Tetracyclic triterpenoids and terpenylated coumarins from the bark of Ailanthus altissima (“Tree of Heaven”)

Tetracyclic triterpenoids (named as altissimanins A–E, 1–5) and a terpenylated coumarin (denominated as altissimacoumarin G, 6), along with fifteen known compounds (7–21) were isolated from the bark of Ailanthus altissima. Structures of compounds 1–6 were established by spectroscopic methods and chemical transformations. Altissimanin A (1) is a tirucallane-type triterpenoid bearing an uncommon oxetane ring in the side-chain, while altissimanins D (4) and E (5) are two unprecedented dimers each consisting of one tirucallane-type and one dammarane-type triterpenoid moiety. All the isolates were evaluated for their cytotoxic effects against a small panel of human cancer cell lines.