Abstract
Two yellow pigments, I and II were isolated from the rhizomes of Cimicifuga dahurica MAXIM. (Ranunculaceae) and were elucidated as geometric isomers, (E)-3-(3'-methyl-2'-butenylidene)-2-indolinone and (Z)-3-(3'-methyl-2'-butenylidene)-2-indolinone, by chemical and spectral studies and by X-ray diffraction analysis, respectively. On standing, and ethanolic solution of II gave a colorless substance, which was regarded as a product of dimerization.
