Alkaloids of Vinca species V: structure elucidation of herbadine, an alkaloid isolated from Vinca libanotica.

Herbadine, a novel dihydroindole alkaloid, was isolated from the arterial parts of Vinca libanotica Zucc. (Apocynaceae). The physical and spectral data (UV, IR, NMR, and mass spectroscopy) indicated the alkaloid to be a derivative of aimaline. Comparative high-resolution NMR studies with quebrachidine and high-resolution mass spectral studies established the structure of the alkaloid to be 2-epi-3-hydroxyquebrachidine. Herbadine was previously isolated from another species by Russian workers and a structure was postulated. The current paper gives evidence for a corrected structure of herbadine.