Sesquiterpenoids from the aerial parts of Pogostemon cablin.

Six sesquiterpenoids including three previously undescribed ones ( 1–3 ) were isolated from the essential oil of the aerial parts of Pogostemon cablin . Their structures were determined to be (+)-(1 S ,4 R ,6 S ,7 R ,10 S )-1-hydroxycadinan-12-ene-5-one ( 1 ), 11-dehydroxy-cinnamosin A ( 2 ), and 1-methoxy-senecrassidiol ( 3 ) by extensive spectroscopic analyses. This is the first report of cadinane-, cyperane-, and caryolane-type sesquiterpenoids from the genus Pogostemon . Particularly, compound 2 was a rare cyperane-type sesquiterpenoid, compound 3 was a caryolane-type sesquiterpenoid with an unusual cis fusion of A/B ring and an unusual α-methano bridge. [ABSTRACT FROM AUTHOR]