Abstract
The beneficial effects of the tea beverage are well-known and mainly attributed to polyphenols which, however, have poor bioaccessibility and bioavailability. The purpose of the present study was the evaluation of colon bioaccessibility and antioxidant activity of tea polyphenolic extract. An 80% methanolic extract (v/v) of tea polyphenols was obtained from green (GT), white (WT) and black tea (BT). Simulated gastrointestinal (GI) digestion was performed on acid-resistant capsules containing tea polyphenolic extract. The main tea polyphenols were monitored by HPLC-diode-array detector (DAD) method; in addition, Total Phenol Content (TPC) and antioxidant activity were evaluated. After GI digestion, the bioaccessibility in the colon stage was significantly increased compared to the duodenal stage for both tea polyphenols and TPC. Similarly, the antioxidant activity in the colon stage was significantly higher than that in the duodenal stage. Reasonably, these results could be attributable in vivo to the activity of gut microbiota, which is able to metabolize these compounds, generating metabolites with a greater antioxidant activity. Our results may guide the comprehension of the colon digestion of polyphenols, suggesting that, although poorly absorbed in the duodenum, they can exert their antioxidant and anti-inflammatory activities in the lower gut, resulting in a novel strategy for the management of gut-related inflammatory diseases.
Highlights
Tea is historically recognized as the typical beverage consumed in the oriental tradition, used for more than 5000 years in diet and folk medicine, especially in Asian countries [1]
Tea polyphenol bioaccessibility was evaluated by using a simulated GI digestion
In order to obtain an overview of the bioaccessibility of the tea polyphenols in the various stages of the GI digestion, we firstly evaluated the Total Phenol Content (TPC) by Folin-Ciocalteu assay
Summary
Tea is historically recognized as the typical beverage consumed in the oriental tradition, used for more than 5000 years in diet and folk medicine, especially in Asian countries [1]. Its consumption has increased all over the world, becoming one of the most popular beverages [2] This spreading is mainly due to the widely accepted beneficial effects of tea on human health, which have been attributed to polyphenols [3], the largest group of phytochemical compounds which includes about 8000 different structures [4]. These compounds are largely contained in several plant-based foods, such as fruits, nuts, tea, coffee and cocoa [5,6], suggesting the pivotal role of their consumption in prevention and management of several diseases, including type 2 diabetes mellitus (T2DM) [6] and cardiovascular disease (CVD) [7]. Suggests that polyphenols, in addition to their well-known antioxidant activity, exert a number of other beneficial effects on Nutrients 2018, 10, 1711; doi:10.3390/nu10111711 www.mdpi.com/journal/nutrients
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