Artemordins A—S, Cadinane‐Type Sesquiterpenoid Dimers from Artemisia ordosica and Their Antihepatoma Activities

Comprehensive Summary Nineteen new cadinane‐involving sesquiterpenoid dimers, artemordins A—S ( 1 — 19 ), together with 13 known SDs ( 20 — 32 ) were isolated from Artemisia ordosica . Their structures and absolute configurations were established by comprehensive spectral analyses, X‐ray single crystal diffraction, theoretical ECD, and NMR calculations. Chemically, artemordins A—F ( 1 — 6 ) were the first examples of two cadinane units constructed by unprecedented C‐3−C‐15′ or C‐3−C‐13′ single bond with an oxido‐rearranged 6/5/6/6 fused ring system; artemordins G—K ( 7 — 11 ) were biogenetically connected by [4 + 2] cycloaddition reaction and artemordins G—J ( 7 — 10 ) possessed a novel 5/6/6/6/6/6/5‐heptacyclic fused ring system. Artemordins L—S ( 12 — 19 ) were formed by esterification, which involved three different types of sesquiterpenoids. Antihepatoma assay suggested that the most active compounds, artemordins B and H ( 2 and 8 ), exhibited inhibitory activities on three hepatoma cell lines with IC 50 values of 26.9 and 25.1 μmol/L (HepG2), 29.5 and 18.3 μmol/L (Huh7), 19.7 and 15.7 μmol/L (SK‐Hep‐1).