title: Flavonoid profiles of three Bupleurum species and in vitro hepatoprotective of activity Bupleurum flavum Forsk.
abstract: BACKGROUND
  Bupleurum L. (Aspiaceae) species are used as herbal remedy in Chinese traditional medicine.
  
  
  OBJECTIVE
  The aim was to investigate the flavonoids in three annual European Bupleurum species, including B. baldense, B. affine and B. flavum, and to test their antioxidant and possible hepatoprotective effects.
  
  
  METHODS
  Flavonoids from the methanol-aqueous extracts were quantified by solid-phase extraction-high-performance liquid chromatography. Bupleurum extracts (1-220 mg/ml) were tested for their antioxidant activity in DPPH and ABTS assays, as well as on isolated liver rat microsomes. In vitro hepatoprotective activity of B. flavum flavonoid (BFF) mixture and rutin, and narcissin, isolated from the same mixture, were evaluated on carbon tetrachloride (CCl4) and tert-butyl hydroperoxide (t-BuOOH) toxicity models in isolated rat hepatocytes.
  
  
  RESULTS
  Narcissin was the dominant flavonol glycoside in B. flavum being present at 24.21 ± 0.19 mg/g, whilst the highest content of rutin (28.63 ± 1.57 mg/g) was found in B. baldense. B. flavum possessed the strongest DPPH (IC50 22.12 μg/ml) and ABTS (IC50 118.15 μg/ml) activity. At a concentration 1 mg/ml of BFF (rutin 197.58 mg/g, narcissin 75.74 mg/g), a stronger antioxidant effect in microsomes was evidenced in comparison with silymarin, rutin and narcissin. The hepatoprotective effect of BFF significantly reduced the elevated levels of lactate dehydrogenase and malondialdehyde, and ameliorated glutathione, being most active in t-BuOOH-induced injury model when compared with CCl4 toxicity (P < 0.001).
  
  
  CONCLUSIONS
  In BFF, synergism of rutin and narcissin could be responsible for stronger protection against mitochondrial induced oxidative stress.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria.
authors.forename: Reneta
authors.initials: R
authors.lastname: Gevrenova
authors.affiliation: Department of Pharmacology, Pharmacotherapy and Toxicology, Laboratory of Drug Metabolism and Drug Toxicity, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kondeva-Burdina
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Denkov
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria.
authors.forename: Dimitrina
authors.initials: D
authors.lastname: Zheleva-Dimitrova
keywords: Antioxidant activity; Bupleurum; flavonoids; hepatocytes; microsomes; solid-phase extraction-high-performance liquid chromatography