Abstract
Epigallocatechin gallate (EGCG) is a principle phenolic antioxidant found in a variety of plants, including green and black tea. The anti-allergic effect of EGCG is unknown. The purpose of this study is to investigate the effects of EGCG on compound 48/80-induced mast cell activation and passive cutaneous anaphylaxis. For this, the influences of EGCG on the compound 48/80-induced cutaneous reaction were measured in vivo and the effects of EGCG on the compound 48/80-induced mast cell activations were examined in vitro. Results are below: as 1) EGCG significantly inhibited compound 48/80-induced passive cutaneous anaphylaxis, 2) the compound 48/80-induced degranulation, calcium influx and histamine release of rat peritoneal mast cells (RPMCs) were significantly inhibited by the pretreatment with EGCG, and 3) the compound 48/80-mediated inhibition of cAMP level in RPMCs was significantly increased by the pretreatment with EGCG. These results suggested that EGCG, the most abundant polyphenol in green tea, inhibits the compound 48/80-induced mast cell activation and the increase of vascular permeability, and potentially serve as effective therapeutic tools for allergic diseases.
Highlights
Mast cells are known to play a crucial role in the development of many physiological changes during an immediate allergic response (Lantz et al, 1998)
Trypan blue exclusion test revealed that the EGCG ranging from 10 μM to 50 μM had no cytotoxicity on rat peritoneal mast cells (RPMCs) (Figure 2)
When RPMCs were incubated with EGCG, RPMCs were showed similar to that seen with the control RPMCs (Figure 3C)
Summary
Mast cells are known to play a crucial role in the development of many physiological changes during an immediate allergic response (Lantz et al, 1998). In IgE-mediated activation, a variety of biological substances (products of complement activation, neuropeptides and certain cytokines), pharmacological compounds (calcium ionophore, compound 48/80, and mellitin), and physical stimuli can elicit the release of mast cell mediators (Chai et al, 2000, 2001; Platts-Mills, 2001). These mediators cause the various symptoms of allergy including dermatitis and asthma. Most of the polyphenols in green tea are flavanols, commonly known as catechins: the major catechins in green tea are (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC), and (-)-epigallocatechin-3-gallate (EGCG) (Ahmad et al, 1998)
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