title: Effect of walnut oil on hyperglycemia-induced oxidative stress and pro-inflammatory cytokines production.
abstract: OBJECTIVE
  In this study, we focused on the effect of hyperglycemia on the generation of reactive oxygen species and on the release of pro-inflammatory cytokines in the human monocytic cell line (U937). We also monitored potential anti-inflammatory effects of walnut oil as well as its protective effect against oxidative damage to biopolymers (DNA and proteins).
  
  
  METHODS
  We cultured U937 cells under normoglycemic or hyperglycemic conditions for 72 h, in the absence or presence of walnut oil. We detected cell proliferation by the MTT test. To determine the antioxidant status of cells, we used the trolox equivalent antioxidant capacity method. We determined the activity of superoxide dismutase (SOD) spectrophotometrically, the oxidative damage to DNA by an enzyme-modified comet assay, and the oxidative damage to proteins by the marker-protein carbonyls and the levels of pro-inflammatory cytokines by the ELISA method.
  
  
  RESULTS
  Hyperglycemia reduced the antioxidant capacity of cells, induced oxidative damage to DNA, and increased the release of pro-inflammatory cytokines. It had no effect on cell proliferation, SOD activity, nor oxidative damage to proteins. Walnut oil significantly increased the antioxidant capacity of cells as well as SOD activity on the second and third day of incubation, but had no effect on cell proliferation and showed no protective effect against oxidative damage to DNA and proteins. The walnut oil showed both anti-inflammatory and pro-inflammatory properties depending on its concentration and time of its incubation with the monocytic cell line.
  
  
  CONCLUSIONS
  Our in vitro results indicate that walnut oil can diminish oxidative stress with its antioxidant properties. However, we could not confirm its protective effect against oxidative damage to DNA and proteins.
authors.affiliation: Jessenius Faculty of Medicine, Institute of Medical Biochemistry, Comenius University, Malá Hora 4, 036 01, Martin, Slovakia.
authors.forename: Lucia
authors.initials: L
authors.lastname: Laubertová
authors.forename: Katarína
authors.initials: K
authors.lastname: Koňariková
authors.forename: Helena
authors.initials: H
authors.lastname: Gbelcová
authors.forename: Zdeňka
authors.initials: Z
authors.lastname: Ďuračková
authors.forename: Ingrid
authors.initials: I
authors.lastname: Žitňanová
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D020552:Comet Assay; D016207:Cytokines / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004249:DNA Damage; D004042:Dietary Fats, Unsaturated / Q000378:metabolism*; D005947:Glucose / Q000009:adverse effects; D006801:Humans; D006943:Hyperglycemia / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D031324:Juglans / Q000737:chemistry*; D009000:Monocytes / Q000276:immunology / Q000378:metabolism*; D009754:Nuts / Q000737:chemistry; D018384:Oxidative Stress; D010938:Plant Oils / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D015203:Reproducibility of Results; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D015415:Biomarkers; D016207:Cytokines; D004042:Dietary Fats, Unsaturated; D010938:Plant Oils; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D005947:Glucose