STUDIES ON TRITERPENOIDS OF POPULUS YUNN ANENSIS DODE.

Three triterpenoids (Ⅰ, Ⅱ and Ⅲ) were isolated from the roots of Populus yunnanensis Dode. which has been used as a folk remedy for the treatment of urinary tract infection and calculus in Yunnan Province.Compound Ⅰ and Ⅲ were identified as friedelin and 21α-hydroxyfriedelan-3-one and comoound Ⅱ as 21α-acetoxyfriedelan-3-one which is a new triterpenoid. ¹³C NMR data of Ⅱ showed that the presence of an α-acetoxy group at C-21 does not affect the boat conformation of ring E similar to the results in the study of some other D:A-friedo-oleananes.