Identification of six new minor diarylheptanoids from the seeds of alpinia katsumadai

Phytochemical investigation of the seeds of Alpinia katsumadai (Zingiberaceae) led to the isolation and identification of six new diarylheptanoid derivatives, katsumains D-G (1-4), 3-(acetyloxy)-alpinikatin (5), and 5-(acetyloxy)alpinikatin (6). The structures of 1-6 were elucidated by spectroscopic data analysis including 1D- and 2D-NMR experiments.