title: An aqueous birch leaf extract of Betula pendula inhibits the growth and cell division of inflammatory lymphocytes.
abstract: BACKGROUND
  Leaf extracts of Betula pendula have been traditionally used for the treatment of patients with rheumatoid arthritis (RA) or osteoarthritis.
  
  
  OBJECTIVE
  We investigated the anti-proliferative capacity of an aqueous leaf extract of Betula pendula (BPE) on human primary lymphocytes in vitro, because activated lymphocytes play a major role in the initiation and maintenance of RA.
  
  
  METHODS
  Lymphocyte proliferation and cell division was measured by the activity of mitochondrial dehydrogenases and by using the membrane-permeable dye carboxyfluorescein diacetate succinimidyl ester (CFSE), respectively. Apoptosis was analyzed by surface staining of phosphatidylserine and intracellular activation of effector caspases 3 and 7 in comparison to the drug methotrexate using flow cytometric and photometrical analysis. In addition, the impact of the extract on cell cycle distribution was investigated by propidium iodide staining of DNA. For the bioassays BPE concentrations of 10-160 μg/mL were investigated. A phytochemical analysis, using LC-MS and HPLC, was conducted to identify the polyphenolic constituents of the birch leaf extract.
  
  
  RESULTS
  Leaf extracts of Betula pendula inhibited the growth and cell division (CD8(+): 40 μg/mL: 45%; 80 μg/mL: 60%; 160 μg/mL: 87%) (CD4(+): 40 μg/mL: 33%; 80 μg/mL: 54%; 160 μg/mL: 79%) of activated, but not of resting T lymphocytes in a significant dose-dependent manner. The inhibition of lymphocyte proliferation due to apoptosis induction (compared to untreated control: 40 μg/mL: 163%; 80 μg/mL: 240%; 160 μg/mL: 348%) and cell cycle arrest was comparable to that of methotrexate. LC-MS analyses showed that the extract contains different quercetin-glycosides.
  
  
  CONCLUSIONS
  Our results give a rational basis for the use of Betula pendula leaf extract for the treatment of immune disorders, like rheumatoid arthritis, by diminishing proliferating inflammatory lymphocytes.
authors.affiliation: Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Centre Freiburg, Breisacher Strasse 115B, Freiburg, Germany. carsten.gruendemann@uniklinik-freiburg.de
authors.forename: Carsten
authors.initials: C
authors.lastname: Gründemann
authors.forename: Christian W
authors.initials: CW
authors.lastname: Gruber
authors.forename: Anke
authors.initials: A
authors.lastname: Hertrampf
authors.forename: Martin
authors.initials: M
authors.lastname: Zehl
authors.forename: Brigitte
authors.initials: B
authors.lastname: Kopp
authors.forename: Roman
authors.initials: R
authors.lastname: Huber
mesh_terms: D000893:Anti-Inflammatory Agents / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D029662:Betula / Q000737:chemistry*; D002455:Cell Division / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006027:Glycosides / Q000494:pharmacology; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008727:Methotrexate / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves; D011794:Quercetin / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects*
chemical_list: D000893:Anti-Inflammatory Agents; D006027:Glycosides; D010936:Plant Extracts; D011794:Quercetin; D008727:Methotrexate