Antioxidant effects of dihydrocaffeic acid in human EA.hy926 endothelial cells.
Dihydrocaffeic acid (DHCA) is a metabolite of caffeic acid with potent antioxidant properties. Since DHCA has been detected in human plasma following coffee ingestion, we tested the hypothesis that DHCA protects the endothelium from oxidative stress in a model in human-derived EA.hy926 endothelial cells. During culture for 16-24 hours, the cells accumulated DHCA against a concentration gradient to low millimolar concentrations. In alpha-tocopherol-loaded cells, DHCA spared alpha-tocopherol during overnight culture in a dose-dependent manner. In response to oxidant stress induced by a water-soluble free radical initiator, both alpha-tocopherol and DHCA diminished oxidation of cis-parinaric acid that had been incorporated into the cells, although their antioxidant activities were not additive. DHCA also decreased intracellular oxidation of dihydrofluorescein due to redox cycling by menadione. This suggests that the protective effects of DHCA were caused by scavenging of intracellular reactive oxygen species. DHCA also increased nitric oxide synthase activity in a dose-dependent manner in cultured cells, which was associated with a comparable increase in endothelial nitric oxide synthase protein. Although the DHCA concentrations required for these effects are higher than those likely to be present in plasma or the interstitium, these results indicate that DHCA can function as an intracellular antioxidant.
Huang
Junjun
J
Department of Medicine, 715 Preston Research Building, Vanderbilt University School of Medicine, Nashville, TN 37232-6303, USA.
de Paulis
Tomas
T
May
James M
JM
D000975:Antioxidants / Q000494:pharmacology*; D002109:Caffeic Acids / Q000032:analysis / Q000494:pharmacology*; D002461:Cell Line, Transformed; D042783:Endothelial Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D005452:Fluoresceins / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D005978:Glutathione / Q000032:analysis; D006801:Humans; D006825:Hybridomas; D015227:Lipid Peroxidation / Q000187:drug effects; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000737:chemistry; D014471:Umbilical Veins; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000032:analysis
D000975:Antioxidants; D002109:Caffeic Acids; D005231:Fatty Acids, Unsaturated; D005452:Fluoresceins; D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; C110423:dihydrofluorescein; C000995:3,4-dihydroxyphenylpropionic acid; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D005978:Glutathione; D024502:alpha-Tocopherol; C013641:parinaric acid