ABSTRACT: To help meet the needs of consumers, producers of dietary tea supplements, and researchers for information on health-promoting tea compounds, we compared the following conditions for the extraction of tea leaves and green tea-containing dietary supplements: 80% ethanol/water at 60 ◦C for 15 min and boiled water for 5 min. The following 7 catechins, 4 theaflavins, and 3 alkaloids were ...

The reductive effect of pectin on tea catechin astringency was investigated by using a taste sensor system and (1)H-NMR spectroscopy. The sensor analysis revealed that the astringency of gallate-type catechins (EGCg and ECg) was reduced by the addition of pectin, whereas that of non-gallate-type catechins (EGC and EC) hardly changed. Changes in the (1)H-NMR chemical shifts of the catechins and ...

It has been reported that inhibition of fatty-acid synthase (FAS) is selectively cytotoxic to human cancer cells. Considerable interest has developed in identifying novel inhibitors of this enzyme complex. Our previous work showed that green tea (-)-epigallocatechin gallate can inhibit FAS in vitro. To elucidate the structure-activity relationship of the inhibitory effects of tea polyphenols, w...

While flavonoids can reportedly protect against cardiac ischemia-reperfusion injury, the relative effectiveness of different flavonoids and the mechanisms involved are unclear. We compared protection by different flavonoids using rat embryonic ventricular H9c2 cells subjected to simulated ischemia-reperfusion (IR) and to tert-butyl hydroperoxide (t-buOOH). Characterization of the IR model showe...

Epigallocatechin gallate (EGCG) is the most abundant component of green tea catechins and has strong physiological activities. In this study, two novel EGCG glycosides (EGCG-G1 and EGCG-G2) were chemoselectively synthesized by a chemical modification strategy. Each of these EGCG glycosides underwent structure identification, and the structures were assigned as follows: epigallocatechin gallate-...

A free radical scavenging activity guided fractionation of the polar extract from roots of Limonium brasiliense (Plumbaginaceae) led to the isolation of five active compounds including: myricetin 3-O-alpha-rhamnopyranoside (1), (-)-epigallocatechin 3-O-gallate (2), (-)-epigallocatechin (3), (+)-gallocatechin (4) and gallic acid (5). These and other chemical constituents are reported for the fir...

Tea contains a variety of bioactive compounds. In this study, we show that two O-methylated catechins, (-)-epigallocatechin-3-O-(3-O-methyl) gallate and (-)-epigallocatechin-3-O-(4-O-methyl) gallate, inhibit in vivo mast cell-dependent allergic reactions more potently than their nonmethylated form, (-)-epigallocatechin-3-O-gallate. Consistent with this, these O-methylated catechins inhibit IgE/...

meta]loproteinases (MMPs), probably including MMP-2 and MMP-9, which may be involyed in tumor cell inyasion and metastasis. Theafiayin and theaflavin digallate also inhibited MMPs from the cu]ture inedium of these tumor cells, as did (-)-epigallocatechin gallate. These results suggest that theaffayin, theaffayin digallate, and (-)-epigallecatechin gallate inhibit umor cell inyasien by inhibitin...

The optical sensor for "tea catechins" was built by immobilizing 2,2'-(1,4-phenylenedivinylene)bis-8-hydroxyquinoline (PBHQ) on TiO₂ nanoparticles (NPs). The sensor worked by "indophenol blue" dye formation on PBHQ-immobilized TiO₂ NPs as a result of p-aminophenol (PAP) autoxidation with dissolved O₂ at pH 10. Among quercetin, rutin, naringenin, naringin, gallic acid, caffeic acid, ferulic acid...