Protective effect of the Chinese prescription Kangen-karyu against high glucose-induced oxidative stress in LLC-PK1 cells

We investigated the effects of Chinese prescription Kangen-karyu on high glucose-induced oxidative stress using LLC-PK1 cells, renal tubular cells, which are the most vulnerable renal tissue to oxidative stress. High-concentration glucose (30 mM) treatment induced LLC-PK1 cell death, but Kangen-karyu, at a concentration of 5, 10 or 50 μg/ml, significantly inhibited high glucose-induced cytotoxicity. In addition, the intracellular reactive oxygen species level was increased by 30 mM glucose treatment, but it was concentration-dependently inhibited by Kangen-karyu treatment. Moreover, 30 mM glucose treatment induced high levels of superoxide anion, nitric oxide and peroxynitrite. However, Kangen-karyu treatment significantly reduced the radical overproduction induced by high glucose, suggesting Kangen-karyu has radical-scavenging activity that would protect against oxidative stress induced by high glucose. Kangen-karyu also reduced the overexpression of inducible nitric oxide synthase and cyclooxygenase-2 proteins induced by high glucose. Furthermore, treatment with Kangen-karyu, at a concentration of 50 μg/ml, inhibited the nuclear translocation of nuclear factor-kappa B induced by 30 mM glucose in LLC-PK1 cells. These findings indicate that Kangen-karyu is a potential therapeutic agent that will reduce the damage caused by hyperglycemia-induced oxidative stress associated with diabetes.