flavan-3-ol and epicatechin-gallate

Plant defense inducers (PDIs) are booming and attractive protection agents designed to immunostimulate the plant to reduce subsequent pathogen colonization. The structure-PDI activity relationships of four flavan-3-ols: Epicatechin (EC), Epigallocatechin (EGC), Epicatechin gallate (ECG), Epigallocatechin gallate (EGCG) and Gallotannic acid (GTA) were investigated in both whole plant and suspension cell systems. ECG, EGCG, and GTA displayed elicitor activities. Their infiltration into tobacco leaves induced hypersensitive reaction-like lesions with topical scopoletin and PR-target transcript accumulations. On the contrary, EC and EGC infiltrations fail to trigger the biochemical changes in tobacco tissues. The tobacco BY-2 cells challenged with ECG, EGCG, or GTA led to alkalinization of the BY-2 extracellular medium while EC and EGC did not trigger any pH variation. This work provides evidence that the esterified gallate pattern is as an essential flavonoid entity to induce plant defense reactions in tobacco. The phytoprotective properties of the esterified gallate-free EC and the esterified gallate-rich GTA were evaluated on the tobacco/

Topics: Catechin; Flavonoids; Molecular Structure; Nicotiana; Phytophthora; Plant Diseases; Plant Leaves

Three subtypes of white tea, Silver Needle (SN), White Peony (WP), and Shou Mei (SM), differ in their taste, aroma, bioactivity, and commercial value. Here, a metabolomics investigation on the chemical compositions combining taste equivalent-quantification and dose-over-threshold (DoT) determination on the taste qualities were applied to comprehensively characterize the white tea subtypes for the first time. Significant differences in the contents of catechins, dimeric catechins, amino acids, phenolic acids, flavonol/flavone glycosides, and aroma precursors were observed among these 3 white teas. Metabolite content comparison and partial least-squares (PLS) analysis suggest that theanine, aspartic acid, asparagine, and AMP were positively correlated with the umami taste in white tea, and flavan-3-ols, theasinensins, procyanidin B3, and theobromine had positive correlations with higher bitterness and astringency tastes. In addition, puckering astringent (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and theogallin, bitter-tasting caffeine, and the mouth-drying/velvety-like astringent γ-aminobutyric acid (GABA) were identified as key taste compounds of white tea infusion by absolute quantification and DoT factor calculations. This work provided systematic and comprehensive knowledge on the chemical components, taste qualities, and sensory active metabolites for the subtypes of white tea.

Topics: Amino Acids; Astringents; Benzopyrans; Biflavonoids; Caffeine; Catechin; Flavones; Flavonoids; Flavonols; Gallic Acid; Glycosides; Hydroxybenzoates; Metabolomics; Odorants; Phenols; Plant Extracts; Polyphenols; Proanthocyanidins; Quinic Acid; Taste; Tea

Many studies have shown that flavan-3-ols inhibit mammalian alpha-amylases but the published IC

Topics: alpha-Amylases; Amylose; Animals; Catechin; Digestion; Flavonoids; Hydrolysis; Inhibitory Concentration 50; Models, Molecular; Oligosaccharides; Starch; Swine; Tea

Interactions between polyphenols and macromolecules may impact polyphenol stability and bioavailability from foods. The impact of milk on tea flavan-3-ol stability to thermal treatment was investigated. Single strength (36.2 protein per L), quarter strength (9.0 g protein per L) milk, and control model beverages were incubated with epigallocatechin gallate and green tea extract at 62 or 37 °C for 180 min. Intact flavan-3-ols and select auto-oxidation products [theasinesins (THSNs) and P-2 dimers] were quantified by LC-MS. Generally, greater polyphenol to protein ratios increased first order degradation rates, consequently decreasing formation of oxidation products. The presence of galloyl and hydroxy moieties was associated with higher stability of monomeric flavan-3-ols with increasing protein concentrations suggesting potential for protein affinity to stabilise flavan-3-ols to thermal treatment. Absence of these moieties led to no observable improvements in stability. These results suggest that protein interactions may be useful in stabilising flavan-3-ols through thermal processing.

Topics: Animals; Beverages; Catechin; Dietary Proteins; Flavonoids; Food Handling; Milk; Polyphenols; Tea

Data from intervention studies suggest a beneficial effect of flavanols on vascular health. However, insufficient data on their intake have delayed the assessment of their health benefits. The aim of this study was to estimate intake of flavanols and their main sources among people living in Germany.. Data from diet history interviews of the German National Nutrition Survey II for 15,371 people across Germany aged 14-80 years were analyzed. The FLAVIOLA Flavanol Food Composition Database was compiled using the latest US Department of Agriculture and Phenol-Explorer Databases and expanded to include recipes and retention factors.. Mean intake of total flavanols, flavan-3-ol monomers, proanthocyanidins (PA), and theaflavins in Germany was 386, 120, 196, and 70 mg/day, respectively. Women had higher intakes of total flavanols (399 mg/day) than men (372 mg/day) in all age groups, with the exception of the elderly. Similar results were observed for monomers (108 mg/day for men, 131 mg/day for women) and PA (190 mg/day; 203 mg/day), although intake of theaflavins was higher in men (74 mg/day; 66 mg/day). There was an age gradient with an increase in total flavanols, monomers, and theaflavins across the age groups. The major contributor of total flavanols in all subjects was pome fruits (27%) followed by black tea (25%).. This study demonstrated age- and sex-related variations in the intake and sources of dietary flavanols in Germany. The current analysis will provide a valuable tool in clarifying and confirming the potential health benefits of flavanols.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Biflavonoids; Catechin; Diet; Female; Flavonoids; Fruit; Germany; Humans; Male; Middle Aged; Nutrition Policy; Nutrition Surveys; Nutritional Status; Proanthocyanidins; Tea

Ten healthy human subjects consumed 500 mL of Choladi green tea, containing 648 mumol of flavan-3-ols after which plasma and urine were collected over a 24 h period and analysed by HPLC-MS. Plasma contained a total of ten metabolites, in the form of O-methylated, sulphated and glucuronide conjugates of (epi)catechin and (epi)gallocatechin, with 29-126 nM peak plasma concentrations (C(max)) occurring 1.6-2.3 h after ingestion, indicative of absorption in the small intestine. Plasma also contained unmetabolised (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate with respective C(max) values of 55 and 25 nM. Urine excreted 0-24 h after consumption of green tea contained 15 metabolites of (epi)catechin and (epi)gallocatechin, but (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate were not detected. Overall flavan-3-ol metabolite excretion was equivalent to 8.1% of intake, however, urinary (epi)gallocatechin metabolites corresponded to 11.4% of (epi)gallocatechin ingestion while (epi)catechin metabolites were detected in amounts equivalent to 28.5% of (epi)catechin intake. These findings imply that (epi)catechins are highly bioavailable, being absorbed and excreted to a much greater extent than most other flavonoids. It is also evident that flavan-3-ol metabolites are rapidly turned over in the circulatory system and as a consequence C(max) values are not an accurate quantitative indicator of the extent to which absorption occurs.

Topics: Catechin; Chromatography, High Pressure Liquid; Flavonoids; Humans; Intestinal Absorption; Spectrometry, Mass, Electrospray Ionization; Tea

In the present study, we investigated the free radical scavenging effects of green tea extract and green tea tannin mixture and its components using a nitric oxide (NO) and superoxide (O(2)(-)) generating system in vitro. Green tea extract showed direct scavenging activity against NO and O(2)(-) and green tea tannin mixture, at the same concentration, showed high scavenging activity. Comparison of the activities of seven pure compounds isolated from green tea tannin mixture showed that (-)-epigallocatechin 3-O-gallate (EGCg), (-)-gallocatechin 3-O-gallate (GCg) and (-)-epicatechin 3-O-gallate (ECg) had higher scavenging activities than (-)-epigallocatechin (EGC), (+)-gallocatechin (GC), (-)-epicatechin (EC) and (+)-catechin (C), showing the importance of the structure of flavan-3-ol linked to gallic acid for this activity. Among the gallate-free tannins, EGC and GC were more effective O(2)(-) scavengers than EC and C, indicating the O-trihydroxy structure in the B ring is an important determinant of such activity. However, this structure did not affect the NO scavenging activity. These findings confirm that green tea tannin has excellent antioxidant properties, which may be involved in the beneficial effect of this compound.

Topics: Catechin; Dose-Response Relationship, Drug; Flavonoids; Free Radical Scavengers; In Vitro Techniques; Nitric Oxide; Oxidants; Oxidation-Reduction; Structure-Activity Relationship; Superoxides; Tannins; Tea