Table 1.
Immune activities, content and recovery from human plasma of major green tea polyphenol, epigallocatechin gallate (EGCG), and black tea polyphenol, theaflavin (TF).
| Tea Bioactives | Content in tea infusion (mg g−1) | Immune activities | Concentration in plasma (peak time) | References |
|---|---|---|---|---|
| Polyphenols | ||||
| EGCG | 113.6 ± 5.85a | Enhances interferon secretion; enhances NK cell activity; regulates NF-κB, RIG-I dependent signal transduction; Inhibits ROS activity; regulates apoptosis of neutrophils; regulates Th1/Th2 polarization | 55 nM (2 h)b 37 nM♂–42 nM♀ (2 h)c |
(25) (26) (27) |
| TF | 0.70 ± 0.08a | Down regulate NF-κB,ICAM-1,VCAM-1; inhibits pro-inflammatory cytokines, e.g., IL-6, regulates neutrophils; inhibits ROS activity | 8 nM♂–16 nM♀ (45 min)d | (28) |
| Alkaloids | ||||
| CAF | Green tea (GT):34.92 ± 0.93a; Black tea (BT):35.13 ± 3.02a |
Regulates neutrophils; suppress monocyte chemotaxis; inhibits TNF-α; neuroprotective effect | 30.89 µM (60 min)e | (29, 30) |
| TBR | GT:0.16 ± 0.03a BT:0.38 ± 0.10a |
Vasodilator; muscle relaxant | 23.17 µM (120 min)e | |
| TPI | GT:1.54 ± 0.02a BT:1.61 ± 0.05a |
Vasodilator; anti-inflammatory in bronchial airways | 23.17 µM (120 min)e |
Tea infusion was prepared with 1 gram of green or black tea in 100 ml of boiled distilled water.
Subject followed overnight fasting before taking 500 ml of green tea. Blood samples were collected at 0, 0.5, 1, 2, 4, 6, 8, and 24-h time interval in reference to drinking tea.
Subjects were given 300 mg of EGCG (Teavigo® capsules, 94% EGCG) with 100 ml of water. Blood sample was collected before the intervention and at 30, 60, 90, 120, 180, 240, and 360 min after the ingestion. The European Food Safety Agency (EFSA) based on clinical trial has recommended intake of EGCG/day to less than 800 mg.
Volunteers consumed 700 mg TF mixed in 150 ml hot water. Symbol designation: ♂, male; ♀, women volunteers.
Subjects followed 4 h fasting before taking 270 mg of caffeine (CAF) and 250 mg of each theobromine (TBR) and theophylline (TPI). Blood sample was collected before the intervention and at 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, till 10 h after methylxanthine dose.