Antifouling indole alkaloids from two marine derived fungi.

In order to find non-toxic antifouling natural products from marine microorganisms, the chemical constituents of two marine derived fungi Penicillium sp. and Aspergillus sydowii have been investigated under bio-guided fractionation. A new indolyl diketopiperazine compound, penilloid A (1), together with 15 known ones were isolated from these two strains. The structure of 1 was elucidated on the basis of NMR and mass spectra. Some alkaloids showed significant antifouling and antibacterial activities. The results indicate that indole alkaloids could be a potential antifouling agent resource.