Dendrowardol C, a novel sesquiterpenoid from Dendrobium wardianum Warner

Dendrowardol C (1)—a novel sesquiterpenoid, with an unprecedented 4/5/6/6 tetracyclic carbon backbone, together with two known cyclopacamphane-type sesquiterpenoids; dendronobilin I (2) and dendrobane A (3) were isolated from the stems of Dendrobium wardianum Warner. The structure of 1 was established on the basis of spectroscopic data and the absolute configuration was determined by single-crystal X-ray diffraction crystallography. The hypothetical biosynthetic pathway of 1 was postulated. Compound 1 showed no cytotoxic activity against human tumor cell lines HL-60, SMMC-7721, A-549, MCF-7, and SW480. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s13659-013-0024-9 and is accessible for authorized users.