Terpenoids from root bark of Celastrus orbiculatus

Phytochemical investigation of root bark of Celastrusorbiculatus afforded 10 terpenoids and eight known compounds. Their structures were established on the basis of spectroscopic and chemical methods. Celastrol and its dimers and adducts displayed moderate inhibitory activity against T cell proliferation. The reaction of celastrol under acidic conditions was undertaken, and a mechanism is presented, which may help towards modification of its structure and elucidation of the biogenetic routes to natural celastrol derivatives.