New bisabolane sesquiterpenoids from the rhizomes of Curcuma xanthorrhiza (Zingiberaceae) II.

Four bisabolane sesquiterpenoids, named bisacurone epoxide ((1))___∼, bisacurone A ((2))___∼) bisacurone B ((3))___∼ and bisacurone C ((4))___∼, were isolated from the chloroform-soluble fractions of the rhizomes of Curcuma xanthorrhiza (Zingiberaceae). The absolute structures of these new compounds were determined on the basis of their spectral data, chemical conversions and X-rat crystallography. In the process of determining the absolute structure of 1__∼, the stereochemistry reported for bisacurone ((5))___∼ in our previous paper was revised.