New guaiane, megastigmane and eudesmane-type sesquiterpenoids and anti-inflammatory constituents from Youngia japonica.

Eleven sesquiterpenoids have been isolated from the whole plants of Youngia japonica (Asteraceae). Among these sesquiterpenoids, five were identified as new compounds on the basis of spectroscopic methods and chemical analysis. Their structures were 3-oxo-8alpha-(4-hydoxyphenyl)acetoxy-10(14),11(13)-guaiadien-12,6-olide ( 1), 3beta-[3-(4-hydroxyphenyl)acetyl-beta- D-glucopyranosyloxy]-8alpha-hydroxy-4(15),10(14),11(13)-guaiatrien-12,6-olide ( 2), 3beta-[3-(4-hydroxyphenyl)acetyl-beta- D-glucopyranosyloxy]-4(15),10(14),11(13)-guaiatrien-12,6-olide ( 3), 3alpha,5beta,6alpha-trihydroxy-4alpha-(beta- D-glucopyranosyloxy)-7-megastigmen-9-one ( 4), and 3alpha-(beta- D-glucopyranosyloxy)-4(15),11(13)-eudesmadien-12-oic acid ( 5). The three known components 3beta-(beta- D-glucopyranosyloxy)-8alpha-(4-hydroxyphenyl)acetoxy-4(15),10(14),11(13)-guaiatrien-12,6-olide ( 8), 3beta-(beta- D-glucopyranosyloxy)-4(15),10(14),11 (13)-guaiatrien-12,6-olide ( 9), and 3alpha-hydroxy-4alpha-(beta- D-glucopyranosyloxy)-5,7-megastigmadien-9-one ( 11) showed inhibitory activity against the proliferation of T and B lymphocytes of mice in vitro at concentrations of 1 x 10 ( - 7), 1 x 10 ( - 6), and/or 1 x 10 ( - 5) M without obvious cytotoxicity. Compound 9, the major component of the plant extract, exhibited weak anti-inflammatory activity at a dosage of 50 mg/kg ( p. o.) in in vivo anti-inflammatory experiments of mice.