Inhibition of aromatase activity by green tea extract catechins and their endocrinological effects of oral administration in rats

Prevention of Male Late-Onset Hypogonadism by Natural Polyphenolic Antioxidants

Androgen production primarily occurs in Leydig cells located in the interstitial compartment of the testis. In aging males, testosterone is crucial for maintaining muscle mass and strength, bone density, sexual function, metabolic health, energy levels, cognitive function, as well as overall well-being. As men age, testosterone production by Leydig cells of the testes begins to decline at a rate of approximately 1% per year starting from their 30s. This review highlights recent findings concerning the use of natural polyphenolics compounds, such as flavonoids, resveratrol, and phenolic acids, to enhance testosterone production, thereby preventing age-related degenerative conditions associated with testosterone insufficiency. Interestingly, most of the natural polyphenolic antioxidants having beneficial effects on testosterone production tend to enhance the expression of the steroidogenic acute regulatory protein (Star) gene in Leydig cells. The STAR protein facilitates the entry of the steroid precursor cholesterol inside mitochondria, a rate-limiting step for androgen biosynthesis. Natural polyphenolic compounds can also improve the activities of steroidogenic enzymes, hypothalamus-pituitary gland axis signaling, and testosterone bioavailability. Thus, many polyphenolic compounds such as luteolin, quercetin, resveratrol, ferulic acid phenethyl ester or gigantol may be promising in delaying the initiation of late-onset hypogonadism accompanying aging in males.

Ameliorative effect of licorice extract against the detrimental effect of glyphosate-based pesticide: Toxicity and health

This study sheds the light on the potential of licorice (Glycyrrhiza glabra) root aqueous extract as a cornerstone for mitigating and detoxifying the residues of the widely used agricultural Glyphosate-based pesticides (GBPs). This study examined the GBPs toxic effects on kidney, liver, thyroid functions, and apoptosis using 50 adult male albino rats. All rats were divided into 5 groups, with 10 each. Control: served as untreated rats. GBP: rats were treated with 1 mL glyphosate solution 24 % orally for three weeks. The glyphosate-treated rats were gavaged with licorice root aqueous extractsolution (100, 200, and 300 mg/mLdistilled water, respectively) daily for three weeks. Licorice root aqueous extract solution (300 mg/mL distilled water) yielded notable reductions in liver, kidney enzymes, albumin, and AFP levels within the serum. Immunological tests, including immunohistochemical evaluations of caspase-3 and TNF-α expressions revealed a dose-dependent attenuation of apoptosis and inflammation with licorice intervention. This will provide a valuable perspective for agricultural practices future and paving the way for a more sustainable approach for using GBPs in animal agriculture industries.

Effects of garlic (Allium sativum L) and Citrullus colocynthis (L.) Schrad individually and in combination on male reproductive damage due to diabetes: suppression of the AGEs/RAGE/Nox-4 signaling pathway

BACKGROUND

Diabetes Mellitus is associated with disturbances in male reproductive function and fertility. Studies have shown that oxidative stress with the subsequent inflammation and apoptosis cause these complications in diabetes. Garlic (G) (Allium sativum L) and Citrullus colocynthis (L.) Schrad (C) both have antidiabetic and antioxidant properties. Recently, we demonstrated their synergistic effects in alleviating reproductive complications when administered concomitantly. However, as even medicinal plants in long term usage may lead to some unwanted side effects of their own, we examined whether with half the original doses of these two medicinal plants we could achieve the desired results.

METHODS

Thirty-five male Wistar rats were divided into five groups (n = 7/group): Control, Diabetic, Diabetic + G (0.5 ml/100 g BW), Diabetic + C (5 mg/kg BW) and Diabetic + GC (0.5 ml/100 g BW of garlic and 5 mg/kg BW of C. colocynthis) groups. The experimental period was 30 days.

RESULTS

Oxidative stress, advanced glycation end products (AGEs), immunoexpression of caspase-3, and expression of mRNAs for receptor for advanced glycation end products (RAGE), NADPH oxidase-4 (NOX-4) and nuclear factor kappa B increased in testis of diabetic rats. Treatment with garlic and C. colocynthis alone showed some beneficial effects, but in the combination form the effectiveness was more profound.

CONCLUSIONS

We conclude that the combination therapy of diabetic rats with lower doses is still as efficient as higher doses; therefore, the way forward for reducing complications in long term consumption.

Long-Term Consumption of Green Tea Can Reduce the Degree of Depression in Postmenopausal Women by Increasing Estradiol

Postmenopausal women face a higher risk of depression due to a combination of social and physiological factors. As a beverage rich in a variety of bioactive substances, green tea has significant effects on metabolism, inflammation and endocrine, and may reduce the risk of depression, but few studies have looked at the effects of green tea on postmenopausal women. Therefore, we designed this study to investigate the effects of long-term green tea consumption on inflammation, endocrine and depression levels in postmenopausal women. We investigated a tea-producing village and eventually included 386 postmenopausal women, both in the tea drinking and control groups. The results showed that there were significant differences in the degree of insomnia, degree of depression, BMI, SII and estradiol between the two groups. And, green tea consumption may reduce the risk of depression through the mediating pathway of sleep, SII and estradiol. In summary, long-term green tea consumption can reduce the risk of depression in postmenopausal women by reducing inflammation and increasing estradiol. This kind of living habit deserves further promotion.

Unlocking Potentially Therapeutic Phytochemicals in Capadulla (Doliocarpus dentatus) from Guyana Using Untargeted Mass Spectrometry-Based Metabolomics

Doliocarpus dentatus is thought to have a wide variety of therapeutic phytochemicals that allegedly improve libido and cure impotence. Although a few biomarkers have been identified with potential antinociceptive and cytotoxic properties, an untargeted mass spectrometry-based metabolomics approach has never been undertaken to identify therapeutic biofingerprints for conditions, such as erectile dysfunction, in men. This study executes a preliminary phytochemical screening of the woody vine of two ecotypes of D. dentatus with renowned differences in therapeutic potential for erectile dysfunction. Liquid chromatography-mass spectrometry-based metabolomics was used to screen for flavonoids, terpenoids, and other chemical classes found to contrast between red and white ecotypes. Among the metabolite chemodiversity found in the ecotype screens, using a combination of GNPS, MS-DIAL, and SIRIUS, approximately 847 compounds were annotated at levels 2 to 4, with the majority of compounds falling under lipid and lipid-like molecules, benzenoids and phenylpropanoids, and polyketides, indicative of the contributions of the flavonoid, shikimic acid, and terpenoid biosynthesis pathways. Despite the extensive annotation, we report on 138 tentative compound identifications of potentially therapeutic compounds, with 55 selected compounds at a level-2 annotation, and 22 statistically significant therapeutic biomarkers, the majority of which were polyphenols. Epicatechin methyl gallate, catechin gallate, and proanthocyanidin A2 had the greatest significant differences and were also relatively abundant among the red and white ecotypes. These putatively identified compounds reportedly act as antioxidants, neutralizing damaging free radicals, and lowering cell oxidative stress, thus aiding in potentially preventing cellular damage and promoting overall well-being, especially for treating erectile dysfunction (ED).

Synergistic properties of garlic and Citrullus colocynthis on reproductive injury caused by diabetes in male rats: Structural and molecular evidence

This study evaluates the synergistic effect of garlic and Citrullus colocynthis on diabetic reproductive damage by suppressing the AGEs/RAGE/Nox-4 signaling pathway. Thirty-five male Wistar rats were divided into five groups (n = 7/group): Control, Diabetic, Diabetic+G (Garlic, 1 mL/100 g b.w), Diabetic+C (C. colocynthis, 10 mg/kg b.w) and Diabetic+GC (Garlic, 1 mL/100 g b.w and C. colocynthis, 10 mg/kg b.w) groups. At the end of the experimental period (30 days), in diabetic rats, glucose increased, and body & testis weight, luteinizing hormone (LH) and testosterone levels, and sperm count decreased significantly and histopathological injuries were observed. In addition, they have increased testicular apoptosis and oxidative stress. Also, the mechanism based on advanced glycation end products (AGEs)/receptors for advanced glycation end products (RAGE)/NADPH oxidase-4 (Nox-4) was activated in diabetic rats. Separate consumption of garlic and C. colocynthis in Diabetic+G and Diabetic+C groups alleviated the negative adverse effect of diabetes to some extent, but when they were used in the combination form (Diabetic+GC) improvement was profound. Testis histopathology, increased body and testis weight, and enhanced capacity in protecting diabetic reproductive injury was seen. Decreases in testosterone and LH concentration and sperm count in diabetic rats were also reversed by combined administration of garlic and C. colocynthis. It regulated oxidative stress markers, meanwhile reducing caspase-3 immunoexpression. In addition, overexpression of RAGE, Nox-4 and nuclear transcription factor-κB (NF-κB) was inhibited by the combination of garlic and C. colocynthis. PRACTICAL APPLICATIONS: Diabetes mellitus is wide spread all around the world with variety of complications in body including reproductive system in which patients suffer from physical and psychological aspects. Despite many efforts in providing agents for controlling diabetes and its complications, economic conditions of some countries make it difficult for people to provide costly medicine and as a result, they have to bear the complications until they pass away. However, traditional medicine is still finding its way, especially in poor countries with emphasis on medicinal plants. There have been many studies on plants to alleviate diabetes or its side effects. But, using one plant for long term, may be not so effective. Here, we attempted to find whether two plants from two different species can show more efficacy than each one alone. We noticed garlic and Citrullus colocynthis despite having beneficial effects when used alone, they could show synergistic effects in combination.

Histidine decarboxylase inhibitors: a novel therapeutic option for the treatment of leydigioma

Recent reports indicate an increase in Leydig cell tumor (LCT) incidence. Radical orchiectomy is the standard therapy in children and adults, although it entails physical and psychosocial side effects. Testis-sparing surgery can be a consideration for benign LCT of 2.5 cm or less in size. Malignant LCTs respond poorly to conventional chemotherapy, so new treatment modalities are needed. In this study, we observed increased histidine decarboxylase expression and pro-angiogenic potential in LCT surgically resected from pediatric patients (fetal to pubertal) vs control samples from patients without endocrine or metabolic disorders which were collected at necropsy. We, therefore, evaluated for the first time the antitumor efficacy of two histidine decarboxylase inhibitors (α-methyl-dl-histidine dihydrochloride (α-MHD) and epigallocatechin gallate (EGCG)), alone and combined with carboplatin, in two preclinical models of LCT. MA-10 and R2C Leydig tumor cells, representing two different LCT subtypes, were used to generate syngeneic and xenograft mouse LCT models, respectively. In the syngeneic model, monotherapy with α-MHD effectively reduced tumor growth and angiogenesis. In the xenografts, which showed co-expression of histidine decarboxylase and CYP19, the combination of EGCG plus carboplatin was the most effective therapy, leading to LCT growth arrest and undetectable levels of plasmatic estradiol. Testicular and body weights remained unaltered. On the basis of this study, histidine decarboxylase may emerge as a novel pharmacological target for LCT treatment.

Safety and preliminary efficacy on cognitive performance and adaptive functionality of epigallocatechin gallate (EGCG) in children with Down syndrome. A randomized phase Ib clinical trial (PERSEUS study)

PURPOSE

Although some caregivers are using epigallocatechin gallate (EGCG) off label in hopes of improving cognition in young adults with Down syndrome (DS), nothing is known about its safety, tolerability, and efficacy in the DS pediatric population. We aimed to evaluate safety and tolerability of a dietary supplement containing EGCG and if EGCG improves cognitive and functional performance.

METHODS

A total of 73 children with DS (aged 6-12 years) were randomized. Participants received 0.5% EGCG (10 mg/kg daily dose) or placebo for 6 months with 3 months follow up after treatment discontinuation.

RESULTS

In total, 72 children were treated and 66 completed the study. A total of 38 participants were included in the EGCG group and 35 in the placebo group. Of 72 treated participants, 62 (86%) had 229 treatment-emergent adverse events (AEs). Of 37 participants in the EGCG group, 13 (35%) had 18 drug-related treatment-emergent AEs and 12 of 35 (34%) from the placebo group had 22 events. In the EGCG group, neither severe AEs nor increase in the incidence of AEs related to safety biomarkers were observed. Cognition and functionality were not improved compared with placebo. Secondary efficacy outcomes in girls point to a need for future work.

CONCLUSION

The use of EGCG is safe and well-tolerated in children with DS, but efficacy results do not support its use in this population.

The Role of Aromatase Enzyme in Hormone Related Diseases and Plant-Based Aromatase Inhibitors as Therapeutic Regimens

Medicinal plants have a long history of use as food and remedy in traditional and modern societies, as well as have been used as herbal drugs and sources of novel bioactive compounds. They provide a wide array of chemical compounds, many of which can not be synthesized via current synthesis methods. Natural products may provide aromatase inhibitory activity through various pathways and may act clinically effective for treating pathologies associated with excessive aromatase secretion including breast, ovarian and endometrial cancers, endometriosis, uterine fibroid, benign prostatic hyperplasia (BPH), prostate cancer, infertility, and gynecomastia. Recent studies have shown that natural products with aromatase inhibitory activity, could also be good options against secondary recurrence of breast cancer by exhibiting chemopreventive effects. Therefore, screening for new plant-based aromatase inhibitors may provide novel leads for drug discovery and development, particularly with increased clinical efficacy and decreased side effects.

Estrogen regulates the expression of retinoic acid synthesis enzymes and binding proteins in mouse skin

Topical 17-beta-estradiol (E2) regulates the hair cycle, hair shaft differentiation, and sebum production. Vitamin A also regulates sebum production. Vitamin A metabolism proteins localized to the pilosebaceous unit (PSU; hair follicle and sebaceous gland); and were regulated by E2 in other tissues. This study tests the hypothesis that E2 also regulates vitamin A metabolism in the PSU. First, aromatase and estrogen receptors localized to similar sites as retinoid metabolism proteins during mid-anagen. Next, female and male wax stripped C57BL/6J mice were topically treated with E2, the estrogen receptor antagonist ICI 182,780 (ICI), letrozole, E2 plus letrozole, or vehicle control (acetone) during mid-anagen. E2 or one of its inhibitors regulated most of the vitamin A metabolism genes and proteins examined in a sex-dependent manner. Most components were higher in females and reduced with ICI in females. ICI reductions occurred in the premedulla, sebaceous gland, and epidermis. Reduced E2 also reduced RA receptors in the sebaceous gland and bulge in females. However, reduced E2 increased the number of retinal dehydrogenase 2 positive hair follicle associated dermal dendritic cells in males. These results suggest that estrogen regulates vitamin A metabolism in the skin. Interactions between E2 and vitamin A have implications in acne treatment, hair loss, and skin immunity.

A comprehensive insight into effects of green tea extract in polycystic ovary syndrome: a systematic review

BACKGROUND

Polycystic ovary syndrome (PCOS), as the most common endocrine disorder in reproductive-aged women, is characterized by oxidative stress and ovarian tissue inflammation. Green tea extract (GTE) potentially possesses therapeutic effects for PCOS because of the antioxidant and anti-inflammatory compounds. This systematic review evaluates the potential roles of GTE on metabolic variables, hormone levels, and ovarian function in PCOS.

METHODS

A systematic review was conducted of published studies reporting the effects of GTE on PCOS. Several major databases, including PubMed, SCOPUS, and Google Scholar, were searched up from inception to April 2021. Clinical trials and animal studies that assessed the effects of GTE on PCOS were eligible for inclusion.

RESULTS

Of 314 articles found in the search, four human studies and four animal studies were included. All studies in humans showed the effects of GTE on weight loss. GTE's effect on decreasing testosterone levels in humans and LH levels in animals were also reported. In addition, increases in FSH and progesterone levels in animal models were observed. Although GTE improved fasting blood sugar and insulin levels, the effect of GTE on inflammatory parameters, such as TNF-alpha and IL-6 and antioxidant status, was limited to animal studies.

CONCLUSION

Therefore, this review suggests that GTE could be considered a potential agent to attenuate PCOS complications mainly due to its effect on weight loss and glycemic levels. However, more studies are needed to formulate conclusions about the effects and mechanisms of GTE in PCOS.

Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels

Thyroid hormones are necessary for the normal functioning of physiological systems. Therefore, knowledge of any factor (whether genetic, environmental or intrinsic) that alters the levels of thyroid-stimulating hormone (TSH) and thyroid hormones is crucial. Genetic factors contribute up to 65% of interindividual variations in TSH and thyroid hormone levels, but many environmental factors can also affect thyroid function. This review discusses studies that have analyzed the impact of environmental factors on TSH and thyroid hormone levels in healthy adults. We included lifestyle factors (smoking, alcohol consumption, diet and exercise) and pollutants (chemicals and heavy metals). Many inconsistencies in the results have been observed between studies, making it difficult to draw a general conclusion about how a particular environmental factor influences TSH and thyroid hormone levels. However, lifestyle factors that showed the clearest association with TSH and thyroid hormones were smoking, body mass index (BMI) and iodine (micronutrient taken from the diet). Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels. Among the pollutants analyzed, most studies observed a decrease in thyroid hormone levels after exposure to perchlorate. Future studies should continue to analyze the impact of environmental factors on thyroid function as they could contribute to understanding the complex background of gene-environment interactions underlying the pathology of thyroid diseases.

The protective effect of Kombucha against silver nanoparticles-induced toxicity on testicular tissue in NMRI mice

Silver nanoparticles (SNPs) can pass from the cell membrane and testicular blood barrier due to their small size, and by increasing oxidative stress they cause disorder in the male reproductive system. Kombucha is a traditional fermented drink with detoxification and potent antioxidant properties. We aimed to examine the protective effect of Kombucha against the damages due to SNPs on the testis tissue. In this experimental study, NMRI mice were randomly separated into four groups (n = 6), namely control (distilled water), SNPs (500 mg/kg), Kombucha extract (9 ml/kg) and SNPs + Kombucha, and were treated with gavage for 35 days. A significant decrease in testosterone level and total antioxidant capacity, and a significant increase in malondialdehyde concentration was observed in the SNPs group in comparison with the control group. Histological studies on the testis of mice treated with SNPs showed vacuolation, decrease in generational epithelium thickness, seminiferous tubules diameter, testis volume and the number of spermatozoa in lumen of the seminiferous tubule and increase in the volume of interstitial space while the mentioned parameters were improved in the SNPs + Kombucha group compared to the SNPs group. Kombucha reduces the adverse effects of SNPs on testis tissue and improves the function of the male reproductive system.

Green tea consumption increases sperm concentration and viability in male rats and is safe for reproductive, liver and kidney health

Green tea is a popularly consumed beverage worldwide and contains polyphenols, whose antioxidant activities could improve sperm parameters and fertility thereof. We investigated the effect of green tea on the male rat reproductive system as well as its safety. Male Wistar rats were administered 2 and 5% aqueous extract of green tea for 52 days’ ad libitum, while the control group received tap water. Total polyphenol, flavanol, flavonol and soluble solids significantly increased in a concentration-dependent manner in vitro (P < 0.01). Weights of body, testis, epididymis, prostate gland, seminal vesicles, and liver, serum levels of testosterone, ferric reducing antioxidant power, creatinine, and sperm motility, remained unchanged (P > 0.05). Kidney weight, sperm concentration and vitality, spontaneous acrosome reaction increased (P < 0.05), while alanine transaminase and aspartate transaminase levels decreased (P < 0.05). Catalase, superoxide dismutase, glutathione and lipid peroxidation remained unchanged in the testes, liver and kidney (P > 0.05). Histological sections of testis, epididymis, kidney and liver showed no conspicuous alteration. Diameter and epithelial height of seminiferous tubule decreased, while caudal epididymis epithelial height increased (P < 0.01). Consumption of green tea in the conditions used in the present study seems to be safe and improved sperm parameters. However, subtle structural changes observed in the decreased diameter and epithelial height of the seminiferous tubule and increased acrosome reaction needs further investigation.

Improvement of Testicular Steroidogenesis Using Flavonoids and Isoflavonoids for Prevention of Late-Onset Male Hypogonadism

Androgen production, being important for male fertility, is mainly accomplished by the Leydig cells from the interstitial compartment of the testis. Testosterone plays a critical role in testis development, normal masculinization, and the maintenance of spermatogenesis. Within seminiferous tubules, appropriate Sertoli cell function is highly dependent on testicular androgen levels and is essential to initiate and maintain spermatogenesis. During aging, testosterone production by the testicular Leydig cells declines from the 30s in humans at a rate of 1% per year. This review outlines the recent findings regarding the use of flavonoids and isoflavonoids to improve testosterone production, contributing to normal spermatogenesis and preventing age-related degenerative diseases associated with testosterone deficiency. With the cumulation of information on the actions of different flavonoids and isoflavonoids on steroidogenesis in Leydig cells, we can now draw conclusions regarding the structure-activity relationship on androgen production. Indeed, flavonoids having a 5,7-dihydroxychromen-4-one backbone tend to increase the expression of the steroidogenic acute regulatory protein (StAR), being critical for the entry of cholesterol into the mitochondria, leading to increased testosterone production from testis Leydig cells. Therefore, flavonoids and isoflavonoids such as chrysin, apigenin, luteolin, quercetin, and daidzein may be effective in delaying the initiation of late-onset hypogonadism associated with aging in males.

Applications of Tea (Camellia sinensis) and its Active Constituents in Cosmetics

Studies on the cosmetic applications of plant extracts are increasingly appearing in the scientific literature, which is due to the growing popularity of skincare products around the world. In the light of the observed changes, a return to natural treatment and skincare with cosmetics free of harmful substances or toxic preservatives is visible. Currently, tea extracts, due to their rich composition and various biological actions, play an important role among the dietary supplements and cosmetics. This review is intended to collect the reports on the properties of the tea plant, its extracts and preparations in cosmetology: for skin care products and for the treatment of selected dermatological diseases. Particular attention is paid to its antioxidant, anti-hyaluronidase, anti-inflammatory, slimming, hair-strengthening, photoprotective and sealing blood vessels properties.

A Comprehensive Insight on the Health Benefits and Phytoconstituents of Camellia sinensis and Recent Approaches for Its Quality Control

Tea, Camellia sinensis, which belongs to the family Theaceae, is a shrub or evergreen tree up to 16 m in height. Green tea is very popular because of its marked health benefits comprising its anticancer, anti-oxidant, and antimicrobial activities, as well as its effectiveness in reducing body weight. Additionally, it was recognized by Chinese people as an effective traditional drink required for the prophylaxis against many health ailments. This is due to the complex chemical composition of green tea, which comprises different classes of chemical compounds, such as polyphenols, alkaloids, proteins, minerals, vitamins, amino acids, and others. The beneficial health effects of green tea ultimately led to its great consumption and increase its liability to be adulterated by either low-quality or non-green tea products with concomitant decrease in activity. Thus, in this review, green tea was selected to highlight its health benefits and phytoconstituents, as well as recent approaches for its quality-control monitoring that guarantee its incorporation in many pharmaceutical industries. More research is needed to find out other more biological activities, active constituents, and other simple and cheap techniques for its quality assurance that ascertain the prevention of its adulteration.

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.

Green Tea Catechin Extract Supplementation Does Not Influence Circulating Sex Hormones and Insulin-Like Growth Factor Axis Proteins in a Randomized Controlled Trial of Postmenopausal Women at High Risk of Breast Cancer

BACKGROUND

Consumption of green tea has been associated with reduced risk of breast cancer. Hormonal modulation has been suggested as one of the potential underlying mechanisms; however, it has yet to be fully elucidated in large, long-term human clinical trials.

OBJECTIVE

We investigated the effects of decaffeinated green tea extract (GTE) on circulating sex hormones and insulin-like growth factor (IGF) proteins.

METHODS

We conducted a placebo-controlled double-blind randomized clinical trial recruiting from 8 clinical centers in Minnesota. Participants were 538 healthy postmenopausal women randomly assigned to the GTE group (463 completed the study; mean age = 60.0 y) and 537 to the placebo group (474 completed; mean age = 59.7 y). Women in the GTE group orally took 4 decaffeinated capsules containing 1315 mg total catechins including 843 mg epigallocatechin-3-gallate daily for 1 y, whereas women in the placebo group took similar capsules containing no tea catechins. Blood sex hormones (estrone, estradiol, androstenedione, testosterone, and sex hormone-binding globulin) and IGF proteins (IGF-1 and IGF binding protein-3) were quantified at baseline and months 6 (for IGF proteins only) and 12, and were assessed as secondary outcomes of the study using a mixed-effect repeated-measures ANOVA model.

RESULTS

Women in the GTE group had significantly higher blood total estradiol (16%; P = 0.02) and bioavailable estradiol (21%; P = 0.03) than in the placebo group at month 12. There was a statistically significant interaction between GTE supplementation and duration of treatment on estradiol and bioavailable estradiol (both Ps for interaction = 0.001). The catechol-O-methyltransferase genotype did not influence blood sex hormones before or after GTE supplementation. The circulating concentrations of IGF proteins were comparable between GTE and placebo groups at all 3 time points.

CONCLUSION

These results suggest that a 12-mo GTE supplementation significantly increases circulating estradiol concentrations in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00917735.

Potential ameliorative effects of epigallocatechin‑3‑gallate against testosterone-induced benign prostatic hyperplasia and fibrosis in rats

Green tea is among the most popular beverages in the world and is an important source of phytoestrogens. Epigallocatechin‑3‑gallate (EGCG) is the major polyphenol in green tea. The aim of this study was to investigate the anti-benign prostatic hyperplasia (BPH) activity and underling mechanisms of EGCG in testosterone-induced BPH rats and in BPH-1 cells. Prostatic levels of oxidative stress and inflammation makers, as well as angiogenesis related growth factors were measured. Additionally, the prostatic levels of sex hormonal mediators (androgen receptor (AR), estrogen receptor (ER)-α and ER-β), hypoxia-inducible factor (HIF)-1α, transforming growth factor-β1 (TGF-β1), type I TGF-β receptor (TGF-βRI), Smad3, phosphorylation-Smad3 (p-Smad3), epithelial-mesenchymal transition (EMT) markers (E-cadherin, collagen-I, fibronectin and α-SMA) and microRNA (miR)-133a/b were analyzed by immunohistochemistry assay, western blot and/or quantitative RT-PCR. It was observed that EGCG attenuated the prostatic oxidative stress and inflammatory microenvironment, ameliorated prostatic hyperplasia and collagen deposition, reduced the levels of angiogenesis related growth factors, inhibited the over-expression of AR, ER-α, HIF-1α, TGF-β1, TGF-βRI and p-Smad3, enhanced the expression of ER-β, increased the levels of miR-133a/b, as well as relieved prostatic EMT in rats. Both HIF-1α inhibitor and EGCG decreased the expression of HIF-1α and TGF-β1, as well as attenuated EMT in BPH-1 cells. It indicated that EGCG could attenuate testosterone-induced BPH and fibrosis.

The association between green tea consumption and breast cancer risk: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to critically evaluate the relation between green tea (GT) consumption and the risk of breast cancer. Popular electronic databases were systematically searched for papers in English language. All case-control and cohort studies in addition to randomized clinical trials were included if they assessed the chemopreventive effects of GT on breast cancer. The quality of included studies was assessed using the Newcastle-Ottawa and Jadad scale. This systematic review comprised 14 studies: 9 case-control studies, 4 cohort studies, and 1 clinical trial. Odds ratio (OR) in case-control studies suggested that women in the group receiving the highest level of GT had 19% reduction in breast cancer risk compared with those who received the lowest level of GT (summary OR = 0.81, p = .031; 95% CI [0.66, 0.981]; heterogeneity, I²  = 71.53, p < .001, random effect model; 9 studies). OR in cohort studies also showed no significant difference (OR = 0.99, p = .94; 95% CI [0.81, 1.138]; heterogeneity, I²  = 19.06, p = .29; fixed-effect model; 4 studies). According to the only clinical trial, treatment with GT could not alter the mammographic density compared with placebo (26% vs. 25%). It cannot be concluded that GT consumption may decrease the risk of breast cancer. Due to high heterogeneity, a pooled analysis of case-control and cohort studies was not performed.

The safety of green tea and green tea extract consumption in adults - Results of a systematic review

A systematic review of published toxicology and human intervention studies was performed to characterize potential hazards associated with consumption of green tea and its preparations. A review of toxicological evidence from laboratory studies revealed the liver as the target organ and hepatotoxicity as the critical effect, which was strongly associated with certain dosing conditions (e.g. bolus dose via gavage, fasting), and positively correlated with total catechin and epigallocatechingallate (EGCG) content. A review of adverse event (AE) data from 159 human intervention studies yielded findings consistent with toxicological evidence in that a limited range of concentrated, catechin-rich green tea preparations resulted in hepatic AEs in a dose-dependent manner when ingested in large bolus doses, but not when consumed as brewed tea or extracts in beverages or as part of food. Toxico- and pharmacokinetic evidence further suggests internal dose of catechins is a key determinant in the occurrence and severity of hepatotoxicity. A safe intake level of 338 mg EGCG/day for adults was derived from toxicological and human safety data for tea preparations ingested as a solid bolus dose. An Observed Safe Level (OSL) of 704 mg EGCG/day might be considered for tea preparations in beverage form based on human AE data.

Urolithin B, a newly identified regulator of skeletal muscle mass

BACKGROUND

The control of muscle size is an essential feature of health. Indeed, skeletal muscle atrophy leads to reduced strength, poor quality of life, and metabolic disturbances. Consequently, strategies aiming to attenuate muscle wasting and to promote muscle growth during various (pathological) physiological states like sarcopenia, immobilization, malnutrition, or cachexia are needed to address this extensive health issue. In this study, we tested the effects of urolithin B, an ellagitannin-derived metabolite, on skeletal muscle growth.

METHODS

C2C12 myotubes were treated with 15 μM of urolithin B for 24 h. For in vivo experiments, mice were implanted with mini-osmotic pumps delivering continuously 10 μg/day of urolithin B during 28 days. Muscle atrophy was studied in mice with a sciatic nerve denervation receiving urolithin B by the same way.

RESULTS

Our experiments reveal that urolithin B enhances the growth and differentiation of C2C12 myotubes by increasing protein synthesis and repressing the ubiquitin-proteasome pathway. Genetic and pharmacological arguments support an implication of the androgen receptor. Signalling analyses suggest a crosstalk between the androgen receptor and the mTORC1 pathway, possibly via AMPK. In vivo experiments confirm that urolithin B induces muscle hypertrophy in mice and reduces muscle atrophy after the sciatic nerve section.

CONCLUSIONS

This study highlights the potential usefulness of urolithin B for the treatment of muscle mass loss associated with various (pathological) physiological states.

Chemoprevention of Breast Cancer by Dietary Polyphenols

The review will discuss in detail the effects of polyphenols on breast cancer, including both the advantages and disadvantages of the applications of these natural compounds. First, we focus on the characterization of the main classes of polyphenols and then on in vitro and in vivo experiments carried out in breast cancer models. Since the therapeutic effects of the administration of a single type of polyphenol might be limited because of the reduced bioavailability of these drugs, investigations on combination of several polyphenols or polyphenols with conventional therapy will also be discussed. In addition, we present recent data focusing on clinical trials with polyphenols and new approaches with nanoparticles in breast cancer. Besides the clinical and translational findings this review systematically summarizes our current knowledge about the molecular mechanisms of anti-cancer effects of polyphenols, which are related to apoptosis, cell cycle regulation, plasma membrane receptors, signaling pathways and epigenetic mechanisms. At the same time the effects of polyphenols on primary tumor, metastasis and angiogenesis in breast cancer are discussed. The increasing enthusiasm regarding the combination of polyphenols and conventional therapy in breast cancer might lead to additional efforts to motivate further research in this field.

Therapeutic Potential of Date Palm Pollen for Testicular Dysfunction Induced by Thyroid Disorders in Male Rats

Hyper- or hypothyroidism can impair testicular function leading to infertility. The present study was designed to examine the protective effect of date palm pollen (DPP) extract on thyroid disorder-induced testicular dysfunction. Rats were divided into six groups. Group I was normal control. Group II received oral DPP extract (150 mg kg^-1), group III (hyperthyroid group) received intraperitoneal injection of L-thyroxine (L-T4, 300μg kg^-1; i.p.), group IV received L-T4 plus DPP extract, group V (hypothyroid group) received propylthiouracil (PTU, 10 mg kg^-1; i.p.) and group VI received PTU plus DPP extract. All treatments were given every day for 56 days. L-T4 or PTU lowered genital sex organs weight, sperm count and motility, serum levels of luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone (T), testicular function markers and activities of testicular 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase (17β-HSD). Moreover, L-T4 or PTU increased estradiol (E2) serum level, testicular oxidative stress, DNA damage and apoptotic markers. Morphometric and histopathologic studies backed these observations. Treatment with DPP extract prevented LT4- or PTU induced changes. In addition, supplementation of DPP extract to normal rats augmented sperm count and motility, serum levels of LH, T and E2 paralleled with increased activities of 3β-HSD and 17β-HSD as well as testicular antioxidant status. These results provide evidence that DPP extract may have potential protective effects on testicular dysfunction induced by altered thyroid hormones.

Implications of Green Tea and Its Constituents in the Prevention of Cancer via the Modulation of Cell Signalling Pathway

Green tea is commonly used as a beverage worldwide, especially in China, Japan, Morocco, and Saudi Arabia. Green tea and its constituents have been considered very effective in the prevention and treatment of various diseases. It contains a variety of catechins, which show a pivotal role in the modulation of biological activities and also act as chemopreventive agents. Earlier studies have confirmed that green tea and its chief constituent epigallocatechin gallate (EGCG) have a potential role in the management of cancer through the modulation of cell signaling pathways. In this review, we focused on the beneficial effects of green tea and its constituents in the cancer prevention and treatment and its impact on modulation of molecular pathways.

Interaction of green tea catechins with breast cancer endocrine treatment: a systematic review

Recent data have shown strong chemopreventive and possibly cancer chemotherapeutic effects of green tea polyphenols and EGCG against breast cancer. This systematic review aims to synthesize data on the possible interaction of green tea catechins with breast cancer endocrine treatment. Electronic databases were searched with the appropriate search terms. Experimental trials suggest a synergistic interaction of green tea catechins with tamoxifen or raloxifene in the treatment of estrogen receptor-positive and estrogen receptor-negative breast cancer through estrogen receptor-dependent and -independent mechanisms. No evidence of an interaction of green tea catechins with aromatase inhibitors or fulvestrant has been reported. As green tea catechins are natural compounds with a rather favorable safety profile, the strategy of co-administrating green tea catechins with tamoxifen seems to be a rational approach in chemoprevention, adjuvant and metastatic breast cancer treatment that needs further investigation.

Tea consumption and risk of type 2 diabetes mellitus: a systematic review and meta-analysis update

OBJECTIVE

Tea has been suggested to decrease blood glucose levels and protect pancreatic β cells in diabetic mice. However, human epidemiological studies showed inconsistent results for the association between tea consumption and type 2 diabetes mellitus (T2DM) risk. The aim of this study was to conduct a meta-analysis to further explore the association between tea consumption and incidence of T2DM.

DESIGN

Systematic review and meta-analysis.

METHODS

We performed a systematic literature search up to 30 August 2013 in PubMed, EMBASE, Chinese Wanfang Database and CNKI database. Pooling relative risks (RRs) were estimated by random-effect models. Two kinds of subgroup analyses (according to sex and regions) were performed. Sensitive analyses were performed according to types of tea.

RESULTS

Overall, no statistically significant relationship between tea consumption and risk of T2DM was found based on 12 eligible studies (pooling RR 0.99, 95% CI 0.95 to 1.03). Compared with the lowest/non-tea group, daily tea consumption (≥3 cups/day) was associated with a lower T2DM risk (RR 0.84, 95% CI 0.73 to 0.97). Subgroup analyses showed a difference between men and women. Overall, the RRs (95% CI) were 0.92 (0.84 to 1.00) for men, and 1.00 (0.96 to 1.05) for women, respectively. Tea consumption of ≥3 cups/day was associated with decreased T2DM risk in women (RR 0.84, 95% CI 0.71 to 1.00). Overall, the RRs (95% CIs) were 0.84 (0.71 to 1.00) for Asians, and 1.00 (0.97 to 1.04) for Americans and Europeans, respectively. No obvious change was found in sensitivity analyses.

CONCLUSIONS

The results suggest that daily tea consumption (≥3 cups/day) is associated with a lower T2DM risk. However, further studies are needed to enrich related evidence, especially with regard to types of tea or sex.

Green tea consumption and breast cancer risk in Japanese women: a case-control study

Although many in vitro and animal studies have suggested a protective effect of green tea against breast cancer, only a few epidemiological studies have examined this association, and findings have been inconsistent. We examined the association between green tea consumption and breast cancer risk in consideration of the hormone receptor status of tumors and investigated whether the association was modified by dietary and genetic factors based on a hospital-based case-control study in Nagano, Japan. A total of 369 pairs completed a validated food frequency questionnaire and provided blood samples. Four single nucleotide polymorphisms (SNPs) were genotyped: CYP19A1 (rs10046), COMT (rs4680), MTHFR C677T (rs1801133), and MTHFR A1298C (rs1801131). We found no inverse association between green tea consumption and breast cancer risk. Compared with women who drank less than 120 ml of green tea per day, the adjusted odds ratio for women who drank more than 600 ml was 1.27 (95% confidence interval = 0.75-2.14; P for trend = 0.20). We also found no inverse association for either tumor subtype. No substantial effect modification was observed for menopausal status, 4 SNPs, or dietary intake of folate or isoflavone. This study provides additional evidence that green tea consumption is not associated with a decreased risk.

Green tea intake is associated with urinary estrogen profiles in Japanese-American women

Scope

Intake of green tea may reduce the risk of breast cancer; polyphenols in this drink can influence enzymes that metabolize estrogens, known causal factors in breast cancer etiology.

Methods and results

We examined the associations of green tea intake (<1 time/week, 1-6 times weekly, or 7+ times weekly) with urinary estrogens and estrogen metabolites (jointly EM) in a cross-sectional sample of healthy Japanese American women, including 119 premenopausal women in luteal phase and 72 postmenopausal women. We fit robust regression models to each log-transformed EM concentration (picomoles per mg creatinine), adjusting for age and study center. In premenopausal women, intake of green tea was associated with lower luteal total EM (P trend = 0.01) and lower urinary 16-pathway EM (P trend = 0.01). In postmenopausal women, urinary estrone and estradiol were approximately 20% and 40% lower (P trend = 0.01 and 0.05, respectively) in women drinking green tea daily compared to those drinking <1 time/week. Adjustment for potential confounders (age at menarche, parity/age at first birth, body mass index, Asian birthplace, soy) did not change these associations.

Conclusions

Findings suggest that intake of green tea may modify estrogen metabolism or conjugation and in this way may influence breast cancer risk.

Effects of Dietary Components on Testosterone Metabolism via UDP-Glucuronosyltransferase

THE POTENTIAL INTERFERENCE IN TESTOSTERONE METABOLISM THROUGH INGESTED SUBSTANCES HAS RAMIFICATIONS FOR: (i) a range of pathologies such as prostate cancer, (ii) medication contra-indications, (iii) disruption to the endocrine system, and (iv) potential confounding effects on doping tests. Conjugation of anabolic steroids during phase II metabolism, mainly driven by UDP-glucuronosyltransferase (UGT) 2B7, 2B15, and 2B17, has been shown to be impaired in vitro by a range of compounds including xenobiotics and pharmaceuticals. Following early reports on the effects of a range of xenobiotics on UGT activity in vitro, the work was extended to reveal similar effects with common non-steroidal anti-inflammatory drugs. Notably, recent studies have evidenced inhibitory effects of the common foodstuffs green tea and red wine, along with their constituent flavonoids and catechins. This review amalgamates the existing evidence for the inhibitory effects of various pharmaceutical and dietary substances on the rate of UGT glucuronidation of testosterone; and evaluates the potential consequences for health linked to steroid levels, interaction with treatment drugs metabolized by the UGT enzyme and steroid abuse in sport.

Phase IB randomized, double-blinded, placebo-controlled, dose escalation study of polyphenon E in women with hormone receptor-negative breast cancer

Epidemiologic data support an inverse association between green tea intake and breast cancer risk, and numerous experimental studies have shown the antitumor effects of its main component, epigallocatechin gallate (EGCG). We conducted a phase IB dose escalation trial in women with a history of stage I to III hormone receptor-negative breast cancer of an oral green tea extract, polyphenon E (Poly E) 400, 600, 800 twice daily or matching placebo for 6 months. The primary endpoint was to determine the maximum tolerated dose (MTD), defined as the dose that causes 25% dose-limiting toxicity (DLT, grade ≥II). Assignment to dose level was based upon an adaptive design, the continual reassessment method. A mammogram and random core biopsy of the contralateral breast were obtained at baseline and 6 months and serial blood/urine collections every 2 months for biomarker analyses. Forty women were randomized: 10 to placebo, 30 to Poly E (16 at 400 mg, 11 at 600 mg, 3 at 800 mg). There was one DLT at 400 mg (grade III rectal bleeding), three DLTs at 600 mg (grade II weight gain, grade III indigestion and insomnia), and one DLT at 800 mg (grade III liver function abnormality). The DLT rate at 600 mg was 27% (3 of 11). Pharmacologic levels of total urinary tea polyphenols were achieved with all three dose levels of Poly E. Using a novel phase I trial design, we determined the MTD for Poly E to be 600 mg twice daily. This study highlights the importance of assessing toxicity for any chemopreventive agent being developed for chronic use in healthy individuals.

Sanguisorba minor extract suppresses plasmin-mediated mechanisms of cancer cell migration

BACKGROUND

Sanguisorba minor, as well as several other edible herbs and vegetables, has been used extensively in traditional medicine. The observed beneficial effects can be attributed at least in part to the direct modulation of several enzymatic activities by its polyphenolic constituents.

METHODS

The ethanol extract of Sanguisorba minor was characterized by reversed-phase liquid chromatography, and most relevant analytes were identified by multiple stage mass spectrometry. The whole extract and the most relevant isolated constituents were tested for their ability to modulate the activity of human plasmin both toward a synthetic substrate and in human breast cancer cell culture models. Kinetic and equilibrium parameters were obtained by a concerted spectrophotometric and biosensor-based approach.

RESULTS

Quercetin-3-glucuronide was recognized as the compound mainly responsible for the in vitro plasmin inhibition by S. minor extract, with an inhibition constant in the high nanomolar range; in detail, our approach based on bioinformatic, enzymatic and binding analyses classified the inhibition as competitive. Most interestingly, cell-based assays showed that this flavonoid was effective in suppressing plasmin-induced loss of cancer cell adhesion.

GENERAL SIGNIFICANCE

Our results show that the extract from Sanguisorba minor limits plasmin-mediated tumor cell motility in vitro, mostly due to quercetin-3-glucuronide. This glucuronated flavonoid is a promising template for rational designing of anticancer drugs to be used in the treatment of pathological states involving the unregulated activity of plasmin.

Effect of 2-month controlled green tea intervention on lipoprotein cholesterol, glucose, and hormone levels in healthy postmenopausal women

There have been no controlled intervention studies to investigate the effects of green tea on circulating hormone levels, an established breast cancer risk factor. We conducted a double-blind, randomized, placebo-controlled intervention study to investigate the effect of the main green tea catechin, epigallocatechin gallate (EGCG), taken in a green tea extract, polyphenon E (PPE). Postmenopausal women (n = 103) were randomized into three arms: placebo, 400-mg EGCG as PPE, or 800-mg EGCG as PPE as capsules per day for 2 months. Urinary tea catechin and serum estrogen, androgen, lipid, glucose-related markers, adiponectin, and growth factor levels were measured at baseline and at the end of months 1 and 2 of intervention. On the basis of urinary tea catechin concentrations, compliance was excellent. Supplementation with PPE did not produce consistent patterns of changes in estradiol (E2), estrone (E1), or testosterone (T) levels. Low-density lipoprotein (LDL)-cholesterol decreased significantly in both PPE groups but was unchanged in the placebo group; the change in LDL-cholesterol differed between the placebo and PPE groups (P = 0.02). Glucose and insulin levels decreased nonsignificantly in the PPE groups but increased in the placebo group; statistically significant differences in changes in glucose (P = 0.008) and insulin (P = 0.01) were found. In summary, green tea (400- and 800-mg EGCG as PPE; ∼5-10 cups) supplementation for 2 months had suggestive beneficial effects on LDL-cholesterol concentrations and glucose-related markers.

A novel inhibitor of fatty acid synthase shows activity against HER2+ breast cancer xenografts and is active in anti-HER2 drug-resistant cell lines

Introduction

Inhibiting the enzyme Fatty Acid Synthase (FASN) leads to apoptosis of breast carcinoma cells, and this is linked to human epidermal growth factor receptor 2 (HER2) signaling pathways in models of simultaneous expression of FASN and HER2.

Methods

In a xenograft model of breast carcinoma cells that are FASN+ and HER2+, we have characterised the anticancer activity and the toxicity profile of G28UCM, the lead compound of a novel family of synthetic FASN inhibitors. In vitro, we analysed the cellular and molecular interactions of combining G28UCM with anti-HER drugs. Finally, we tested the cytotoxic ability of G28UCM on breast cancer cells resistant to trastuzumab or lapatinib, that we developed in our laboratory.

Results

In vivo, G28UCM reduced the size of 5 out of 14 established xenografts. In the responding tumours, we observed inhibition of FASN activity, cleavage of poly-ADPribose polymerase (PARP) and a decrease of p-HER2, p- protein kinase B (AKT) and p-ERK1/2, which were not observed in the nonresponding tumours. In the G28UCM-treated animals, no significant toxicities occurred, and weight loss was not observed. In vitro, G28UCM showed marked synergistic interactions with trastuzumab, lapatinib, erlotinib or gefitinib (but not with cetuximab), which correlated with increases in apoptosis and with decreases in the activation of HER2, extracellular signal-regulated kinase (ERK)1/2 and AKT. In trastuzumab-resistant and in lapatinib-resistant breast cancer cells, in which trastuzumab and lapatinib were not effective, G28UCM retained the anticancer activity observed in the parental cells.

Conclusions

G28UCM inhibits fatty acid synthase (FASN) activity and the growth of breast carcinoma xenografts in vivo, and is active in cells with acquired resistance to anti-HER2 drugs, which make it a candidate for further pre-clinical development.

Sex hormone activity in alcohol addiction: integrating organizational and activational effects

There are well-known sex differences in the epidemiology and etiopathology of alcohol dependence. Male gender is a crucial risk factor for the onset of alcohol addiction. A directly modifying role of testosterone in alcohol addiction-related behavior is well established. Sex hormones exert both permanent (organizational) and transient (activational) effects on the human brain. The sensitive period for these effects lasts throughout life. In this article, we present a novel early sex hormone activity model of alcohol addiction. We propose that early exposure to sex hormones triggers structural (organizational) neuroadaptations. These neuroadaptations affect cellular and behavioral responses to adult sex hormones, sensitize the brain's reward system to the reinforcing properties of alcohol and modulate alcohol addictive behavior later in life. This review outlines clinical findings related to the early sex hormone activity model of alcohol addiction (handedness, the second-to-fourth-finger length ratio, and the androgen receptor and aromatase) and includes clinical and preclinical literature regarding the activational effects of sex hormones in alcohol drinking behavior. Furthermore, we discuss the role of the hypothalamic-pituitary-adrenal and -gonadal axes and the opioid system in mediating the relationship between sex hormone activity and alcohol dependence. We conclude that a combination of exposure to sex hormones in utero and during early development contributes to the risk of alcohol addiction later in life. The early sex hormone activity model of alcohol addiction may prove to be a valuable tool in the development of preventive and therapeutic strategies.

Urinary polyphenols, glutathione S-transferases copy number variation, and breast cancer risk: results from the Shanghai women's health study

In vitro studies have found that flavanol epigallocatechin (EGC) and flavonols, but not flavanol epicatechin (EC), activate glutathione S-transferases (GSTs), a family of phase II enzymes that detoxify reactive oxygen species, such as catechol estrogen metabolites. This study was designed to investigate prospectively whether urinary excretion of tea polyphenols interacts with GST polymorphisms to influence breast cancer risk. We conducted a study of 352 incident breast cancer cases and 701 individually matched controls nested within the Shanghai Women's Health Study cohort of women aged 40-70 yr at baseline. Liquid chromatography tandem mass spectrometry was used to measure urinary excretion of flavanols and flavonols. Real-time multiplex PCR was used to quantify the copy number variation in the GSTM1 and GSTT1 genes. Urinary excretion of flavonols and flavanols, particularly EGC (P = 0.02), was significantly higher among women null for GSTM1 than those positive for GSTM1. Flavonols and flavanols (EGC in particular) were associated with a reduced risk of breast cancer among those null for GSTM1 and GSTT1, with a P-value of 0.04 for the interaction between EGC and GSTM1 polymorphism. In contrast, among women possessing both GSTM1 and GSTT1, breast cancer risk increased with levels of flavonols, particularly kaempferol. The differential associations between polyphenols and breast cancer risk by GST polymorphisms, if confirmed, may provide a new avenue for the personalized prevention of breast cancer.

Green tea and breast cancer

The identification of modifiable lifestyle factors that could reduce the risk of breast cancer is a research priority. Despite the enormous chemopreventive potential of green tea and compelling evidence from animal studies, its role in breast cancer development in humans is still unclear. Part of the uncertainty is related to the relatively small number of epidemiological studies on green tea and breast cancer and that the overall results from case-control studies and prospective cohort studies are discordant. In addition, the mechanisms by which green tea intake may influence risk of breast cancer in humans remain not well studied. We review the human studies that have evaluated the relationship between green tea intake and four biomarkers (sex steroid hormones, mammographic density, insulin-like growth factor, adiponectin) that are believed to be important in breast cancer development. Results from these biomarker studies are also inconclusive. Limitations of observational studies and areas of further investigations are discussed.

Green tea drinking and subsequent risk of breast cancer in a population-based cohort of Japanese women

Introduction

Although many in vitro and animal studies have demonstrated a protective effect of green tea against breast cancer, findings from epidemiological studies have been inconsistent, and whether high green tea intake reduces the risk of breast cancer remains unclear.

Methods

In this Japan Public Health Center-based Prospective Study, 581 cases of breast cancer were newly diagnosed in 53,793 women during 13.6 years' follow-up from the baseline survey in 1990 to 1994. After the five-year follow-up survey in 1995 to 1998, 350 cases were newly diagnosed in 43,639 women during 9.5 years' follow-up. The baseline questionnaire assessed the frequency of total green tea drinking while the five-year follow-up questionnaire assessed that of two types of green tea, Sencha and Bancha/Genmaicha, separately.

Results

Compared with women who drank less than one cup of green tea per week, the adjusted hazard ratio (HR) for women who drank five or more cups per day was 1.12 (95% confidence interval (CI) 0.81 to 1.56; P for trend = 0.60) in the baseline data. Similarly, compared with women who drank less than one cup of Sencha or Bancha/Genmaicha per week, adjusted HRs for women who drank 10 or more cups per day were 1.02 (95% CI 0.55 to 1.89; P for trend = 0.48) for Sencha and 0.86 (0.34 to 2.17; P for trend = 0.66) for Bancha/Genmaicha. No inverse association was found regardless of hormone receptor-defined subtype or menopausal status.

Conclusions

In this population-based prospective cohort study in Japan we found no association between green tea drinking and risk of breast cancer.

Effects of catechin, epicatechin and epigallocatechin gallate on testosterone production in rat leydig cells

Catechins have been reported to have many pharmacological properties such as the effects of anti-oxidative, anti-inflammatory, anti-carcinogenic, anti-ultraviolet, and reduction of blood pressure as well as glucose and cholesterol levels. However, the effect of catechins on the reproductive mechanism is still unknown. In the present study, the effects of catechins on testosterone secretion in rat testicular Leydig cells (LCs) were explored. Both in vivo and in vitro investigations were performed. Purified LCs were incubated with or without catechin (CCN), epicatechin (EC), epigallocatechin gallate (EGCG, 10(-10)-10(-8) M) under challenge with human chorionic gonadotropin (hCG, 0.01 IU/ml), forskolin, SQ22536 (an adenylyl cyclase inhibitor), 8-bromo-adenosine 3':5'-cyclic monophosphate (8-Br-cAMP), A23187 (a calcium ionophore), and nifedipine (10(-5) M), respectively. To study the effects of catechins on steroidogenesis, steroidogenic precursors-stimulated testosterone release was examined. The functions of the steroidogenic enzymes including protein expression of cytochrome P450 side chain cleavage enzyme (P450scc) and steroidogenic acute regulatory (StAR) protein were investigated and expressed by Western blotting. Catechins increased plasma testosterone in vivo in male rats. In vitro, low-dose concentration of catechins increased gonadotropin releasing hormone (GnRH)-stimulated luteinizing hormone (LH) release by anterior pituitary gland and hCG-stimulated testosterone release by LCs of male rats. These results suggested that catechins stimulated testosterone production by acting on rat LCs via the mechanism of increasing the action of cAMP, but not P450scc, StAR protein or the activity of intracellular calcium. EC, one of the catechins increased the testosterone secretion by rat LCs via the enzyme activities of 17beta-hydroxysteroid dehydrogenase (17beta-HSD).

Effect of different doses of un-fractionated green and black tea extracts on thyroid physiology

Tea is a rich source of polyphenolic flavonoids including catechins, which are thought to contribute to the health benefits of it. Flavonoids have been reported to have antithyroid and goitrogenic effect. The purpose of this study was to evaluate whether high doses of green and black tea have a harmful effect on thyroid physiology. Un-fractionated green and black tea extracts were administered orally to male rats for 30 days at doses of 1.25 g%, 2.5 g% and 5.0 g%. The results showed that green tea extract at 2.5 g% and 5.0 g% doses and black tea extract only at 5.0 g% dose have the potential to alter the thyroid gland physiology and architecture, that is, enlargement of thyroid gland as well as hypertrophy and/or hyperplasia of the thyroid follicles and inhibition of the activity of thyroid peroxidase and 5(')-deiodinase I with elevated thyroidal Na+, K+-ATPase activity along with significant decrease in serum T3 and T4, and a parallel increase in serum thyroid stimulating hormone (TSH). This study concludes that goitrogenic/antithyroidal potential of un-fractionated green tea extract is much more than black tea extract because of the differences in catechin contents in the tea extracts.

Goitrogenic/antithyroidal potential of green tea extract in relation to catechin in rats

Catechins are flavonoids found in abundance in green tea, have elicited high interest due to their beneficial effects on health. Though flavonoids have been reported to have an antithyroid effect and also to be goitrogenic there have been no reports about the effect of green tea on rat thyroid. The present study was designed to examine whether high doses of green tea has any harmful effect on thyroid physiology. For this purpose green tea extract was administered orally to male albino rats for 30 days at doses of 1.25 g%, 2.5 g% and 5.0 g%, respectively. Similarly, pure catechin was administered at doses of 25, 50 and 100mg/kg body weight which is equivalent to above doses of green tea extract. Lower body weight gain associated with marked hypertrophy and/or hyperplasia of the follicles was noted in the high dose of green tea and catechin treated groups. Decreased activity of thyroid peroxidase and 5'-deiodinase I and substantially elevated thyroidal Na,K+ATPase activity have been observed. Moreover, serum T3 and T4 levels were found to reduce followed by significant elevation of serum TSH. Taken together, these results suggest that catechin present in green tea extract might behave as antithyroid agent and possibly the consumption of green tea at high dose could alter thyroid function adversely.

Beneficial effects of green tea: a literature review

The health benefits of green tea for a wide variety of ailments, including different types of cancer, heart disease, and liver disease, were reported. Many of these beneficial effects of green tea are related to its catechin, particularly (-)-epigallocatechin-3-gallate, content. There is evidence from in vitro and animal studies on the underlying mechanisms of green tea catechins and their biological actions. There are also human studies on using green tea catechins to treat metabolic syndrome, such as obesity, type II diabetes, and cardiovascular risk factors.Long-term consumption of tea catechins could be beneficial against high-fat diet-induced obesity and type II diabetes and could reduce the risk of coronary disease. Further research that conforms to international standards should be performed to monitor the pharmacological and clinical effects of green tea and to elucidate its mechanisms of action.

Is green tea drinking associated with a later onset of breast cancer?

BACKGROUND

Studies have found that tea polyphenols inhibit aromatase. Because of the substantial difference in levels of estrogens between premenopausal and postmenopausal women, the relationship between tea consumption and breast cancer risk may depend on menopausal status.

METHODS

We examined this hypothesis in the Shanghai Women's Health Study, a population-based cohort study of 74,942 Chinese women.

RESULTS

We found a time-dependent interaction between green tea consumption and age of breast cancer onset (p for interaction, 0.03). In comparison with non-tea drinkers, women who started tea-drinking at 25 years of age or younger had a hazard ratio (HR) of 0.69 (95% confidence interval [CI]: 0.41-1.17) to develop premenopausal breast cancer. On the other hand, compared with non-tea drinkers, women who started tea drinking at 25 years of age or younger had an increased risk of postmenopausal breast cancer with an HR of 1.61 (95% CI: 1.18-2.20). Additional analyses suggest regularly drinking green tea may delay the onset of breast cancer.

CONCLUSIONS

Further studies are needed to confirm our findings.