A unique acyclic sesquiterpene-flavanone adduct and a new cyclic diarylheptanoid from Alpinia katsumadai

Two new compounds, sumadain D (1), and (3S,5S,6R,7S)-5,6-dihydroxy-1,7-diphenyl-methylcentrolobine (2), together with three known compounds, (lR, 4S, 6R) 1,4-dihydroxy-menthene (3), rhodomollein XI (4) and beta-daucosterol (5), were isolated from the seeds of Alpinia katsumadai. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic techniques (UV, IR, MS, and 1D and 2D NMR), and the absolute configurations were established by comparing experimental and circular dichroism (CD) spectra. Compounds (3-5) were isolated for the first time from this plant. Compound 1 was a unique acyclic sesquiterpene-flavanone adduct, and compound 2 was a new cyclic diarylheptanoid.