guanosine-triphosphate and epicatechin-gallate

Health benefits of green tea polyphenols (GTPs) have been reported in many animal models, but human studies are inconclusive. This is partly due to a lack of biomarkers representing green tea consumption. In this study, GTP components and metabolites were analyzed in plasma and urine samples collected from a phase II intervention trial carried out in 124 healthy adults who received 500- or 1000-mg GTPs or placebo for 3 months. A significant dose-dependent elevation was found for (-)-epicatechin-3-gallate (ECG) (p<0.001, trend test) and (-)-epigallocatechin-3-gallate (EGCG) (p<0.05, trend test) concentrations in plasma at both 1-month and 3-months after intervention with GTPs. No significant increase of (-)-epicatechin (EC) or (-)-epigallocatechin (EGC) was observed in plasma after GTP intervention. A mixed-effects model indicated significant effects of dose (EGCG) and dose by time interaction (ECG), but not for EC and EGC. Analysis of phase 2 metabolic conjugates revealed a predominance of free GTPs in plasma, up to 85% for EGCG, while a majority of GTPs in urine were sulfated and glucuronidated conjugates (up to 100% for EC and 89% for EGC). These results suggest that plasma ECG and EGCG concentrations are reliable biomarkers for green tea consumption at the population level.

Topics: Adult; Biomarkers; Catechin; Dose-Response Relationship, Drug; Female; Flavonoids; Guanosine Triphosphate; Humans; Male; Middle Aged; Phenols; Polyphenols; Reproducibility of Results; Tea

Green tea polyphenols (GTPs) are found to be potent inhibitors of amyloid fibril formation. We report the effective inhibitory property of (-)-epicatechin gallate (ECG) during the alkali-salt induced fibrillogenesis of hen egg white lysozyme (HEWL) at 37 °C. Spectroscopic techniques such as fluorescence, circular dichroism and microscopic images show that (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) show moderate inhibition of fibrillation with ECG as the most potent polyphenol. Aromatic interactions, hydrophobic interactions, the radical scavenging activity and autoxidation of polyphenols are likely to be the major reasons for ECG being the most effective inhibitor.

Topics: Alkalies; Animals; Benzothiazoles; Catechin; Chickens; Circular Dichroism; Guanosine Triphosphate; Hydrogen-Ion Concentration; Kinetics; Microscopy, Fluorescence; Muramidase; Nephelometry and Turbidimetry; Protein Structure, Secondary; Salts; Thiazoles; Time Factors; Tryptophan