title: Direct evidence that (-)-epicatechin increases nitric oxide levels in human endothelial cells.
abstract: BACKGROUND
  The dietary flavanol (-)-epicatechin has been suggested to mediate its vasodilatory effect by increasing nitric oxide levels in endothelial cells.
  
  
  OBJECTIVE
  To directly prove the formation of nitric oxide (NO) in human endothelial cells (HUVEC) in vitro by trapping NO to yield a fluorescent nitrosamine.
  
  
  METHODS
  HUVEC were treated with (-)-epicatechin; nitrite and NO formation were determined by reductive chemiluminescence detection and the NO-sensitive fluorophore 5-methoxy-2-(1H-naphthol[2,3-d]imidazol-2-yl)-phenol copper complex (MNIP-Cu), respectively. MNIP was synthesized in a rapid and convenient one-step microwave reaction. Endothelial nitric oxide synthase (eNOS) mRNA levels and mRNA stability were measured.
  
  
  RESULTS
  Incubation with (-)-epicatechin (0.3-10 μM) led to elevated NO levels in HUVEC measured via reductive chemiluminescence detection and visualized as the fluorescent NO derivative of MNIP. Expression of eNOS mRNA and mRNA stability were not affected by (-)-epicatechin treatment within the time frame studied.
  
  
  CONCLUSIONS
  (-)-Epicatechin augments the level of NO in endothelial cells, a process suggested to be responsible for the vasodilatory properties of the compound.
authors.affiliation: Institut für Biochemie und Molekularbiologie I, Medizinische Fakultät, Heinrich-Heine-Universität, P.O.-Box 101007, 40001, Duesseldorf, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Brossette
authors.forename: Claas
authors.initials: C
authors.lastname: Hundsdörfer
authors.forename: Klaus-Dietrich
authors.initials: KD
authors.lastname: Kröncke
authors.forename: Helmut
authors.initials: H
authors.lastname: Sies
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Stahl
mesh_terms: D002392:Catechin / Q000494:pharmacology*; D002478:Cells, Cultured; D003300:Copper / Q000378:metabolism; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D049449:Luminescence; D008856:Microscopy, Fluorescence; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D009942:Organometallic Compounds / Q000378:metabolism; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D009942:Organometallic Compounds; D012333:RNA, Messenger; D009569:Nitric Oxide; D003300:Copper; D002392:Catechin; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III