A new seco-amorphane-type sesquiterpenoid from Artemisia annua L.

Four terpenoids were isolated from the neutral portion of petroleum ether extract of Artemisia annua by several chromatographic methods, such as silica gel, MCI Gel CHP-20, ODS, Sephadex LH-20 and semi-preparative HPLC. Their structures were identified by HR-MS and nuclear magnetic resonance spectroscopy. These compounds were defined as (1S,4S,5R,6S,9R,10R)-4-ethoxy-9,10-dimethyloctahydrofuro-(3,2-i)-isochromen-11(4H)-one (1), 3a,4,5,6,6a,7-hexahydro-3,6-dimethyl-9-methyl-2H-naphtho8a,1-bfuran-2,8(3H)-dione (2), kobusone (3) and 1,2-campholide (4). Compound 1 is a new compound, of which the absolute configuration was established by single crystal X-ray crystallographic analysis. Compound 2 is a new natural product. Compounds 3 and 4 are first isolated from the Artemisia genus.