In vitro α-glucosidase inhibitory activity of isolated fractions from water extract of Qingzhuan dark tea

BMC Complementary and Alternative Medicine

Research Article

Wei Zhang¹  Zhi Yu²  Hongkai Zhu²  Shuyuan Liu²  Yuqiong Chen² 

[1] College of Life Science, Xinyang Normal University, 464000, Xinyang, China;Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, 430070, Wuhan, China;

关键词: Camellia sinensis;    Dark tea;    Tea extracts;    α-Glucosidase;    Anti-diabetes;   

DOI  :  10.1186/s12906-016-1361-0

 received in 2016-02-23, accepted in 2016-09-09,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundNatural products have being used as potential inhibitors against carbohydrate-hydrolyzing enzymes to treat diabetes mellitus. Chinese dark tea has various interesting bioactivities. In this study, the active compounds from Qingzhuan dark tea were separated and their anti-diabetic activity was examined using an in vitro enzymatic model.MethodsThe chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions of a Chinese dark tea (Qingzhuan tea) were prepared by successively isolating the water extract with different solvents and their in vitro inhibitory activities against α-glucosidase were assessed. The fraction with the highest inhibitory activity was further characterized to obtain the main active components of Qingzhuan tea.ResultsThe ethyl acetate fraction had the greatest inhibitory effect on α-glucosidase, followed by n-butanol, sediment and residual aqua fractions (with the IC50 values of 0.26 mg/mL, 2.94 mg/mL, 3.02 mg/mL, and 5.24 mg/mL, respectively), mainly due to the high content of polyphenols. Among the eight subfractions (QEF1-8) isolated from the ethyl acetate fraction, QEF8 fraction showed the highest α-glucosidase inhibitory potential in a competitive inhibitory manner (the Ki value of 77.10 μg/mL). HPLC-MS analysis revealed that (−)-epigallocatechin gallate (EGCG) and (−)-epicatechin gallate (ECG) were the predominant active components in QEF8.ConclusionThese results indicated that Qingzhuan tea extracts exerted potent inhibitory effects against α-glucosidase, EGCG and ECG were likely responsible for the inhibitory activity in Qingzhuan tea. Qingzhuan tea may be recommended as an oral antidiabetic diet.

【 授权许可】

CC BY   
© The Author(s). 2016