Characterization of Three Labdane Diterpenes from Aframomum alboviolaceum.

Two labdane diterpenes were isolated from the seeds and the rhizomes of AFRAMOMUM ALBOVIOLACEUM (Ridley) K. Schum (Zingiberaceae) and identified by GC-MS, (1)H-, and (13)C-NMR as ( E)-labda-8(17),12-diene-15,16-dial ( 1) and ( E)beta,17-epoxy-labd-12-ene-15,16-dial ( 2). A third minor compound could be the methyl ( E)-14xi,15-epoxylabd-8(17),12-dien-16-oate. The simultaneous occurrence of these three molecules has been mentioned only in one other species of the same genus, AFRAMOMUM DANIELLII (1).