An azafluorenone alkaloid and a megastigmane from Unonopsis lindmanii (Annonaceae)

The azafluorenone alkaloid 5,8-dimethoxy-7-hydroxy-1-methyl-4-azafluoren-9-one and the megastigman (–)-(5R*, 6S*)-megastigman-3-one-10,7-olide were isolated from aerial parts of Unonopsis lindmanii (Annonaceae), along with the known compounds (3S*, 5S*, 8R*)-3,5-dihydroxymegastigma-6,7-dien-9-one (grasshopper ketone), N-trans-feruloyltyramine, (–)-anonaine, (–)-asimilobine, liriodenine and (–)-syringaresinol. This is the first description of the presence of megastigmanes in Annonaceae. The structures of the compounds were elucidated based on spectroscopic data.