4carried out beoause of its antibiotic properties and conspicuous orange colour. Investigations on pristimerin were resumed here when it was found that the roots of Triptervqium reselii Sprague & Takeda, and especially Celastrus striaillosus Nakai were suitable sources for celastrol. The following chemical and WWR evidences allow the recently proposed structure I5 to be extended to the full expression II. Information on the carbocyclic skeleton, especially C, D and E rings, was gained from selenium dehydrogenation of the ester anhydride III' (permanganate oxidation product of pristimerin). The minute amount of product, in the form of its trinitrobenzolate, m.p. 140-148', absorbed at 260, 282,