Officinatrione: an unusual (17S)-17,18-seco-lupane skeleton, and four novel lupane-type triterpenoids from the roots of Taraxacum officinale

Abstract Novel 5 lupane-type of triterpenois, i.e., 3β-acetoxy-18α,19α-epoxylupan-21β-ol ( 1 ), 18α,19α-epoxy-21β-hydroxylupan-3-one ( 2 ), lup-18-ene-3,21-dione ( 3 ), lupa-18,21-dien-3β-yl acetate ( 4 ), and (17 S )-17,18- seco -lup-19(21)-ene-3,18,22-trione ( 5 ), named officinatrione, as well as 16 known compounds from the roots of Taraxacum officinale collected in Takatsuki city, Osaka, Japan. Of the above compounds, 5 was the first lupane-type triterpene, of which the D-ring was open to form a nine-membered ring. Compounds 2 and 5 exhibited moderate cytotoxic activities against L1210 cell line (IC 50 10.5 and 10.1 μM).