Hydrolyzable tannins from the fruits of Terminalia chebula Retz and their α-glucosidase inhibitory activities

초록

Nine hydrolyzable tannins, including three previously unknown and six artifacts, were isolated, together with thirty-nine known ones, from the fruits of Terminalia chebula Retz. (Combretaceae). They were identified as 1,2,3-tri-O-galloy1-6-O-cinnamoyl-beta-D-glucose, 1,2,3,6-tetra-O-galloy1-4-O-cinnamoyl-beta-D-glucose, 4-O-(2 '',4 ''-di-O-galloyl-alpha-L-rhamnosyl)ellagic acid, 1'-O-methyl neochebulanin, dimethyl neochebulinate, 6'-O-methyl neochebulagate, dimethyl neochebulagate, dimethyl 4'-epi-neochebulagate, and methyl chebulagate by the spectroscopic interpretation. After evaluation for alpha-glucosidase inhibition of all isolated compounds, 1,2,3,6-tetra-O-galloyl-4-O-cinnamoyl-beta-D-glucose and 4-O-(2 '',4 ''-di-O-galloyl-alpha-L-rhamnosyl)ellagic acid showed significant inhibitory activities with IC50 values of 2.9 and 6.4 mu M. respectively. In addition, inhibition kinetic studies showed that both compounds have mixed-type inhibitory activities with the inhibition constants (Ki) of 1.9 and 4.0 mu M, respectively. (C) 2017 Elsevier Ltd. All rights reserved.

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