Forrestiacids C and D, unprecedented triterpene-diterpene adducts from Pseudotsuga forrestii

Forrestiacids C ( 1 ) and D ( 2 ), a pair of C-25 epimeric triterpene–diterpene adducts were isolated from the needles and twigs of the vulnerable conifer Pseudotsuga forrestii . This unprecedented class of compounds might be generated via an intermolecular Michael addition reaction of a rearranged 6/6/5/5-fused spiro-lanostene with an abietene. Their structures were established by spectroscopic data and X-ray crystallography. The adducts showed inhibitory activities against the ATP-citrate lyase (ACL) and acetyl-CoA carboxylase 1 (ACC1), two rate-limiting enzymes in the de novo lipogenesis pathway. Forrestiacids C ( 1 ) and D ( 2 ), a pair of terpenoid heterodimeric epimers from the vulnerable conifer Pseudotsuga forrestii , represent an unprecedented class of Michael adducts of a rearranged 6/6/5/5-fused spiro-lanostene with an abietene. They exhibited inhibitory effects against the ATP-citrate lyase (ACL) and acetyl-CoA carboxylase 1 (ACC1), two potential drug targets for the lipogenesis-related disorders.