Phenols, Acetylenes, and Sesquiterpene Lactones fromInulanthera nuda

Abstract

Five new compounds, the sesquiterpene lactones 1 and 2, the 2H-pyran-2-one 9, the flavone glycoside 10, and the organic diacid 11 were isolated from the CH2Cl2 extract (1 and 2) and from the BuOH part of the MeOH extract (9 – 11) of the aerial parts of Inulanthera nuda Källersjö (Asteraceae). The structures were established by spectroscopic methods, including UV, IR, EI-MS, D/CI-MS and TSP-MS, 1H- and 13C-NMR as well as two-dimensional NMR techniques. The sesquiterpene lactones were identified as 1α,4β,10β-trihydroxyguaia-2,11(13)-dieno-12,6α-lactone (1) and 4β,10β-dihydroxy-1α-methoxyguaia-2,11(13)-dieno-12,6α-lactone (2), while 9 was found to be 4-(β-D-glucopyranosyloxy)-6-methyl-2H-pyran-2-one, 10 was determined as luteolin 7-(2″-O-acetyl-β-D-glucuronoside) and 11 as (Z)-2-(4-hydroxybenzyl)butenedioic acid. The new compounds were accompanied by six more compounds (3 – 8) from the CH2Cl2 extract and ten compounds from the BuOH extract (including 12 – 16). Compounds 3 and 4 were identified as (E)- and (Z)-O-acetyldendranthemenol, while the structures of 5 – 8 were elucidated as the flavones salvigenin, 5-hydroxy-3′,4′,6,7-tetramethoxyflavone, eupatorin, and cirsilineol, respectively, from their spectroscopic data (EI- and D/CI-MS, UV, 1H- and 13C-NMR). Compounds 12 – 16 were determined as scopolin, maltol 3-glucoside, and the flavone glycosides luteolin 7-glucuronide, apigenin 7-glucuronide, and scutellarein 7-glucuronide based on spectral evidences (D/CI- and TSP-MS, UV, 1H- and 13C-NMR). The additional five compounds from the BuOH extract were identified on-line by HPLC-MS as chlorogenic acid, 3,4-dicaffeoylquinic acid, 1,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, and 3,4-dicaffeoylisoquinic acid. The identification was based on comparison of retention times and UV and mass spectra with authentic samples.