Anti-glycative and anti-inflammatory effects of caffeic acid and ellagic acid in kidney of diabetic mice.

Protective effects of caffeic acid (CA) and ellagic acid (EA) in kidney of diabetic mice were examined. CA or EA at 2.5 and 5% was mixed in diet and supplied to diabetic mice for 12 wk. Results showed that the intake of CA or EA increased renal content of these compounds, alleviated body weight loss, decreased urine output, increased plasma insulin and decreased blood glucose levels at weeks 6 and 12 (p<0.05). The intake of these compounds dose dependently reduced plasma blood urea nitrogen and elevated creatinine clearance (p<0.05). CA or EA at 5% significantly decreased the levels of plasma HbA1c, urinary glycated albumin, renal carboxymethyllysine, pentosidine, sorbitol and fructose (p<0.05), and significantly diminished renal activity of aldose reductase and sorbitol dehydrogenase, as well as suppressed renal aldose reductase mRNA expression (p<0.05). CA or EA dose dependently lowered renal levels of IL-6, IL-1beta, tumor necrosis factor (TNF)-alpha and monocyte chemoattractant protein 1 (MCP-1) (p<0.05). Furthermore, CA or EA dose dependently down-regulated tumor necrosis factor-alpha and monocyte chemoattractant protein-1 mRNA expression in kidney (p<0.05). Based on the observed anti-glycative and anti-inflammatory effects, the supplement of CA or EA might be helpful for the prevention or attenuation of diabetic kidney diseases.