the stereocenters in these compounds were determined by Riguera's method and circular dichroism.