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The autoxidation of tea catechins by dissolved oxygen proceeds in pH-neutral aqueous solutions, and the major products are oligomers. However, the reaction mechanisms have not been clarified. In this study, the autoxidation of (−)-epigallocatechin-3- O -gallate (1) was examined. The autoxidation with β-cyclodextrin, which includes the A-ring of 1 , significantly suppressed oligomer production and increased the formation of products generated by the oxidative cleavage of the B-ring, indicating the participation of the A-ring in the oligomerization. Further, the autoxidation of 1 in the presence of phloroglucinol, a mimic of the catechin A-ring, yielded products via the nucleophilic addition of phloroglucinol to the B-ring quinone of 1. These results indicated that the oxidative A–B ring couplings accounted for the major oligomerization mechanism. • Autoxidation of epigallocatechin gallate (1) yields oligomers as major products. • The oligomerization was suppressed by presence of β-cyclodextrin. • Autoxidation of 1 with phloroglucinol, a mimic of catechin A-ring, yielded coupling products. • The products were produced by addition of phloroglucinol to B-ring quinone of 1. • The key mechanism of oligomerization is coupling between B-ring quinones and A-rings. [ABSTRACT FROM AUTHOR]

Most teas, including white tea, are produced from tender shoots containing both leaf and stem. However, the effect of the stem on white tea quality remains unclear, especially during withering, an essential process. Therefore, this study investigated the withering-induced changes in the leaves and stems of Camellia sinensis cv. 'Fudingdabai' by multi-group analysis. During withering, the levels of catechin and theobromine (i.e., major flavor-related compounds) decreased slightly, mainly in the leaves. The abundance of some proteinaceous amino acids related to fresh taste increased in stems due to increased protein hydrolysis. In addition, changes in biosynthetic pathways caused a decrease in theanine (a major non-proteinaceous amino acid) and an increase in gamma-aminobutyric acid in stems. Terpenes, mainly in the stems, were partially affected by withering. Phenylacetaldehyde, a major contributor to white tea aroma, increased mainly in the stems. These findings reflect the positive contribution of the stem to white tea quality. • Catechin and theobromine decreased during withering, which mainly occurred in leaf. • Some protein hydrolysis-derived amino acid contents increased in withering stems. • Theanine synthesis decreased and GABA synthesis increased in withering stems. • Stem is vital for bud-leaf type white tea quality, because of its abundant terpenes. • Withering increased the aroma-related phenylacetaldehyde content mainly in the stem. [ABSTRACT FROM AUTHOR]

Shaking constitutes a pivotal technique for enhancing black tea quality; nevertheless, its impact on the transformation mechanism of non-volatile metabolites (NVMs) in black tea remains obscure. The present study aimed to investigate the impact of shaking-withering methods (SWM) and traditional-withering methods (TWM) on black tea quality and NVMs conversion. A total of 57 NVMs and 14 objective quantitative indicators were obtained. SWM enhanced sweetness and umami taste, as well as appearance and liquor color brightness of black tea. Eight key differential NVMs were identified by multivariate statistical and dose over threshold value analysis. Metabolic pathway and evolution law analysis revealed that SWM enhanced the oxidation of catechins and flavonol glycosides, promoted the decarboxylation of glutamic acid, then facilitated the formation of theaflavin-3,3′-digallate, finally enhanced the taste and color quality of black tea. This study offers theoretical guidance and technical support for the targeted processing of high-quality black tea. [Display omitted] • Addition of shaking in withering led to sweet taste and bright color in black tea • Eight differential non-volatile metabolites were identified among withering methods • Catechins and flavonoids metabolisms were crucial for tea flavor through shaking • Shaking reduced ester types of catechins and flavonoid glycosides contents • Shaking increased theaflavin-3′-gallate and theaflavin-3,3′-digallate contents [ABSTRACT FROM AUTHOR]

• Steamed green tea had higher concentrations of sucrose and free amino acids. • Steaming retained more compounds associated with sweet and fresh tastes, such as free amino acids. • Frying produced more compounds with bitter tastes, such as catechin. Fixation is a crucial step in green tea processing that can impact quality. In this study, we explored the differences in the chemical components of steamed and fried green teas made from the same batch of fresh tea leaves using different fixing methods. Results showed that concentrations of sucrose and free amino acids were significantly higher in steamed green tea. Abundances of 12 compounds including purine nucleoside, pyrimidine nucleoside derivatives, and catechins were higher in fried green tea, while 34 compounds such as amino acids and their derivatives, benzofurans and flavonoids were higher in steamed green tea. Thus, steaming retained more compounds associated with sweet and fresh tastes, such as free amino acids, while frying produced more compounds with bitter tastes, such as catechin. This might explain why steamed green tea is mellower than fried tea. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first electroanalytical method for the estimation of total phenolic and alkaloid contents in tea samples. • The method utilized catechin and caffeine oxidation signals. • A boron-doped diamond electrode was employed. • Through the analysis of black and green tea samples, the applicability was demonstrated. This work outlines the simultaneous estimation of the total phenolic and alkaloid contents in the tea samples by using catechin (C) and caffeine (CAF) oxidation signals at a non-modified boron-doped diamond (BDD) electrode. Two irreversible oxidation peaks, about + 1.03 (for C) and + 1.45 V (for CAF) vs Ag/AgCl in acetate buffer solution at pH 4.7, were seen in the cyclic voltammetric profile of the binary mixtures of C and CAF. In optimal conditions and utilizing the square-wave mode, the BDD electrode allows for simultaneous quantification of C and CAF within the concentration ranges of 5.0–100.0 µg mL−1 (1.72 × 10-5 − 3.45 × 10-3 mol/L) and 1.0–50.0 µg mL−1 (5.15 × 10-6 − 2.57 × 10-4 mol/L) respectively. The corresponding detection limits are 1.22 µg mL−1 (4.21 × 10-6 mol/L) for C and 0.11 µg mL−1 (5.66 × 10-7 mol/L) for CAF. Other phenolic compounds (like tannic acid, gallic acid, epicatechin, and epigallocatechin gallate) and other alkaloids (theophylline and theobromine) present in tea samples were examined for selectivity assessment. Ultimately, the applicability of the proposed approach was demonstrated by estimating the total phenolic and alkaloid contents in the black and green tea samples, expressed as C and CAF equivalents. The results obtained were contrasted against those acquired using UV–Vis spectrometry. [ABSTRACT FROM AUTHOR]

• Widely targeted metabolomics reveals chemical periodic change in whole process. • 568 Differential metabolites (VIP > 1.0, P < 0.05, FC > 1.50 or < 0.67) selected. • Anaerobic fermentation is regarded as critical process for the quality formation. • 7 Amino acids, 4 phenolic acids, 6 flavonoids and their glycosides accumulated. • N -, O -methylation, hydrolyzation, glycosylation, oxidation involved in fermentation. Yunnan pickled tea is produced from fresh tea-leaves through fixation, rolling, anaerobic fermentation and sun-drying. In this study, widely targeted metabolomics using UHPLC-QQQ-MS/MS and HPLC analysis were carried out to elaborate its quality formation during the whole process. Results confirmed the contribution of preliminary treatments and anaerobic fermentation to the quality formation. A total of 568 differential metabolites (VIP > 1.0, P < 0.05, FC > 1.50 or < 0.67) were screened through OPLS-DA. (-)-Epigallocatechin and (-)-epicatechin significantly (P < 0.05) increased from the hydrolyzation of ester catechins, such as (-)-epigallocatechin gallate and (-)-epicatechin gallate in anaerobic fermentation. Additionally, the anaerobic fermentation promoted vast accumulations of seven essential amino acids, four phenolic acids, three flavones and flavone glycosides, pelargonidin and pelargonidin glycosides, flavonoids and flavonoid glycosides (i.e. kaempferol, quercetin, taxifolin, apigenin, myricetin, luteolin and their glycosides) through relevant N -methylation, O -methylation, hydrolyzation, glycosylation and oxidation. [ABSTRACT FROM AUTHOR]

Highlights • EGCG esterification with stearic acid was partial and yielded a mixture of esters. • NaCl (1.6–8 %wt) was added to a 0.8 %wt PGPR-0.25 %wt BC-1 %wt WPI double emulsion. • Droplet size, viscosity and stability of emulsions depended on salt concentration. • Storage reduced EGCG and esterified EGCG encapsulation in the 4.3 %wt NaCl emulsion. • Neither of the catechins made the emulsion more resistant to oxidation. Abstract Double (W1/O/W2) emulsions of 0.8 %wt PGPR-0.25 %wt BC-1 %wt WPI and NaCl (1.6–8 %wt) were characterized regarding their microstructure, droplet size, stability and viscosity. Droplet size increased with salt concentration. Salt addition at 4–5% wt limited the instability rate. Viscosity increased with NaCl concentration up to 4.8 %wt, above which it decreased. Eventually, the emulsion with 4.3 %wt salt was selected for catechin incorporation. In order to increase its antioxidant activity, Epigallocatechin Gallate (EGCG) was esterified with stearic acid. Esterification was partial and a mixture of esters was obtained. Both EGCG and its esterified derivatives were incorporated in the double emulsion. Storage reduced encapsulation. Encapsulation efficiency was reduced in the order "EGCG in the W1 phase" emulsion > "EGCG in the O phase" emulsion > "esterified EGCG in the W1 phase" emulsion. The presence of both catechins did not have a great effect on retarding emulsion oxidation. [ABSTRACT FROM AUTHOR]

Interaction of metal, especially iron ions with flavanols is considered as an important feature of these compounds and is believed to contribute to their both antioxidant and prooxidant properties. The aim of this study was to examine how Fe 2+ binding to form a 4:1 (flavanol:Fe 2+ ) mixtures affects the antioxidant properties of flavanols. ABTS ∗ scavenging, protection against fluorescence bleaching induced by AAPH and hypochlorite, protection against lipid peroxidation and protection against hypochlorite-induced hemolysis demonstrated that flavonol-Fe 2+ mixtures retain antioxidant properties, although, in most cases, they are lower with respect to the flavanols alone. No superoxide dismutase-like or catalase-like activity of the mixtures was revealed. [ABSTRACT FROM AUTHOR]

(−)-Epicatechin (EC) and (−)-epigallocatechin gallate (EGCG) (0.001–5%) were found to reduce N ε -(carboxymethyl) lysine (CML) concentrations by up to 0.80 ± 0.11 mM and 0.85 ± 0.07 mM, respectively, as quantified by HPLC-MS during heating at 80 °C and 100 °C in a glucose-lysine model system at pH 5, 7 and 8, which mimic different food processing conditions. With the addition of 1 mM EC, the free CML concentration in coconut milk was reduced to 5.7 ± 0.1 μg/mL (∼2.8 × 10 −2  mM), which was significantly lower than that in unheated coconut milk (6.1 ± 0.2 μg/mL (∼3.0 × 10 −2  mM), p < 0.05) indicating that the free CML may be eliminated by the addition of EC in coconut milk. Products of EC/EGCG quinones reacted with CML by a Michael addition or Schiff base addition in model systems were tentatively identified by UPLC-ESI-MS/MS. [ABSTRACT FROM AUTHOR]

Catechins are the major bioactive compounds existing in tea leaves ( Camellia sinensis ). Dehydroascorbic acid is (DHAA) a reactive dicarbonyl species and previous studies have demonstrated that catechins could effectively trap DHAA to form ascorbyl adducts of catechins, especially epigallocatechin gallate (EGCG). Since catechins in the aqueous solution are unstable due to their structural features, ascorbic acid (AA) is usually added to bottled tea beverages to protect catechins. However, whether ascorbyl adducts of catechins are formed in bottled tea beverages remains unclear. In this study, formation of ascorbyl adducts of EGCG increased along with increased incubation time when EGCG and AA were dissolved in the aqueous solution. Next, 6C-DHAA-EGCG and 8C-DHAA-EGCG were detected in both green tea and oolong tea beverages, and their concentrations ranged from 0.23 to 1.95 µM and 0.28 to 1.97 µM, respectively. Furthermore, an 8C-ascorbyl adduct derived from gallocatechin gallate was also found in some tea beverages. [ABSTRACT FROM AUTHOR]

Bitterness and astringency are two important quality attributes of green tea infusion, and catechins are the main contributor to the bitterness and astringency. The aim of this work was to quantitatively analyse the bitterness and astringency of green tea infusion according to the concentrations of catechins. The concentration–taste curves of catechins showed a pattern that fit the cubic functions, and their R 2 values were higher than 0.956. The bitterness of green tea was highly correlated with the concentrations of (−)-epigallocatechin gallate and (−)-epicatechin gallate (ECG) ( R 2  = 0.7769, p  < 0.01), and the astringency ( R 2  = 0.7878, p  < 0.01) was highly correlated with the concentrations of ECG and flavonol glycosides (myricetin 3- O -galactoside and quercetin-3- O -rutinoside). Taste interactions between different catechins and between catechins and other substances were determined. These results may enhance the understanding of tea chemistry for improving the taste of products from green tea. [ABSTRACT FROM AUTHOR]

This is the first study to investigate the extent of reduction in acrylamide formation during baking with the addition of (−)-epigallocatechin gallate (EGCG) extracted from green tea, and to determine whether EGCG influences the texture and colour attributes of bread, or interacts with other ingredients. EGCG powders were added to white bread formulations at the concentrations of 3.3, 6.6 and 9.9 g·kg −1 . The amount of acrylamide in the bread was analysed using liquid chromatography-mass spectrometry. EGCG addition significantly reduced the acrylamide formation by 37% compared to the control and decreased the moisture content of the bread by 6%. It did not affect its texture attribute, but increased the lightness and the yellowness and decreased the redness of bread crust (with contrasting results in crumb). It also decreased granule size and porosity. In conclusion, EGCG fortification is a feasible method to decrease acrylamide formation in baked bread. [ABSTRACT FROM AUTHOR]

Major green tea catechin, epigallocatechin-3-gallate (EGCG), binds non-covalently to numerous dietary proteins, including beta-lactoglobulin of cow’s milk. The effects of glycation of proteins via Maillard reaction on the binding capacity for polyphenols and the antiradical properties of the formed complexes have not been studied previously. Binding constant of BLG glycated by milk sugar lactose to EGCG was measured by the method of fluorophore quenching. Binding of EGCG was confirmed by CD and FTIR. The antioxidative properties of the complexes were examined by measuring ABTS radical scavenging capacity, superoxide anion scavenging capacity and total reducing power assay. Glycation of BLG does not significantly influence the binding constant of EGCG for the protein. Conformational changes were observed for both native and glycated BLG upon complexation with EGCG. Masking effect of polyphenol complexation on the antioxidative potential of the protein was of the similar degree for both glycated BLG and native BLG. [ABSTRACT FROM AUTHOR]

[Display omitted] • IDA was composed of phenylboronic acids, pyrocatechol violet, and alizarin red S. • TP, TC, and EGCG were key quality indicators of black tea fermentation. • SVM model achieved accurate qualitative evaluation of fermentation degrees. • SCARS-SVR model achieved accurate prediction of TP, TC, and EGCG. • In-situ quality monitoring of black tea fermentation was realized. Herein, a new indicator-displacement array (IDA) sensor was developed for the quality evaluation of black tea fermentation. On the principle of the reversible covalent binding of phenylboronic acid and catechol, phenylboronic acids were selected as acceptors for targeted binding to polyphenols. Pyrocatechol violet and alizarin red S were used as indicators of the reaction. The IDA sensors have sensitive differential responses to fermented tea samples, achieving an assessment of the fermentation degree with accuracies of 80.39–88.00% by support vector machine (SVM). In addition, the key polyphenol components of the fermentation process were accurately predicted by the IDA and SVM regression with ratio of prediction to deviation values of 1.55–1.72, 2.03–2.21, and 2.03–2.08 for total polyphenols, total catechins, and epigallocatechin-3-O-gallate, respectively. In conclusion, the developed IDA sensor is capable of the in-situ quality monitoring of black tea fermentation, with the advantages being cost-effectiveness, sensitivity, and rapidity. [ABSTRACT FROM AUTHOR]

• EWP–polyphenol–US and EWP–polyphenol–WB were formed via C N and C S bonds. • CF, CA, EGCG, CT, or QE were conjugated to EWP primarily through Cys, His, and Trp. • Cross-linking sites detected by LC–MS/MS was consistent with amino acid results. • Different induction system led to different cross-linking sites of EWP with polyphenol. • Polyphenols have the strongest reactivity with ovalbumin, ovotransferrin and ovomucoid. There has been strong interest in developing effective strategies to inhibit lipid oxidation in emulsified food products such as ω-3 fatty acids, carotenoids, or carotenoids. Dual-functional protein emulsifiers with antioxidant and emulsifying properties are in the spotlight. Our aim was to investigate the influence of caffeic acid (CF), chlorogenic acid (CA) with a C3-C6 structure, epigallocatechin gallate (EGCG), catechin (CT), and quercetin (QE) with a C6-C3-C6 structure on the cross-linking sites and structure of egg white protein (EWP)–polyphenol conjugates fabricated by the free radical method under conventional water bath (WB) and ultrasound assisted (US) conditions. Results of structural analysis and liquid chromatography–tandem mass spectrometry indicated that the structure of EWP–polyphenol conjugates and the cross-linking sites of the two are influenced by the polyphenol structure and the free radical system. Our study provides important information about the mechanism of research into proteins and polyphenols using the free radical method. [ABSTRACT FROM AUTHOR]

HPLC analysis of samples from four major fermentation procedures of Jing-Wei Fu brick tea showed that the level of major tea catechins epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) dropped increasingly to about 1/3 in the final product. Phytochemical study of the final product led to the discovery of four new B-ring fission metabolites of catechins (BRFCs) Fuzhuanin C–F ( 1 – 4 ) together with three known BRFCs ( 5 – 7 ), six known catechins ( 8 – 13 ), five simple phenols ( 14 – 18 ), seven flavones and flavone glycosides ( 19 – 25 ), two alkaloids ( 26 , 27 ), three triterpenoids ( 28 – 30 ) and one steroid ( 31 ). The structures were elucidated by spectroscopic methods including 1D and 2D NMR, LC–HR-ESI-MS, IR, and CD spectra. Five compounds ( 16 – 18 , 28 , 29 ) were reported for the first time in tea. Possible pathways for the degradation of major tea catechins and the generation of BRFCs were also provided. [ABSTRACT FROM AUTHOR]

Highlights: [•] Green tea antioxidants were efficiently trapped within liposomes in cheese. [•] Encapsulation efficiency of green tea antioxidants within liposomes was high. [•] Adding green tea catechins elevated the phase transition of liposomes to >50°C. [ABSTRACT FROM AUTHOR]

Highlights: [•] Application of SPE and LLE for sample clean-up and enrichment of EGCG. [•] A stability and purity-indicating analysis protocol for EGCG in nutraceutical preparations. [•] The use of gallic acid as an internal standard to overcome the scarcity of EGCG standard. [•] A validated, stability-indicating TLC densitometric assay for analysis of EGCG. [ABSTRACT FROM AUTHOR]

Highlights: [•] The association of tea polyphenols (EGCG) with casein micelles were quantified. [•] The presence of EGCG affected the primary stage of renneting. [•] The presence of EGCG hindered the formation of a casein micelles network. [•] Above saturation concentrations, gelation, as measured by rheology, did not occur. [ABSTRACT FROM AUTHOR]

Highlights: [•] A partially purified cranberry procyanidins (PCP) was prepared. [•] PCP contained 77.2% (w/w) polymers with degree of polymerization above ten. [•] Flavan-3-ols depolymerized PCP into A-type and B-type oligomers. [•] Using EGCG as a chain breaker resulted in oligomers with EGCG as a terminal unit. [•] The yield of B-type oligomers was higher than that of A-type oligomers. [ABSTRACT FROM AUTHOR]

• UPLC-Q-TOF/MS was developed for LC-MS metabolomics analysis in tea of Xinyang Region. • PCA, HCA and OPLS-DA could completely divide those teas into green and white tea. • 110 Relevant metabolites conduced to the identification of production season. • The Prolonged withering convert catechins and phenolic acids into theaflavins. • Kaempferol and taxifolin might contribute to DPPH scavenging ability of white tea. Contents of 20 bioactive compounds in 12 teas produced in Xinyang Region were determined by high performance liquid chromatography. Ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometry was developed for untargeted metabolomics analysis. Antioxidant activities were measured by 4 various assays. Those teas could be completely divided into green and white tea through principal component analysis, hierarchical cluster analysis and orthonormal partial least squares-discriminant analysis (R2Y = 0.996 and Q2 = 0.982, respectively). The prolonged withering generated 472 differentiated metabolites between white and green tea, prompted significant decreases (variable importance in the projection > 1.0, p-value < 0.05 and fold change > 1.50) of most catechins and 8 phenolic acids to form 4 theaflavins, and benefited for the accumulation of 17 flavonoids and flavonoid glycosides, 8 flavanone and their derivatives, 20 free amino acids, 12 sugars and 1 purine alkaloid. Additionally, kaempferol and taxifolin contributed to 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability of white tea. [ABSTRACT FROM AUTHOR]

Abstract: Japanese post-fermented teas are produced by a combination of aerobic and anaerobic microbial fermentation of the leaves of tea plant. Recently, it was revealed that tea products contain characteristic polyphenols identical to the tea catechin metabolites produced by mammalian intestinal bacteria, such as (2S)-1-(3′,4′,5′-trihydroxyphenyl)-3-(2″,4″,6″-trihydroxyphenyl)-propan-2-ol (EGC-M1). In the present study, degradation of epigallocatechin-3-O-gallate (EGCg) and epigallocatechin (EGC) with acetone powder prepared from Japanese post-fermented tea was examined. Under aerobic conditions, EGCg was hydrolysed to EGC and gallic acid, which were further converted to gallocatechin (GC) and pyrogallol, respectively. Under anaerobic conditions, EGCg was hydrolysed to EGC, which was further metabolised to GC, EGC-M1 and (4R)-5-(3,4,5-trihydroxyphenyl)-4-hydroxypentanoic acid (EGC-M2). Gallic acid was degraded to pyrogallol and then further decomposed. Anaerobic treatment of EGC with the acetone powder yielded EGC-M1, EGC-M2, (4R)-5-(3,4,5-trihydroxyphenyl)-γ-valerolactone, and (4R)-5-(3,4 -dihydroxyphenyl)-γ-valerolactone. Furthermore, similar anaerobic treatment of rutin and hesperidin yielded 3,4-dihydroxyphenylacetic acid and 3-(3,4-dihydroxyphenyl)propanoic acid, respectively. [Copyright &y& Elsevier]

Abstract: This study showed the relationship between tea leaf age, bud and first two leaves, and shade levels, on the relative concentrations of six major compounds of tea leaf, namely l-theanine, caffeine, and the major tea catechins; (−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin (EC), and (−)-epicatechin gallate (ECG), all of which are reported to have positive effects on human health, as well as at the ferric reducing antioxidant power of bud and leaf extracts. The concentration of l-theanine and caffeine decreased as leaf age increased moving from bud to first and then second leaf, while the concentration of the four catechins increased from the bud to first and second leaves. In most cases this increase was generally relatively small but in the case of EGC it was 7 to 10-fold. Certain chemical components of freshly picked, minimally processed and essentially unoxidised tea may potentially be used as markers for age, quality, authenticity and area of growth. [Copyright &y& Elsevier]

Abstract: Catechins [(−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG)] were analysed by HPLC using an ODS column, an electrochemical detector (0.75V vs. Ag/AgCl) and an eluting solvent composed of water containing buffer (84% v/v), acetonitrile (12% v/v) and ethylacetate (4% v/v) in the presence of metal ions (Cu2+, Fe2+ and Fe3+). HPLC peaks were affected by metal ions: the peak intensities of ECG and EGCG decreased, but the peak intensities of EC and EGC were not affected seriously. Fe2+ most markedly decreased the peak intensities of EGCG. EDTA was added to mask metal ions and an optimum condition was proposed. The effects of the metal ions on HPLC analysis are discussed from the viewpoints of metal complex formation with catechins and oxidation of catechins on the basis of ultraviolet–visible (UV–vis) spectrophotometry, electrospray ionisation mass spectrometry (ESI-MS) and cyclic voltammetry (CV). [Copyright &y& Elsevier]

Abstract: Green tea (Camellia sinensis) is one of the most widely consumed beverages in the world. The cancer chemopreventive qualities of green tea have been well documented. Epigallocatechin gallate (EGCG) is often described as the most potently chemopreventive green tea catechin; however, the low bioavailability of EGCG is a limiting factor for its biological effect. Thus, the aim of this work was to test the chemopreventive potential of green tea extract and EGCG after tannase-mediated hydrolysis. The results showed that the biotransformed compounds retained most of the beneficial properties of the original compounds, and some beneficial properties were improved in the biotransformed compounds. Biotransformation of EGCG decreased its toxicity without affecting its antiproliferative effects. Furthermore, human cells gene expression profiling showed that the biotransformed compounds modulated the expression of several genes related to carcinogenesis. These results demonstrate the benefits of the biotechnological modification of natural food molecules, allowing the improvement of the nutraceutical potential of a beverage as green tea. [Copyright &y& Elsevier]

Abstract: The variations in the contents of catechins and purine alkaloids in relation to the chlorophyll contents in albino tea cultivar ‘Anji baicha’ and normal cultivar ‘Longjing 43’, grown in Anji and Guilin, were determined. The results showed that, compared to ‘Anji baicha’, ‘Longjing 43’ had significantly higher (−)-epigallocatechin (EGC), (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), theobromine and caffeine contents in Anji, and significantly higher (+)-catechin (C), ECG and caffeine contents in Guilin. ‘Anji baicha’ only had C content significantly higher than ‘Longjing 43’ in Anji. Correlation analysis indicated that C, EGC and (−)-epigallocatechin gallate (EGCG) were significantly and negatively correlated with chlorophyll contents, suggesting that chlorophylls might play vital roles in the regulation of catechin biosynthesis. Moreover, no significant correlation was observed between purine alkaloids and chlorophylls, indicating that the biosynthesis of purine alkaloids might be affected by genotypic factors other than chlorophyll biosynthesis. [Copyright &y& Elsevier]