Penibrasdines A-E: Five cyclopiazonic acid-related indole alkaloids from the fungus Penicillium brasilianum.

Five undescribed cyclopiazonic acid indole alkaloids (CPAs), penibrasdines A - E (1-5), and eleven known analogues were isolated from the fungus Penicillium brasilianum. Their structures and configurations were elucidated based on HRESIMS, 1D and 2D NMR spectroscopic data, ECD calculations, and single-crystal X-ray diffraction. Penibrasdine A (1) bearing a rigid and sterically congested hexacyclic indole-tetrahydrofuran scaffold, is the epimer of penicillamine A. Bioactivity evaluation indicated that all isolated compounds showed no effective antibacterial activity against the tested bacterial strains.