A total of thirteen sesquiterpenoids with diverse skeletons including four new sesquiterpenoids, glandulosines A - D (1-4), a new natural product, glandulosine E (5), and eight known sesquiterpene lactones (6-13) were isolated from the roots of Cichorium glandulosum Boiss. et Huet (Asteraceae). Their structures were determined by extensive spectroscopic experiments including NMR, electronic circular dichroism (ECD), calculated ECD, Rh2(OCOCF3)4-induced ECD, and single-crystal X-ray diffraction analysis, as well as chemical methods. This is the first report of the crystal structure of 11β,13-dihydrolactucin (11). Thirteen isolated sesquiterpenoids (1-13) were evaluated for their anti-inflammatory activities in vitro, and three guaiane sesquiterpene lactones, glandulosine E (5), scorzoside (9), and lactucin (10) showed moderate inhibitory activity against LPS-induced nitric oxide (NO) production in RAW 264.7 macrophages.
Keywords: Anti-inflammatory activity; Cichorium glandulosum Boiss. et Huet (Asteraceae); ECD calculation; Rh(2)(OCOCF(3))(4)-induced ECD; Sesquiterpenoids.
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