Petrosifungins A and B, novel cyclodepsipeptides from a sponge-derived strain of Penicillium brevicompactum

A strain of Penicillium brevicompactum derived from a specimen of the Mediterranean sponge Petrosia ficiformis was investigated for its secondary metabolites. Using fast centrifugal partitioning chromatography (FCPC) two previously unknown cyclodepsipeptides, petrosifungins A (1) and B (2), were isolated, both containing two neighboring units of the nonproteinogenic amino acid L-pipecolinic acid. The absolute configurations of all amino acids were established to be L using GITC derivatization and Marfey's method. Furthermore, the known metabolite brevianamide A (3) was isolated. The likewise known compounds mycophenolic acid (4) and asperphenamate (5) were identified from their spectroscopic properties directly in the extract using HPLC-UV, -MS, and -NMR coupling.