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1.
A near-infrared reflectance spectroscopic (NIRS) method for the prediction of polyphenol and alkaloid compounds in the leaves of green tea [Camellia sinensis (L.) O. Kuntze] was developed. Reference measurements of the individual catechins, gallic acid, caffeine, and theobromine were performed by reversed-phase HPLC. The total polyphenols were determined according to the colorimetric Folin-Ciocalteu assay. Using the partial least-squares algorithm, very good calibration statistics were obtained for the prediction of gallic acid, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, caffeine, and theobromine (R(2) > 0.85) with standard deviation/standard error of cross-validation (SD/SECV) ratio ranging from 2.00 to 6.27. Simultaneously, the dry matter content of the tea leaves can be analyzed very precisely (R(2) = 0.94; SD/SECV = 4.12). Furthermore, it is possible to discriminate tea leaves of different age by principal component analysis on the basis of the received NIR spectra. Prediction of the total polyphenol content is performed with a lower accuracy, which might be due to the lack of specificity in the colorimetric reference method. The study demonstrates that NIRS technology can be successfully applied as a rapid method not only for breeding and cultivation purposes but also to estimate the quality and taste of green tea and to control industrial processes, for example, decaffeination.  相似文献   

2.
A simple and reliable method of high-performance liquid chromatography (HPLC) was developed for the quality control of oolong tea (the dry leaves of Camellia sinensis ): the quality control included the HPLC fingerprint and the quantitative determination of seven bioactive compounds chemicals, namely, (-)-gallocatechin, (-)-epigallocatechin, (-)-epigallocatechin gallate, caffeine, (-)-epicatechin, gallocatechin gallate, and (-)-epicatechin gallate. The developed analyses of the chemicals excelled in quantifying the chemicals in oolong tea. The chemical fingerprint of oolong tea was established using the raw materials of three main production sites in China, that is, Fujian (southern and northern parts), Taiwan, and Guangdong. The fingerprints from different cultivated sources were analyzed by hierarchical cluster analysis, similarity analysis, principal component analysis (PCA), analysis of variance (ANOVA), and discriminant analysis. The results indicated that the combination of chromatographic fingerprint and quantification analysEs could be used for the quality assessment of oolong tea and its derived products.  相似文献   

3.
Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable an epidemiological evaluation of catechins, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-catechin, (-)-epicatechin, (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg) in 8 types of black tea, 18 types of red and white wines, apple juice, grape juice, iced tea, beer, chocolate milk, and coffee. Tea infusions contained high levels of catechins (102-418 mg of total catechins/L), and tea was the only beverage that contained GC, EGC, ECg, and EGCg in addition to (+)-catechin and (-)-epicatechin. Catechin concentrations were still substantial in red wine (27-96 mg/L), but low to negligible amounts were found in white wine, commercially available fruit juices, iced tea, and chocolate milk. Catechins were absent from beer and coffee. The data reported here provide a base for the epidemiological evaluation of the effect of catechins on the risk for chronic diseases.  相似文献   

4.
The effect of polyphenolic compounds isolated from green tea (Camellia sinensis) on the production of toxic end metabolites of Porphyromonas gingivalis was investigated. Green tea polyphenols completely inhibited the production of n-butyric acid and propionic acid at a concentration of 1.0-2.0 mg/mL in general anaerobic medium (GAM). (-)-Epigallocatechin gallate (EGCg), which is a major component of tea polyphenols also inhibited the production of phenylacetic acid at 0.5 mg/mL in GAM broth. In the experiment using resting cells of P. gingivalis, phenylacetic acid was produced from l-phenylalanine and phenylpyruvic acid, but this reaction was also inhibited by EGCg, (-)-epicatechin gallate, and (-)-gallocatechin gallate. However, (+)-catechin, (+)-gallocatechin, (-)-epicatechin, and (-)-epigallocatechin did not inhibit those reactions. These results indicate that the inhibitory effect on the production of toxic end metabolites of P. gingivalis can be attributed to the presence of the galloyl moiety, which is ester-linked with the 3-OH of the catechin moiety in the polyphenolic compounds. This study shows that continuous application of tea polyphenols on a daily basis can be considered as a useful and practical method for the prevention of periodontal diseases.  相似文献   

5.
After intravenous administration of (-)-epicatechin gallate to Wistar male rats, its biliary metabolites were examined. Deconjugated forms of (-)-epicatechin gallate metabolites were prepared by beta-glucuronidase/sulfatase treatment and purified by HPLC. Five compounds were subjected to FAB-MS and NMR analyses. These metabolites were shown to be (-)-epicatechin gallate, 3'-O-methyl-(-)-epicatechin gallate, 4'-O-methyl-(-)-epicatechin gallate, 4' '-O-methyl-(-)-epicatechin gallate, and 3',4' '-di-O-methyl-(-)-epicatechin gallate. After oral administration, five major metabolites excreted in rat urine were purified in their deconjugated forms and their chemical structures identified. They were degradation products from (-)-epicatechin gallate, pyrogallol, 5-(3,4-dihydroxyphenyl)-gamma-valerolactone, 4-hydroxy-5-(3,4-dihydroxyphenyl)valeric acid, 3-(3-hydroxyphenyl)propionic acid, and m-coumaric acid. Time course analysis of the identified (-)-epicatechin gallate metabolites showed that (-)-epicatechin gallate and its conjugate appeared in the plasma with their highest levels 0.5 h after oral administration; their levels rapidly decreased, and then they disappeared by 6 h. The degradation products, mainly in their conjugated forms, emerged at 6 h, peaked at 24 h, and disappeared by 48 h. In urine samples, (-)-epicatechin gallate and its methylated metabolites were hardly detected and the degradation products began to be excreted in the 6-24 h period, peaked in the 24-48 h period, and then began to disappear. The most abundant metabolite in both the plasma and the urine was found to be the conjugated form of pyrogallol. On the basis of these results, a possible metabolic route of (-)-epicatechin gallate orally administered to the rat is proposed.  相似文献   

6.
It has been known that tea catechins, (-)-epicatechin (1), (-)-epigallocatechin (2), (-)-epicatechin gallate (3), and (-)-epigallocatechin gallate (4) are epimerized to(-)-catechin (5), (-)-gallocatechin (6), (-)-catechin gallate (7), and (-)-gallocatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats. In this study, the effect of heat-epimerized catechins on cholesterol absorption was compared with tea catechins. Both tea catechins and heat-epimerized catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized catechins were more effective than tea catechins. The effect of purified catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were more effective to precipitate cholesterol than 3 and 4, respectively. These observations strongly suggest that heat-epimerized catechins may be more hypocholesterolemic than tea catechins.  相似文献   

7.
Green tea polyphenols, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), all showed antioxidative effect in liposomes for lipid oxidation initiated in the lipid phase (antioxidant efficiency EC > EGCG > ECG > EGC) or in the aqueous phase (EC ? EGC > EGCG > ECG) as monitored by the formation of conjugated dienes. For initiation in the lipid phase, β-carotene, itself active as an antioxidant, showed antagonism with the polyphenols (EC > ECG > EGCG > EGC). The Trolox equivalent antioxidant capacity (TEAC EGC > EGCG > ECG > EC) correlates with the lowest phenol O-H bond dissociation enthalpy (BDE) as calculated by density functional theory (DFT). Surface-enhanced Raman spectroscopy (SERS) was used to assess the reducing power of the phenolic hydroxyls in corroboration with DFT calculations. For homogeneous (1:9 v/v methanol/chloroform) solution, the β-carotene radical cation reacted readily with each of the polyphenol monoanions (but not with the neutral polyphenols) with a rate approaching the diffusion limit for EC as studied by laser flash photolysis at 25 °C monitoring the radical cation at 950 nm. The rate constant did not correlate with polyphenol HOMO/LUMO energy gap (DFT calculations), and β-carotene was not regenerated by an electron transfer reaction (monitored at 500 nm). It is suggested that the β-carotene radical cation is rather reacting with the tea polyphenols through addition, as further evidenced by steady-state absorption spectroscopy and liquid chromatography-mass spectroscopy (LC-MS), in effect preventing regeneration of β-carotene as an active lipid phase antioxidant and leading to the observed antagonism.  相似文献   

8.
Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable epidemiological evaluation of these compounds, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-catechin, (-)-epicatechin, (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg) in 24 types of fruits, 27 types of vegetables and legumes, some staple foods, and processed foods commonly consumed in The Netherlands. Most fruits, chocolate, and some legumes contained catechins. Levels varied to a large extent: from 4.5 mg/kg in kiwi fruit to 610 mg/kg in black chocolate. (+)-Catechin and (-)-epicatechin were the predominant catechins; GC, EGC, and ECg were detected in some foods, but none of the foods contained EGCg. The data reported here provide a base for the epidemiological evaluation of the effect of catechins on the risk for chronic diseases.  相似文献   

9.
We have investigated the inhibitory effects of polyphenols from natural products, such as green tea, bilberry, grape, ginkgo, and apple, on rainbow trout gelatinase activities. Gelatinases from the skin, muscle, and blood of rainbow trout contained serine proteinase, metalloproteinase, and other proteinase activities as measured by gelatin zymography. The polyphenols of green tea caused the strong inhibition of some gelatinase activities when compared with those of the other products. This inhibition was quite similar to that of metalloproteinase by ethylenediaminetetraacetic acid, suggesting that the effects of green tea polyphenols on proteinase activities are specific for metalloproteinases. The major catechins of green tea polyphenols were then separated and identified by reverse-phase chromatography to be (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epicatechin. The effects of these catechins on gelatinase activities were examined; the most potent inhibitor of metalloproteinase activities was found to be EGCG. These results have indicated that green tea polyphenols including EGCG are useful for regulating metalloproteinase activities of fish meat.  相似文献   

10.
(-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin gallate (EGCg), and Trolox inhibited the decreases of apolipoprotein B-100 (apoB) and alpha-tocopherol in a radical reaction of human plasma initiated by Cu(2+). The concentrations of EC, EGC, ECg, EGCg, and Trolox for 50% inhibition (IC50) of apoB fragmentation were 39.1, 42.2, 14.6, 21.3, and 36.2 microM, respectively. Similar IC50 values were observed for alpha-tocopherol consumption, indicating the close relationship between apoB fragmentation and alpha-tocopherol consumption. These results demonstrate that tea catechins serve as an effective antioxidant in plasma and that the gallate group has a strong antioxidative activity.  相似文献   

11.
Lignocellulose prepared from sawdust was investigated for its potential application in obtaining a raw decaffeinated tea polyphenol fraction from tea extract. Tea polyphenols having gallate residues, namely, (-)epigallocatechin gallate (EGCg) and (-)epicatechin gallate (ECg), were adsorbed on the lignocellulose column, while caffeine was passed through it. Adsorbed polyphenols were eluted with 60% ethanol, and the elute was found to consist mainly of EGCg and ECg. The caffeine/EGCg ratio was 0.696 before lignocellulose column treatment, but it became 0.004 after the column treatment. These results suggest that the lignocellulose column provides a useful and convenient process of purification of tea polyphenol fraction accompanied by decaffeination.  相似文献   

12.
Phenolic compounds are responsible for major organoleptic characteristics of plant-derived food and beverages; these substances have received much attention, given that the major function of these compounds is their antioxidant ability. In the context of this study, our major aim was study the binding of several phenolic compounds such as (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, malvidin-3-glucoside, tannic acid, procyanidin B4, procyanidin B2 gallate, and procyanidin oligomers to different proteins (bovine serum albumin and human alpha-amylase) by fluorescence quenching of protein intrinsic fluorescence. From the spectra obtained, the Stern-Volmer, the apparent static, and the bimolecular quenching constants were calculated. The structure of polyphenols revealed to significantly affect the binding/quenching process; in general, the binding affinity increased with the molecular weight of polyphenol compounds and in the presence of galloyl groups. For catechin monomer and procyanidin dimer B4, the K(SV) was 14,100 and 13,800 M(-1), respectively, and for galloyl derivatives, the K(SV) was 19,500 and 21,900 M(-1), respectively. Tannic acid was shown to be the major quenching molecule for both proteins. However, comparing different proteins, the same polyphenol showed different quenching effects, which are suggested to be related to the three-dimensional structure of the proteins studied. For (+)-catechin and BSA, the K(SV) was 8700 M(-1), and with alpha-amylase, it was 14,100 M(-1); for tannic acid, the K(SV) was 10,0548 and 11,0674 M(-1), respectively. From the results obtained, besides the main binding analysis performed, we conclude that this technique is more sensitive than thought because we can detect several interactions that have not been proven by other methods, namely, nephelometry. Overall, fluorescence quenching has proven to be a very sensitive technique with many potentialities to analyze the interaction between polyphenols and proteins.  相似文献   

13.
We examined the potential antioxidant activity and the immunopharmacological activity of new epicatechin conjugates obtained by depolymerization of grape polymeric flavanols in the presence of cysteamine or cysteine and with or without gallate. The compounds studied were (-)-epicatechin (1), cysteinyl-epicatechin (2), cysteamine-epicatechin (3), (-)-epicatechin gallate (4), cysteinyl-epicatechin gallate (5), and cysteamine-epicatechin gallate (6) When incubated with an erythrocyte suspension, flavanols protected the erythrocyte membrane from hemolysis induced by 2,2'-azobis(2-amidinopropane) dihydrochloride, an azo free-radical initiator. All the epicatechin derivatives tested were more efficient as antioxidant than epicatechin. The most potent antioxidant was compound 6. The compounds were tested for their capacity to modulate IL-1beta and IL-6, which are the main cytokine factors influencing the acute phase of the inflammatory response. (-)-Epicatechin and its related compounds inhibited the production of IL-1beta and IL-6 in whole blood incubated in the presence of Escherichia coli lipopolysaccharide. The most efficient inhibitor of cytokine formation was compound 3.  相似文献   

14.
(-)-Epigallocatechin-3-gallate (EGCG), a major polyphenol of green tea, undergoes substantial biotransformation to species that includes the methylated compounds. Recent studies have demonstrated that the methylated EGCG has many biological activities. In this study, we have investigated the composition of the three O-methylated EGCG derivatives, (-)-epigallocatechin-3-O-(3-O-methyl)gallate (3' '-Me-EGCG), (-)-epigallocatechin-3-O-(4-O-methyl)gallate (4' '-Me-EGCG) and (-)-4'-methyl epigallocatechin-3-O-(4-O-methyl)gallate (4',4' '-di-Me-EGCG) in tea leaves which were picked from various species and at various seasons, ages of leaves, locations, and fermentation levels. Higher levels of 3' '-Me-EGCG and 4' '-Me-EGCG were detected in Chinshin-Kanzai (a species of Camellia sinensis) cultivated in the mountain area of Sansia, Taipei County, Taiwan. Also, these O-methylated EGCG levels were found to be higher in autumn and winter than in spring and summer. The young leaves were found to be richer in the O-methylated compounds than old leaves and the amount of O-methylated EGCG was higher in unfermented longjin green tea than in semifermented oolong tea. However, the fermented black tea and puerh tea did not contain these compounds. 4',4' '-diMe-EGCG could not be detected in either fresh tea leaves or commercial tea leaves. We also found that 3' '-Me-EGCG has a higher inhibitory effect on the nitric oxide generation and inducible nitric oxide synthase (iNOS) expression as compared with EGCG, while 4' '-Me-EGCG and 4',4' '-di-Me-EGCG were less effective.  相似文献   

15.
Theanine, caffeine, and catechins in fresh tea leaves and oolong tea were determined by using capillary electrophoresis (CE). CE separated these tea polyphenols from three other tea ingredients, namely, caffeine, theophylline, and theanine, within 8 min. The young leaves (apical bud and the two youngest leaves) were found to be richer in caffeine, (-)-epigallocatechin gallate (EGCg), and (-)-epicatechin gallate (ECg) than old leaves (from 5th to 7th leaves). On the other hand, the old leaves (from 8th to 10th leaves) contained higher levels of theanine, (-)-epigallocatechin (EGC), and (-)-epicatechin (EC). Results from a comparison of fresh young tea and oolong tea compositions indicated oolong tea contained more theanine and catechins than fresh young tea. Furthermore, it was found that the levels of theanine, EGC, and EGCg in young leaves rose markedly with the withering process. Caffeine did not markedly change. However, fully or partially fermented teas (oolong tea or pauchong tea) have a common initial step in the withering process. Fresh tea leaves or oolong tea extract (0.1%, w/v) markedly inhibited neurosphere adhesion, cell migration, and neurite outgrowth in rat neurospheres. Theanine (348 micrograms/mL) and caffeine at high concentration (50 micrograms/mL) did not inhibit neurosphere adhesion or migration activities, but EGCg at 20 micrograms/mL effectively inhibited neurosphere adhesion for 24 h. These results indicated that EGCg might affect neural stem cell survival or differentiation.  相似文献   

16.
Tea is a complex mixture containing a range of compounds from simple phenolics to complex thearubigins, many of which have well-recognized antioxidant properties. This paper describes the application of high-performance liquid chromatography-mass spectrometry (HPLC-MS(n)) methods for the rapid and routine analysis of more than 30 phenolics in tea. Green and black tea infusions were injected directly onto a reversed phase HPLC column, and the phenolics eluted using two different mobile phase gradients, one optimized to resolve catechin derivatives and the other, flavonols and theaflavins. Compounds, identified on the basis of their retention time, absorbance spectrum, and MS fragmentation pattern, included (+)-catechin, (-)-epicatechin, theaflavin and their various gallate derivatives, quercetin and kaempferol mono-, di-, and triglycosides, quinic acid esters of gallic acid and hydroxycinnamates, and the purine alkaloids, caffeine and theobromine.  相似文献   

17.
A green tea extract (GTE) was incorporated into bread as a source of tea catechins. The stability of tea catechins in the breadmaking process including unfrozen and frozen dough was studied. A method was developed for the separation and quantification of tea catechins in GTE, dough, and bread samples using a RP-HPLC system. The separation system consisted of a C18 reversed-phase column, a gradient elution system of water/methanol and formic acid, and a photodiode array UV detector. Tea catechins were detected at 275 nm. GTEs at 50, 100, and 150 mg per 100 g of flour were formulated. The results obtained showed that green tea catechins were relatively stable in dough during freezing and frozen storage at -20 degrees C for up to 9 weeks. There were no further detectable losses of tea catechins in bread during a storage of 4 days at room temperature. It was also revealed that (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) were more susceptible to degradation than (-)-epicatechin gallate (ECG) and (-)-epicatechin (EC). (-)-EGCG and (-)-ECG were normally selected as the quality indices of green tea catechins, and their retention levels in freshly baked bread were ca. 83 and 91%, respectively. One piece of bread (53 g) containing 150 mg of GTE/100 g of flour will provide 28 mg of tea catechins, which is approximately 35% of those infused from one green tea bag (2 g).  相似文献   

18.
Longan fruits contain a significant amount of polyphenols. In the present study, polyphenols were extracted from longan pericarp tissues, and then two representative polyphenols were separated and purified by polyamide column chromatography, Sephadex LH-20 column chromatography, and silica gel column chromatography. On the basis of 1H NMR, 13C NMR, and electrospray ionization mass spectrometric (ESI-MS) data, the two compounds were identified as 4-O-methylgallic acid and (-)-epicatechin, respectively. In terms of reaction with longan polyphenol oxidase (PPO), (-)-epicatechin was further identified as the PPO substrate that caused longan fruit to brown. The results of antioxidant activity showed that 4-O-methylgallic acid had higher reducing power and 2,2-diphenyl-1-picrylhydrazyl- (DPPH-), hydroxyl radical-, and superoxide radical-scavenging activities than (-)-epicatechin.  相似文献   

19.
The inhibitory effects of tea catechins, the O-methylated derivatives of (-)-epigallocatechin-3-O-gallate (EGCG), and the polyphenol extracts from tea leaves (Camellia sinensis L.) on oxazolone-induced type IV allergy in male ICR mice were investigated. Four major tea catechins and two O-methylated derivatives, (-)-epigallocatechin-3-O-(3-O-methyl)gallate (EGCG3' 'Me) and (-)-epigallocatechin-3-O-(4-O-methyl)gallate (EGCG4' 'Me), showed significant inhibitory effects on mouse type IV allergy after a percutaneous administration at a dose of 0.13 mg/ear. Among tea catechins, the compounds including galloyl moieties, such as EGCG and (-)-epicatechin-3-O-gallate (ECG), showed the strongest inhibitory activities on mouse type IV allergy. The inhibitory activities of EGCG3' 'Me and EGCG4' 'Me were higher than that of EGCG at a dose of 0.05 mg/ear. Polyphenol extract from tea leaves of Benihomare cultivar, which includes EGCG3' 'Me, strongly inhibited mouse type IV allergy after percutaneous administration in comparison with that from Yabukita cultivar, which does not include EGCG3' 'Me, at doses of 0.05 and 0.13 mg/ear. EGCG3' 'Me is thought to contribute, at least in part, to the inhibitory ability of Benihomare tea leaves on mouse type IV allergy. EGCG and the polyphenol extracts from Benihomare and Yabukita tea leaves also inhibited mouse type IV allergy by oral administration at 1 h before the sensitization and at 1 h before the challenge with oxazolone. Therefore, daily intake of tea drinks could have potential to prevent type IV allergy.  相似文献   

20.
Protection against nitric oxide toxicity by tea   总被引：2，自引：0，他引：2  
It is found that green tea and black tea are able to protect against nitric oxide (NO(*)) toxicity in several ways. Both green tea and black tea scavenge NO(*) and peroxynitrite, inhibit the excessive production of NO(*) by the inducible form of nitric oxide synthase (iNOS), and suppress the LPS-mediated induction of iNOS. The NO(*) scavenging activity of tea was less than that of red wine. The high activity found in the polyphenol fraction of black tea (BTP) could not be explained by the mixed theaflavin fraction (MTF) or catechins [epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate (EGCG)], which were tested separately. Synergistic effects between the compounds, or the presence of a potent, unidentified NO(*) scavenger, may explain the high activity of BTP. The peroxynitrite scavenging of tea was comparable to that of red wine. The main activity was found in the polyphenol fraction. MTF and the catechins were found to be potent peroxynitrite scavengers. Tea and tea components were effective inhibitors of iNOS. Of the tea components tested, only MTF had an activity higher than that of the tea powders. The polyphenol fractions of tea were much more active than the tea powders in suppressing the induction of iNOS. On the basis of its abundance and activity, EGCG was the most active inhibitor. The protective effect of tea on NO(*) toxicity is discussed in relation to the beneficial effect of flavonoid intake on the occurrence of cardiovascular heart disease.  相似文献   

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