Alkaloids from Ammocharis tinneana

Abstract

Sixteen alkaloids have been isolated from fresh bulbs of Ammocharis tinneana (Amaryllidaceae), seven of which contain a 1,2β-epoxide group. 6α-Hydroxycrinamidine and 6α-hydroxyundulatine are reported here for the first time from a natural source. The structures and stereochemistry of these new alkaloids have been determined by physical and spectroscopic methods. 1H and 13C NMR spectra of flexinine, 1,2β-epoxyambelline and 11-O-acetyl-1,2β-epoxyambelline were completely assigned by means of 2D NMR techniques.