title: Contribution of flavonoids and catechol to the reduction of ICAM-1 expression in endothelial cells by a standardised Willow bark extract.
abstract: BACKGROUND
  A quantified aqueous Willow bark extract (STW 33-I) was tested concerning its inhibitory activity on TNF-α induced ICAM-1 expression in human microvascular endothelial cells (HMEC-1) and further fractionated to isolate the active compounds.
  
  
  RESULTS
  At 50 μg/ml the extract, which had been prepared from Salix purpurea L., decreased ICAM-1 expression to 40% compared to control cells without showing cytotoxic effects. Further liquid-liquid partition revealed an ethyl acetate phase with potent reduction of ICAM-1 expression to 40% at 8 μg/ml. This fraction was comprehensively characterised by the isolation of flavanone aglyca and their corresponding glycosides, chalcone glycosides, salicin derivatives, cyclohexane-1,2-diol glycosides, catechol and trans-p-coumaric acid. All compounds were investigated for their activity on TNF-α induced ICAM-1 expression. The flavonoid and chalcone glycosides were not active up to 50 μM, whereas catechol and eriodictyol at the same concentration showed a significant reduction of ICAM-1 expression to 50% of control. Interestingly, other isolated flavanone aglyca like taxifolin, dihydrokaempferol and naringenin showed only weak or moderate inhibitory activity. Eriodictyol was a minor compound in the extract, whereas the catechol content in the extract (without excipients) reached 2.3%, determined by HPLC. One of the isolated cyclohexan-1,2-diol glucosides, 6'-O-4-hydroxybenzoyl-grandidentin, is a new natural compound.
  
  
  CONCLUSIONS
  As catechol is quantitatively important in Willow bark extracts it can be concluded from the in vitro data that not only flavonoids and salicin derivatives, but also catechol can probably contribute to the anti-inflammatory activity of Willow bark extracts.
authors: Lehrstuhl für Pharmazeutische Biologie, Universität Regensburg, 93040 Regensburg, Germany.
authors: A
authors: A
authors: Freischmidt
authors: G
authors: G
authors: Jürgenliemk
authors: B
authors: B
authors: Kraus
authors: S N
authors: SN
authors: Okpanyi
authors: J
authors: J
authors: Müller
authors: O
authors: O
authors: Kelber
authors: D
authors: D
authors: Weiser
authors: J
authors: J
authors: Heilmann
mesh_terms: D000085:Acetates / Q000737:chemistry; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D002396:Catechols / Q000494:pharmacology*; D002470:Cell Survival; D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000737:chemistry; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D044950:Flavanones / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D015394:Molecular Structure; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D011794:Quercetin / Q000031:analogs & derivatives / Q000494:pharmacology; D032108:Salix / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000009:adverse effects
chemical_list: D000085:Acetates; D000893:Anti-Inflammatory Agents; D002396:Catechols; D003373:Coumaric Acids; D044950:Flavanones; D005419:Flavonoids; D010936:Plant Extracts; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; C007650:ethyl acetate; D011794:Quercetin; C003377:taxifolin; C005273:naringenin; C034221:catechol; C007619:eriodictyol