Cyclocarya paliurus extract alleviates diabetic nephropathy by inhibiting oxidative stress and aldose reductase

Diabetes is the leading cause of end-stage renal disease because diabetic nephropathy (DN) develops in 30-40% of the patients. This study investigated the protective effect of the aqueous extract from leaves of Cyclocarya paliurus (Batal.) Iljinsk (ACP) on DN by inhibiting oxidative stress and aldose reductase (AR) activity. ACP was obtained by hot water extraction. The in vitro antioxidant capability and AR inhibition of ACP were investigated by employing various established systems. DN rats were used to assess the reno-protective effect of ACP. Results showed that the polysaccharide and total polyphenol contents of ACP were (479.3 +/- 19.8) mg/g and (38.3 +/- 2.3) mg/g, respectively. ACP exhibited strong antioxidant ability and AR inhibition in vitro and in vivo; furthermore, the inhibition mechanism of ACP in AR takes the form of uncompetitive inhibition. In addition, the animals treated with ACP showed significant amelioration of blood glucose, serum biomarkers related to renal function, urinary protein excretion, and histopathological changes in the kidney. The results suggest that ACP has a potential role in ameliorating renal damage involved in DN.