Exploration of Indole Alkaloids from Marine Fungus Pseudallescheria boydii F44-1 Using an Amino Acid-Directed Strategy.

The composition of the culture medium has great influence on the metabolite production of the marine fungus Pseudallescheria boydii F44-1. By adding amino acids to GPY culture medium, two new bisindole alkaloids, pseudboindoles A and B (1 and 2), together with 11 known indole alkaloids were isolated from the culture broth. Their structures were elucidated by comprehensive analysis of the NMR, MS, IR, and UV spectra. The 3,3'-cyclohexylidenebis(1H-indole) (3) showed cytotoxic activity against various cancer cell lines.