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

Abstract From the CHCl3-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.