title: Cytotoxic sesquiterpene lactones from aerial parts of Xanthium sibiricum.
abstract: Chemical investigation of the aerial parts of Xanthium sibiricum led to the isolation of four new xanthanolide-type sesquiterpene lactones, including two xanthanolide dimers, pungiolide D (1) and pungiolide E (2), and two xanthanolide monomers, 8-epi-xanthatin-1α,5α-epoxide (3) and 1β-hydroxyl-5α-chloro-8-epi-xanthatin (4), together with four known compounds, pungiolide A (5), 8-epi-xanthatin-1β,5β-epoxide (6), xanthatin (7), and 11α,13-dihydro-8-epi-xanthatin (8). The structures of these compounds were elucidated on the basis of spectroscopic data analysis. Pungiolide D (1) displayed an unusual structure featuring a 5/5/6-fused tricyclic system in the unit B. Compound 4 was shown to be a rare sesquiterpene lactone containing halogen, and its absolute configuration was determined by X-ray crystallographic analysis. The evaluation of the cytotoxic activities of the isolated new compounds against the SNU387 liver and A-549 lung human cancer cell lines showed that compound 4 possessed significant in vitro cytotoxicity with an IC50 value of 5.1 µM against SNU387 liver cells.
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China.
authors.forename: Lun
authors.initials: L
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Fu
authors.initials: F
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Ya-Xiong
authors.initials: YX
authors.lastname: Tang
authors.forename: Ming-Kui
authors.initials: MK
authors.lastname: Wang
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D045744:Cell Line, Tumor; D018360:Crystallography, X-Ray; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D020128:Inhibitory Concentration 50; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D035261:Plant Components, Aerial / Q000737:chemistry*; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization; D031210:Xanthium / Q000737:chemistry*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D007783:Lactones; D012717:Sesquiterpenes