title: Antiviral biflavonoids from Radix Wikstroemiae (Liaogewanggen).
abstract: BACKGROUND
  Radix Wikstroemiae is a common Chinese herbal medicine. The ethyl acetate fraction of the ethanolic extract of W. indica possesses potent in vitro antiviral activity against respiratory syncytial virus (RSV). This study aims to identify the antiviral components of the active fraction.
  
  
  METHODS
  The active fraction of the Radix Wikstroemiae extract was isolated with chromatographic methods such as silica gel, Sephadex LH-20 and semi-preparative high performance liquid chromatography (HPLC) columns. The structures of the isolated compounds were determined based on spectroscopic analyses. The in vitro antiviral activity of the compounds against RSV was tested with the cytopathic effect (CPE) reduction assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method.
  
  
  RESULTS
  Four biflavonoids, namely neochamaejasmin B, genkwanol B, genkwanol C and stelleranol, were isolated and characterized. Genkwanol B, genkwanol C and stelleranol, which are stereo isomers of spirobiflavonoids, showed potent anti-RSV activity whereas neochamaejasmin B did not.
  
  
  CONCLUSIONS
  Neochamaejasmin B, genkwanol B, genkwanol C and stelleranol were isolated from Radix Wikstroemiae and the complete absolute configurations of five chiral carbons in stelleranol were substantiated for the first time. Furthermore, the anti-RSV activity of genkwanol B, genkwanol C and stelleranol was reported for the first time.
authors.affiliation: Institute of Traditional Chinese Medicine and Natural Products, Jinan University, Guangzhou, 510632, China. tliyl@jnu.edu.cn.
authors.forename: Weihuan
authors.initials: W
authors.lastname: Huang
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.forename: Yifei
authors.initials: Y
authors.lastname: Wang
authors.forename: Wencai
authors.initials: W
authors.lastname: Ye
authors.forename: Vincent Ec
authors.initials: VE
authors.lastname: Ooi
authors.forename: Hau Yin
authors.initials: HY
authors.lastname: Chung
authors.forename: Yaolan
authors.initials: Y
authors.lastname: Li