Pentacyclic triterpenes from Euphorbia stygiana.

Two pentacyclic triterpenes, D-friedomadeir-14-en-3beta-yl acetate and D:C-friedomadeir-7-en-3beta-yl acetate, named madeiranyl acetate and isomadeiranyl acetate, respectively, were isolated from leaves of Euphorbia stygiana, together with the two known madeiranes, D-friedomadeir-14-en-3-one and D:C-friedomadeir-7-en-3-one, which were obtained from the stem bark. In addition, four known lupane and taraxerane-type triterpenes, namely lupenyl acetate, lupenone, taraxeryl acetate and taraxerone, were also isolated from the same source. Structures were elucidated by physical, chemical and spectroscopic methods (1H NMR, 13C NMR, IR and mass spectra) and by comparison with literature data, and in the case of D:C-friedomadeir-7-en-3beta-yl acetate by X-ray analysis as well.