Abstract: The present paper reports on a new diterpenoid, weisiensin A (C28 H36O9, mp 298-300°C), which is isolated from the ethereal extract of the dry leaves of Rabdosia weisiensis C. Y. Wu, the chemical structure has been shown to be 1α, 6α, 7β-Triacetoxy-3β, llP-dihydroxy-ent-kaur-16-en-15-one( 1) on the basis of spectroscopic evidence and compared with known compounds. Trichorabdal A ( 2 ), a known component, is also isolated from this plant and its 12C NMR data are assigned.

Key words: Diterpenoid