Antimalarial Eudesmane Sesquiterpenoids from .

Eleven new angeloylated eudesmane sesquiterpenoids, dobinins D-N (, , , , , , and -), and four known compounds (, , , and ) were isolated from the roots of . A new oxidation product () was also obtained from dobinin H (). Their structures were elucidated by spectroscopic data and single-crystal X-ray diffraction analyses. Dobinins K-N (-) are the first examples of rearrangement noreudesmane analogue sesquiterpenoids with a unique 6/5-fused carbon skeleton. A putative biosynthetic pathway of compounds - is proposed. Compound exhibited significant antimalarial activity superior to artemisinin with the inhibition ratio of 59.1%, and compounds , , and exhibited moderate antimalarial activities against BY265RFP with inhibition ratios ranging from 14.5% to 18.5% at a dose of 30 mg/kg/day. In addition, the apoptosis of BY265RFP by the depolarization of mitochondrial membrane potential with striking ROS production, after parasitized erythrocyte lysis mediated by cytokines IL-12 and IFN-γ, may be a possible mechanism of antimalarial action of compound against BY265RFP.