Epigallocatechin-3-gallate(EGCG),a prominent plant-based catechin predominantly derived from Camellia sinensis and widely available on the market as a health supplement,has garnered significant attention for its poten...Epigallocatechin-3-gallate(EGCG),a prominent plant-based catechin predominantly derived from Camellia sinensis and widely available on the market as a health supplement,has garnered significant attention for its potential therapeutic benefits,particularly in the context of type 2 diabetes mellitus(T2DM).This review explores the multifaceted role of EGCG in addressing the“ominous octet”—the 8 core pathophysiological defects associated with T2DM.The literature search was carried out using key terms“EGCG”OR“epigallocatechin-3-gallate”OR“epigallocatechin gallate”AND“diabetes”OR“insulin resistance”OR“hyperglycemia”in the PubMed and Scopus databases.The search was constrained to articles published between January 2018 and April 2024,focusing on the document type.Full-text articles published in English and relevant to EGCG that featured a single active ingredient,included clearly explained diabetes relief mechanism,and included ominous octet aspects were included in the final review.The outcomes of the included studies were reviewed and categorized based on 8 core pathophysiological defects,collectively referred to as the ominous octet in T2DM.This review concludes that EGCG is a potent hypoglycemic agent that has beneficial effects against the ominous octet in addition to its pharmacological activities in modulating gut microbiota dysbiosis,carbohydrate digestion and metabolism,glucose transporter-mediated intestinal glucose-uptake,endothelial dysfunction,and renal damage that are significantly associated with pathogenesis of T2DM.This extensive scientific evidence suggests that EGCG may offer a novel approach to traditional antidiabetic therapies,potentially improving glycemic control and mitigating complications associated with T2DM.The inhibitory effects of EGCG on sodium-glucose transport proteins and their role in reducing renal glucose reabsorption remain unexplored,highlighting a significant research gap.Future research should also aim to broaden the scope by investigating the “egregious eleven,”which comprise a more comprehensive range of diabetic pathophysiological features.This review underscores the therapeutic promise of EGCG for managing T2DM and encourages ongoing research to fully elucidate its clinical applications.展开更多
DNA methylation plays important roles in regulating gene expression during development.However,little is known about the influence of DNA methylation on secondary metabolism during leaf development in the tea plant(Ca...DNA methylation plays important roles in regulating gene expression during development.However,little is known about the influence of DNA methylation on secondary metabolism during leaf development in the tea plant(Camellia sinensis).In this study,we combined the methylome,transcriptome,and metabolome to investigate the dynamic changes in DNA methylation and its potential regulatory roles in secondary metabolite biosynthesis.In this study,the level of genomic DNA methylation increased as leaf development progressed from tender to old leaf.It additionally exhibited a similar distribution across the genomic background at the two distinct developmental stages studied.Notably,integrated analysis of transcriptomic and methylomic data showed that DNA hypermethylation primarily occurred in genes of the phenylpropanoid,flavonoid,and terpenoid biosynthesis pathways.The effect of methylation on transcription of these secondary metabolite biosynthesis genes was dependent on the location of methylation(i.e.,in the promoter,gene or intergenic regions)and the sequence context(i.e.,CpG,CHG,or CHH).Changes in the content of catechins and terpenoids were consistent with the changes in gene transcription and the methylation state of structural genes,such as serine carboxypeptidase-like acyltransferases 1A(SCPL1A),leucoanthocyanidin reductase(LAR),and nerolidol synthase(NES).Our study provides valuable information for dissecting the effects of DNA methylation on regulation of genes involved in secondary metabolism during tea leaf development.展开更多
This study provides different opinion for exploring the mechanism of catechin(CAT)relieving nonalcoholic steatohepatitis(NASH),it is more innovative to explore from the perspective of intestinal microorganism.Through ...This study provides different opinion for exploring the mechanism of catechin(CAT)relieving nonalcoholic steatohepatitis(NASH),it is more innovative to explore from the perspective of intestinal microorganism.Through in vitro fermentation experiments,CAT could improve the abundance of Enterococcus,and Enterococcus faecalis(EF)accounts for the vast majority of Enterococcus in human gut.The experimental results in vivo showed that EF group and CAT+EF group could reduce the body weight,liver index and epididymal fat index of NASH mice,and improve the changes of serum and liver indexes.Hematoxylin-eosin staining observation showed that these two groups have greatly improved the fatty degeneration,balloon degeneration and necrotic focus caused by NASH.The alleviation of CAT+EF group was more obvious.Results of targeted metabonomics showed that CAT could promote EF to produce more methyl palmitate(C_(16:0)),which plays a great role in relieving NASH.Our results indicated that EF could alleviate NASH and CAT+EF group had better alleviation may due to more production of methyl palmitate(C_(16:0))by EF.This study provides a new idea for CAT to alleviate NASH.展开更多
The catechin Epigallocatechin-3-O-Gallate (EGCG) which is found in of Green Tea extracts (GTE), displays a variety of microbicidal properties. It is largely believed that EGCG inhibits the growth of cariogenic and per...The catechin Epigallocatechin-3-O-Gallate (EGCG) which is found in of Green Tea extracts (GTE), displays a variety of microbicidal properties. It is largely believed that EGCG inhibits the growth of cariogenic and periodontopathic bacteria. Objective: In this paper we compared the inhibitory activity of EGCG and a commercial GTE on the growth of Veillonella parvula. Chlorhexidine was used as positive control. Methodology: V. parvula ATCC 10790 and a clinical isolate obtained from a periodontal disease patient were cultured in the presence of EGCG or a commercial GTE, and the measurements of bacterial growth inhibition were compared to the values obtained with 0.12 and 0.2% chlorhexidine. Results: Chlorhexidine inhibited bacterial growth, however in contrast to a previous report, neither EGCG nor the GTE showed any effect on bacterial growth. Conclusions: The data show and confirm that chlorhexidine is a growth inhibitor of V. parvula while EGCG and GTE do not display such effect.展开更多
Objective:To discuss the effect of catechins on myocardial injury and inflammatory factors in rats with coronary heart disease under PI3K/Akt/eNOS signaling pathway.Methods:A total of 50 healthy adult pathogen-free(SP...Objective:To discuss the effect of catechins on myocardial injury and inflammatory factors in rats with coronary heart disease under PI3K/Akt/eNOS signaling pathway.Methods:A total of 50 healthy adult pathogen-free(SPF)-grade SD rats were divided into five groups by random number table method.Except for the blank group,the other four groups were fed with high fat to construct a rat model of coronary artery disease.After the model was successfully constructed,the blank group and the model group were given saline by gavage,the positive group was given 25 mg/kg aspirin by gavage,the low-dose group was given 20 mg/kg catechin by gavage,and the high-dose group was given 60 mg/kg catechin by gavage.The expression levels of PI3K/Akt/eNOS signaling pathway-related proteins,myocardial injury markers,myocardial infarction and myocardial inflammatory factors were observed and compared in the five groups.Results:Overall,there were significant differences in the expression levels of PI3K,p-Akt/Akt,and p-eNOS/eNOS in the five groups of rats(P<0.05);there were significant differences in the expression levels of CK-MB and c Tn I in the five groups of rats(P<0.05);there were significant differences in ischemic area,infarct area,and myocardial infarction range in the four groups of rats,except for the blank group(P<0.05);there were significant differences in the expression levels of IL-1β,IL-18,TNF-α,and ET-1 in the five groups of rats(P<0.05).Conclusion:Catechins can reduce the severity of myocardial injury,reduce the range of myocardial infarction,and reduce myocardial inflammation in rats with coronary heart disease by up-regulating expression level of PI3K/Akt/eNOS signaling pathway-related proteins.Compared with aspirin,high-dose catechins have a more prominent protective effect on the myocardium of rats with coronary heart disease.展开更多
[Objective] This study aimed to analyze the difference in the contents of gallic acid and catechins of tea resources from Yunnan Province. [Method] By using high performance liquid chromatography （HPLC）, the content...[Objective] This study aimed to analyze the difference in the contents of gallic acid and catechins of tea resources from Yunnan Province. [Method] By using high performance liquid chromatography （HPLC）, the contents of gallic acid （GA）, catechins （C）, epicatechin （EC）, epigallocatechin （EGC）, epicatechin gallate （ECG） and epigallocatechin gallate （EGCG） of 121 tea germplasms from the China National Germplasm Tea Repositories （CNGTR） at the Tea Research Institute of Yunnan Academy of Agricultural Sciences （TRIYAAS） were measured. [Result] The content of GA ranged from 0.210% to 1.902%, with an average of 0.834%, explaining rela- tively low GA content among tea germplasms. The content of C ranged from 0.069% to 8.865%, with an average of 1.916%. The content of EC ranged from 0.126% to 2.865%, with an average of 1.112%. The content of EGC ranged from 0.00% to 3.709%, with an average of 0.954%. The content of ECG ranged from 0.739% to 8.957%, with an average of 4.063%. The content of EGCG ranged from 0.819% to 11.77%, with an average of 5.939%. The content of total C ranged from 6.354% to 22.654%, with an average of 14.042%. [Conclusion] There was relatively big difference of catechin contents among different tea resources, indicating that there was plentiful biodiversity of Yunnan tea germplasms. At the same time, three tea germplasms with high epigallocatechin gallate content （≥10%） was selected preliminarily, which would provide important materials for breeding tea cultivars with high EGCG content in the future.展开更多
The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the ...The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the hair dyestuff. Four kinds of hair colouring techniques using Cat were examined and each of their dyeability was compared in order to improve it. The first dyeing method is dyeing hair by the redissolved catechinone, which is preliminarily obtained by the oxidation of Cat (Redissolution Dyeing Method). The second one is dyeing hair in the dye solution just after the dye being formed by the enzymatic reaction (Sequential Dyeing Method). The third one is dyeing hair in solution containing Cat and the dyeing process is accompanied by the oxidation of Cat (Simultaneous Oxidation Dyeing Method). The fourth one is two-step dyeing that the hair immersed in Cat solution at the first step and then it is oxidised enzymatically to colour at the second step (Post-Oxidation Dyeing Method). The hair is dyed pale yellow by Redissolution Method, deeper yellowish brown by Sequential and Simultaneous Oxidation Dyeing Method and slightly reddish brown by Post-Oxidation Method with Cat. The order of their dyeability is the Simultaneous Oxidation ≈ Post-Oxidation > Sequential > Redissolution Dyeing Method at 30°C. The dyeability of Redissolution Method increases with an increase in dyeing temperature (T) between 20°C - 60°C. In Simultaneous Oxidation Method, the T increment also provides higher dyeability, and the colour of dyed hair becomes duller over 50°C. The Post-Oxidation Method shows higher dyeability at the lower oxidation temperature (20 °C - 40°C).展开更多
A molecular imprinted polymer（MIP） was prepared with quereetin as the template and methaerylie acid（MAA） as the functional monomer. Aeetonitrile and methanol were used as the porogen with ethylene glycol dimethaer...A molecular imprinted polymer（MIP） was prepared with quereetin as the template and methaerylie acid（MAA） as the functional monomer. Aeetonitrile and methanol were used as the porogen with ethylene glycol dimethaerylate （EGDMA） as the erosslinker and 2,2＇-azobis （ isobutyronitrile ） （ AIBN ） as the initiator. The experimental parameters of the equilibrium isotherms were estimated via linear and nonlinear regression analyses. The linear equadon as the functions of the adsorption concentration of the single compound in its solution and the competitive adsorption of the single compound in its mixed compounds solution was then expressed, and the adsorption equilibrium data were correlated to Langmuir and Freundlich isotherm models. The mixture compounds show competitive adsorption on the specific binding sites of quereetin-MIP. Furthermore, the competitive Langmnir isotherms were applied to the mixture compounds. The adsorption concentrations of quercetin, （＋）eatechin（＋C）, and （-）epieateehin（EC） on the quercetin molecular imprinted polymer were compared. The quercetin-imprinted polymer shows extraordinarily higher adsorption ability for quercetin than for the two eateehin compounds that were also assessed.展开更多
Hair colouring was carried out by using catechinone prepared from (+)-catechin by enzymatic or chemical oxidation reaction. The difference of dyeability between the catechinone produced by enzymatic reaction (EC) and ...Hair colouring was carried out by using catechinone prepared from (+)-catechin by enzymatic or chemical oxidation reaction. The difference of dyeability between the catechinone produced by enzymatic reaction (EC) and that produced by chemical reaction (CC) was studied changing the dyeing condition such as dye concentration, dyeing temperature, pH or the sort and concentration of salts. The colour of the hair dyed by EC or CC at 30°C is yellowish or reddish brown, respectively. The colour of the hair dyed by EC and CC is deeper at a higher dye concentration and at a higher temperature. Hair is dyed deepest by EC or CC at the solution pH = 6.04 or 5.45, respectively. The dyeability is increased by adding NaCl (≤4 M) or CaCl2 (≤1 M), while it is decreased by adding AlCl3. The colour fastness of the dyed hair to washing or ultraviolet light is high enough for practical use. Furthermore, it was found that colourants are obtained from tea extracts which contain catechin derivatives. Hair is dyed reddish brown by the colourants.展开更多
Catechin and epicatechin are two isomeric flavonoids. Despite the vital properties highlighted by numerous scientific studies, very little data is available on the intrinsic reactivity of these compounds. To provide m...Catechin and epicatechin are two isomeric flavonoids. Despite the vital properties highlighted by numerous scientific studies, very little data is available on the intrinsic reactivity of these compounds. To provide more details on the stability and reactivity of catechin and epicatechin, this study is performed by means of theoretical calculation methods. For this purpose, geometry optimizations and frequency calculations at the B3LYP/6-31 + G (d, p) level of theory has been carried out and Natural Bond Orbital (NBO) analysis and VEDA (Vibrational Energy Distribution Analysis). The geometric and energy parameters and NBO analysis show that catechin appears more stable than epicatechin. The hydroxyl group position on the ring C of the catechol structure represents a factor that influences this relative stability. The global and local reactivity parameters reveal that epicatechin becomes more reactive than catechin. They indicate that their hydroxyl groups correspond to their most receptive sites. Fukui indices, VEDA and acidity study establish that O28–H29 remains the most reactive.展开更多
A novel colourant for hair dyeing was prepared by an enzymatic reaction with (+)-catechin and its characteristics as a hair dyestuff were studied. The study is aimed at inventing the hair dyestuff that is human- and e...A novel colourant for hair dyeing was prepared by an enzymatic reaction with (+)-catechin and its characteristics as a hair dyestuff were studied. The study is aimed at inventing the hair dyestuff that is human- and eco-friendly. One potentially powerful dyestuff was obtained from (+)-catechin treated with tyrosinase after screening experiments using biobased materials. The obtained reddish orange colourant, 4-(3,4-dihydro-3α,5,7-trihydroxy-2H-1-benzopyran-2α-yl) 1,2-benzoquinone named “catechinone”, shows enough dyeability for decolourised white hair. Catechinone does not cause erythema or oedema on skin of rabbits. The colour is controlled by the addition of other biobased materials and a variety of colours of dyed hair are acquired. The fastness to light or washing for hair dyed by catechinone is high enough for practical use.展开更多
Catechinone hair dyestuff was produced chemically from (+)-catechin by the oxidation with O2 in basic water/alcohol mixed solution. The effects of reaction conditions such as basicity, sorts of added base, temperature...Catechinone hair dyestuff was produced chemically from (+)-catechin by the oxidation with O2 in basic water/alcohol mixed solution. The effects of reaction conditions such as basicity, sorts of added base, temperature, alcohol molar fraction of solvent and sorts of added alcohols on the catechinone formation were studied in order to increase the efficiency of the dyestuff production. The amount of obtained catechinone increases with increasing basicity of the reaction solution. The dyestuff is obtained by adding monoethanol amine, diethanol amine, triethanol amine, l-arginine, Na2CO3, K2CO3, Na3PO4 or NaOH into the solution as a base and the most preferable base is monoethanol amine. The optimum temperature for the production in water/ethanol solution is 30°C. It was found that water-soluble alcohols such as methanol, ethanol, 2-propanol, 1-propanol and tert-butyl alcohol are available for preparing the dyestuff. The optimum alcohol molar fraction of the mixed solvent used for the dye formation is 0.45 for methanol, 0.25 for ethanol and 0.20 for 2-propanol, 0.15 for 1-propanol and 0.10 for tert-butyl alcohol. The amount of the obtained dyestuff reaches a maximum at 1) 0.35 and 0.59, 2) 0.35 or 3) 0.35 mol·kg¨1 of the concentration of (+)-catechin for the 1) water/methanol, 2) water/ethanol or 3) water/1-propanol system, respectively.展开更多
Objective:To identify the bioactive compounds in catechins isolation and its components from green tea GMB-4 clone.Methods:Green tea GMB-4 clones were extracted with distilled water at 90C.Samples were eluted into the...Objective:To identify the bioactive compounds in catechins isolation and its components from green tea GMB-4 clone.Methods:Green tea GMB-4 clones were extracted with distilled water at 90C.Samples were eluted into the column with 10%ethanol.Subsequently,the column was eluted with95%ethanol and evaporated separately.Green tea extract was identified by thin layer chromatography.Catechins were separated by the stationary phase in column chromatography using polyamide with 10%ethanol eluent and 95%ethanol.The results of isolations were analyzed by high performance liquid chromatographic(HPLC)and LCMS/MS.Analysis of catechins by HPLC was done by external standard.Results:Fraction from 10%ethanol showed that four major peaks at retention time of1.663,2.367,2.950 and 4.890,indicated the presence of four catechins components including catechin,epicatechins,gallocatechin and epigallocatechin.Whereas,fraction from 95%ethanol showed two main peaks at retention time of 5.167 and 9.82,which indicated the presence of epigallocatechin gallate(EGCG)and epicatechin gallate(ECG).EGCG(m/z 459),epigallocatechin(m/z 307),ECG(m/z 443),and epicatechin(m/z 291)were isolated and separated successfully using HPLC and LC-MS/MS.Conclusions:The HPLC and LC-MS/MS methods were successfully tuned for the qualitative analysis of green tea extract with EGCG and ECG.Four major catechins were separated and identified by LC-MS/MS,such as EGCG,epigallocatechin,ECG and epicatechin.The result of HPLC analysis showed that EGCG and ECG were main components from catechins isolation of green tea GMB-4 clone.展开更多
The over-activated microglial cells induce neuroinflammation which has the main role in neurological disorders.The over-activated microglia can disturb neuronal function by releasing inflammatory mediators leading to ...The over-activated microglial cells induce neuroinflammation which has the main role in neurological disorders.The over-activated microglia can disturb neuronal function by releasing inflammatory mediators leading to neuronal dysfunctions and death.Thus,inhibition of over-activated microglia may be an effective therapeutic approach for modulating neuroinflammation.Experimental studies have indicated anti-neuroinflammatory effects of flavonoids such as green tea catechins.The current research was aimed to review the effect of green tea catechins in inhibiting microglial cells,inflammatory cascades,and subsequent neurological diseases.展开更多
Tea is one of the most popular beverages, consumed by over two thirds of the world’s population; but the aluminum accumulation property of tea plant is becoming the focus of many researches because of aluminum’s kn...Tea is one of the most popular beverages, consumed by over two thirds of the world’s population; but the aluminum accumulation property of tea plant is becoming the focus of many researches because of aluminum’s known adverse effect on human health. Investigation of the interactions of catechins with Al3+ showed that during the interaction of catechins with Al3+, the UV-vis spectrum of catechins was changed. Absorption of EGCG at 274 nm decreased and increased at 322 nm; EC and C’s at 278 nm changed little. The ratio of Al3+ to EGCG was 1:1 in pH 5.0 buffer solution; in pH 6.2 buffer solution, the ratio in the Al-EGCG complex was 1:1. Interestingly, while the ratio reached to over 2, after the complex of Al-EGCG started polymerization, the ratio in the polymer was 2:1. In pH 6.2 buffer solution, the complex behavior of C with Al3+ was the same as that of EGCG, with a little difference for EC. When the ratio of Al3+ to EC was <1, the complex in ratio was 1:2, but, the complex polymerized when the ratio of Al3+ to EC was >1. It was found that the ratio of Al3+ to EC in the polymer was 1:1. Polymerization of Al-catechin complexes might reduce aluminum absorption in the intestine. Kow value was also employed to study the properties of aluminum species in tea infusion (at gastric and intestine pH condition) and the effect of catechins and tea polyphenols on Kow in buffer solution. Results showed that Kow value rose much higher at the intestine pH than at the gastric pH. Tea polyphenols and catechins could greatly reduce aluminum Kow value in acetic buffer, indicating that these compounds may reduce aluminum absorption during tea intake.展开更多
This study was carried out to characterize total residual catechins and their fractions, polyphenolic contents and antioxidant activities of black teas enriched with high levels of theaflavin-3,3’-digallate. The made...This study was carried out to characterize total residual catechins and their fractions, polyphenolic contents and antioxidant activities of black teas enriched with high levels of theaflavin-3,3’-digallate. The made teas were processed from eleven selected cultivars. A comparative study was carried out between the processed teas and those from commercially grown Kenyan cultivars in relation to the above chemical parameters. A correlation matrix analysis was also conducted to find out whether a relationship existed between the antioxidant activities and the said chemical parameters. The total residual catechins were found to range between 3.10% and 8.08%. The total polyphenol levels varied between 19.00% and 28.90%, while the antioxidant activities of the teas ranged from 82.70% to 91.70%. There was a significant p < 0.001 correlation between the antioxidant activity and total polyphenols (r = 0.8948). There was also a high correlation p < 0.001 between the antioxidant activity and total catechins (r = 0.8878). Out of the four catechin fractions, the antioxidant activity correlated most with EGCG (r = 0.8774). The total polyphenolic contents and antioxidant activities for most of the cultivars were comparable to those of the green tea reference standard. From the figures obtained, it can be concluded that the most of the newly developed black teas of the selected cultivars have higher quality and enhanced antioxidant activities and that they can be recommended for commercial production.展开更多
With the current trend of increasing efforts to develop non-isocyanate-based polyurethanes(NIPUs),this study aimed to check the feasibility of the development of a method using cyclic carbonate modified catechin and a...With the current trend of increasing efforts to develop non-isocyanate-based polyurethanes(NIPUs),this study aimed to check the feasibility of the development of a method using cyclic carbonate modified catechin and amine to synthesis non-isocyanate urethane with the objective to further extend these results to polyurethane synthesis.The methods used in this study consist of four steps:glycidilation of catechin,hydrolysis of epoxide,cyclic carbonate synthesis,and carbamate synthesis through condensation of butylamine.The resulting products were analyzed using FTIR(Fourier transform infrared)spectroscopy and NMR(nuclear magnetic resonance)spectroscopy.The results showed that carbamate could be successfully obtained through this four-steps synthesis,opening the possibility to further developments for the synthesis of polyurethanes starting from catechin and condensed tannins.展开更多
Theabrownins(TBs)are the characteristic functional and quality components of dark teas such as Pu’er tea and Chin-brick tea.TBs are a class of water-soluble brown polymers with multi-molecular weight distribution pro...Theabrownins(TBs)are the characteristic functional and quality components of dark teas such as Pu’er tea and Chin-brick tea.TBs are a class of water-soluble brown polymers with multi-molecular weight distribution produced by the oxidative polymerisation of tea polyphenols during the fermentation process of dark tea,both enzymatically and non-enzymatically.TBs have been extracted and purified from dark tea all the time,but the obtained TBs contain heterogeneous components such as polysaccharides and caffeine in the bound state,which are difficult to remove.The isolation and purification process was tedious and required the use of organic solvents,which made it difficult to industrialise TBs.In this study,epigallocatechin(EGC),epigallocatechin gallate(EGCG),epigallocatechin gallate(ECG),EGC/EGCG(mass ratio 1:1),EGCG/ECG(mass ratio 1:1),EGC/ECG(mass ratio 1:1)and EGC/EGCG/ECG(mass ratio 1:1:1)as substrates and catalyzed by polyphenol oxidase(PPO)and peroxidase(POD)in turn to produce TBs,named TBs-dE-1,TBs-dE-2,TBs-dE-3,TBs-dE-4,TBs-dE-5,TBs-dE-6 and TBs-dE-7.The physicochemical properties and the antibacterial activity and mechanism of TBs-dE-1–7 were investigated.Sensory and colour difference measurements showed that all seven tea browning samples showed varying degrees of brownish hue.Zeta potential in aqueous solutions at pH 3.0–9.0 indicated that TBs-dE-1–7 was negatively charged and the potential increased with increasing pH.The characteristic absorption peaks of TBs-dE-1–7 were observed at 208 and 274 nm by UV-visible(UV-vis)scanning spectroscopy.Fourier transform infrared(FT-IR)spectra indicated that they were phenolic compounds.TBs-dE-1–7 showed significant inhibition of Escherichia coli DH5α(E.coli DH5α).TBs-dE-3 showed the strongest inhibitory effect with minimum inhibitory concentration(MIC)of 1.25 mg mL–1 and MBC of 10 mg mL–1,followed by TBs-dE-5 and TBs-dE-6.These three TBs-dEs were selected to further investigate their inhibition mechanism.The TBs-dE was found to damage the extracellular membrane of E.coli DH5α,causing leakage of contents,and increase intracellular reactive oxygen content,resulting in abnormal cell metabolism due to oxidative stress.The results of the study provide a theoretical basis for the industrial preparation and product development of TBs.展开更多
Catechins in green tea have various useful features including antioxidant activity and preventive effects on metabolic syndrome. Various beverages that are enriched with tea catechins are marketed as Foods for Specifi...Catechins in green tea have various useful features including antioxidant activity and preventive effects on metabolic syndrome. Various beverages that are enriched with tea catechins are marketed as Foods for Specified Health Uses (FOSHU) in Japan. However, recent reports have indicated that excessive consumption of green tea extracts as a dietary supplement are associated with adverse health effects such as liver disorders. Various catechins and caffeine are constituents of FOSHU tea-based beverages. The amount of catechins in FOSHU products is displayed on labels as total catechin content, but the content of individual catechins are not provided. Although health hazards of FOSHU products have rarely been reported, precise information about the content and types of catechins in FOSHU products is needed to ensure safety. We used high-performance liquid chromatography with a photodiode array (HPLC/PDA) to simultaneously identify and quantify catechins and caffeine in green tea-based popular beverages and FOSHU beverages. This technique allowed simultaneous quantitation of five types of catechins and caffeine in green tea without complicated sample preparation. Epigallocatechin gallate (EGCG) and epigallocatechin EGC were the main catechins in various FOSHU beverages and the concentrations of almost all catechins were higher in FOSHU, than in popular green tea-based beverages. The concentrations of EGCG in green tea-based popular beverages and in FOSHU beverages were 5.4 - 7.3 and 10.2 - 41.9 mg/100mL, respectively, with the highest concentration being in a product named Healthya (approximately 147 mg/bottle). The simultaneous determination of compounds such as catechins and caffeine in FOSHU beverages can help to estimate beneficial and adverse effects to prevent deleterious effects on health and the excessive consumption of FOSHU beverages containing high concentrations of tea catechins should be avoided.展开更多
Micro RNAs（miRNAs） are endogenous non-protein-coding small RNAs that play crucial and versatile regulatory roles in plants. Using a computational identification method, we identified 55 conserved miRNAs in tea（Came...Micro RNAs（miRNAs） are endogenous non-protein-coding small RNAs that play crucial and versatile regulatory roles in plants. Using a computational identification method, we identified 55 conserved miRNAs in tea（Camellia sinensis） by aligning miRNA sequences of different plant species with the transcriptome library of tea strain 1005. We then used quantitative real-time PCR（qRT-PCR） to analyze the expression of 31 identified miRNAs in tea leaves of different ages, thereby verifying the existence of these miRNAs and confirming the reliability of the computational identification method. We predicted which miRNAs were involved in catechin synthesis using ps RNAtarget Software based on conserved miRNAs and catechin synthesis pathway-related genes. Then, we used RNA ligase-mediated rapid amplification of c DNA ends（RLM-RACE） to obtain seven miRNAs cleaving eight catechin synthesis pathway-related genes including chalcone synthase（CHS）, chalcone isomerase（CHI）, dihydroflavonol 4-reductase（DFR）, anthocyanidin reductase（ANR）, leucoanthocyanidin reductase（LAR）, and flavanone 3-hydroxylase（F3H）. An expression analysis of miRNAs and target genes revealed that miR529d and miR156 g-3 p were negatively correlated with their targets CHI and F3H, respectively. The expression of other miRNAs was not significantly related to their target genes in the catechin synthesis pathway. The RLM-RACE results suggest that catechin synthesis is regulated by miRNAs that can cleave genes involved in catechin synthesis.展开更多
基金supported by the Ministry of Higher Education(MOHE),Malaysia,through Fundamental Research Grant Scheme(FRGS/1/2022/SKK10/UTAR/02/1)Universiti Tunku Abdul Rahman,Malaysia,through UTAR-Research Grant(IPSR/RMC/UTARRF/2024-C1/L04)。
文摘Epigallocatechin-3-gallate(EGCG),a prominent plant-based catechin predominantly derived from Camellia sinensis and widely available on the market as a health supplement,has garnered significant attention for its potential therapeutic benefits,particularly in the context of type 2 diabetes mellitus(T2DM).This review explores the multifaceted role of EGCG in addressing the“ominous octet”—the 8 core pathophysiological defects associated with T2DM.The literature search was carried out using key terms“EGCG”OR“epigallocatechin-3-gallate”OR“epigallocatechin gallate”AND“diabetes”OR“insulin resistance”OR“hyperglycemia”in the PubMed and Scopus databases.The search was constrained to articles published between January 2018 and April 2024,focusing on the document type.Full-text articles published in English and relevant to EGCG that featured a single active ingredient,included clearly explained diabetes relief mechanism,and included ominous octet aspects were included in the final review.The outcomes of the included studies were reviewed and categorized based on 8 core pathophysiological defects,collectively referred to as the ominous octet in T2DM.This review concludes that EGCG is a potent hypoglycemic agent that has beneficial effects against the ominous octet in addition to its pharmacological activities in modulating gut microbiota dysbiosis,carbohydrate digestion and metabolism,glucose transporter-mediated intestinal glucose-uptake,endothelial dysfunction,and renal damage that are significantly associated with pathogenesis of T2DM.This extensive scientific evidence suggests that EGCG may offer a novel approach to traditional antidiabetic therapies,potentially improving glycemic control and mitigating complications associated with T2DM.The inhibitory effects of EGCG on sodium-glucose transport proteins and their role in reducing renal glucose reabsorption remain unexplored,highlighting a significant research gap.Future research should also aim to broaden the scope by investigating the “egregious eleven,”which comprise a more comprehensive range of diabetic pathophysiological features.This review underscores the therapeutic promise of EGCG for managing T2DM and encourages ongoing research to fully elucidate its clinical applications.
基金supported by the Natural Science Foundation of Guangdong Province(Grant Nos.2022A1515111141 and 2023A1515010786)。
文摘DNA methylation plays important roles in regulating gene expression during development.However,little is known about the influence of DNA methylation on secondary metabolism during leaf development in the tea plant(Camellia sinensis).In this study,we combined the methylome,transcriptome,and metabolome to investigate the dynamic changes in DNA methylation and its potential regulatory roles in secondary metabolite biosynthesis.In this study,the level of genomic DNA methylation increased as leaf development progressed from tender to old leaf.It additionally exhibited a similar distribution across the genomic background at the two distinct developmental stages studied.Notably,integrated analysis of transcriptomic and methylomic data showed that DNA hypermethylation primarily occurred in genes of the phenylpropanoid,flavonoid,and terpenoid biosynthesis pathways.The effect of methylation on transcription of these secondary metabolite biosynthesis genes was dependent on the location of methylation(i.e.,in the promoter,gene or intergenic regions)and the sequence context(i.e.,CpG,CHG,or CHH).Changes in the content of catechins and terpenoids were consistent with the changes in gene transcription and the methylation state of structural genes,such as serine carboxypeptidase-like acyltransferases 1A(SCPL1A),leucoanthocyanidin reductase(LAR),and nerolidol synthase(NES).Our study provides valuable information for dissecting the effects of DNA methylation on regulation of genes involved in secondary metabolism during tea leaf development.
基金supported by the National Natural Science Foundation of China(32202200)Shanghai Excellent Academic/Technical Leaders Project(23XD1430500).
文摘This study provides different opinion for exploring the mechanism of catechin(CAT)relieving nonalcoholic steatohepatitis(NASH),it is more innovative to explore from the perspective of intestinal microorganism.Through in vitro fermentation experiments,CAT could improve the abundance of Enterococcus,and Enterococcus faecalis(EF)accounts for the vast majority of Enterococcus in human gut.The experimental results in vivo showed that EF group and CAT+EF group could reduce the body weight,liver index and epididymal fat index of NASH mice,and improve the changes of serum and liver indexes.Hematoxylin-eosin staining observation showed that these two groups have greatly improved the fatty degeneration,balloon degeneration and necrotic focus caused by NASH.The alleviation of CAT+EF group was more obvious.Results of targeted metabonomics showed that CAT could promote EF to produce more methyl palmitate(C_(16:0)),which plays a great role in relieving NASH.Our results indicated that EF could alleviate NASH and CAT+EF group had better alleviation may due to more production of methyl palmitate(C_(16:0))by EF.This study provides a new idea for CAT to alleviate NASH.
文摘The catechin Epigallocatechin-3-O-Gallate (EGCG) which is found in of Green Tea extracts (GTE), displays a variety of microbicidal properties. It is largely believed that EGCG inhibits the growth of cariogenic and periodontopathic bacteria. Objective: In this paper we compared the inhibitory activity of EGCG and a commercial GTE on the growth of Veillonella parvula. Chlorhexidine was used as positive control. Methodology: V. parvula ATCC 10790 and a clinical isolate obtained from a periodontal disease patient were cultured in the presence of EGCG or a commercial GTE, and the measurements of bacterial growth inhibition were compared to the values obtained with 0.12 and 0.2% chlorhexidine. Results: Chlorhexidine inhibited bacterial growth, however in contrast to a previous report, neither EGCG nor the GTE showed any effect on bacterial growth. Conclusions: The data show and confirm that chlorhexidine is a growth inhibitor of V. parvula while EGCG and GTE do not display such effect.
文摘Objective:To discuss the effect of catechins on myocardial injury and inflammatory factors in rats with coronary heart disease under PI3K/Akt/eNOS signaling pathway.Methods:A total of 50 healthy adult pathogen-free(SPF)-grade SD rats were divided into five groups by random number table method.Except for the blank group,the other four groups were fed with high fat to construct a rat model of coronary artery disease.After the model was successfully constructed,the blank group and the model group were given saline by gavage,the positive group was given 25 mg/kg aspirin by gavage,the low-dose group was given 20 mg/kg catechin by gavage,and the high-dose group was given 60 mg/kg catechin by gavage.The expression levels of PI3K/Akt/eNOS signaling pathway-related proteins,myocardial injury markers,myocardial infarction and myocardial inflammatory factors were observed and compared in the five groups.Results:Overall,there were significant differences in the expression levels of PI3K,p-Akt/Akt,and p-eNOS/eNOS in the five groups of rats(P<0.05);there were significant differences in the expression levels of CK-MB and c Tn I in the five groups of rats(P<0.05);there were significant differences in ischemic area,infarct area,and myocardial infarction range in the four groups of rats,except for the blank group(P<0.05);there were significant differences in the expression levels of IL-1β,IL-18,TNF-α,and ET-1 in the five groups of rats(P<0.05).Conclusion:Catechins can reduce the severity of myocardial injury,reduce the range of myocardial infarction,and reduce myocardial inflammation in rats with coronary heart disease by up-regulating expression level of PI3K/Akt/eNOS signaling pathway-related proteins.Compared with aspirin,high-dose catechins have a more prominent protective effect on the myocardium of rats with coronary heart disease.
基金Supported by National Natural Science Foundation of China(31160175)Technology Innovation Talents Project of Yunnan Province(2011CI068)+1 种基金Special Fund for National Modern Agricultural Industrial Technology System Construction(nycytx-23)Seed Preservation Project of Ministry of Agriculture(NB2012-2130135)~~
文摘[Objective] This study aimed to analyze the difference in the contents of gallic acid and catechins of tea resources from Yunnan Province. [Method] By using high performance liquid chromatography （HPLC）, the contents of gallic acid （GA）, catechins （C）, epicatechin （EC）, epigallocatechin （EGC）, epicatechin gallate （ECG） and epigallocatechin gallate （EGCG） of 121 tea germplasms from the China National Germplasm Tea Repositories （CNGTR） at the Tea Research Institute of Yunnan Academy of Agricultural Sciences （TRIYAAS） were measured. [Result] The content of GA ranged from 0.210% to 1.902%, with an average of 0.834%, explaining rela- tively low GA content among tea germplasms. The content of C ranged from 0.069% to 8.865%, with an average of 1.916%. The content of EC ranged from 0.126% to 2.865%, with an average of 1.112%. The content of EGC ranged from 0.00% to 3.709%, with an average of 0.954%. The content of ECG ranged from 0.739% to 8.957%, with an average of 4.063%. The content of EGCG ranged from 0.819% to 11.77%, with an average of 5.939%. The content of total C ranged from 6.354% to 22.654%, with an average of 14.042%. [Conclusion] There was relatively big difference of catechin contents among different tea resources, indicating that there was plentiful biodiversity of Yunnan tea germplasms. At the same time, three tea germplasms with high epigallocatechin gallate content （≥10%） was selected preliminarily, which would provide important materials for breeding tea cultivars with high EGCG content in the future.
文摘The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the hair dyestuff. Four kinds of hair colouring techniques using Cat were examined and each of their dyeability was compared in order to improve it. The first dyeing method is dyeing hair by the redissolved catechinone, which is preliminarily obtained by the oxidation of Cat (Redissolution Dyeing Method). The second one is dyeing hair in the dye solution just after the dye being formed by the enzymatic reaction (Sequential Dyeing Method). The third one is dyeing hair in solution containing Cat and the dyeing process is accompanied by the oxidation of Cat (Simultaneous Oxidation Dyeing Method). The fourth one is two-step dyeing that the hair immersed in Cat solution at the first step and then it is oxidised enzymatically to colour at the second step (Post-Oxidation Dyeing Method). The hair is dyed pale yellow by Redissolution Method, deeper yellowish brown by Sequential and Simultaneous Oxidation Dyeing Method and slightly reddish brown by Post-Oxidation Method with Cat. The order of their dyeability is the Simultaneous Oxidation ≈ Post-Oxidation > Sequential > Redissolution Dyeing Method at 30°C. The dyeability of Redissolution Method increases with an increase in dyeing temperature (T) between 20°C - 60°C. In Simultaneous Oxidation Method, the T increment also provides higher dyeability, and the colour of dyed hair becomes duller over 50°C. The Post-Oxidation Method shows higher dyeability at the lower oxidation temperature (20 °C - 40°C).
基金Supported by the Center for Advanced Bioseparation Technology and the Postdoctoral Program of Inha University.
文摘A molecular imprinted polymer（MIP） was prepared with quereetin as the template and methaerylie acid（MAA） as the functional monomer. Aeetonitrile and methanol were used as the porogen with ethylene glycol dimethaerylate （EGDMA） as the erosslinker and 2,2＇-azobis （ isobutyronitrile ） （ AIBN ） as the initiator. The experimental parameters of the equilibrium isotherms were estimated via linear and nonlinear regression analyses. The linear equadon as the functions of the adsorption concentration of the single compound in its solution and the competitive adsorption of the single compound in its mixed compounds solution was then expressed, and the adsorption equilibrium data were correlated to Langmuir and Freundlich isotherm models. The mixture compounds show competitive adsorption on the specific binding sites of quereetin-MIP. Furthermore, the competitive Langmnir isotherms were applied to the mixture compounds. The adsorption concentrations of quercetin, （＋）eatechin（＋C）, and （-）epieateehin（EC） on the quercetin molecular imprinted polymer were compared. The quercetin-imprinted polymer shows extraordinarily higher adsorption ability for quercetin than for the two eateehin compounds that were also assessed.
文摘Hair colouring was carried out by using catechinone prepared from (+)-catechin by enzymatic or chemical oxidation reaction. The difference of dyeability between the catechinone produced by enzymatic reaction (EC) and that produced by chemical reaction (CC) was studied changing the dyeing condition such as dye concentration, dyeing temperature, pH or the sort and concentration of salts. The colour of the hair dyed by EC or CC at 30°C is yellowish or reddish brown, respectively. The colour of the hair dyed by EC and CC is deeper at a higher dye concentration and at a higher temperature. Hair is dyed deepest by EC or CC at the solution pH = 6.04 or 5.45, respectively. The dyeability is increased by adding NaCl (≤4 M) or CaCl2 (≤1 M), while it is decreased by adding AlCl3. The colour fastness of the dyed hair to washing or ultraviolet light is high enough for practical use. Furthermore, it was found that colourants are obtained from tea extracts which contain catechin derivatives. Hair is dyed reddish brown by the colourants.
文摘Catechin and epicatechin are two isomeric flavonoids. Despite the vital properties highlighted by numerous scientific studies, very little data is available on the intrinsic reactivity of these compounds. To provide more details on the stability and reactivity of catechin and epicatechin, this study is performed by means of theoretical calculation methods. For this purpose, geometry optimizations and frequency calculations at the B3LYP/6-31 + G (d, p) level of theory has been carried out and Natural Bond Orbital (NBO) analysis and VEDA (Vibrational Energy Distribution Analysis). The geometric and energy parameters and NBO analysis show that catechin appears more stable than epicatechin. The hydroxyl group position on the ring C of the catechol structure represents a factor that influences this relative stability. The global and local reactivity parameters reveal that epicatechin becomes more reactive than catechin. They indicate that their hydroxyl groups correspond to their most receptive sites. Fukui indices, VEDA and acidity study establish that O28–H29 remains the most reactive.
文摘A novel colourant for hair dyeing was prepared by an enzymatic reaction with (+)-catechin and its characteristics as a hair dyestuff were studied. The study is aimed at inventing the hair dyestuff that is human- and eco-friendly. One potentially powerful dyestuff was obtained from (+)-catechin treated with tyrosinase after screening experiments using biobased materials. The obtained reddish orange colourant, 4-(3,4-dihydro-3α,5,7-trihydroxy-2H-1-benzopyran-2α-yl) 1,2-benzoquinone named “catechinone”, shows enough dyeability for decolourised white hair. Catechinone does not cause erythema or oedema on skin of rabbits. The colour is controlled by the addition of other biobased materials and a variety of colours of dyed hair are acquired. The fastness to light or washing for hair dyed by catechinone is high enough for practical use.
文摘Catechinone hair dyestuff was produced chemically from (+)-catechin by the oxidation with O2 in basic water/alcohol mixed solution. The effects of reaction conditions such as basicity, sorts of added base, temperature, alcohol molar fraction of solvent and sorts of added alcohols on the catechinone formation were studied in order to increase the efficiency of the dyestuff production. The amount of obtained catechinone increases with increasing basicity of the reaction solution. The dyestuff is obtained by adding monoethanol amine, diethanol amine, triethanol amine, l-arginine, Na2CO3, K2CO3, Na3PO4 or NaOH into the solution as a base and the most preferable base is monoethanol amine. The optimum temperature for the production in water/ethanol solution is 30°C. It was found that water-soluble alcohols such as methanol, ethanol, 2-propanol, 1-propanol and tert-butyl alcohol are available for preparing the dyestuff. The optimum alcohol molar fraction of the mixed solvent used for the dye formation is 0.45 for methanol, 0.25 for ethanol and 0.20 for 2-propanol, 0.15 for 1-propanol and 0.10 for tert-butyl alcohol. The amount of the obtained dyestuff reaches a maximum at 1) 0.35 and 0.59, 2) 0.35 or 3) 0.35 mol·kg¨1 of the concentration of (+)-catechin for the 1) water/methanol, 2) water/ethanol or 3) water/1-propanol system, respectively.
基金supported by a grant of Directorate of General Higher Education,Ministry of Education and Culture of Indonesia for the"BPPDN"scholarship
文摘Objective:To identify the bioactive compounds in catechins isolation and its components from green tea GMB-4 clone.Methods:Green tea GMB-4 clones were extracted with distilled water at 90C.Samples were eluted into the column with 10%ethanol.Subsequently,the column was eluted with95%ethanol and evaporated separately.Green tea extract was identified by thin layer chromatography.Catechins were separated by the stationary phase in column chromatography using polyamide with 10%ethanol eluent and 95%ethanol.The results of isolations were analyzed by high performance liquid chromatographic(HPLC)and LCMS/MS.Analysis of catechins by HPLC was done by external standard.Results:Fraction from 10%ethanol showed that four major peaks at retention time of1.663,2.367,2.950 and 4.890,indicated the presence of four catechins components including catechin,epicatechins,gallocatechin and epigallocatechin.Whereas,fraction from 95%ethanol showed two main peaks at retention time of 5.167 and 9.82,which indicated the presence of epigallocatechin gallate(EGCG)and epicatechin gallate(ECG).EGCG(m/z 459),epigallocatechin(m/z 307),ECG(m/z 443),and epicatechin(m/z 291)were isolated and separated successfully using HPLC and LC-MS/MS.Conclusions:The HPLC and LC-MS/MS methods were successfully tuned for the qualitative analysis of green tea extract with EGCG and ECG.Four major catechins were separated and identified by LC-MS/MS,such as EGCG,epigallocatechin,ECG and epicatechin.The result of HPLC analysis showed that EGCG and ECG were main components from catechins isolation of green tea GMB-4 clone.
文摘The over-activated microglial cells induce neuroinflammation which has the main role in neurological disorders.The over-activated microglia can disturb neuronal function by releasing inflammatory mediators leading to neuronal dysfunctions and death.Thus,inhibition of over-activated microglia may be an effective therapeutic approach for modulating neuroinflammation.Experimental studies have indicated anti-neuroinflammatory effects of flavonoids such as green tea catechins.The current research was aimed to review the effect of green tea catechins in inhibiting microglial cells,inflammatory cascades,and subsequent neurological diseases.
文摘Tea is one of the most popular beverages, consumed by over two thirds of the world’s population; but the aluminum accumulation property of tea plant is becoming the focus of many researches because of aluminum’s known adverse effect on human health. Investigation of the interactions of catechins with Al3+ showed that during the interaction of catechins with Al3+, the UV-vis spectrum of catechins was changed. Absorption of EGCG at 274 nm decreased and increased at 322 nm; EC and C’s at 278 nm changed little. The ratio of Al3+ to EGCG was 1:1 in pH 5.0 buffer solution; in pH 6.2 buffer solution, the ratio in the Al-EGCG complex was 1:1. Interestingly, while the ratio reached to over 2, after the complex of Al-EGCG started polymerization, the ratio in the polymer was 2:1. In pH 6.2 buffer solution, the complex behavior of C with Al3+ was the same as that of EGCG, with a little difference for EC. When the ratio of Al3+ to EC was <1, the complex in ratio was 1:2, but, the complex polymerized when the ratio of Al3+ to EC was >1. It was found that the ratio of Al3+ to EC in the polymer was 1:1. Polymerization of Al-catechin complexes might reduce aluminum absorption in the intestine. Kow value was also employed to study the properties of aluminum species in tea infusion (at gastric and intestine pH condition) and the effect of catechins and tea polyphenols on Kow in buffer solution. Results showed that Kow value rose much higher at the intestine pH than at the gastric pH. Tea polyphenols and catechins could greatly reduce aluminum Kow value in acetic buffer, indicating that these compounds may reduce aluminum absorption during tea intake.
文摘This study was carried out to characterize total residual catechins and their fractions, polyphenolic contents and antioxidant activities of black teas enriched with high levels of theaflavin-3,3’-digallate. The made teas were processed from eleven selected cultivars. A comparative study was carried out between the processed teas and those from commercially grown Kenyan cultivars in relation to the above chemical parameters. A correlation matrix analysis was also conducted to find out whether a relationship existed between the antioxidant activities and the said chemical parameters. The total residual catechins were found to range between 3.10% and 8.08%. The total polyphenol levels varied between 19.00% and 28.90%, while the antioxidant activities of the teas ranged from 82.70% to 91.70%. There was a significant p < 0.001 correlation between the antioxidant activity and total polyphenols (r = 0.8948). There was also a high correlation p < 0.001 between the antioxidant activity and total catechins (r = 0.8878). Out of the four catechin fractions, the antioxidant activity correlated most with EGCG (r = 0.8774). The total polyphenolic contents and antioxidant activities for most of the cultivars were comparable to those of the green tea reference standard. From the figures obtained, it can be concluded that the most of the newly developed black teas of the selected cultivars have higher quality and enhanced antioxidant activities and that they can be recommended for commercial production.
基金LERMAB is supported by a grant overseen by the French National Research Agency(ANR)as part of the“Investissements d’Avenir”Program(ANR-11-LABX-0002-01.Lab of Excellence ARBRE)by the“Impact Biomolecules”Project of the“Lorraine Universitéd’Excellence”“Investissements d’avenir–ANR 15-004”by the French Ministry of Agriculture and the Lorraine-FEDER for the support of“EXTRAFOREST”Project.
文摘With the current trend of increasing efforts to develop non-isocyanate-based polyurethanes(NIPUs),this study aimed to check the feasibility of the development of a method using cyclic carbonate modified catechin and amine to synthesis non-isocyanate urethane with the objective to further extend these results to polyurethane synthesis.The methods used in this study consist of four steps:glycidilation of catechin,hydrolysis of epoxide,cyclic carbonate synthesis,and carbamate synthesis through condensation of butylamine.The resulting products were analyzed using FTIR(Fourier transform infrared)spectroscopy and NMR(nuclear magnetic resonance)spectroscopy.The results showed that carbamate could be successfully obtained through this four-steps synthesis,opening the possibility to further developments for the synthesis of polyurethanes starting from catechin and condensed tannins.
基金financially supported by the National Natural Science Foundation of China(31871813).
文摘Theabrownins(TBs)are the characteristic functional and quality components of dark teas such as Pu’er tea and Chin-brick tea.TBs are a class of water-soluble brown polymers with multi-molecular weight distribution produced by the oxidative polymerisation of tea polyphenols during the fermentation process of dark tea,both enzymatically and non-enzymatically.TBs have been extracted and purified from dark tea all the time,but the obtained TBs contain heterogeneous components such as polysaccharides and caffeine in the bound state,which are difficult to remove.The isolation and purification process was tedious and required the use of organic solvents,which made it difficult to industrialise TBs.In this study,epigallocatechin(EGC),epigallocatechin gallate(EGCG),epigallocatechin gallate(ECG),EGC/EGCG(mass ratio 1:1),EGCG/ECG(mass ratio 1:1),EGC/ECG(mass ratio 1:1)and EGC/EGCG/ECG(mass ratio 1:1:1)as substrates and catalyzed by polyphenol oxidase(PPO)and peroxidase(POD)in turn to produce TBs,named TBs-dE-1,TBs-dE-2,TBs-dE-3,TBs-dE-4,TBs-dE-5,TBs-dE-6 and TBs-dE-7.The physicochemical properties and the antibacterial activity and mechanism of TBs-dE-1–7 were investigated.Sensory and colour difference measurements showed that all seven tea browning samples showed varying degrees of brownish hue.Zeta potential in aqueous solutions at pH 3.0–9.0 indicated that TBs-dE-1–7 was negatively charged and the potential increased with increasing pH.The characteristic absorption peaks of TBs-dE-1–7 were observed at 208 and 274 nm by UV-visible(UV-vis)scanning spectroscopy.Fourier transform infrared(FT-IR)spectra indicated that they were phenolic compounds.TBs-dE-1–7 showed significant inhibition of Escherichia coli DH5α(E.coli DH5α).TBs-dE-3 showed the strongest inhibitory effect with minimum inhibitory concentration(MIC)of 1.25 mg mL–1 and MBC of 10 mg mL–1,followed by TBs-dE-5 and TBs-dE-6.These three TBs-dEs were selected to further investigate their inhibition mechanism.The TBs-dE was found to damage the extracellular membrane of E.coli DH5α,causing leakage of contents,and increase intracellular reactive oxygen content,resulting in abnormal cell metabolism due to oxidative stress.The results of the study provide a theoretical basis for the industrial preparation and product development of TBs.
文摘Catechins in green tea have various useful features including antioxidant activity and preventive effects on metabolic syndrome. Various beverages that are enriched with tea catechins are marketed as Foods for Specified Health Uses (FOSHU) in Japan. However, recent reports have indicated that excessive consumption of green tea extracts as a dietary supplement are associated with adverse health effects such as liver disorders. Various catechins and caffeine are constituents of FOSHU tea-based beverages. The amount of catechins in FOSHU products is displayed on labels as total catechin content, but the content of individual catechins are not provided. Although health hazards of FOSHU products have rarely been reported, precise information about the content and types of catechins in FOSHU products is needed to ensure safety. We used high-performance liquid chromatography with a photodiode array (HPLC/PDA) to simultaneously identify and quantify catechins and caffeine in green tea-based popular beverages and FOSHU beverages. This technique allowed simultaneous quantitation of five types of catechins and caffeine in green tea without complicated sample preparation. Epigallocatechin gallate (EGCG) and epigallocatechin EGC were the main catechins in various FOSHU beverages and the concentrations of almost all catechins were higher in FOSHU, than in popular green tea-based beverages. The concentrations of EGCG in green tea-based popular beverages and in FOSHU beverages were 5.4 - 7.3 and 10.2 - 41.9 mg/100mL, respectively, with the highest concentration being in a product named Healthya (approximately 147 mg/bottle). The simultaneous determination of compounds such as catechins and caffeine in FOSHU beverages can help to estimate beneficial and adverse effects to prevent deleterious effects on health and the excessive consumption of FOSHU beverages containing high concentrations of tea catechins should be avoided.
基金funded by the National Natural Science Foundation of China (31170651)the Project from the Ministry of Agriculture, China (KCa16022A)the Major Science and Technology Project in Fujian Province, China (2015NZ 0002-1)
文摘Micro RNAs（miRNAs） are endogenous non-protein-coding small RNAs that play crucial and versatile regulatory roles in plants. Using a computational identification method, we identified 55 conserved miRNAs in tea（Camellia sinensis） by aligning miRNA sequences of different plant species with the transcriptome library of tea strain 1005. We then used quantitative real-time PCR（qRT-PCR） to analyze the expression of 31 identified miRNAs in tea leaves of different ages, thereby verifying the existence of these miRNAs and confirming the reliability of the computational identification method. We predicted which miRNAs were involved in catechin synthesis using ps RNAtarget Software based on conserved miRNAs and catechin synthesis pathway-related genes. Then, we used RNA ligase-mediated rapid amplification of c DNA ends（RLM-RACE） to obtain seven miRNAs cleaving eight catechin synthesis pathway-related genes including chalcone synthase（CHS）, chalcone isomerase（CHI）, dihydroflavonol 4-reductase（DFR）, anthocyanidin reductase（ANR）, leucoanthocyanidin reductase（LAR）, and flavanone 3-hydroxylase（F3H）. An expression analysis of miRNAs and target genes revealed that miR529d and miR156 g-3 p were negatively correlated with their targets CHI and F3H, respectively. The expression of other miRNAs was not significantly related to their target genes in the catechin synthesis pathway. The RLM-RACE results suggest that catechin synthesis is regulated by miRNAs that can cleave genes involved in catechin synthesis.
