Two pairs of epimers and three undescribed diterpenoids from Pseudocaryopteris paniculata .

A phytochemical investigation on the petroleum ether partition of the whole plant of Pseudocaryopteris paniculata , yield seven new compounds: one phytanes diterpenoid (2 Z ,6 E ,10 E ) 14-keto-2,6,10-trimethyl pentadeca-2,6,10-trien-1-carboxylic acid ( 1 ), five clerodane diterpenoids: paniculatins A-E ( 2 , 3a / 3b , 4a / 4b ), one abietane diterpenoid: ent -uncinatone ( 5 ), together with 12 known compounds. Their structures were elucidated on the basis of 1D and 2D Nuclear Magnetic Resonance （NMR_, Infrared Radiation (IR), and mass spectroscopic data. Compound 2 , 5, and 11 showed weak selective cytotoxic activity of 11 human cancer cell lines.