Protective Effect of Lipoic Acid against Methylglyoxal-Induced Oxidative Stress in LLC-PK

Methylglyoxal (MG), a reactive dicarbonyl compound, is a metabolic byproduct of glycolysis often found at high levels in blood from diabetic patients. The effect of lipoic acid on MG-induced oxidative stress was investigated using LLC-PK 1 renal tubular epithelial cells, which are susceptible to oxidative stress. MG (500 M ) treatment induced LLC-PK 1 cell death to nearly 50% compared with non-treated control cells, but lipoic acid significantly inhibited the MG-induced cytotoxicity in a concentration-dependent manner. In addition, lipoic acid treatment dose-dependently reduced the intracellular reactive oxygen species level increased by 500 M MG. The nitric oxide level was also increased by 500 M MG treatment, but it was significantly inhibited by lipoic acid. Furthermore, lipoic acid treatment at 50 M inhibited the nuclear translocation of nuclear factor-kappa B induced by MG treatment in LLC-PK 1 cells. These findings indicate that lipoic acid has potential as a therapeutic agent against the development of diabetic complications related to MG-induced oxidative stress in diabetes.