Abietane-type and labdane-type diterpenoids from the cones of Chamaecyparis obtusa

A novel compound, 8(17),12E,14-labdatrien-19-al (trans-communal), was isolated from ethyl acetate extract of young cones of hinoki (Chamaecyparis obtusa Endl.). The chemical structure of the compound was determined mainly with various nuclear magnetic resonance spectral techniques. Its stereochernistry was determined by derivation to a known compound, trans-communol. In addition to this compound. four known compounds - ferruginol, chamaecydin. 12-hydroxy-6.7-seco-ableta-8,11.13-triene-6,7-dial, and trans-communic acid - were isolated. All isolated compounds were subjected to an antifeedant bioassay against the pest insect Spodoptera litura. Results of the bioassay showed that chamaecydin and 12-hydroxy-6,7-seco-abieta-8,11,13-triene-6,7-dial had antifeedant activity.