Triterpenoids from Hippocratea excelsa.: The crystal structure of 29-hydroxytaraxerol

The root bark of Hippocratea excelsa afforded a new derivative of beta-amyrin, which was identified as its ferulate, together with components new in this species. They were identified as the rare 29-hydroxytaraxerol, 29-hydroxyglutinol, 29-hydroxyfriedelin and the sterol 60-hydroxystigmast-4-en-3-one. The known triterpene quinone methides pristimerin and tingenone characteristics of this genus, beta-sitosterol, trans-polyisoprene, squalene, beta-amyrin, and the alditol galacticol characteristic of the Celastraceae were also isolated. The structures were established on the basis of spectral analysis, including homo- and heteronuclear correlation NMR experiments (COSY, DEPT, HMQC and HMBC) and by comparison with data reported in the literature. The structure of 29-hydroxytaraxerol was confirmed by X-ray diffraction. The antimicrobial and antifungal activities of the compounds were studied, but no significant activity was found.