[Studies on sesquiterpene lactones from Carpesium faberi]

By using various chromatographic techniques,18 sesquiterpene lactones were isolated from the acetone extract of Carpesium faberi. Their structures were identified on the basis of comprehensive spectroscopic data, involving 2 carabrane sesquiterpenoids [carabrone(1), 4R-carabrol(2)], 3 eudesmane sesquiterpenoids [granilin(3), 3-epi-isotelekin(4), 1α-hydroxypinatifidin(5)], 8 guaiane sesquiterpenoids [4β,10α-dihydroxy-5α(H)-1,11(13)-guaidien-8α,12-olide(6), 8-epi-helenium lactone(7), 4-epi-isoinuviscolide(8), 9β,10β-epoxy-4α-hydroxy-1β-H,11α-H-guaian-8α,12-olide(9), 4α,10α-dihydroxy-1β(H),5β(H)-guaian-11-(13)-en-8α,12-olide(10), 4α-hydroxy-9β,10β-epoxy-11β-H,5α-H-guaian-11(13)-en-8α,12-olide(11), 4α-hydroxy-1β,5α,11α-H-guaian-9(10)-en-8α,12-olide(12), inuviscolide(13)], 1 pseudoguaiane sesquiterpenoid [(+)-confertin(14)], 3 germacrane sesquiterpenoids [madolin B(15), carabrolactone A(16),11(13)-dehydroivaxillin(17)], 1 xanthane sesquiterpenoid [tomentosin(18)]. Furthermore, the absolute configuration of 1 was confirmed by Cu-Kα X-ray crystallographic analysis,and the R-configuration of the chiral center at C-4 in 2 was established by the modified Mosher's method.The compounds 2-5, 7 and 9-15 were isolated from this plant for the first time, and compounds 4-5, 7, and 12-15 were isolated from this genus for the first time.In addition, the neurotrophic activity of compounds 1-3, 6 and 17 were evaluated by morphological observation and statistical analysis of cells differentiation, using rat pheochromocytoma(PC12)cells as a model system. However, all compounds were inactive.