Penigrines A-E: Five undescribed azepine-indole alkaloids from Penicillium griseofulvum

Penigrines A-E (1-5), five undescribed azepine-indole alkaloids, were isolated from the fungus Penicillium griseofulvum. Their structures with absolute configurations were determined by NMR, HRESIMS, ECD calculation, and X-ray diffraction experiments. Penigrine C (3) possesses an undescribed 6-oxa-8-azabicyclo[3.2.2]nonane7,9-dione moiety that fused to an indole core, and penigrines D and E (4 and 5) are a pair of epimers. The plausible biosynthetic pathways of 1-5 are proposed. Penigrine A (1) shows the potential for heart failure treatment.