Effect of apple extracts on NF-κB activation in human umbilical vein endothelial cells

Paul A. Davis, John A. Polagruto, Giuseppe Valacchi, Anh Phung, Karel Soucek, Carl L Keen, M. Eric Gershwin

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

The mechanisms by which foods, such as fruit, are able to reduce the risk of chronic disease are still unclear. Several fruit products, including apples and apple juice, that are flavonoidrich are reported to increase antioxidant levels in human subjects. This is supported by the finding from our previous studies that the chronic consumption of apple juice by human subjects reduced ex vivo low-density lipoprotein (LDL) oxidation; we hypothesized that this was due to the flavonoid in the apple juice, which, as we reported earlier, reduced in vitro LDL oxidation. To further explore whether the mixture of flavonoids and other phytochemicals in apples are biologically relevant antioxidants, we tested the effects of this flavonoid-rich apple extract (AE) on oxidant-related pathways in a model of the endothelium: human umbilical vascular endothelial cells (HUVECs). The effects of AE on oxidant-responsive (i.e., tumor necrosis factor [TNF]-α-induced) nuclear factor (NF)-κB signaling in cell culture were assessed in transfected HUVECs by using a construct that expressed luciferase under the control of NF-κB. Incubation of HUVEC for 24 hrs with up to 10 mM (as gallic acid equivalents) of AE demonstrated no cytotoxicity, as determined by lactate dehydrogenase release, caspase 3 activation, and apoptosis marker-based FACS analysis. AE after a 24-hr incubation period at either 200 or 2000 nM showed a complex pattern of decreased basal and TNF-α-stimulated NF-κB signaling (63% maximal decrease) as assessed by luciferase activity in the transfected HUVECs, as well as by reduced levels of IκBα protein phosphorylation detected by Western blot analysis. We suggest that AE downregulates NF-κB signaling and that this is indicative of an antioxidant effect of the flavonoids present in AE.

Original languageEnglish (US)
Pages (from-to)594-598
Number of pages5
JournalExperimental Biology and Medicine
Volume231
Issue number5
StatePublished - May 2006

Keywords

  • Antioxidants
  • Apple extract
  • Human umbilical vascular endothelial cells
  • NF-κB

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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    Davis, P. A., Polagruto, J. A., Valacchi, G., Phung, A., Soucek, K., Keen, C. L., & Gershwin, M. E. (2006). Effect of apple extracts on NF-κB activation in human umbilical vein endothelial cells. Experimental Biology and Medicine, 231(5), 594-598.