Calophyline A, a New Rearranged Monoterpenoid Indole Alkaloid from Winchia calophylla

Calophyline A (1), a novel unprecedented rearranged monoterpenoid indole alkaloid, along with a new natural product N-methyl aspidodasycarpine (2) and six known analogues, was isolated from the trunk barks of Winchia calophylla. The structure of compound 1 was elucidated on the basis of spectroscopic data and then confirmed by a single-crystal X-ray crystallographic analysis. A hypothetical biogenetic pathway for compound 1 was proposed. All isolated compounds were evaluated for their in vitro cytotoxicity against a small panel of human cancer cell lines.