Effects Of Tea Polyphenols Research Articles

Effects of ensiling processes and antioxidants on fatty acid concentrations and compositions in corn silages.

BackgroundCorn silage is the main dietary component used for ruminant breeding in China and is an important dietary source of fatty acids for these animals. However, little is known regarding effective means to protect the fatty acid (FA) contents in silages. In this study, we examined the changes in FA contents and compositions during corn ensiling and screened several antioxidants for their inhibition of lipid oxidation during corn ensiling.MethodsWe conducted two different experiments. In Experiment 1, corn was ensiled in 30 polyethylene bottles (bottle volume: 1 L, silage density: 600 g/dm3) and three bottles were opened at 0.5 d, 1 d, 1.5 d, 2 d, 2.5 d, 3 d, 5 d, 7 d, 14 d, and 28 d after ensiling. In Experiment 2, corn was treated with various antioxidants: (1) No additives (CK); (2) BHA (Butylated hydroxyanisole); (3) TBHQ (Tertiary butyl hydroquinone); (4) TPP (Tea polyphenols); and (5) VE (Vitamin E). These treatments were applied at 50 mg/kg and 100 mg/kg of fresh weight with each treatment replicated 3 times.ResultsDuring ensiling in Experiment 1, saturated fatty acids (SFA; C16:0 and C18:0) and malondialdehyde (MDA) contents tended to increase, whereas unsaturated fatty acids (UFA; C18:1, C18:2 and C18:3) tended to decrease. However, these changes were only significant on the first 2 days of ensiling. In Experiment 2, all of the antioxidants tested affected the total FA contents and those of unsaturated fatty acids (C18:1, C18:2 and C18:3) and MDA. The effects of TBHQ and TPP were greater than those of the other antioxidants.ConclusionsThe reduced total FA contents in corn silages were due to unsaturated fatty acids’ oxidation during the early stages of ensiling. Adding an antioxidant could prevent fatty acids’ oxidation in corn silages.

Determination of theanine and γ-aminobutyric acid in tea by high performance liquid chromatography with precolumn derivatization

A method of precolumn derivatization-high performance liquid chromatography (HPLC) for the determination of theanine and gamma-aminobutyric acid (GABA) in tea was established. o-Phthalaldehyde (OPA) and N-acetyl-L-cysteine (NAC) were chosen as the derivatization reagents. The effects of teapolyphenol (Tp), proline (Pro) and Vitamin C (Vc) on derivatization yields were investigated. The results indicated that Vc not only stabilized the stock solution of OPA, but also enhanced the yield of GABA derivative. However, the yield of theanine derivative was less affected. The HPLC separation system was also optimized. The resolution of the derivatives was improved by adjusting the pH value and phosphate-citric buffer concentration of the mobile phase. The limits of detection (LODs) for GABA and theanine were 3.01 x 10(-5) mmol/L and 7.98 x 10(-5) mmol/L, and the limits of quantification (LOQs) were 9.99 x 10(-5) mmol/L and 2.658 x 10(-4) mmol/L, respectively. The linear ranges of GABA and theanine were 0.01 - 0.4 mmol/L with the correlation coefficient of 0.996 and 0.05 - 0.8 mmol/L with the correlation coefficient of 0.995, respectively. The main recoveries for GABA and theanine in green tea, Oolong tea, and black tea, ranged from 99.29% to 119.60% and from 62.88% to 141.06% respectively. The method with simple procedure and efficient separation was proved to be suitable for the determination of GABA and theanine in tea.

Effects of Tea Polyphenols, Lysozyme and Chitosan on Improving Preservation Quality of Pomfret Fillet

The purpose of this study was to evaluate the impact of different concentrations of tea polyphenols (A1: 0.1%(w/v), A2: 0.5%, A3: 1%), lysozyme (B1: 0.01%, B2: 0.05%, B3: 0.08%) and chitosan (C1: 0.5%, C2: 1%, C3: 2%, C4: 3%) on the quality of pomfret during the storage in order to improve the quality of pomfret fresh preservation. The sensory evaluation, aerobic plate count (APC), trimethylamine (TMA), total volatile basis nitrogen (TVB-N),Kvalue and pH value with different treatments were determined. The results showed that the shelf-life of the control group was 4 days under the cold storage, and the effect of fresh preservation was better with the increasing of the concentration of tea polyphenols, especially the APC could be significantly lower under the treatment groups of A2 and A3 than that under the control group from the 2nd day (P<0.05), the shelf-life was increased by 2 to 3 days. The treatments of B1 and B2 could restrain the increasing of gram-positive bacteria and reduced the contain of TVB-N, TMA-N andKvalue significantly (P<0.05), the shelf-life was increased by 1 to 2 days. The preservation effect of the treatment of C3 was better than those of control group and other groups with chitosan. The APC, TMA-N, TVB-N andKvalue could be significantly lower than those of the control group from the 2nd day, so the shelf-life was increased by 3 days. All of tea polyphenols and chitosan could improve the quality of aquaculture and prolong the shelf-life of pomfret by restraining the increasing of APC and the enzyme activity. The results will offer theory reference to the preservation of pomfrets and the application of bio-preservative.

Effects of tea polyphenol on quality and shelf life of pork sausages.

The effects of tea polyphenol on quality and shelf life of pork sausages stored at 20°C for 42days were examined. The control and the treated sausage samples added with 0.03% tea polyphenol were analyzed periodically for microbiological (total viable counts and lactic acid bacteria counts), physical (Hunter color of L(*), a(*), b(*)), chemical (pH, TBA value) and sensory characteristics. It was found that samples added with tea polyphenol showed lower changes in total viable count, pH, TBA value and sensory characteristics than control samples, respectively. The results indicated that the sausage samples with tea polyphenol added was to enable the good quality and sensory characteristics than the control sausage samples and prolonged the shelf life of the sausages.

In vitro effects of tea polyphenols on the secretion of TNF-α, IFN-γ and IL-2R by peripheral blood CD8＋ T lymphocytes from vitiligo patients

Objective To detect the level of cytokines and their receptors secreted by peripheral blood CD8＋ T lymphocytes from vitiligo patients, and to evaluate the influence of tea polyphenols on their secretion. Methods CD8＋ T lymphocytes were isolated from the peripheral blood of 12 patients with progressive vitiligo, 12 patients with stable vitiligo and 10 healthy controls, and cultured in vitro for 20 days. Then, some CD8＋ T lymphocytes were treated with tea polyphenols of 100 mg/L for two days. Enzyme-linked immunosorbent assay （ELISA） was carried out to determine the levels of tumor necrosis factor （TNF）-a, interferon （IFN）-a and interleukin-2 receptor （IL-2R） in the culture supernatants of CD8＋ T lymphoeytes before and after the treatment with tea polyphenols. Analysis of variance and t test were conducted to assess differences in these parameters among these groups and changes between pretreatment and posttreatment, respectively. Results There was a sequential decrease in the level of TNF-a （（ 191.302±6.077） vs. （175.966± 2.467） vs. （173.664 ± 3.600） ng/L, F = 4.784, P 〈 0.05）, bat a sequential increase in that of IFN-a （ （280.182 ± 36.070） vs. （371.670 ± 24.352） vs. （447.147 ± 8.432） ng/L, F= 9.036, P〈 0.01） and IL-2R （（8.375 ± 0.161） vs. （8.845 ±0.161） vs. （9.345 ± 0.125） ng/L, F = 9.639, P 〈 0.01） in the culture supernatant of CD8＋ T lymphocytes from patients with progressive vitiligo to patients with stable vitiligo and healthy controls. After two days of tea polyphenol treatment, a statistical decrease was observed in the level of TNF-a in the culture supematant of CD8 ＋ T lymphocytes from patients with progressive vitiligo （（ 164.797 ± 1.784） ng/L, P 〈 0.01 ）, patients with stable vitiligo （（166.150 ± 3.576） rig/L, P 〈 0.05） and healthy controls （（155.028 ± 5.759） ng/L, P 〈 0.05）, but no statistical changes were noted for IFN-＇y or IL-2R （all P 〉 0.05） despite a slight elevation in the level of IFN-＇y in the culture supernatant of CD8＋ T lymphocytes from patients with stable vitiligo and in that of IL-2R from all the three groups as well as a mild reduction in that of IFN-Y from patients with progressive vitiligo and healthycontrols. Conclusions The changes of cytokines and their receptors secreted by CD8＋ T lymphocytes may be associated with the induction and progression of vitiligo. Tea polyphenols may treat vitiligo via suppressing the secretion of TNF-a by CD8＋ T lymphocytes. Key words: Vitiligo, CDS-positive T-lymphocytes; Tumor necrosis factor alpha; Interferon type II; Recep-tors, interleukin-2; Tea polyphenols

Effects of tea polyphenols on the post-mortem integrity of large yellow croaker (Pseudosciaena crocea) fillet proteins

Tea polyphenols (TP) are known to be important for the post-mortem deterioration of fish muscle and can enhance food quality. To shed light on the influence of TP on the status of large yellow croaker muscle proteins, control and treated fillets (0.1% TP, 0.2% TP and 0.3% TP, w/v) were analysed periodically for myofibrillar protein functional properties (Ca2+-ATPase activity, surface hydrophobicity, total sulfhydryl content, emulsion stability index and rheological behaviour). Degradation of the myofibrillar protein myosin could be clearly observed; several proteins were also observed to vary in abundance following post-mortem storage for 25days. The present study offers new evidence that TP have an effective impact on muscle protein integrity post-mortem.

Effect of tea polyphenols on the dilational rheology of Human Whole Saliva (HWS): Part 1, HWS characterization

Human whole saliva (HWS) is a physiological secretion that performs a number of essential functions including protection of oral health, lubrication of mouth tissues and food pre-digestion. The complexity of the saliva proteome reflects the unique physiochemical functionality of this biofluid. In addition, saliva influences the transduction of aroma, taste and tactile (mouthfeel) perceptions through the interaction with food and beverages. This work, which is presented as two distinct contributions, reports on the extensive interfacial properties characterization (air–liquid) of saliva either alone or after exposure to tea polyphenols. This first part discusses the complex nature of the salivary film in terms of kinetic and viscoelastic (dilational surface rheology) properties. The formation of the surface film is analyzed with time and explained in terms of the progressively irreversible adsorption of protein fractions of larger molecular weight. The viscoelastic response to appropriate frequency modulation is modelled using a general mixed kinetic model, which satisfactorily reproduces the experimental data in better agreement than the traditional Lucassen diffusive model.

Chemopreventive and Therapeutic Potential of Tea Polyphenols in Hepatocellular Cancer

The prophylactic and therapeutic properties of tea have been attributed to green tea catechins and black tea theaflavins besides several other polyphenolic compounds. Tea polyphenols possess potent antioxidant and antiinflammatory properties and modulate several signaling pathways. These biochemical facets of tea polyphenols are responsible for its anticancer properties. Several lethal cancers, such as liver cancer, develop within a background of oxidative stress and inflammation. Liver cancer, also known as hepatocellular carcinoma (HCC), has been shown to occur throughout the world including Asia, Africa, Western Europe, and the United States. Phytochemicals, such as tea polyphenols, provide an effective and promising alternative for the chemoprevention and treatment of HCC. In this article, we systematically review, for the first time, the effects of tea polyphenols in the preclinical in vitro and in vivo HCC models. The review also examines, in critical detail, the biochemical mechanisms involved in the chemopreventive and antineoplastic effects of tea polyphenols in hepatic cancer. Finally, we highlight the role of synergy, bioavailability and pharmacokinetics of tea polyphenols, current status of clinical trials, discuss future directions, and comment on the future challenges involved in the effective use of tea polyphenols for the prevention and management of liver cancer.

Effect of tea polyphenols on the dilational rheology of human whole saliva (HWS): Part 2, polyphenols–HWS interaction

In the second part of this communication we screen a few tea polyphenols for their ability to interact with pre-adsorbed salivary proteins at the air–liquid interface. Using interfacial dilational rheology characterisation, we measure the variation in surface elasticity of a pre-adsorbed salivary film after exposure to tea polyphenols solutions in order to probe the degree of mutual interaction. We observe that this interaction with salivary proteins varies according to the chemical structure and degree of polyphenols complexity (number of phenols rings). The evolution of the salivary film after exposure to polyphenol solutions is characterised through surface dilational response to appropriate frequency modulation and the results are analysed using a general mixed kinetic model, which reproduces correctly the experimental data except for the galloylated theaflavins.

Tea Polyphenols Modulate Antioxidant Redox System on Cisplatin‐induced Reactive Oxygen Species Generation in a Human Breast Cancer Cell

Tea polyphenols (TPP) have potent antioxidant and anticancer properties, particularly in patients undergoing radiation or chemotherapy. However, few studies have been conducted on treatments using a combination of TPP and the conventional chemical anticancer drug cisplatin (CP). This study was designed to investigate the mechanism of the cytotoxicity of total TPP and CP, which may synergistically induce cell death in cancer cells. Here, breast cancer cells (MCF-7) were treated with various concentrations of TPP alone or in combination with the chemotherapeutic drug CP. The effect of TPP on cell growth, intracellular reactive oxygen species (ROS) level, apoptosis and gene expression of caspase-3, caspase-8 and caspase-9 and p53 was investigated. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed that the MCF-7 cells were less sensitive to growth inhibition by TPP treatment than either CP or the combination therapy. Propidium iodide nuclear staining indicated that exposure to this combination increased the proportion of apoptotic nuclei compared with a single-agent treatment. Flow cytometry analysis was used to quantify changes in intracellular ROS. Detection of activated caspases by fluorescently labelled inhibitors of caspases (FLICA) combined with the plasma membrane permeability assay demonstrated that the percentage of early and late apoptotic/secondary necrotic cells was higher in the cells treated with the combination than in those treated with either TPP or CP alone. The combined TPP and CP treatment synergistically induced apoptosis through both caspase-8 and caspase-9 activation and p53 over-expression. This suggests that TPP plus CP may be used as an efficient antioxidant-based combination therapy for estrogen receptor (ER)-positive and p53-positive breast cancer.

Protective effects of tea polyphenols against the destruction of melanocytes by CD8+ T ceils from vitiligo patients

Objective To evaluate the protective effects of tea polyphenols against the destruction of melanocytes by CD8+ T cells from vitiligo patients.Methods Skin tissue was resected from the margin of vitiligo lesions followed by the isolation and culture of CD8+ T lymphocytes,and from the normal skin of vitiligo patients followed by the isolation and culture of melanocytes.Flow cytometry was carried out to evaluate the purity of CD8+ T cells.The melanocytes were cocultured with the CD8 + T cells at different ratios followed by the evaluation of killing effect of CD8+ T cells.Various concentrations (200 and 400 μg/ml) of tea polyphenols were added into the co-culture system of CD8+ T cells and melanocytes at a ratio of 5 ∶ 1 followed by an additional culture of 48 hours.Then,flow cytometry was performed to detect the apoptosis in melanocytes in the coculture system.Results CD8+ T lymphocytes were successfully obtained from the marginal area of vitiligo lesions with a purity of more than 90％,which highly expressed the antigens CD137 and CD69.The coculture with CD8+ T cells markedly accelerated the apoptosis in melanocytes,while the accelerative effect was inhibited by tea polyphenols of 200 and 400 μg/ml.Conclusions The CD8+ T cells infiltrating the edge of vitiligo lesions display a potential destructive effect on autologous melanocytes from vitiligo patients,and tea polyphenols have a protective effect against the destruction of melanocytes by CD8+ T cells. Key words: Vitiligo; T-lymphocytes, cytotoxic; Melanocytes; Tea polyphenols

Protective effect of tea polyphenols on the blood-brain barrier

AbstractThis study was to investigate the protective effects of tea polyphenols on the blood-brain barrier (BBB) of rats with global cerebral ischemia/reperfusion (GCIR) injury. Sprague Dawley rats underwent four-vessel occlusion to construct the model of GCIR. Half an hour before complete occlusion, they were treated with tea polyphenols (TP) (6.4%; 100 or 200 mg/kg) via tail intravenous injection. 24 h after reperfusion, BBB permeability was evaluated by measuring brain water content (BWC) and residual amount of Evan’s blue dye in cerebral tissue. In addition to this, MMP-9 and collagen IV protein expression in cerebral tissue were also detected using immunohistochemistry. ANOVA and SNK-q were used to do statistical analysis. Statistical significance was considered at P<0.05. Compared to the untreated, the TP-treated rats had significantly decreased BWC (P<0.05), decreased residual amount of Evan’s blue dye in cerebral tissue (P<0.05), down-regulated MMP-9 (P<0.05) and up-regulated collagen IV expression in brain tissue (P<0.05). It can be concluded from these findings that TP may reduce the MMP-9 mediated collagen IV degradation caused by GCIR to protect the BBB.

Effect of tea polyphenols on the physical and chemical characteristics of dried-seasoned squid (Dosidicus gigas) during storage

The effects of tea polyphenols (TP) dip treatment on the physical and chemical characteristics of dried-seasoned squid (Dosidicus gigas) during storage at 25 °C were assessed. After the storage, the b* value increased significantly, while the free amino acids (FAA) including Ser, Gly, Arg, Tyr and Lys, and the dominant reducing sugar (RS), lactose, decreased remarkably, which revealed the occurrence of browning reaction in dried-seasoned squid. The progressive conversion of trimethylamine oxide (TMAO) and production of thiobarbituric acid (TBA) and total volatile basic nitrogen (TVB-N) were found during the entire period of storage. Furthermore, the advantages of reducing moisture loss, inhibiting oxidation of lipids, depressing TMAO breakdown and TVB-N accumulation were observed, while the browning reaction exhibited no significant decrease for the TP samples. These results indicated that the addition of TP could maintain quality of dried-seasoned squid.

Effect of Tea Polyphenols on the Adhesion of Highly Metastatic Human Lung Carcinoma Cell Lines to Endothelial Cells in Vitro

Tea polyphenols are known to play roles in critical steps of human lung carcinoma cell metastasis. For understanding the mechanisms whereby they inhibit tumor metastasis, the present study was conducted to investigate their effects on the adhesion of highly metastatic lung carcinoma cell lines (PG cells) to endothelial cells (EC cells) and adhesion molecule expression in vitro. The expression of CD44 or CD54 in the PG cells was detected by flow cytometry and adhesion of PG cells to EC cells was assessed by confocal microscopy double fluorescence staining. The results showed that tea polyphenols: (1) inhibited the expression of CD44 and CD54, two important adhesion molecules in the PG cells in a dose-dependent manner; (2) significantly blocked the adhesion of PG cells to EC cells not only in a state of rest but also when active; and (3) influenced CD44 and CD54 expression during the adhesion process of PG cells to EC cells. The data indicated that the blocking role of tea polyphenols in the adhesion of PG cells to EC cells is related to CD44 and CD54. The mechanism of tea polyphenol prevention of human lung carcinoma metastasis might be through inhibiting adhesion molecule expression to block cancer cell adhesion.

Effects of Tea Polyphenols Dip Treatment on the Quality of Catfish Fillets during Partial Freezing Storage

The effects of tea polyphenols(TP) dip treatment on the quality changes of catfish fillets during partial freezing storage for 25 days were investigated. The catfish were filleted, after being gutted and cleaned, and given a dip treatment in 0.15% TP solution for 30min at room temperature. And then, they were packed in plastic bags, stored at -3°C. The sensory scores, total bacterial count(TVC), pH values, Total Volatile Basic Nitrogen(TVB-N) and TBARS values were used to evaluate the catfish quality. The results showed that TVC, pH, TVB-N and TBARS values of catfish, which was processed with TP, could be significantly restrained, and sensory scores decreased slowly as well. So it can be concluded that tea polyphenols have great effects on the inhibitions of bacteria growth and anti-oxidation of fat, and thus significantly delay the spoilage of partial-frozen catfish.

Effect of Tea Polyphenol on Oxidative Injury in S180 Cells Induced Hepatocarcinoma Mice

The purpose of this study was to evaluate the antioxidant nature of tea polyphenol on S180 cells induced liver cancer in mice. In the present study, hepatocellular carcinoma was induced by tumor transplantation of liver in situ. The antitumor activity of tea polyphenol has been determined in vivo in hepatocellular carcinoma mice after treatment of drug (50, 100, 150 mg/kg body weight) by gavage for 20 days. Results showed that a significant increase in serum aspartate transaminase (AST), alkaline phosphatase (ALP), alanine aminotransfere (ALT), malondialdehyde (MDA) level, decrease in serum white blood cells (WBC), serum total protein (TP), albumin (ALB), A/G, tumor necrosis factor-α (TNF-α) and interferon-gamma (IFN-γ), liver reduced glutathione (GSH) levels were observed. In addition, the levels of enzymic and non-enzymic antioxidants were decreased when subjected to S180 cells induction. These altered enzyme levels were ameliorated significantly by administration of tea polyphenol at the concentration of 50, 100, 150 mg/kg body weight in drug-treated animals. These results indicate that the protective effect of tea polyphenol was associated with inhibition of MDA induced by S180 cells and to maintain the antioxidant enzyme levels.

Effects of Tea Polyphenols and their Polymers on MAPK Signaling Pathways in Cancer Research

The biological activities and mechanisms of tea polyphenols and their polymerics have been attractive issues in cancer research. The inhibition of tea polyphenols on cancer cells decreased cell proliferation and increased apoptosis. Tremendous evidences have shown that tea polyphenols suppress tumor promotion by inhibiting enzyme activities and blocking signal transduction pathways. Specifically, the mitogen activated protein kinases (MAPK) pathways have been implicated as an important target molecular for cancer prevention and therapy. The purpose of this review is to discuss the relationship between tea polyphenols and MAPK signaling pathways in cancer.

Up-Regulation of the Gap Junction Intercellular Communication by Tea Polyphenol in the Human Metastatie Lung Carcinoma Cell Line

Our previous study has proven that tea polyphenol has a role in lung neoplasms. The present communication was to investage the anti-proliferation effect of tea polyphenol on the PG cells, which was a high metastatic human lung carcinoma cell line, by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-diphenytetrazoliumromide (MTT) cell viability assay, and to study the change of intracellular calcium concentration, connexin43 (Cx43) expression, gap junctional intercellular communication (GJIC) and cell cycle distribution after the tea polyphenol treatment by laser scanning confocal microscopy and flow cytometry. The results showed that 1) tea polyphenol could kill the PG cells in a dose-depent manner via inhibiting the PG cell proliferation and blocking the PG cell cycle progression staying in G0/G1 phase and not transfering in S and G2/M phases to reduce the PG cell proliferation index; 2) the increases of intracellular calcium concentration, GJIC and Cx43 expression were related with the tea polyphenol doses. The data suggested that tea polyphenol could inhibit the growth of PG cells, which mechanism was associated with the up-regulation of GJIC.

The effects of tea polyphenols on the injury of fibrinolytic functions induced by high-methionine dietary in rats

To study the protective impact of tea polyphenols (TP) on the injury of fibrinolytic functions induced by high-methionine dietary in rats. 50 male Wistar rats were divided by stratified based on body weight into 5 groups with 10 in each group: namely control group, model group, low-dose TP group, medium-dose TP group and high-dose TP group. The rats in model group and TP groups were fed with 3% methionine dietary, control group rats with routine diet. In addition, rats in low-dose, medium-dose and high-dose TP groups were treated with TP at 50, 100 and 200 mg/kg dosage respectively by gavages every day, control group and model group rats were given with same amount distilled water. The animals were sacrificed after 8 weeks. The levels of tissue-type plasminogen activator (t-PA) and type-1 plasminogen activator inhibitor (PAI-1) in plasma were determined by ELISA assays, mRNA levels of t-PA and PAI-1 in aortic arch were detected by RT-PCR, t-PA and PAI-1 expression in aortic arch were detected by immunohistochemistry strept-avidin-biotin complex (SABC). After experiment, the t-PA expression of aortic arch in control group, model group, low-dose TP group, medium-dose TP group and high-dose TP group were 133.03 ± 10.14, 95.46 ± 11.08, 111.97 ± 11.91, 130.23 ± 10.80, 139.39 ± 9.41 (F = 14.15, P < 0.01), respectively, and the PAI-1 expression were 90.91 ± 8.67, 166.76 ± 12.18, 139.63 ± 12.71, 134.66 ± 13.19, 109.49 ± 10.82 (F = 31.44, P < 0.01). The t-PA concentration of plasma were (10.69 ± 1.26), (6.13 ± 0.92), (8.56 ± 1.19), (9.69 ± 0.92), (11.97 ± 1.08) ng/ml, respectively (F = 41.98, P < 0.01), and the PAI-1 concentration of plasma were (6.31 ± 0.81), (16.98 ± 1.27), (11.39 ± 0.82), (8.46 ± 0.67), (8.08 ± 0.91) ng/ml, respectively (F = 207.74, P < 0.01). The mRNA levels of t-PA in aortic arch were 1.12 ± 0.02, 0.75 ± 0.14, 1.01 ± 0.09, 0.95 ± 0.08, 1.05 ± 0.13 (F = 5.77, P < 0.05), and the mRNA levels of PAI-1 in aortic arch were 1.25 ± 0.11, 1.74 ± 0.06, 1.23 ± 0.05, 1.09 ± 0.14, 1.23 ± 0.04 (F = 23.56, P < 0.01). The results indicate that TP seems to have regulatory function on transcription and protein levels of t-PA and PAI-1, in addition to maintaining the balance between PAI-1 and t-PA and healing the injury of fibrinolytic functions in rats induced by high-methionine dietary.

Effect of tea polyphenols on global cerebral ischemia reperfusion injury in rats

Objective To investigate the effect of tea polyphenols on global cerebral ischemia reperfusion injury in rats.Method Forty-five pathogen-free male SD rats weighing 180-220 g were randomly divided into 3 groups( n =15 each):sham operation group (group S),cerebral ischemia reperfusion group (group IR) and tea polyphenols group (group TP).Global cerebral ischemia reperfusion injury was establish by four-vessel occlusion method.At 24 h of reperfusion,five rats were chosen and Evan's blue(EB) was injected iv,and then sacrificed and brain was removed for determination of EB content; another five rats were sacrificed and brain was removed for determination of water content; five rats were chosen for Morris water maze test.Result Compared with group S,EB content and water content in brain tissue were increased in groups IR and 'rP,and escape latency was prolonged,frequency of crossing the original platform was reduced in group IR ( P ＜ 0.05 ).Compared with group IR,EB content and water content in brain tissue were decreased,and escape latency was shortened,frequency of crossing the original platform was increased in group Tp ( P ＜ 0.05).Conclusion Tea polyphenols can attenuate global cerebral ischemia reperfusion injury in rats. Key words: Phenols; Tea; Reperfusion injury; Brain