Phomapyrrolidones A–C, Antitubercular Alkaloids from the Endophytic Fungus Phoma sp. NRRL 46751

Three new alkaloids, phomapyrrolidones A–C (1–3), bearing a cyclopenta[b]fluorene ring system were isolated from the mycelium extract of the endophytic fungal strain Phoma sp. NRRL 46751, inhabiting Saurauia scaberrinae. Methylation of 1 afforded its N-methyl derivative 4. The planar structures and relative configurations of 1–4 were elucidated by extensive spectroscopic analysis. Phomapyrrolidones B (2) and C (3) exhibited weak antitubercular activity at subcytotoxic concentrations.