Abstract:

Two novel bis-labdanic diterpenoids named calcaratarin G and calcaratarin H were isolated from the rhizomes of Alpinia calcarata Rosc. Their structures were elucidated to be a pair of stereoisomers on the basis of the spectral evidence. The 2D NMR techniques including ¹H-¹H COSY, HMQC, HMBC, NOESY and HRFABMS were extensively applied to establish the structures.

Key words: Alpinia calcarata , bis-labdanic diterpenoids, calcaratarin G, calcaratarin H