Anonazepine, a new alkaloid from the leaves of Annona muricata (Annonaceae)

Abstract From the CHCl 3 -soluble extract of Annona muricata L. (Annonaceae) leaves, one new 3-benzazepine-type alkaloid, anonazepine ( 1 ), and four known aporphine-type alkaloids, (+)-laurotetanine ( 2 ), (+)-norglaucine ( 3 ), (−)-xylopine ( 4 ), and lanuginosine ( 5 ), were isolated. Except for (−)-xylopine ( 4 ), these remaining known alkaloids were first reported in A. muricata . The structures of the isolated alkaloids were established by 1D and 2D NMR spectroscopy and MS, as well as comparison with literature data. The new 3-benzazepine-type alkaloid existed in an inseparable mixture of two equilibrium conformers. Its absolute configuration was determined based on comparing their experimental and calculated ECD data. The anti-inflammatory activity of the isolated alkaloids was investigated, but none of the alkaloids showed a significant result.