Antimicrobial Phenolic Bisabolanes and Related Derivatives from Penicillium aculeatum SD-321, a Deep Sea Sediment-Derived Fungus

Three new phenolic bisabolane sesquiterpenes, peniciaculins A (1) and B (2) and (7S)-(-)-10-hydroxysydonic acid (3), together with a new nor-bisabolane derivative, 1-hydroxyboivinianin A (4), as well as six known bisabolanes (5-10), were identified from the culture of Penicillium aculeatum SD-321, a fungus isolated from deep-sea sediments. The structures of these compounds were mainly determined by analysis of spectroscopic data, and the absolute configurations of compounds 1-4 were established by comparing their ECD spectra with those of known analogues or by TDDFT-ECD calculations. Compound 1 represents the first example of a bisabolane analogue linked to a diphenyl ether moiety via an ether bond, while compound 2 appears to be the first dimeric bisabolane analogue where the two monomers are coupled to each other via an ester bond. The isolated compounds were evaluated for antimicrobial activity against 10 human and aquatic pathogenic bacteria and three plant-pathogenic fungi.