Postprandial glycaemia-lowering effect of a green tea cultivar Sunrouge and cultivar-specific metabolic profiling for determining bioactivity-related ingredients

Abstract

Although the major green tea catechins can inhibit the activity of carbohydrate-hydrolyzing enzymes, there is a paucity of information describing the potential of other green tea ingredients and numerous green tea cultivars. Herein, we reveled that a green tea cultivar Sunrouge significantly suppressed the postprandial blood glucose level in mice. Unlike the most representative Japanese green tea cultivar, Yabukita, the suppression by Sunrouge was observed clearly during the initial period after oral dosing of starch. Sunrouge also strongly inhibited the carbohydrate-hydrolyzing enzymes α-glucosidase and α-amylase when compared with that of Yabukita and many other cultivars. Liquid chromatography–mass spectrometry (LC–MS)-based metabolic profiling (MP) of 42 Japanese green tea cultivars was performed. Multivariate statistical analysis enabled visualization of the differences among cultivars with respect to their ability to inhibit carbohydrate-hydrolyzing activities. Analysis of metabolites, contributing to the discrimination and prediction of the bioactivity of cultivars, showed that O-methylated catechins, epicatechin-3-O-(3-O-methyl) gallate (ECG3”Me) and epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3”Me), were newly identified α-glucosidase inhibitors. Such ability was also observed in epigallocatechin-3-O-gallate (EGCG), epicatechin-3-O-gallate (ECG), delphinidin-3-O-glucoside and myricetin-3-O-glucoside. The amounts of these compounds in Sunrouge were higher than that in many other cultivars. These results suggest that Sunrouge has high potential for suppressing the elevation of the postprandial blood glucose level, and an MP approach may become a valuable strategy for evaluating the anti-hyperglycemic activity of green tea and for screening its active ingredients.

Preliminary phytochemical analysis and evaluation of in vitro antioxidant, antiproliferative, antidiabetic, and anticholinergics effects of endemicGypsophilataxa from Turkey

“…AChE is exists in all excitable cells, while BChE enzyme is present more commonly in the central neural system, plasma, and liver (Gulçin et al, 2017). Inhibition of the carbohydrate digestion enzymes such as α-glycosidase and α-amylase can cause to reduction of postprandial blood glucose level when fed with a high-carbohydrate diet (Wasai et al, 2018). Therefore, it can be an important strategy for the management of postprandial blood glucose level in type 2 DM as well as borderline patients.…”

Metabolic Profiling for Evaluating the Dipeptidyl Peptidase-IV Inhibitory Potency of Diverse Green Tea Cultivars and Determining Bioactivity-Related Ingredients and Combinations

“…Green tea catechins have been found to lower the level of postprandial blood glucose in mice after dosing of starch. , A retrospective cohort analysis showed that a reduced risk of type 2 diabetes was associated with the consumption of green tea . Recently, we reported that green tea extract (GTE) derived from the representative Japanese tea cultivar has an inhibitory effect on elevated blood glucose levels in mice . DPP-IV inhibitory activity was found in GTE derived from one of Bangladesh tea cultivars. , In addition, this activity was also reported in epigallocatechin-3- O -gallate (EGCG), the major green tea catechin .…”

“…A current research provided the possibility that food-derived phenolic compounds could cause a delay of glucose absorption by inhibiting carbohydrate-hydrolyzing enzymes such as α-glucosidase and α-amylase, which would in turn reduce the level of postprandial blood glucose. It appears to be an appropriate strategy for treating and preventing type 2 diabetes. − Incretins, both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide, are representative peptide hormones secreted from enteroendocrine cells in the gastrointestinal tract after food intake. , In healthy individuals, incretin action is responsible for 60–70% of the secretion of postprandial insulin in response to glucose . However, secreted incretins are short-lived because they are rapidly degraded, and their level and effectiveness are markedly reduced, especially in patients with type 2 diabetes .…”

Antidiabetic Effects of Flavan-3-ols and Their Microbial Metabolites

“…Similarly, epicatechin-3- O -(3- O -methyl) gallate (ECG3”Me), epigallocatechin-3- O -(3- O -methyl) gallate (EGCG3”Me), EGCG, and epicatechin-3- O -gallate (ECG) inhibited α-glucosidase, and in this case EGCG3”Me had the strongest effect. Their IC 50 values were 14.7, 8.1, 13.3, and 61.1 µM respectively [ 21 ]. C was also shown to inhibit α-glucosidase stronger than acarbose (IC 50 = 87.55 µg/mL vs. 199.53 ± 1.12 μg/mL, respectively) [ 22 ].…”

“…[40] [21]. C was also shown to inhibit α-glucosidase stronger than acarbose (IC 50 = 87.55 µg/mL vs. 199.53 ± 1.12 µg/mL, respectively) [22].…”