title: Protective Pleiotropic Effect of Flavonoids on NAD⁺ Levels in Endothelial Cells Exposed to High Glucose.
abstract: NAD(+) is important for oxidative metabolism by serving as an electron transporter. Hyperglycemia decreases NAD(+) levels by activation of the polyol pathway and by overactivation of poly(ADP-ribose)-polymerase (PARP). We examined the protective role of three structurally related flavonoids (rutin, quercetin, and flavone) during high glucose conditions in an in vitro model using human umbilical vein endothelial cells (HUVECs). Additionally we assessed the ability of these flavonoids to inhibit aldose reductase enzyme activity. We have previously shown that flavonoids can inhibit PARP activation. Extending these studies, we here provide evidence that flavonoids are also able to protect endothelial cells against a high glucose induced decrease in NAD(+). In addition, we established that flavonoids are able to inhibit aldose reductase, the key enzyme in the polyol pathway. We conclude that this protective effect of flavonoids on NAD(+) levels is a combination of the flavonoids ability to inhibit both PARP activation and aldose reductase enzyme activity. This study shows that flavonoids, by a combination of effects, maintain the redox state of the cell during hyperglycemia. This mode of action enables flavonoids to ameliorate diabetic complications.
authors.affiliation: Department of Toxicology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, Netherlands.
authors.forename: Daniëlle M P H J
authors.initials: DM
authors.lastname: Boesten
authors.affiliation: Department of Toxicology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, Netherlands.
authors.forename: Saskia N I
authors.initials: SN
authors.lastname: von Ungern-Sternberg
authors.affiliation: Department of Toxicology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, Netherlands.
authors.forename: Gertjan J M
authors.initials: GJ
authors.lastname: den Hartog
authors.affiliation: Department of Toxicology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, Netherlands.
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
mesh_terms: D000449:Aldehyde Reductase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D047309:Flavones / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D005947:Glucose / Q000633:toxicity*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007908:Lens, Crystalline / Q000187:drug effects / Q000201:enzymology; D009243:NAD / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D020011:Protective Agents / Q000494:pharmacology*; D011794:Quercetin / Q000494:pharmacology; D012431:Rutin / Q000494:pharmacology; D013552:Swine
chemical_list: D047309:Flavones; D005419:Flavonoids; D020011:Protective Agents; D009243:NAD; D012431:Rutin; D011794:Quercetin; D000449:Aldehyde Reductase; D011065:Poly(ADP-ribose) Polymerases; D005947:Glucose; C043562:flavone