Walnut Polyphenolics Inhibit In Vitro Human Plasma and LDL Oxidation

• Published in: The Journal of nutrition Vol. 131; no. 11; pp. 2837 - 2842
• Main Authors: Anderson, Koren J., Teuber, Suzanne S., Gobeille, Alayne, Cremin, Peader, Waterhouse, Andrew L., Steinberg, Francene M.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.11.2001; American Institute of Nutrition; American Society for Nutritional Sciences
• Subjects: Adult; alpha-tocopherol; alpha-Tocopherol - analysis; analysis; antioxidant; antioxidant activity; Antioxidants; Antioxidants - isolation & purification; Antioxidants - pharmacology; Biological and medical sciences; blood; cardioprotective effect; Chromatography, High Pressure Liquid; drug effects; ellagic acid; Ellagic Acid - pharmacology; English walnuts; epidemiological studies; Epidemiology; Feeding. Feeding behavior; Flavonoids; Fundamental and applied biological sciences. Psychology; Humans; isolation & purification; Juglans regia; LDL; Lipids; Lipoproteins, LDL; Lipoproteins, LDL - blood; liquid chromatography; low density lipoprotein; mass spectrometry; mortality; Nuts; oxidation; Oxidation-Reduction; Oxidation-Reduction - drug effects; oxidative stress; pharmacology; Phenols; Phenols - isolation & purification; Phenols - pharmacology; Plant Extracts; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Plasma; Polymers; Polymers - isolation & purification; Polymers - pharmacology; polyphenol; Polyphenols; propane; thiobarbituric acid; thiobarbituric acid-reactive substances; Vertebrates: anatomy and physiology, studies on body, several organs or systems; walnuts; CD; antioxidant; AAPH; GAE; TBARS; MDA; polyphenol; English walnuts; TEAC; LDL; ellagic acid; LC-ELSD/MS; ABTS; Human; Polyphenol; Fruit; Walnut; Food intake; Plant origin; Antioxidant; In vitro; Feeding; Blood plasma
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/131.11.2837

Recent epidemiologic studies have associated nut consumption with a reduced incidence of cardiovascular mortality. However, little is known about the contribution of nut polyphenols to antioxidant and cardiovascular protection. In this investigation, polyphenol-rich extracts from English walnuts (Juglans regia) were studied and compared with ellagic acid for their ability to inhibit in vitro plasma and LDL oxidation, as well as their effects on LDL α-tocopherol during oxidative stress. In addition, the Trolox equivalent antioxidant activity (TEAC) was determined and liquid chromatography electrospray detection mass spectrometry (LC-ELSD/MS) analyses of the walnut extracts were performed. 2,2′-Azobis′(2-amidino propane) hydrochloride (AAPH)-induced LDL oxidation was significantly inhibited by 87 and 38% with the highest concentration (1.0 μmol/L) of ellagic acid and walnut extract, respectively. In addition, copper-mediated LDL oxidation was inhibited by 14 and 84% in the presence of ellagic acid and walnut extract, respectively, with a modest, significant LDL α-tocopherol sparing effect observed. Plasma thiobarbituric acid reacting substance (TBARS) formation was significantly inhibited by walnut extracts and ellagic acid in a dose-dependent manner, and the extracts exhibited a TEAC value greater than that of α-tocopherol. LC-ELSD/MS analysis of the walnut extracts identified ellagic acid monomers, polymeric ellagitannins and other phenolics, principally nonflavonoid compounds. These results demonstrate that walnut polyphenolics are effective inhibitors of in vitro plasma and LDL oxidation. The polyphenolic content of walnuts should be considered when evaluating their antiatherogenic potential.