Prophylactic Effects of Purple Shoot Green Tea on Cytokine Immunomodulation through Scavenging Free Radicals and NO in LPS-Stimulated Macrophages

Abstract

Polyphenols and flavonoids from non-fermented green tea and fully-fermented black tea exhibit antioxidant abilities that function as natural health foods for daily consumption. Nonetheless, evidence regarding prophylactic effects of purple shoot tea on immunomodulation remains scarce. We compared the immunomodulatory effects of different tea processes on oxidative stress and cytokine expressions in lipopolysaccharide (LPS)-stimulated macrophages. Major constituents of four tea products, Taiwan Tea Experiment Station No.12 (TTES No. 12) black and green tea and purple shoot black and purple shoot green tea (TB, TG, PB and PG, respectively), were analyzed to explore the prophylactic effects on expressions of free radicals, nitric oxide (NO), monocyte chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in LPS-activated RAW264.7 cell models. PG contained abundant levels of total polyphenols, flavonoids, condensed tannins and proanthocyanidins (371.28 ± 3.83; 86.37 ± 1.46; 234.67 ± 10.1; and 24.81 ± 0.75 mg/g, respectively) contributing to excellent free radical scavenging potency. In both the LPS-activated inflammation model and the prophylactic model, all tea extracts suppressed NO secretion in a dose-dependent manner, especially for PG. Intriguingly, most tea extracts enhanced expressions of IL-6 in LPS-stimulated macrophages, except PG. However, all teas disrupted downstream transduction of chemoattractant MCP-1 for immune cell trafficking. In the prophylactic model, all teas inhibited inflammatory responses by attenuating expressions of IL-6 and TNF-α in a dose-dependent manner, especially for TG and PG. Our prophylactic model demonstrated PG exerts robust effects on modulating LPS-induced cytokine expressions of MCP-1, IL-6 and TNF-α through scavenging free radicals and NO. In light of the prophylactic effects on LPS-related inflammation, PG effectively scavenges free radicals to modulate cytokine cascades that could serve as a functional beverage for immunomodulation.

Advances in Purple Tea Research: Chemical Compositions, Anthocyanin Synthesis and Regulation, Processing, and Health Benefits

“…An experimental model of macrophage stimulation by lipopolysaccharide (LPS) showed strong inhibition of LPS-induced expression of cytokines monocyte chemoattractant protein-1 (MCP-1), IL-6, and TNF-α by PG through scavenging of free radicals and NO in a prophylactic model. Given the preventive effect of PG on lipopolysaccharide (LPS)-related inflammation, habitual consumption of PG can effectively scavenge reactive oxygen species (ROS) and, thus, regulate cytokine cascades, which can be used as a functional food for immunomodulation [85]. De Moura C. et al maximized the extraction of bioactive compounds and antioxidant activity from green tea derived from purple leaves and optimized the extraction conditions.…”

Versatile Effects of GABA Oolong Tea on Improvements in Diastolic Blood Pressure, Alpha Brain Waves, and Quality of Life

“…The amounts of total phenolics, catechins, and free amino acids in the various tea extracts were determined by high-performance liquid chromatography (HPLC) and colorimetric assay, as reported previously [13]. The total contents of phenolic compounds and catechins in teas were then determined by using a standard curve prepared with gallic acid and expressed in terms of milligrams of gallic acid equivalents (GAE) per gram of extract solid.…”

“…In our prior study, the identification of eight major catechins was determined by HPLC according to retention times obtained from authentic standards run under identical conditions [13]. The major catechins in all tea leaves include (+)-catechin (C), gallocatechin (GC), (−)-epigallocatechin (EGC), (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), and (−)-epigallocatechin gallate (EGCG), with EGCG and EGC being the most abundant in the tea products in this study (Table 3).…”

Versatile Effects of GABA Oolong Tea on the Improvement of Diastolic Blood Pressure, Alpha-Brain Wave and Quality of Life

“…The amounts of total phenolics and catechins in the various tea extracts were determined by high-performance liquid chromatography (HPLC) and colorimetric assay as reported previously [13]. The total content of phenolic compounds and catechins teas were then determined by a standard curve prepared with gallic acid and expressed in terms of milligrams of gallic acid equivalents (GAE) per gram of extract solid.…”