Commercial Green Tea Research Articles

Identification of Japanese and Chinese Green Tea Cultivars by Using Simple Sequence Repeat Markers to Encourage Proper Labeling

To identify commercial Japanese monovarietal green tea and imported green tea samples, leading Japanese cultivars were fingerprinted by using six simple sequence repeat markers analyzed by a capillary sequencer. Two well-authenticated imported Chinese monovarietal green tea samples were also fingerprinted by the same markers, one of which, was Fuyun, was a clonally propagated cultivar, and the other, Jiukengzhong, was seed-propagated. At least three markers used in this study identified 16 leading Japanese cultivars and Fuyun. Although Jiukengzhong was a mixed population with diverse genotypes, some individuals had a unique allele in one simple sequence repeat marker that was not detected in the 16 leading Japanese cultivars, an additional 39 cultivars, and Fuyun. This allele was effective as a detection marker for Jiukengzhong. These results support the use of simple sequence repeat markers for the identification of Japanese monovarietal green tea and also of imported green tea made from foreign cultivars.

Selective effects of tea extract and its phenolic compounds on human peripheral blood mononuclear cell cytokine secretions

Background The effects of black tea extract (BTE) and some of its pure phenolics on human peripheral blood mononuclear cell (PBMC) cytokine secretion were examined in vitro.Materials and methods The main steps of the study included chromatographic analysis of BTE and commercial green tea extract, Polyphenon 60, determination of the total antioxidant capacity of both the extracts and their phenolics, and finally evaluation of their effects on PBMCs.Findings Four major peaks in the chromatogram of BTE belonged to caffeine, gallic acid, epigallocatechin and epigallocatechin gallate, and the latter showed the highest antioxidant capacity. While pure phenolics at the concentration of 20 mM did not significantly affect PBMC cytokine secretion, BTE and Polyphenon 60 suppressed interleukin-1β, tumor necrosis factor-α and interleukin-6. Interestingly, the secretion of interferon-γ after 24 h was slightly, but significantly, boosted by the extracts.Conclusion BTE has selective pro-inflammatory cytokine-suppressing effects on human PBMCs.

Significance of Chromatographic and Voltammetric Data for the Classification of Green Teas in Türkiye: A Principle Component Analysis Approach

Tea (Camellia sinensis) is one of the most popular beverages in Anatolia; it provides a significant source of phenolic compounds in the Turkish diet. All around Anatolia, tea traditionally is usually served black but in recent years green tea is becoming a popular alternative, mostly due to its higher content of antioxidant compounds. The growing green tea consumption resulted in the appearance of commercial green tea brands with different additives. In this study, the flavonoid content of methanol extracts of various commercial green tea samples was determined by HPLC analysis. Rutin, apigenin, luteolin, luteolin-4-glucoside, naringenin, quercetin, isoquercitrine, and quercetin-4-glucoside were studied as model bioactive flavonoid compounds successfully separated and detected. HPLC detection was performed under isocratic conditions through a C18 analytical column with methanol and 0.01 M orthophosphoric acid (pH 7) (50:50, v/v) as the mobile phase. Variable wavelength UV-Vis (230 nm), fluorescence (Ex: 250 nm, Em: 450 nm), and a programmable electrochemical detector (+ 1.30 V vs. Ag/AgCl) were employed for detection. Based on the chemometric tools (principle component analysis, PCA), the flavonoid patterns of the samples were used successfully to identify and classify the commercial brands with additives from unmodified ones. This might help to make a very easy and rapid classification simply based on rough data without focusing on detailed analysis methods. Additionally, cyclic voltammetry (CV) data of the samples was obtained and used again in PCA to identify the commercial brands. Also, based on the CV data, the samples were sorted according to their anodic oxidation potential, which is a measure of the free radical scavenging (antioxidant) capacity of the samples.

ICatechins;Alkaloids;Theanine;Chlorophyll contents of Korean and Japanese commericial green teas

This study used HPLC to analyze the contents of chlorophylls, catechins, alkaloids and theanine of commercial Korean (Uzen, Sezak, Jungzak,) and japanese green tea(Kunpu. Nichigetsu, Matu-no-midori). Chlorophyll of the japanese green tea were higher than those of the korean green tea. The content of total catechin were lower by water extracts than by ethanol extracts. Therefore total catechin contents in kunpu(l1l.41 ㎎/g)by ethanol extract were the highest. Caffeine content was the highest in Matu-no-midori(34.21 ㎎/g) for the ethanol extracts, and in Sezak(32.25 ㎎/g) for the water extract. Theanine levels of the 80% ethanol/water extracts ranged form 14.70 to 39. 95㎎/g of tea leaves and water extracts ranged from 48.68 to 55.85 ㎎/g of tea leaves. In contrast to theanine levels of the 80% ethanol extracts of tea leaves were generally similar to those of the water extracts.

Analysis of antioxidants by microchip capillary electrophoresis with chemiluminescence detection based on luminol reaction

A microchip including two micro-channels for electrophoretic flow and one micro-flow line for pumping flow was designed for the analysis of antioxidants by microchip capillary electrophoresis with a chemiluminescence detection system. The chemiluminescence reaction of luminol with hydrogen peroxide in the presence of Cu(II) catalyst was adopted in the present system, where active oxygen species, such as superoxide radical anions, generates. Nitroblue tetrazolium, superoxide dismutase, and catechin (catechin mixture from green tea) were analyzed as model analytes of antioxidants using the system. Negative peaks from baseline formed by the chemiluminescence reaction were observed based on reaction between active oxygen (superoxide radical anion) and antioxidants (analytes). The components of analytes mixture, nitroblue tetrazolium and superoxide dismutase, were well separated and detected within ca. 2 min. Catechin was also detected around 2 min, resulting in a response curve over the range of 0.1–1 mM. The amounts of catechin in the real samples of commercial green tea beverages were successfully determined.

Synergistic effect of green tea extract and probiotics on the pathogenic bacteria, Staphylococcus aureus and Streptococcus pyogenes

The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against Staphylococcus aureus and Streptococcus pyogenes (100 μg ml−1) were considerably lower than those against the probiotic strains tested (>800 μg ml−1) and Escherichia coli (800 μg ml−1). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by 24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately. These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important adjuncts to, or alternatives to, conventional antibiotic therapy.

Pharmacokinetics of Green Tea Catechins in Extract and Sustained-Release Preparations

Catechins are a major constituent of green tea. For green tea to have cancer therapeutic benefit, catechin concentrations in the range of 100 nM are required continuously until apoptosis (programmed cell death) is induced. To prolong elevated plasma and interstitial concentrations of catechins, a sustained-release formulation of green tea extract was tested and compared to a commercial green tea extract (Tegreen97®). Sustained-release formulations are usually developed in the pharmaceutical industry to slowly deliver the compound over a period of time and increase the dosing interval. Plasma and interstitial fluid (ISF) pharmacokinetics of catechins were determined following an oral dose in the rat. The sustained-release formulation profile included multiple smaller peaks of total catechins in both plasma and ISF. Interstitial fluid profiles of green tea extract indicate that higher catechins concentration and longer duration in tissue than in blood may make a sustained-release form unnecessary.

알칼리 이온수로 제조한 녹차의 품질 특성

시판되고 있는 녹차잎을 75℃에서 알칼리 이온수로 10분간 추출하여 녹차를 제조한 뒤, 물리화학적 특성을 분석하였다. 알칼리 이온수로 제조한 녹차의 총 페놀 함량, 총 플라바놀 함량과 아스코르브산 함량은 pH가 증가할수록 감소하는 경향을 보였다. Hunter 색도 L, a, b값은 pH 증가에 따라 각각 감소, 감소, 증가하는 경향을 나타내었다. 녹차의 주된 성분인 epicatechin류의 함량은 pH가 증가할수록 감소하였고, 카페인은 유의차를 나타내지 않았다. DPPH 라디칼 소거능도 pH가 증가할수록 감소하였으며, tyrosinase 억제능은 pH 8.85의 알칼리 이온수 녹차에서 가장 높게 측정되었다.

Effects of herbal products and their constituents on human cytochrome P450 2E1 activity

Ethanolic extracts from fresh Echinacea purpurea and Spilanthes acmella and dried Hydrastis canadensis were examined with regard to their ability to inhibit cytochrome P450 2E1 mediated oxidation of p-nitrophenol in vitro. In addition, individual constituents of these extracts, including alkylamides from E. purpurea and S. acmella, caffeic acid derivatives from E. purpurea, and several of the major alkaloids from H. canadensis, were tested for inhibition using the same assay. H. canadensis (goldenseal) was a strong inhibitor of the P450 2E1, and the inhibition appeared to be related to the presence of the alkaloids berberine, hydrastine and canadine in the extract. These compounds inhibited 2E1 with K I values ranging from 2.8 μM for hydrastine to 18 μM for berberine. The alkylamides present in E. purpurea and S. acmella also showed significant inhibition at concentrations as low as 25 μM, whereas the caffeic acid derivatives had no effect. Commercial green tea preparations, along with four of the individual tea catechins, were also examined and were found to have no effect on the activity of P450 2E1.

Structure−Activity Relationships of Tea Compounds against Human Cancer Cells

The content of the biologically active amino acid theanine in 15 commercial black, green, specialty, and herbal tea leaves was determined as the 2,4-dinitrophenyltheanine derivative (DNP-theanine) by a validated HPLC method. To define relative anticarcinogenic potencies of tea compounds and teas, nine green tea catechins, three black tea theaflavins, and theanine as well as aqueous and 80% ethanol/water extracts of the same tea leaves were evaluated for their ability to induce cell death in human cancer and normal cells using a tetrazolium microculture (MTT) assay. Compared to untreated controls, most catechins, theaflavins, theanine, and all tea extracts reduced the numbers of the following human cancer cell lines: breast (MCF-7), colon (HT-29), hepatoma (liver) (HepG2), and prostate (PC-3) as well as normal human liver cells (Chang). The growth of normal human lung (HEL299) cells was not inhibited. The destruction of cancer cells was also observed visually by reverse phase microscopy. Statistical analysis of the data showed that (a) the anticarcinogenic effects of tea compounds and of tea leaf extracts varied widely and were concentration dependent over the ranges from 50 to 400 microg/mL of tea compound and from 50 to 400 microg/g of tea solids; (b) the different cancer cells varied in their susceptibilities to destruction; (c) 80% ethanol/water extracts with higher levels of flavonoids determined by HPLC were in most cases more active than the corresponding water extracts; and (d) flavonoid levels of the teas did not directly correlate with anticarcinogenic activities. The findings extend related observations on the anticarcinogenic potential of tea ingredients and suggest that consumers may benefit more by drinking both green and black teas.

전자빔 조사가 녹차 품질 특성에 미치는 영향

The commercial green tea leaves were packaged with polyethylene film and irradiated by electron beam at doses of 0, 5, 10, 20, and 30 kGy. After irradiation, green teas were prepared by soaking the leaves in water (1 g/100 mL) at for 10 min, and the physicochemical characteristics of green tea were determined. Electron beam irradiation decreased total phenol contents (TPC), total flavanol contents (TFC), ascorbic acid contents (AAC). Irradiation at dose of 20 kGy decreased TPC, TFC, and AAC from 223.46, 32.50, and 6.03 mg/g to 202.88, 31.16, and 5.57 mg/g, respectively, compared with non irradiated control. Electron beam irradiation also decreased catechins, caffeine, and nitrite scavenging activity of green tea. However, the changes of overall color and radical scavenging activity of irradiated green tea were negligible.

HPLC Analysis of Catechins, Theaflavins, and Alkaloids in Commercial Teas and Green Tea Dietary Supplements: Comparison of Water and 80% Ethanol/Water Extracts

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 separated in a 70‐min single HPLC analysis: (−)‐epigallocatechin, (−)‐catechin, (+)‐epicatechin, (−)‐epigallocatechin‐3‐gallate, (−)–gallocatechin‐3‐gallate, (−)‐epicatechin‐3‐gallate, (−)‐catechin‐3‐gallate, theaflavin, theaflavin‐3‐gallate, theaflavin‐3′‐gallate, theaflavin‐3,3′‐digallate, caffeine, theobromine, and theophylline. The following ranges of concentrations of flavonoids (catechins plus theaflavins) in the tea leaves extracted with 80% ethanol were observed (in mg/g): in 32 black teas, 19.8 to 115.1; in 24 green teas, 12.3 to 136.3; in 14 specialty teas, 4.9 to 118.5; in 7 herbal teas, 0 to 46.0. Total alkaloids in all teas ranged from 0 to 32.6 mg/g. Significantly greater amounts of flavonoids were extracted from the tea leaves with aqueous ethanol than with boiled water. Levels of tea catechins in 10 capsules sold as dietary supplements were about 50 to 75% lower than the amounts listed on the labels. Catechin content of 4 commercial green tea extracts ranged from 96 to 696 mg/g. The results make it possible to maximize the extraction of tea compounds to better relate the flavonoid and alkaloid content of teas and dietary tea supplements to their health‐promoting effects.

Distribution of Catechins, Theaflavins, Caffeine, and Theobromine in 77 Teas Consumed in the United States

ABSTRACT: To help define the composition of commercial teas consumed in the United States, we have developed and validated an high-performance liquid chromatography (HPLC) method to analyze levels of catechins, theaflavins, and alkaloids in 77 commercial black, green, specialty (brown rice, white, oolong), and herbal teas extracted with hot water to simulate home use. The following 13 compounds were separated in a single analysis on an Inertsil ODS-3v column with acetonitrile/potassium dihydrogen phosphate as the mobile phase: (−)-epigallocatechin, (+)-catechin, (−)-epicatechin, (−)-epigallocatechin-3-gallate, (−)-gallocatechin-3-gallate, (−)-epicatechin-3-gallate, (−)-catechin-3-gallate, theaflavin, theaflavin-3-gallate, theaflavin-3′-gallate, theaflavin-3, 3′-digallate, caffeine, and theobromine. The data show that (1) extraction time from 3 min to 20 min did not significantly affect measured levels of tea compounds and (2) there was a wide variation in the composition of the tea compounds both within each tea category and among categories: black teas contained both theaflavins and catechins, green and white teas contained catechins and trace amounts of theaflavins, herbal teas contained very low amounts of all tea compounds. A statistical profile of the distribution of catechins, theaflavins, caffeine, and theobromine in the evaluated teas offers consumers a choice of teas containing high levels of health-promoting compounds.

Determination of green tea catechins in human plasma using liquid chromatography–electrospray ionization mass spectrometry

A method for the sensitive and specific determination of eight green tea catechins, consisting of catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin-3-gallate (CG), epicatechin-3-gallate (ECG), gallocatechin-3-gallate (GCG) and epigallocatechin-3-gallate (EGCG), in human plasma was established. For optimization of conditions for LC-ESIMS, the separation of the eight catechins was achieved chromatographically using Inertsil ODS-2 column combined with a gradient elution system of 0.1M aqueous acetic acid and 0.1M acetic acid in acetonitrile. Detection using a mass spectrometer was performed with selected ion monitoring at m/z=289 for E and EC, 305 for GC and EGC, 441 for CG and ECG, and 457 for GCG and EGCG under negative ESI. A preparative procedure, consisting of the addition of perchloric acid and acetonitrile to the plasma for deproteinizing and the subsequent addition of potassium carbonate solution to remove excess acid, was developed. In six different plasma with the eight catechins spiked at two different concentrations, the average recoveries were in the range between 72.7 and 84.1%, which resulted from the matrix effect and preparative loss, with coefficients of variance being 8.2-19.8% among individuals. The levels of the catechins in prepared plasma solutions that were kept at 5 degrees C within 24h were stable, which allows us to simply analyze many prepared plasma solutions using an autosampler overnight. When using this method to analyze the eight catechins in human plasma after oral ingestion of a commercial green tea beverage, we detected all the catechins absorbed into human blood for the first time. This also suggested that extremely small amounts of the eight catechins orally ingested may be absorbed based on each absorptive property for the catechins. The method should enable pharmacokinetic studies of green tea catechins in humans.

Catechin and Caffeine Content of Green Tea Dietary Supplements and Correlation with Antioxidant Capacity

The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. Polyphenols are antioxidants, and EGCG, due to its high levels, is widely accepted as the major antioxidant in green tea. Therefore, commercial green tea dietary supplements (GTDS) may be chemically standardized to EGCG levels and/or biologically standardized to antioxidant capacity. However, label claims on GTDS may not correlate with actual phytochemical content or antioxidant capacity nor provide information about the presence and levels of caffeine. In the current study, 19 commonly available GTDS were evaluated for catechin and caffeine content (using high-performance liquid chromatography) and for antioxidative activity [using trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays]. Product labels varied in the information provided and were inconsistent with actual phytochemical contents. Only seven of the GTDS studied made label claims of caffeine content, 11 made claims of EGCG content, and five specified total polyphenol content. Caffeine, EGCG, and total polyphenol contents in the GTDS varied from 28 to 183, 12-143, and 14-36% tablet or capsule weight, respectively. TEAC and ORAC values for GTDS ranged from 187 to 15340 and from 166 to 13690 mumol Trolox/g for tablet or capsule, respectively. The antioxidant activities for GTDS determined by TEAC and ORAC were well-correlated with each other and with the total polyphenol content. Reliable labeling information and standardized manufacturing practices, based on both chemical standardization and biological assays, are recommended for the quality control of botanical dietary supplements.

Antimicrobial Activities of Tea Catechins and Theaflavins and Tea Extracts against Bacillus cereus

We evaluated the antimicrobial activities of seven green tea catechins and four black tea theaflavins, generally referred to as flavonoids, as well as the aqueous extracts (infusions) of 36 commercial black, green, oolong, white, and herbal teas against Bacillus cereus (strain RM3190) incubated at 21°C for 3, 15, 30, and 60 min. The results obtained demonstrate that (i) (−)-gallocatechin-3-gallate, (−)-epigallocatechin-3-gallate, (−)-catechin-3-gallate, (−)-epicatechin-3-gallate, theaflavin-3, 3′-digallate, theaflavin-3′-gallate, and theaflavin-3-gallate showed antimicrobial activities at nanomolar levels; (ii) most compounds were more active than were medicinal antibiotics, such as tetracycline or vancomycin, at comparable concentrations; (iii) the bactericidal activities of the teas could be accounted for by the levels of catechins and theaflavins as determined by high-pressure liquid chromatography; (iv) freshly prepared tea infusions were more active than day-old teas; and (v) tea catechins without gallate side chains, gallic acid and the alkaloids caffeine and theobromine also present in teas, and herbal (chamomile and peppermint) teas that contain no flavonoids are all inactive. These studies extend our knowledge about the antimicrobial effects of food ingredients.

Comparative Studies on the Hypolipidemic and Growth Suppressive Effects of Oolong, Black, Pu-erh, and Green Tea Leaves in Rats

The four major commercial teas, oolong, black, pu-erh, and green teas, have been manufactured in southeast Asia. In this study, we evaluated the growth suppressive and hypolipidemic effect of these four different tea leaves by oral feeding to male Sprague-Dawley rats for 30 weeks. The results showed that the suppression of body weights of tea leaves-fed groups were in the order: oolong tea > pu-erh tea > black tea > green tea. Pu-erh tea and oolong tea could lower the levels of triglyceride more significantly than that of green tea and black tea, but pu-erh tea and green tea were more efficient than oolong tea and black tea in lowering the level of total cholesterol. In lipoprotein, 4% pu-erh tea could increase the level of HDL-C and decrease the level of LDL-C, but other teas simply decrease the levels of both. The activity of antioxidant enzyme SOD is increased in all tea-fed groups as compared to the basal diet-fed group. Finally, relative weight ratios of liver to epididylmal adipose tissue were lower in feeding oolong tea and pu-erh tea groups. On the basis of these findings, it seemed that the fully fermented pu-erh and black tea leaves and partially fermented oolong tea leaves were more effective on their growth suppressive and hypolipidemic effects as compared to the nonfermented green tea leaves.

Determination of quercetin in human plasma after ingestion of commercial canned green tea by semi‐micro HPLC with electrochemical detection Dongri Jin, Hideki Hakamata, Kouji Takahashi, Akira Kotani and Fumiyo Kusu. Biomedical Chromatography Vol. 18 Issue 9, 2004, pages 662–666

AbstractThe original article to which this Erratum refers was published in Biomedical Chromatography 18(9) 2004, 662–666.

Flavonoids and Antioxidant Capacity of Various Cabbage Genotypes at Juvenile Stage

ABSTRACT: Ten fresh cabbage genotypes (Brassica oleraceavar capitata) representing fresh‐market, processing, and storage types were evaluated for total phenols, antioxidant capacity, and flavonoids at the 3‐wk juvenile stage, at which time plants are uniform in size when grown under identical soil and environmental conditions. The genotypes studied, ‘Bobcat,’‘Fresco,’‘Little Rock,’‘Marvelon,’‘Rinda,’‘Ramada,’‘Transam,’‘Genesee,’‘Huron,’ and ‘Octoking,’ showed significant variations in concentration of phenolic phytochemicals and antioxidant capacity. Total phenols ranged from 110.2 mg gallic acid equivalents/100g in ‘Genesee’ to 153.3 mg gallic acid equivalents/100 g in ‘Bobcat’. Total antioxidant capacity varied from 108.4 to 176.1 mg vitamin C equivalents/100 g, and flavonoids from nondetectable to 2.61 mg quercetin/100 g and from 1.30 to 7.03 mgkaempferol/100 g. Apigenin, luteolin, and myricetin were not detected. Five nutritional soil supplements from agricultural and food processing sources (quer‐cetin flavonoid complex, commercial vegetable juice, crushed onion, crushed garlic, and green tea) were added to the cabbage genotype ‘Rinda’ once a week for 3 wk to assess their efficacy in increasing phenolic concentrations in cabbage leaves. Addition of the supplements generally resulted in increased levels of total phenols (97% with commercial vegetable juice), antioxidant capacity (41% with crushed onion), and quercetin plus kaempferol (110% with commercial vegetable juice) in the juvenile ‘Rinda’ plants with no significant increase with the addition of green tea. Nutritional soil supplements could provide enhanced levels of bioactive phenolic compounds as antioxidants in cabbage and therefore to consumers.

Determination of quercetin in human plasma after ingestion of commercial canned green tea by semi-micro HPLC with electrochemical detection.

Determination of quercetin in human plasma was carried out by semi-micro high-performance liquid chromatography with electrochemical detection. Peak heights for quercetin were found to be linearly related to the amount of each quercetin injected from 1.5 to 750 pg. The detection limit (signal-noise ratio, S/N = 3) of the present method for quercetin was 0.3 pg. Glucuronic and sulfate forms of quercetin in plasma were hydrolyzed enzymatically using beta-glucuronidase and sulfatase, respectively. Quercetin in plasma and the hydrolyzed solution were extracted with ethyl acetate and determined by the present method. The time courses of concentrations of quercetin in human plasma showed maxima at 1-1.5 h after ingestion of 340 mL of commercial canned green tea.