Flavanols from the Camellia sinensis var. assamica and their hypoglycemic and hypolipidemic activities

Abstract

α-Glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. To identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. One new flavanol, named (–)-epicatechin-3-O-(Z)-coumarate (1), and 16 known analogs (2—17) were isolated from the aqueous extract of the pu-erh tea. Their structures were determined by spectroscopic and chemical methods. Furthermore, the water extract of pu-erh tea and its fractions exhibited inhibitory activities against α-glucosidases and lipases in vitro; compound 15 showed moderate inhibitory effect against sucrase with an IC50 value of 32.5 μmol/L and significant inhibitory effect against maltase with an IC50 value of 1.3 μmol/L. Compounds 8, 10, 11 and 15 displayed moderate activity against a lipase with IC50 values of 16.0, 13.6, 19.8, and 13.3 μmol/L, respectively.

Antioxidant Activity of Methanol Extract from Several Indonesian Green Teas

“…This finding provides evidence that polyphenols in the tea extract are the predominant source of the radical scavenging activities of these tea, which is likely exerted through donation of a hydrogen or electron transfer from the phenolic structure to the radicals (Adjimani and Asare, 2015). Previous studies reported this property comes from polyphenols such as epichatechin, epichatechin galate (Kristanti and Punbusayakul, 2008), and especially epigallochatechin gallate (Wang et al, 2017) which is a catechin derivate possessing eight free hydroxyl groups, thus explaining high antioxidant activity.…”

The Pharmacological Activity of Camellia sinensis (L.) Kuntze on Metabolic and Endocrine Disorders: A Systematic Review

“…In a similar work, Xu et al (2014) [38] found that pu-erh tea polysaccharides with aging for 3 years and 5 years resulted in inhibition of α-glucosidase enzyme activity with same potency as acarbose (3 years aging) and three times more potently than acarbose (5 years aging). Besides, water extract of pu-erh tea moderately inhibited sucrose activity (IC 50 = 14.4 µg/mL) and maltase (IC 50 = 11.4 µg/mL), the compound epigallo-catechin-3-O-gallate having the greatest inhibitory activity with IC 50 = 32.5 µM against sucrose and IC 50 = 1.3 µM against maltase [14]. In another study, the ethyl acetate fraction from Qingzhuan tea extracts showed significant α-glucosidase inhibitory potential (IC 50 = 0.26 µg/mL), attributing this activity to the compounds epigallocatechin gallate and epicatechin gallate.…”

“…Particularly, diabetes was the most study disease in in vitro studies (n = 16) and obesity in in vivo studies (n = 20), and clinical trials (n = 6). In several in vitro and in vivo studies, the effect of extracts and isolated compounds of Camellia sinensis on two different pathologies were studied in the same research work [9][10][11][12][13][14][15][16]. This review is divided into six sections, based on the pathologies, diabetes, hypercholesterolemia, hypertension, metabolic syndrome, obesity, and osteoporosis.…”

“…Furthermore, other studies showed that pu-erh tea and Traditional Korean Chungtaejeon, which are fermented teas, possess anti-obesity properties by ameliorating hepatic lipid metabolism and decreasing fat mass [9,92]. Studies on bioactive compounds isolated from tea extracts have shown that epigallocatechin-3-gallate is responsible of reducing body weight, fat infiltration in liver tissue, and of increasing serum lipid profiles [11,93] and teasaponin reduced body weight gain and improved gut microbiota alteration and cognitive decline in obese C57BL/6J mice [14].…”

Comparison of hypoglycemic effects of ripened pu-erh tea and raw pu-erh tea in streptozotocin-induced diabetic rats

“…Wang et al found that avanols from the water extract of pu-erh tea showed an inhibition effect on aglucosidase, suggesting potential hypoglycemic effects. 6 In the study of Deng et al, a single administration of polysaccharides from pu-erh tea decreased the postprandial blood sugar in mice, and the mechanism was due to the inhibition of a-glucosidase. 7 Huang et al reported that the 95% ethanol precipitate and ethyl acetate fractions of pu-erh tea showed remarkable inhibition against a-glycosidase in vitro.…”