4-nor-β-Patchoulene sesquiterpenoids from the essential oil of Pogostemon cablin

Four nor -β-patchoulene sesquiterpenoids including three new compounds ( 1 – 3 ) and a new natural product ( 4 ) were isolated from the essential oil of the leaves and stems of Pogostemon cablin . Their structures were elucidated by detailed spectroscopic analysis, using 1D- and 2D-NMR techniques. This is the first report of 4- nor -β-patchoulenes from plants. All isolates were evaluated for the cytotoxic activities on human cancer cells in vitro . Compound 3 showed weak cytotoxic activities against NCI-H1975 and HePG-2 with IC 50 values of 49.9 μg/mL and 56.0 μg/mL, respectively.