Sesquiterpenoids from the roots of Vladimiria muliensis

An unusual aromadendrane-type sesquiterpenoid with a rare hemiketal-containing 10/3 ring system, named vladimuliecin C (1), and one new eudesmane-type sesquiterpenoid, named vladimuliecin D (4), together with four known sesquiterpenoids, were isolated from the roots of Vladimiria muliensis. The structures of these compounds were elucidated by analysis of spectroscopic data. The absolute configuration of 1 was assigned by X-ray diffraction analysis. A possible biosynthetic process for the formation of 1 is proposed. Compound 1 showed moderate cytotoxicity against three human tumor cell lines.