title: Baeckein E, a new bioactive C-methylated biflavonoid from the roots of Baeckea frutescens.
abstract: A phytochemical study of Baeckea frutescens afforded a new biflavonoid named as baeckein E (1), along with four known C-methylated flavonols, baeckeins A (2) and B (3), 6-methylquercetin (6) and 6-methylquercetin-4'-O-β-D-glucopyranoside (7), and two known biflavonoids baeckeins C (4) and D (5). The structure of compound 1 was elucidated on the basis of spectroscopic analysis, including HR-ESI-MS, 1D and 2D NMR spectra, and the absolute configurations of C-2 and C-3 for compound 1 were assigned by circular dichroism spectrometry combined with quantum chemical calculations. The antioxidant and cytoprotective activities of compounds 1-7 were also investigated.
authors.affiliation: a Department of Pharmacognosy , Zhengzhou University , Zhengzhou , 450001 , P.R China.
authors.forename: Bei-Xi
authors.initials: BX
authors.lastname: Jia
authors.forename: Feng-Xiao
authors.initials: FX
authors.lastname: Ren
authors.forename: Lu
authors.initials: L
authors.lastname: Jia
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000975:Antioxidants / Q000302:isolation & purification*; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification*; D015394:Molecular Structure; D027822:Myrtaceae / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry
chemical_list: D000975:Antioxidants; D005419:Flavonoids; C000590653:baeckein E