Cleistanone: A Triterpenoid from Cleistanthus indochinensis with a New Carbon Skeleton

Abstract

Cleistanone (1) was isolated from the leaves of Cleistanthus indochinensis and features a new type of triterpenoid carbon skeleton. Its structure was confirmed by X‐ray diffraction analysis. A plausible biosynthetic pathway was proposed for 1 and is thought to proceed through a Wagner–Meerwein rearrangement. Cleistanone (1) was found to show cytotoxic activity against human oral epidermoid carcinoma KB cells.