Protective effect of arabinose and sugar beet pulp against high glucose-induced oxidative stress in LLC-PK1 cells

The protective effects of l-arabinose and sugar beet pulp (SBP) on high glucose-induced oxidative stress were investigated using LLC-PK1 cells. Under the high glucose-induced cellular oxidative model, the treatment of 45 mM of glucose led to the decrease in cell viability and increase in lipid peroxidation. However, l-arabinose and SBP significantly inhibited the high glucose-induced cytotoxicity and lipid peroxidation. In addition, the formation of nitric oxide (NO) was increased by the treatment of 45 mM glucose, while the treatment of l-arabinose or SBP inhibited significantly the NO formation compared with high glucose-treated control. The superoxide anion production of groups treated with l-arabinose or SBP was significantly lower than that of the control treated with high glucose. Furthermore, l-arabinose and SBP elevated the glucose uptake, resulting in lower glucose concentration compared with non-treated control. High glucose levels induced the overexpressions of bax, inducible NO synthase and cyclooxygenase-2, but l-arabinose or SBP treatment down-regulated the expressions of these genes. Arabinose and SBP also inhibited the expression of nuclear factor-kappa B induced by 45 mM glucose in LLC-PK1 cells. In particular, arabinose exhibited stronger inhibitory activities on high glucose-induced oxidative stress than SBP did. These findings indicate that l-arabinose and SBP are promising antioxidative agents with protective activities against hyperglycemia.