Concentrations Of Green Tea Polyphenols Research Articles

A self-powered droplet sensor based on a triboelectric nanogenerator toward the concentration of green tea polyphenols.

Self-powered liquid droplet sensors based on triboelectric nanogenerators have attracted extensive attention in the field of biochemical sensing applications. Numerous research studies have investigated the effects of factors such as molecular species, molecular concentration, molecular charge, and molecular dipole moment in solution on the output electrical signals of the sensor. In this study, we prepared a self-powered droplet sensor using conductive copper film tape, polytetrafluoroethylene, and conductive aluminum foil tape. The sensor can continuously output pulsed electrical signals with minimal environmental impact. In comparison with other types of sensors, this sensor boasts a rapid response time of 10 ms and excellent sensitivity. The relationship between the friction-induced output current and voltage of the droplets and the concentration of green tea polyphenols (GTPs) was studied using the self-powered liquid droplet sensor with five different green tea samples. It was found that GTPs were the main factor contributing to the changes in output electrical signals in green tea water droplets. Fluorescence spectroscopy was used to reveal that the magnitude of the output current was inversely proportional to the concentration of GTPs in green tea. These results demonstrate the potential application of self-powered liquid droplet sensors in biochemical sensing applications based on concentration-dependent output signals.

Prospective randomized trial evaluating blood and prostate tissue concentrations of green tea polyphenols and quercetin in men with prostate cancer.

We evaluated if chronic consumption of quercetin (Q) with green tea extract (GTE) enhances the bioavailability of GT polyphenols (GTPs) and reduces methylation activity as previously observed in mouse xenograft tumors. In this prospective, randomized, parallel design, placebo controlled study, thirty-one men with prostate cancer consumed daily 1 gram of GTE (830 mg of GTP) with 800 mg of Q (GT + Q) or placebo (GT + PL) for four weeks before prostatectomy. First morning voided urine was collected at baseline, 3 weeks and the day of surgery, and prostate tissue on the day of surgery. In week 3, plasma concentration of GTPs and Q was measured in blood collected before and 2 hours after the morning dose. Prostate tissue epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) were detected in 67 and 93% of participants in the GT + Q group and 75 and 94% of participants in the GT + PL group. Q was increased 14-fold, 12-fold and 4.5-fold in plasma, urine, and prostate tissue, respectively, in the GT + Q compared to the GT + PL-group. There was a trend for decreased EGC levels in urine collected prior to prostatectomy in the GT + Q compared to GT + PL-group (p = 0.053). Plasma epigallocatechin (EGC) showed a trend to increase (p = 0.066) two hours after capsule intake in the GT + Q vs. the GT + PL-group. There was no significant difference between the groups in GTP content or methylation activity in prostate tissue or RBCs. No liver toxicity was observed. Although our findings are suggestive, further studies are warranted evaluating if Q alters GTP metabolism.

Mathematical Modeling and Release Kinetics of Green Tea Polyphenols Released from Casein Nanoparticles.

Drug release kinetics plays an important role in determining the mechanism of drug release, which in turn helps in formulating controlled/sustained release formulations. In our study, different concentrations of green tea polyphenols (GTP) were encapsulated into casein nanoparticles which showed a maximum encapsulation efficiency (76.9%) at a GTP concentration of 5 mg/mL. The casein nanoparticles were characterized through particle size analysis, zeta potential, AFM, and HR SEM, followed by molecular docking studies, which confirmed the binding of GTP to casein nanoparticles. In-vitro release studies carried out at different temperatures and pH showed no significant difference in the release pattern, but the release was prolonged even up to 48 h. On varying pH of the release medium, an increase in the percentage of release was observed as the pH shifted from acidic to basic. All release data showed good correlation with Zero order kinetics, an ideal model for release of drugs from nanoparticulate sustained release formulations, with anomalous mode of drug transport. Antioxidant activity of the released GTP determined through DPPH assay showed potent antioxidant effect of GTP even after 48 h of its release. Our data indicated that casein nanoparticles could be used as a potent vehicle for the delivery of GTP for achieving a sustained release.

Sustained Release of Green Tea Polyphenols from Liposomal Nanoparticles; Release Kinetics and Mathematical Modelling.

Background: Green tea polyphenols (GTP) are known to have several health benefits. In spite of these benefits, its application as a therapeutic agent is limited due to some of its limitations such as stability, bioavailability, and biotransformation. To overcome these limitations, liposomal nanoparticles have been used as a carrier of the GTP. Objective: Encapsulation of GTP to the liposomal nanoparticles in order to achieve a sustained release of the GTP and to determine the drug release kinetics and the mechanism of the release. Materials and Methods: GTP encapsulated liposomal nanoparticles were prepared using phosphatidyl choline and cholesterol. The synthesized particles were characterized for their particle size and morphology. In vitro release studies were carried out, followed by drug release kinetics, and determining the mechanism of release. In vitro, antioxidant assay was determined following 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Results: Atomic force microscope (AFM) and high resolution scanning electron microscope (HR SEM) images showed spherical particles of the size of 64.5 and 252 nm. An encapsulation efficiency as high as 77.7% was observed with GTP concentration of 5 mg.mL-1. In vitro release studies showed that the loading concentrations of GTP were independent to the cumulative percentage of the drug release. GTP release by varying the pH and temperature showed a direct correlation between the release parameter and the percentage of drug release. The higher the pH and temperature, the higher was the percentage of the drug release. The release data showed a good correlation with Zero order kinetics and the mechanism of the release being anomalous mode. Radical scavenging activity of the released GTP showed a potent scavenging activity. Conclusion: GTP encapsulated liposomal nanoparticles could be used as a delivery vehicle for achieving a sustained release.

Green tea and quercetin sensitize PC-3 xenograft prostate tumors to docetaxel chemotherapy.

BackgroundChemotherapy with docetaxel (Doc) remains the standard treatment for metastatic and castration-resistance prostate cancer (CRPC). However, the clinical success of Doc is limited by its chemoresistance and side effects. This study investigated whether natural products green tea (GT) and quercetin (Q) enhance the therapeutic efficacy of Doc in CRPC in mouse models.MethodsMale severe combined immunodeficiency (SCID) mice (n = 10 per group) were inoculated with androgen-independent prostate cancer PC-3 cells subcutaneously. When tumors were established the intervention started. Mice were administered with GT + Q, Doc 5 mg/kg (LD), GT + Q + LD Doc, Doc 10 mg/kg (HD) or control. The concentration of GT polyphenols in brewed tea administered as drinking water was 0.07 % and Q was supplemented in diet at 0.4 %. Doc was intravenously injected weekly for 4 weeks, GT and Q given throughout the study.ResultsGT + Q or LD Doc slightly inhibited tumor growth compared to control. However, the combination of GT and Q with LD Doc significantly enhanced the potency of Doc 2-fold and reduced tumor growth by 62 % compared to LD Doc in 7-weeks intervention. A decrease of Ki67 and increase of cleaved caspase 7 were observed in tumors by the mixture, along with lowered blood concentrations of growth factors like VEGF and EGF. The mixture significantly elevated the levels of tumor suppressor mir15a and mir330 in tumor tissues. An increased risk of liver toxicity was only observed with HD Doc treatment.ConclusionsThese results provide a promising regimen to enhance the therapeutic effect of Doc in a less toxic manner.

Abstract 5345: Enhanced inhibition of PC-3 xenograft prostate tumor growth by combination of green tea and quercetin with docetaxel

Abstract Chemotherapy with docetaxel (Doc) is a standard treatment for metastatic and castration-resistant prostate cancer. However, the development of chemoresistance and its side effects limit the clinical success of Doc. Previously we demonstrated that the combined use of natural products green tea (GT) and quercertin (Q) with Doc synergistically enhanced the anti-proliferative effect in androgen-independent prostate cancer PC-3 cells. The objective of the present study was to confirm the combined effect of GT, Q and Doc in xenograft prostate cancer mouse models and determine underlying mechanisms. Male severe combined immunodeficiency (SCID) mice (n = 10 per group) were inoculated with 5×105 PC-3 cells subcutaneously. When tumors reached a size of about 100mm3 the intervention started. Mice were administered with GT+Q, Doc 5mg/kg (LD), GT+Q+LD Doc, Doc 10mg/kg (HD) or control. The concentration of GT polyphenols in brewed tea administered as drinking water was 0.07% and Q was supplemented in diet at 0.4%. Doc was given through tail vein once a week for 4 weeks. There was a nonsignificant inhibition of tumor growth by GT+Q or LD Doc alone compared to control. However the combination treatment with GT+Q+LD Doc significantly inhibited the tumor growth by 62% compared to LD Doc alone after 7 weeks intervention. The combined effect was comparable to that by HD Doc treatment. Western blot analysis demonstrated a significantly increased ratio of Bax to Bcl-2 protein expression by GT+Q+LD Doc treatment compared to GT+Q or LD Doc. ELISA analysis of blood samples demonstrated that the combination treatment significantly decreased the blood concentrations of several growth factors, including VEGF, EGF, TGF-β, FGF-β, and TNF-α compared to GT+Q or LD Doc alone. A liver toxicity evaluation revealed that the blood alanine aminotransferase (ALT) level was significantly elevated with HD Doc treatment compared to control, while not changed by other groups. Further mechanistic investigations using protein array and tissue microarray assays are ongoing. This study provides a promising regimen by combining GT and Q with Doc to enhance chemotherapeutic effect in advanced prostate cancer in a less toxic manner. The results warrant future clinical trials to confirm the combined effect of the mixture in humans. Citation Format: Piwen Wang, Susanne Henning, David Heber, Jaydutt Vadgama. Enhanced inhibition of PC-3 xenograft prostate tumor growth by combination of green tea and quercetin with docetaxel. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5345. doi:10.1158/1538-7445.AM2015-5345

Effects of supplementation with dietary green tea polyphenols on parasite resistance and acute phase protein response to Haemonchus contortus infection in lambs

The objective of this study was to determine the effects of supplementation with dietary green tea polyphenols (GTPs) on parasite resistance and acute phase protein (APP) response to Haemonchus contortus infection in lambs. Thirty male Ujumqin lambs were randomly assigned to five treatment groups for an 8-week feeding period. Treatments included: (1) uninfected as control, (2) infected but not given GTP (INFGTP0) and (3)–(5) infected and fed 2, 4, or 6g GTP/kg feed (dry matter basis; INFGTP2, INFGTP4, and INFGTP6, respectively). Fecal and blood samples were collected to determine fecal egg count (FEC), packed cell volume (PCV), and APP concentrations. Live weight was measured once every 2 weeks. At the end of the feeding period, lambs were slaughtered to determine the adult H. contortus burden. The results demonstrated interaction effects between treatment and sampling time on the average daily gain (ADG; P=0.0005), FEC (P<0.0001), PCV (P=0.0005), and concentrations of serum amyloid A (SAA), haptoglobin (Hp), lipopolysaccharide binding protein (LBP), and α1-acid glycoprotein (α1AGP) (P<0.0001). From days 0 to 56, the ADG values for all infected lambs were lower than that of uninfected lambs, but the ADG values for all GTP-fed lambs were higher than that of INFGTP0 lambs, especially from days 28 to 42. The FECs of all GTP-fed lambs were higher than those of uninfected lambs but lower than that of INFGTP0 lambs. The PCVs of all infected lambs were lower than those of uninfected lambs, but PCV increased with increasing amounts of GTP supplementation. Furthermore, supplementation with different concentrations of GTP significantly reduced the numbers of adult H. contortus, including both males and females (P<0.0001), and the H. contortus burden in INFGTP6 lambs was reduced to uninfected levels. Overall, the SAA, Hp, LBP, and α1AGP concentrations of all infected lambs were higher than those of uninfected lambs from days 0 to 56. Two peaks in expression were observed from days 0 to 3 and at day 28, and APP concentrations of all GTP-fed lambs were lower than those of INFGTP0 lambs, except for SAA in INFGTP6 lambs. In conclusion, quantitative measurements of APP responses to H. contortus infection provide valuable diagnostic information for monitoring infection progression and treatment responses in lambs. An appropriate dose of dietary GTP supplementation can increase host resistance by reducing H. contortus burden and weight loss and suppressing blood APP expression.

Concentrated Extract of Green Tea Polyphenols Enhances the Toxicity of the Elderberry Lectin Nigrin b to Mice

The effect of the administration of large amounts of green tea polyphenols is a matter of controversy. We explored whether a polyphenol mixture from a concentrated green tea extract (Polyphenon 60) could alter the effects on mice of the type 2 (two chains) ribosome-inactivating protein nigrin b isolated from Sambucus nigra L. Nigrin b triggers specific reversible toxic effects on the mouse intestines featured by apoptosis of mice Lieberkuhn crypt cells upon parenteral administration of sub-lethal amounts. Independent administration to mice of 30 mg/kg body weight of Polyphenon 60 by oral gavage or 10 mg/kg body weight of nigrin b administered via the intraperitoneal route (i.p.) did not affect survival. In contrast, the simultaneous treatment greatly enhanced nigrin b toxicity leading to the death of some animals. The histological analysis revealed that the most serious injury was inflicted on the small intestine crypts, which disappeared, and on the liver, which evidenced hepatotoxicity showing haemorrhagic areas. These findings raise concerns about the abuse of high concentrations of green tea polyphenols especially when the intestinal mucosa is damaged, for instance by toxins or therapeutic drugs.

Enhanced inhibition of prostate cancer xenograft tumor growth by combining quercetin and green tea

The chemopreventive activity of green tea (GT) is limited by the low bioavailability and extensive methylation of GT polyphenols (GTPs) in vivo. We determined whether a methylation inhibitor quercetin (Q) will enhance the chemoprevention of prostate cancer in vivo. Androgen-sensitive LAPC-4 prostate cancer cells were injected subcutaneously into severe combined immunodeficiency (SCID) mice one week before the intervention. The concentration of GTPs in brewed tea administered as drinking water was 0.07% and Q was supplemented in diet at 0.2% or 0.4%. After 6-weeks of intervention tumor growth was inhibited by 3% (0.2% Q), 15% (0.4% Q), 21% (GT), 28% (GT+0.2% Q) and 45% (GT+0.4% Q) compared to control. The concentration of non-methylated GTPs was significantly increased in tumor tissue with GT+0.4% Q treatment compared to GT alone, and was associated with a decreased protein expression of catechol-O-methyltransferase and multidrug resistance-associated protein (MRP)-1. The combination treatment was also associated with a significant increase in the inhibition of proliferation, androgen receptor and phosphatidylinositol 3-kinase/Akt signaling, and stimulation of apoptosis. The combined effect of GT+0.4% Q on tumor inhibition was further confirmed in another experiment where the intervention started prior to tumor inoculation. These results provide a novel regimen by combining GT and Q to improve chemoprevention in a non-toxic manner and warrant future studies in humans.

Green Tea Polyphenols and Cancer Chemoprevention of Genitourinary Cancer

Green tea, which has higher concentrations of polyphenols than other teas, has been correlated with reduced risk of various malignancies with most data supporting a potential protective role in prostate neoplasia. Preclinical studies over the last 25 years implicate constituent green tea catechins, epigallocatechin-3-gallate (EGCG) being the predominant form, as the main mechanistic ingredient in the observed biologic effects, which vary from proapoptotic effects to inhibition of androgen receptor and signal transduction pathways. There have been few prospective clinical trials of green tea polyphenols (GTP), especially with well-characterized formulations and doses. Although there have been hints of beneficial clinical activity in prostate neoplasia, other studies have raised concerns about the limited bioavailability and very low target-tissue concentrations of GTPs. At present there is no proven role for GTP supplementation in the prevention of genitourinary (GU) malignancies, but novel GTP formulations and further clinical testing may still support a future for GTP supplementation in GU cancer prevention.

Green Tea Polyphenol Epigallocatechin-3-Gallate Enhance Glycogen Synthesis and Inhibit Lipogenesis in Hepatocytes

The beneficial effects of green tea polyphenols (GTP) against metabolic syndrome and type 2 diabetes by suppressing appetite and nutrient absorption have been well reported. However the direct effects and mechanisms of GTP on glucose and lipid metabolism remain to be elucidated. Since the liver is an important organ involved in glucose and lipid metabolism, we examined the effects and mechanisms of GTP on glycogen synthesis and lipogenesis in HepG2 cells. Concentrations of GTP containing 68% naturally occurring (−)-epigallocatechin-3-gallate (EGCG) were incubated in HepG2 cells with high glucose (30 mM) under 100 nM of insulin stimulation for 24 h. GTP enhanced glycogen synthesis in a dose-dependent manner. 10 μM of EGCG significantly increased glycogen synthesis by 2fold (P < 0.05) compared with insulin alone. Western blotting revealed that phosphorylation of Ser9 glycogen synthase kinase 3β and Ser641 glycogen synthase was significantly increased in GTP-treated HepG2 cells compared with nontreated cells. 10 μM of EGCG also significantly inhibited lipogenesis (P < 0.01). We further demonstrated that this mechanism involves enhanced expression of phosphorylated AMP-activated protein kinase α and acetyl-CoA carboxylase in HepG2 cells. Our results showed that GTP is capable of enhancing insulin-mediated glucose and lipid metabolism by regulating enzymes involved in glycogen synthesis and lipogenesis.

Green Tea Polyphenols and Cancer Chemoprevention of Genitourinary Cancer

Green tea, which has higher concentrations of polyphenols than other teas, has been correlated with reduced risk of various malignancies with most data supporting a potential protective role in prostate neoplasia. Preclinical studies over the last 25 years implicate constituent green tea catechins, epigallocatechin-3-gallate (EGCG) being the predominant form, as the main mechanistic ingredient in the observed biologic effects, which vary from proapoptotic effects to inhibition of androgen receptor and signal transduction pathways. There have been few prospective clinical trials of green tea polyphenols (GTP), especially with well-characterized formulations and doses. Although there have been hints of beneficial clinical activity in prostate neoplasia, other studies have raised concerns about the limited bioavailability and very low target-tissue concentrations of GTPs. At present there is no proven role for GTP supplementation in the prevention of genitourinary (GU) malignancies, but novel GTP formulations and further clinical testing may still support a future for GTP supplementation in GU cancer prevention.

Effects of green tea polyphenols, insulin-like growth factor I and glucose on developmental competence of bovine oocytes

The present study examined the effects of green tea polyphenols (GTP), insulin-like growth factor-I (IGF-I) and glucose on oocyte in vitro maturation, subsequent embryo development and blastocyst quality in bovine. Cumulus-oocyte complexes (COC) were aspirated from the ovaries and cultured in synthetic oviduct fluid supplemented with MEM amino acids (SOFaa) media supplemented with one of the following supplements: GTP (0, 10, 15 and 20 µM), IGF-I (0, 50, 100 and 150 ng/mL) or glucose (0, 1.5, 5.6 and 20 mM) for 24 h. The results showed that oocytes cultured in media supplemented with 15 µM GTP, 100 ng/mL IGF-I and 5.6 mM glucose, in separate experiments, have higher cleavage and blastocyst rates compared with oocytes cultured in media without or with other concentration of GTP, IGF-I and glucose. Then these three substances with the concentration above were added together into SOFaa media and constituted a modified medium (Modified SOFaa). The COC were cultured in control SOFaa media and modified SOFaa media, respectively. The results showed that modified SOFaa media increased the intracellular glutathione concentration of matured oocytes, blastocyst rates and total cell numbers and cell numbers of inner cell mass per blastocyst compared with the control. Supplementing of GTP, IGF-I and glucose synchronously to maturation media can increase the intracellular GSH concentration of oocytes after in vitro maturation, and improve the embryo development and blastocyst quality in bovine.

Abstract B67: Inhibition of NFκB and proapoptotic Effect of Green Tea in Prostate Tumor Tissue: A Phase II clinical Trial in Men with Prostate Cancer

Abstract Background: Green tea polyphenols (GTPs) have been shown to play a role in the regulation of cell proliferation, apoptosis and inflammation in prostate cancer cells in vitro and in animal models using human prostate cancer cell xenografts. While there is extensive epidemiological and basic scientific evidence for these effects of GTPs, data from human intervention studies is much more limited. Objective: We conducted a phase II intervention study to evaluate the anticarcinogenic effects of green tea in prostate cancer by administering green tea in men prior to prostatectomy. Design: 79 men, diagnosed with prostate cancer and scheduled for prostatectomy, were randomized to either 6 cups of brewed green tea or water daily for 3-8 weeks prior to surgery. 67 men (GT group, N=34; control group, N=33) completed the intervention. Blood and urine samples were collected before and after the intervention and sections of prostate tissue were frozen as OCT blocks following the pathology evaluation. Serum prostate specific antigen (PSA) concentration was determined by ELISA assay and prostate tissue PSA protein concentration was measured by Western blot. The prostate concentration of GTPs and their metabolites was measured using high-performance liquid chromatography (HPLC) with CoulArray electrochemical detection. The protein expression of Ki67 (proliferation), Bcl2, Bax (apoptosis) and nuclear factor kappa B (NFκB) (inflammation) were determined by immunostaining in prostate tissue of confirmed tumor areas. Results: Statistical analysis within each treatment arm showed that the serum PSA concentration was significantly decreased in the GT group (final vs. baseline blood) (P&amp;lt;0.01), while no change was observed in the control group. Prostate tissue PSA protein expression was lower in men consuming GT compared to water control (p=0.06). Bioactive GTPs including epigallocatechin gallate (EGCG) and its methyl metabolite 4″-O-methyl EGCG and epicatechin gallate (ECG) were detected in prostate tissue from 31 of 34 men consuming GT but were absent in prostates in the control group. Intranuclear NFκB staining was decreased significantly while there was no change in cytoplasmic NFκB staining in prostate tumors from men drinking GT by comparison to tumors from the control group. The ratio of cytoplasmic staining of pro-apoptotic Bax to Bcl-2 was increased significantly while cytoplasmic Bcl2 and Bax staining were not changed. Nuclear Ki67 staining was not changed with GT consumption. Conclusion: Green tea consumption may contribute to the inhibition of prostate tumor growth through reducing inflammation and stimulating apoptosis. Analyses of additional markers are needed to confirm these findings. Citation Format: Susanne M. Henning, Piwen Wang, William J. Aronson, Catherine L. Carpenter, David Heber. Inhibition of NFκB and proapoptotic effect of green tea in prostate tumor tissue: A phase II clinical trial in men with prostate cancer. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B67.

Abstract B68: Antioxidant activity of green tea: A phase II clinical trial in men with prostate cancer

Abstract Background: Green tea (GT) contains green tea polyphenols (GTPs) which have been shown to play a role in the regulation of cell proliferation and apoptosis in prostate cancer cells in vitro and in animal models using human prostate cancer cell xenografts. GTPs are also potent scavengers of reactive oxygen species (ROS) which play a role in tumorigenesis. While there is extensive epidemiological and basic science evidence for these effects of GTPs, data from human intervention studies is much more limited. Objective: We conducted a phase II intervention study to evaluate the anticarcinogenic and antioxidant effects of green tea in prostate cancer by administering green tea in men prior to prostatectomy. Design: 79 men, diagnosed with prostate cancer and scheduled for prostatectomy, were randomized to either 6 cups of brewed green tea (GT group, N=34) or water (control group, N=33) daily for 3-8 weeks prior to surgery. 67 men completed the intervention. Blood and urine samples were collected before and after the intervention, and a section of prostate tissue was obtained following the pathology evaluation. Serum prostate specific antigen (PSA) concentration was determined by ELISA assay and prostate tissue PSA protein concentration was measured by Western blot. The prostate concentration of GTPs and their metabolites was measured using high-performance liquid chromatography (HPLC) with CoulArray electrochemical detection. The concentration of 8-hydroxydeoxyguanosine (8-OHdG), a biomarker for oxidative DNA damage, was measured in urine by HPLC. In addition, gene expression of the antioxidant enzymes superoxide dismutase (SOD) and catalase were determined in normal and tumor prostate tissue using real-time quantitative PCR. Results: Statistical analysis within each treatment arm showed that the serum PSA concentration significantly decreased in the GT group (final vs. baseline blood) (P&amp;lt;0.01), while no change was observed in the control group. The comparison of percent change in serum PSA between GT and control group showed a decreasing trend (p=0.085). Prostate tissue PSA protein expression was lower in men consuming GT compared to water control (p=0.06). The major bioactive component of GTPs, epigallocatechin gallate (EGCG) and its methyl metabolite 4″-O-methyl EGCG were found in prostate tissue in similar amounts, along with a small amount of epicatechin gallate. As compared to the pre-intervention level there was a significant decrease in urinary 8-OHdG concentration after GT intervention (83 vs. 50 nmol/g creatinine), while there was no change in the control group (54 vs. 55 nmol/g creatinine). Gene expression of SOD (p=0.087) and catalase (p=0.15) in the prostate tumor tissue normalized to normal prostate tissue in each individual showed a decreasing trend in men consuming GT as compared to the water control. Conclusion: The consumption of 6 cups of GT provided antioxidant protection, which may contribute to an inhibitory effect on prostate tumor growth in humans. Large-scale human intervention studies are needed to confirm these findings. Citation Format: Piwen Wang, William Aronson, Narine Abgaryan, Catherine L. Carpenter, Jaydutt V. Vadgama, David Heber, Susanne M. Henning. Antioxidant activity of green tea: A phase II clinical trial in men with prostate cancer. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B68.

Mitigation of Oxidative Damage by Green Tea Polyphenols and Tai Chi Exercise in Postmenopausal Women with Osteopenia

BackgroundOsteoporosis is a degenerative bone disease predominantly in postmenopausal women. Green tea polyphenols (GTP) and Tai Chi (TC) have been shown to be beneficial on human bone health. This study examined the efficacy of GTP and TC on mitigation of oxidative damage in postmenopausal women with osteopenia.MethodsA 6-month randomized and placebo-controlled clinical trial was conducted in 171 postmenopausal women with osteopenia, who were recruited from Lubbock County, Texas. These participants were treated with placebo, GTP (500 mg daily), placebo + TC (60-minute group exercise, 3 times/week), or GTP (500 mg daily) + TC (60-minute group exercise, 3 times/week), respectively. Their blood and urine samples were collected at the baseline, 1-, 3- and 6-months during intervention for assessing levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidative DNA damage biomarker, and concentrations of serum and urine GTP components.ResultsThe elevated concentrations of serum and urinary GTP components demonstrated a good adherence for the trial. A significant reduction of urinary 8-OHdG concentrations was found in all three treated groups during 3-month (P<0.001) and 6-month (P<0.001) intervention, as compared to the placebo group. The significant time- and dose-effects on mitigation of the oxidative damage biomarker were also found for GTP, TC, and GTP+TC intervened groups.ConclusionOur study demonstrated that GTP and TC interventions were effective strategies of reducing the levels of oxidative stress, a putative mechanism for osteoporosis in postmenopausal women, and more importantly, working in an additive manner, which holds the potential as alternative tools to improve bone health in this population.Trial RegistrationClinicalTrials.gov NCT00625391

Abstract 607: Enhanced inhibition of prostate cancer xenograft tumor growth by combining quercetin and green tea

Abstract The chemopreventive activity of green tea (GT) and green tea polyphenols (GTPs) in prostate cancer has been demonstrated in preclinical cell culture and animal models. However, extensive methylation of GTPs in vivo to less active methyl-metabolites may be limiting the anti-cancer activity of GT. The objective of the present study was to investigate whether quercetin (Q), a natural inhibitor of catechol-O-methyltransferase (COMT), will increase tissue concentrations of non-methylated GTPs and enhance the inhibition of xenograft tumor growth in severe combined immune deficient (SCID) mice. Androgen-sensitive LAPC-4 prostate cancer cells were injected subcutaneously into SCID mice (n=12 per group). SCID mice were randomly assigned to four groups: control, GT, Q, and GT + Q treatment. The interventions were initiated when tumors reached volume of 10mm3. The final concentration of GTPs in brewed tea administered as drinking water was 0.07% and Q was supplemented in AIN-93G diet at a concentration of 4g/kg diet. There were no differences in food intake, body weight or water consumption during the intervention. Tissue bioavailability of GTPs was increased significantly by 2 to 3-fold in lung, kidney and xenograft tumors and showed a trend to increase by 1.3-fold in liver tissue by GT and Q treatment compared to GT alone. Methylation of epigallocatechin gallate (EGCG), the main polyphenol in green tea, was decreased in tissues from mice in the GT+Q group. After 6 weeks, tumor growth was inhibited by 16% (Q alone), 21% (GT alone), and 45% (GT+Q) compared to the control group. Western blot analysis demonstrated a significant inhibition of methyl transferases such as COMT (31%) and DNA methyltransferase (DNMT) (52%) in tumors from the GT+Q group compared to the control. It has been demonstrated previously that EGCG can act as androgen receptor (AR) antagonist as well as inhibit angiogenesis via inhibition of the vascular endothelial growth factor (VEGF). Together Q+GT inhibited protein expression of AR (35%), prostate-specific antigen (PSA) (39%), and VEGF (25%) more than either GT or Q alone. This study demonstrates an enhanced inhibition of prostate tumor growth when GT and Q are co-administered and this is likely due to inhibition of methylation resulting in enhanced anti-tumor activity of EGCG via effects on angiogenesis, and androgen-mediated tumor growth. This study sets the stage for future human interventions to confirm the increase in bioavailability and chemoprevention using GT in combination with Q. This project was supported by DOD grant W81XWH-10-1-0298 and NIH grant RO3 CA150047-01. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 607. doi:1538-7445.AM2012-607

Inhibitory Effects of Green Tea Polyphenols on the Retrogradation of Starches from Different Botanical Sources

This paper aims at investigating the effects of green tea polyphenols (GTPs) on the retrogradation of potato, rice, and maize starches. Starch/GTPs mixing ratios were 2/0, 2/0.1, 2/0.2, and 2/0.3 (w/w) that equated with starch containing 0%, 5%, 10%, and 15% GTPs (based on starch weight), respectively. The analytic samples had a water–starch/GTPs ratio of 2:1. The effects of GTPs on the retrogradation of these starches were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The analysis of DSC indicates that the temperature and enthalpy of gelatinization of all the tested starches decreased as the GTPs level increased. After storage at 4 °C, retrogradation enthalpy (ΔHret) for potato starches with 5%, 10%, and 15% GTPs appeared after 10 days of storage, however ΔHret for rice and maize starches with 10% and 15% GTPs did not appear until storage of 20 days, and both the ΔHret and degree of retrogradation of the three starches significantly decreased with the increased level of GTPs. After 10 days of storage at 4 °C, the analysis of XRD shows that the intensity of X-ray diffraction peaks of potato starch gradually decreased with the concentration of GTPs increasing, and rice and maize starch gels with 10% and 15% GTPs had almost no recrystallization of the retrogradation. It is concluded that the addition of GTPs considerably inhibits the retrogradation of rice, maize, and potato starches.

Effect of green tea polyphenols on the gelatinization and retrogradation of rice starches with different amylose contents

The effect of green tea polyphenols (GTP) on the property of rice starch was investigated. 0, 5, 10 and 15% of GTP (based on rice starch weight) was added to rice starches with high (HAC), intermediate (IAC) and low (LAC) amylose contents, respectively. The gelatinization and retrogradation properties of rice starches with different amylose content containing different levels of GTP were analyzed by differential scanning calorimetry (DSC). The results exhibited that GTP could retard retrogradation of the three rice starches, which was further proved by X-ray diffraction investigation. In the DSC analysis, the temperature and enthalpy of starches gelatinization decreased with the concentration of GTP increasing. After storage at 4°C for 20 days, retrogradation enthalpy (ΔHret) for all rice starches with different levels GTP began to appear, and the ΔHret and degree of retrogradation (DR%) of the three rice starches significantly decreased with the increased level of GTP. The X-ray diffractogram indicate that all the three gelatinized rice starch gels showed B-type X-ray diffraction patterns, and the B-type X-ray diffraction patterns gradually disappeared with the concentration of GTP increasing. Key words: Green tea polyphenols, rice starch, gelatinization, retrogradation, differential scanning calorimetry, X-ray diffraction.

COMPARISON STUDY OF THE EFFECTS OF DIFFERENT CRUDE GREEN TEA POLYPHENOLS ON THE QUALITY OF DRIED CATFISH DURING AMBIENT STORAGE

ABSTRACT The comparative antioxidant effect of adding different crude green tea polyphenols (GTP) and vitamin C (VC) on the susceptibility of dried catfish (Clarias gariepinus) quality changes during ambient storage was investigated. Catfish fillet was treated with different concentrations of GTP: 1% NaCl plus 0.01% GTP, 1% NaCl plus 0.03% GTP and 1% NaCl plus 0.01% of VC before drying process. Control muscle sample (CK) was treated only with 1% of NaCl solution (without GTP extract) contained only 1% NaCl, but not GTP. Samples were oven‐dried for 5 days at 45C. The quality change was evaluated over a course of 4 weeks for pH, volatile basis nitrogen, peroxide value, thiobarbituric acid reactive substances and free fatty acid. The results indicated that the most effective antioxidant was GTP and there was no significant differences (P &lt; 0.01) between laboratory‐extracted crude green tea polyphenol and commercial crude green tea polyphenol. This study pointed out that GTP is a good natural antioxidant in comparison with VC and CK, so, it could be easily used in food industry to improve quality and shelf life of food products.PRACTICAL APPLICATIONSFish is a very important foodstuff because of its high protein content and nutritional value. It is also a greatly perishable product, especially in hot climates and tropical areas where cold preservation techniques are often missing and quality losses can occur very rapidly after catch. Addition of antioxidants during drying process can be used to inhibit lipid oxidation and microbial and insect infestation. However, questions regarding the safety of synthetic antioxidants together with consumer's preference have led to increased interest and research on natural antioxidants. Consumers favor natural antioxidants, which may have a positive effect on human health. Green tea polyphenol (GTP) as a natural antioxidant has lower toxicity than synthetic antioxidants like butylated hydroxyanisole and butylated hydroxytoluene, and more effectiveness than VC. It can be used as an alternative to VC to extend the quality of fish and fish products during storage.