Modulation of Oxidative Stress by Gamma-Glutamylcysteine (GGC) and Conjugated Linoleic Acid (CLA) Isomer Mixture in Human Umbilical Vein Endothelial Cells.

摘要

Individually, y-glutamylcysteine (GGC), a dipeptide and precursor of glutathione (GSH), and conjugated linoleic acid (CLA), a trans-fatty acid, exhibit antioxidant properties. The objective of this study was to compare effects of co-administration of GGC and CLA to treatment with GGC alone on oxidative stress and GSH synthesis in human endothelial cells. Changes in levels of 8-epi-PGF2a, thiobarbituric acid reactive substances (TBARS), GSH, total antioxidants, GSH synthetase (GSS) expression, and transcription factor DNA binding were assessed in human umbilical vein endothelial cells (HUVEC) treated with GGC alone (100 micro mol/L) or combined with CLA isomer mixture (10, 50, 100 micro mol/L) for 24 h. Significantly higher levels of TBARS, 8-epi-PGF2a, GSH, and GSS protein were found in cells treated with GGC and 10 lmol/L CLA, compared to cells treated with GGC alone, indicative of prooxidant effects of CLA. Approximately 40% cell death was microscopically observed in cells incubated with GGC and 100 micro mol/L CLA. Despite lower levels of GSH, treatment with GGC and 50 micro mol/L CLA appeared to be protective from oxidative stress similar to treatment with GGC alone, as indicated by lower levels of TBARS, compared to control cells not treated with GGC and CLA.