molecules Article Antidiabetic Effect of Cyclocarya paliurus Leaves Depends on the Contents of Antihyperglycemic Flavonoids and Antihyperlipidemic Triterpenoids Yang Liu 1, Yanni Cao 1, Shengzuo Fang 1,2,*, Tongli Wang 3 ID , Zhiqi Yin 4, Xulan Shang 1,2, Wanxia Yang 1,2 and Xiangxiang Fu 1,2 1 College of Forestry, Nanjing Forestry University, Nanjing 210037, China;
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[email protected]; Tel.: +86-25-8542-7797 Received: 16 April 2018; Accepted: 29 April 2018; Published: 29 April 2018 Abstract: Cyclocarya paliurus has been used commonly to treat diabetes in China. However, the effective components and the effect of plant origin remain unclear. In this study, C. paliurus leaves with different chemical compositions were selected from five geographical locations, and their effects on streptozotocin (STZ)-induced diabetic mice were evaluated with both ethanol and aqueous extracts. Glucose levels, lipid levels, and biomarkers of liver and kidney function were measured. The principal components of both C. paliurus ethanol and aqueous extracts from different geographical locations differed quantitatively and qualitatively. Results showed that C. paliurus extracts with better antihyperglycemic effects were characterized by higher contents of total flavonoids, especially quercetin-3-O-glucuronide and kaempferol-3-O-glucuronide.