Nardochinoids A-C, Three Dimeric Sesquiterpenoids with Specific Fused-Ring Skeletons from Nardostachys chinensis

Three unusual sesquiterpenoid dimers, nardochinoids A-C (1-3), were isolated from Nardostachys chinensis Batal. Comyound 1 features a rare fused 3,8-dioxatricyclo [7.2.1.0(1,6)]dodecane-11-one ring system, compound 2 is the first nitrogen-containing nornardosinane-aristolane sesquiterpene conjugate, and compound 3 represents the first example of the dimer of a nornardosinane and a nardosinane sesquiterpene. Their structures were characterized by NMR spectroscopic methods and X-ray single-crystal diffraction analysis. Compound 3 showed significant anti-inflammatory activities.