title: Effect of flavonoids on basal and insulin-stimulated 2-deoxyglucose uptake in adipocytes.
abstract: METHODS
  The adipose tissue is a major site of insulin action and contributes substantially to energy homeostasis. Insulin increases the extraction of glucose from circulation into adipose tissue by recruiting the glucose transporter GLUT4 to the plasma membrane. It has been proposed that dietary flavonoids may interfere with glucose transport processes.
  
  
  RESULTS
  We have used murine 3T3-L1 adipocytes and isolated mature human adipocytes to assess the interaction of selected flavonoids with glucose uptake, both in the basal state and after insulin stimulation. Kinetic characterization of 2-deoxyglucose uptake in the basal state revealed in both cell types an apparent K(m) of around 8 mM with no change in affinity but a significant increase in maximal influx in the presence of insulin. A screening of representative flavonoids of different structural classes revealed the flavanone naringenin and the isoflavone daidzein to affect glucose transport significantly with half-maximal inhibition at concentrations of around 60-80 μM for basal and 70-110 μM for insulin-stimulated glucose uptake in both 3T3-L1 adipocytes and mature human adipocytes.
  
  
  CONCLUSIONS
  Considering attainable plasma concentrations of flavonoids in vivo, we assume that even under physiological conditions naringenin and daidzein could impair glucose removal from plasma, which may pose a risk to patients with diabetes mellitus.
authors.affiliation: Else-Kröner-Fresenius Center for Nutritional Medicine, Technische Universität München, Freising, Germany.
authors.forename: Melina
authors.initials: M
authors.lastname: Claussnitzer
authors.forename: Thomas
authors.initials: T
authors.lastname: Skurk
authors.forename: Hans
authors.initials: H
authors.lastname: Hauner
authors.forename: Hannelore
authors.initials: H
authors.lastname: Daniel
authors.forename: Manuela J
authors.initials: MJ
authors.lastname: Rist
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects*; D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000368:Aged; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism*; D005260:Female; D044950:Flavanones / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007529:Isoflavones / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008875:Middle Aged; D010636:Phenols / Q000494:pharmacology; D059808:Polyphenols; D055815:Young Adult
chemical_list: D044950:Flavanones; D005419:Flavonoids; D051275:Glucose Transporter Type 4; D007328:Insulin; D007529:Isoflavones; D010636:Phenols; D059808:Polyphenols; C004742:daidzein; D003847:Deoxyglucose; C005273:naringenin; D005947:Glucose; C028610:flavanone