Labdane and Bisnorlabdane Type Diterpenes from Alpinia speciosa K. SCHUM.

Two new diterpenes were isolated from the rhizomes of Alpinia speciosa K. SCHUM. (Zingiberaceae) and their structures were established by the spectral evidences as I and II. The latter has an unusual bisnorlabdane carbon skeleton. It is the first example that diterpenes were obtained from Alpinia genus.