Cytotoxic and ACAT-inhibitory sesquiterpene lactones from the root of Ixeris dentata forma albiflora

Ixeris dentata forma albiflora was extracted with 80% aqueous MeOH, and the concentrated extract was partitioned with EtOAc, n-BuOH and H2O. Eight sesquiterpenes were isolated through repeated silica gel and octadecyl silica gel (C-18, ODS) column chromatography of the EtOAc and n-BuOH fractions. Physicochemical analysis using NMR, MS and IR revealed the chemical structures of the sesquiterpenes, which were zaluzanin (1), 9a-hydroxyguaian-4(15),10(14),11(13)-triene-6,12-olide (2), 3 beta-O-beta-D-glucopyranosyl-8 beta-hydroxyguaian-4(15),10(14)-diene-6,12-olide (3), 3-O-beta-D-glucopyranosyl-8 beta-hydroxyguauan-10(14)-ene-6,12-olide (4), ixerin M (5), glucozaluzanin C (6), crepiside 1 (7), and ixerin D (8). This is the first time that these sesquiterpene lactones have been isolated from this plant. Compounds 1, 2 and 7 revealed relatively high cytotoxicities on human colon carcinoma cell and lung adenocarcinoma cell, while compounds 5 and 7 showed acyl-CoA: cholesterol acyltransferase (ACAT) inhibitory activity.