11α,13- and 11β,13 -Dihydro-4H-xanthalongin 4-O-β-Glucopyranosides: New Sesquiterpene Lactone Glycosides from Flowers ofArnica amplexicaulisandA. mollis^1,*

Abstract

The flowers of A. amplexicaulis afforded, in addition to xanthalongin ( 1), 11beta,13-dihydroxanthalongin (2), its 11-epimer (3), and 11alpha,13-dihydro-4H-xanthalongin (4), the new xanthanolide glycosides 11alpha, 13-dihydro-4 H-xanthalongin 4- O-beta-D-glucopyranoside (5) and its 11-epimer (6). The glycosides were also isolated from the flowers of A. mollis. The structures were elucidated by NMR spectroscopy (1)H-NMR, COSY, (13)C-NMR, HETCOR, DEPT), MS (EI, FAB, FD), and enzymatic hydrolysis of the glycosides. The chemo-taxonomic importance is discussed.

Sesquiterpene Lactone Glycosides from Arnica longifolia

“…were extracted and purified using standard chromatographic methods. The only spot found in TLC of the glycoside fraction gave violet-colored reaction products, which later turned to green, as previously observed for 4H-tomentosin derivatives (2,4). Its R f value was found to be identical by direct comparison with a mixture of the isomeric tomentosin glycosides 9 and 10, previously isolated from A. amplexicaulis (2).…”

“…Xanthanolide-type sesquiterpene lactones were exclusively found in species of the subgenus Chamissonis (1). Whereas tomentosin (1), which was also named xanthalongin (2,4,7,8), and its 11,13-dihydro derivatives (2 ± 4) were found in A. amplexicaulis, A. longifolia and A. mollis, the tricyclic xanthanolide carabrone (6) was found in A. longifolia alone (1), supporting the outstanding position of this species in the subgenus Chamissonis.…”

“…However, only a few sesquiterpene lactone glycosides have been found in Arnica to date. The isomeric 11a,13and 11b,13dihydro-4H-tomentosin-b-glucopyranosides (9 and 10) were the first two compounds isolated from A. amplexicaulis and A. mollis (2). A reinvestigation of the latter species afforded the first guaianolide glycoside (3).…”

Allergenic sesquiterpene lactones from cushion bush (Leucophyta brownii Cass.): new and old sensitizers in a shrub‐turned‐a‐pot plant

“…Some Arnica species contain tomentosin and closely related xanthanolides, and this seems to be in accordance with the findings of the present study, because 2 patients, nos. 2 and 11, had positive patch test reactions to both Arnica and tomentosin, and another had doubtful positive reactions to both (Table ) . Doubtful positive reactions to Arnica and tomentosin alone (individually) were seen in patients nos.…”

Clonal propagation of Arnica montana L., a medicinal plant

“…Most of the reports about the Arnica genus regard the chemistry, systematics (Willuhn et al, 1995), and identification of several biologically active chemical compounds such as helenalin, an anti-inflammatory sesquiterpene lactone (Malarz et al, 1993;Paßreiter et al, 1995;Lyß et al, 1997;Merfort et al, 1997), caffeoylquinic acids from flowers of A. montana and A. chamissonis (Merfort, 1992), flavonoid glycosides in A. longifolia subgenus chamissonis (Skibinski et al, 1994), and guaianolide glucosides from flowers of A. mollis (Merfort et al, 1996). Micropropagation protocols for A. montana described earlier were based on the use of cytokinin -auxin combinations (Zǎpârţan, 1996a).…”