title: DNA Topoisomerase Inhibitory Activity of Constituents from the Flowers of Inula japonica.
abstract: Fourteen compounds were isolated from the flowers of Inula japonica THUNB. (Asteraceae), including two new compounds, (1S,2S,4S,5S,8S,10R)-2-acetoxy-4,3-dihydroxy-pseudoguai-7(11)-en-12,8-olide (1) and (1S,2S,4S,5S,8S,10R)-2,4,13-trihydroxy-pseudoguai-7(11)-en-12,8-olide (2), and twelve known compounds, budlein B (3), 6β-hydroxytomentosin (4), 6-deacetoxybritanin (5), 4-epipulchellin (6), britanin (7), tomentosin (8), (+)-dihydroquercetin (9), (-)-syringaresinol (10), quercetagetin 3,4'-dimethyl ether (11), luteolin (12), britanin G (13) and inuchinenolide C (14). Structures of 1 and 2 were determined based on one and two dimensional (1D)- and (2D)-NMR data and Mosher's esterification method. Compounds 9 and 12 showed inhibitory activities toward DNA topoisomerase I with IC50 values of 55.7 and 37.0 µM, respectively, compared to camptothecin (CPT) with an IC50 of 24.5 µM. Compounds 7-9 and 11-14 exhibited more potent inhibitory activity against topoisomerases II with IC50 values of 6.9, 3.8, 3.0, 6.9, 10.0, 14.7 and 13.8 µM, respectively, than that of etoposide (VP-16) with an IC50 of 26.9 µM. Compounds 4-7 and 10-14 exhibited weak cytotoxicities to the selected cancer cell lines.
authors.affiliation: College of Pharmacy, Yeungnam University.
authors.forename: Donggen
authors.initials: D
authors.lastname: Piao
authors.forename: Taein
authors.initials: T
authors.lastname: Kim
authors.forename: Hai Yan
authors.initials: HY
authors.lastname: Zhang
authors.forename: Hyun Gyu
authors.initials: HG
authors.lastname: Choi
authors.forename: Chong Soon
authors.initials: CS
authors.lastname: Lee
authors.forename: Hyuk Jae
authors.initials: HJ
authors.lastname: Choi
authors.forename: Hyeun Wook
authors.initials: HW
authors.lastname: Chang
authors.forename: Mi-Hee
authors.initials: MH
authors.lastname: Woo
authors.forename: Jong-Keun
authors.initials: JK
authors.lastname: Son
mesh_terms: D045744:Cell Line, Tumor; D035264:Flowers / Q000737:chemistry*; D006801:Humans; D038143:Inula / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D016339:Spectrometry, Mass, Fast Atom Bombardment; D059003:Topoisomerase Inhibitors / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D059003:Topoisomerase Inhibitors