Therapeutic effect of green tea extract on oxidative stress in aorta and heart of streptozotocin diabetic rats

Unravelling the anti-inflammatory and antioxidant effects of standardized green and black caffeinated coffee, tea, and their mixtures in an obese male rat model: Insights from biochemical, metabolomic, and histopathological analyses

Obesity is one of the major metabolic syndrome risk factors upon which altered metabolic pathways follow. This study aimed to discern altered metabolic pathways associated with obesity and to pinpoint metabolite biomarkers in serum of obese rats fed on high fructose diet using metabolomics. Further, the effect of standardized green versus black caffeinated aqueous extracts (tea and coffee) in controlling obesity and its comorbidities through monitoring relevant serum biomarkers viz. Leptin, adiponectin, spexin, malondialdehyde, total antioxidant capacity. Liver tissue oxidative stress (catalase, super oxide dismutase and glutathione) and inflammation (IL-1β and IL-6) markers were assessed for green coffee and its mixture with green tea. Results revealed improvement of all parameters upon treatments with more prominence for those treated with green caffeinated extract (coffee and tea) especially in mixture. Upon comparing with obese rat group, the green mixture of coffee and tea exhibited anti-hyperlipidemic action through lowering serum triglycerides by 35.0% and elevating high density lipoprotein by 71.0%. Black tea was likewise effective in lowering serum cholesterol and low density lipoprotein by 28.0 and 50.6%, respectively. GC-MS- based metabolomics of rat serum led to the identification of 34 metabolites with obese rat serum enriched in fatty acids (oleamide).

Epigallocatechin gallate inhibits Francisella tularensis growth and suppresses the function of DNA-binding protein HU

Francisella tularensis is a highly infectious intracellular bacterium causing tularemia disease and is regarded as a potential biological weapon. The development of a vaccine, effective treatment, or prophylactic substances targeted against tularemia is in the forefront of interest and could help to prevent or mitigate possible malevolent acts by bioterrorism utilizing F. tularensis. The viability of F. tularensis, and thus of a tularemia disease outbreak, might potentially be suppressed by simple commonly available natural substances. Epigallocatechin gallate (EGCG) is contained in green tea and its antimicrobial effect has been described. Here, we show that EGCG can suppress F. tularensis growth and is able to reduce the bacterium's ability to replicate inside mouse bone marrow-derived macrophages (BMMs) without side effects on BMMs' own viability. We suggest one (but not the only) mechanism of EGCG action. We demonstrate that EGCG can block the main functions of HU protein, the important regulator of F. tularensis virulence, leading to overall attenuation of F. tularensis viability. EGCG can delay death of mice infected by F. tularensis and can be used as a prophylactic agent against tularemia disease. Postponing death by up to 2 days can provide sufficient opportunity to administer another treatment agent.

The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis

Purpose

A bulk of observational studies have revealed the protective role of green tea supplementation in cardiovascular diseases. The current systematic review and meta-analysis study aimed to establish the effects of green tea supplementation on cardiovascular risk factors including lipid profile, blood pressure, glycemic control markers and CRP.

Methods

A systematic literature search of randomized clinical trials (RCTs) that investigated the effects of green tea supplementation and cardiovascular risk factors was undertaken in online databases including PubMed/Medline, Scopus, Web of Science, and Embase using a combination of green tea and cardiovascular risk factors search terms. Meta-analyses were carried out using a random-effects model. The I2 index was used to assess the heterogeneity of RCTs.

Results

Among the initial 11,286 studies that were identified from electronic databases search, 55 eligible RCTs with 63 effect sizes were eligible. Results from the random effects meta-analysis showed that GTE supplementation significantly reduced TC (WMD = -7.62; 95% CI: -10.51, -4.73; P = < 0.001), LDL-C (WMD = -5.80; 95% CI: -8.30, -3.30; P = < 0.001), FBS (WMD = -1.67; 95% CI: -2.58, -0.75; P = < 0.001), HbA1c (WMD = -0.15; 95% CI: -0.26, -0.04; P = 0.008), DBP (WMD = -0.87; 95% CI: -1.45, -0.29; P = 0.003), while increasing HDL-C (WMD = 1.85; 95% CI: 0.87, 2.84; P = 0.010). Subgroup analyses based on the duration of supplementation (≥ 12 vs. < 12 weeks), dose of green tea extract (GTE) (≥1,000 vs. < 1,000 mg/d), sex (male, female, and both), baseline serum levels of lipid profile, and glycemic control factors demonstrated different results for some risk factors.

Conclusion

The current study suggests improvements in the lipid and glycemic profiles following green tea supplementation. These findings support previous evidence showing the health benefits of green tea supplementation on cardiometabolic risk factors.

Aspalathin and Other Rooibos Flavonoids Trapped α-Dicarbonyls and Inhibited Formation of Advanced Glycation End Products In Vitro

The excessive dietary intake of simple sugars and abnormal metabolism in certain diseases contribute to the increased production of α-dicarbonyls (α-DCs), such as methylglyoxal (MGO) and glyoxal (GO), the main precursors of the formation of advanced glycation end products (AGEs). AGEs play a vital role, for example, in the development of cardiovascular diseases and diabetes. Aspalathus linearis (Burman f.) R. Dahlgren (known as rooibos tea) exhibits a wide range of activities beneficial for cardio-metabolic health. Thus, the present study aims to investigate unfermented and fermented rooibos extracts and their constituents for the ability to trap MGO and GO. The individual compounds identified in extracts were tested for the capability to inhibit AGEs (with MGO or GO as a glycation agent). Ultra-high-performance liquid chromatography coupled with an electrospray ionization mass spectrometer (UHPLC-ESI-MS) was used to investigate α-DCs' trapping capacities. To evaluate the antiglycation activity, fluorescence measurement was used. The extract from the unfermented rooibos showed a higher ability to capture MGO/GO and inhibit AGE formation than did the extract from fermented rooibos, and this effect was attributed to a higher content of dihydrochalcones. The compounds detected in the extracts, such as aspalathin, nothofagin, vitexin, isovitexin, and eriodictyol, as well as structurally related phloretin and phloroglucinol (formed by the biotransformation of certain flavonoids), trapped MGO, and some also trapped GO. AGE formation was inhibited the most by isovitexin. However, it was the high content of aspalathin and its higher efficiency than that of metformin that determined the antiglycation and trapping properties of green rooibos. Therefore, A. linearis, in addition to other health benefits, could potentially be used as an α-DC trapping agent and AGE inhibitor.

Prevention and Treatment of Cardiovascular Diseases with Plant Phytochemicals: A Review

Cardiovascular diseases (CVDs) are the world's leading killers, accounting for 30% deaths. According to the WHO report, CVDs kill 17.9 million people per year, and there will be 22.2 million deaths from CVD in 2030. The death rates rise as people get older. Regarding gender, the death rate of women by CVD (51%) is higher than that of men (42%). To decrease and prevent CVD, most people rely on traditional medicine originating from the plant (phytochemicals) in addition to or in preference to commercially available drugs to recover from their illness. The CVD therapy efficacy of 92 plants, including 15 terrestrial plants, is examined. Some medicinal plants well known to treat CVD are, Daucus carota, Nerium oleander, Amaranthus Viridis, Ginkgo biloba, Terminalia arjuna, Picrorhiza kurroa, Salvia miltiorrhiza, Tinospora cordifolia, Mucuna pruriens, Hydrocotyle asiatica, Bombax ceiba, and Andrographis paniculate. The active phytochemicals found in these plants are flavonoids, polyphenols, plant sterol, plant sulphur compounds, and terpenoids. A general flavonoid mechanism of action is to prevent low-density lipoprotein oxidation, which promotes vasodilatation. Plant sterols prevent CVD by decreasing cholesterol absorption in the blood. Plant sulphur compound also prevent CVD by activation of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) and inhibition of cholesterol synthesis. Quinone decreases the risk of CVD by increasing ATP production in mitochondria while terpenoids by decreasing atherosclerotic lesion in the aortic valve. Although several physiologically active compounds with recognized biological effects have been found in various plants because of the increased prevalence of CVD, appropriate CVD prevention and treatment measures are required. More research is needed to understand the mechanism and specific plants' phytochemicals responsible for treating CVD.

Cardioprotection by Citrus grandis (L.) Peel Ethanolic Extract in Alloxan-Induced Cardiotoxicity in Diabetic Rats

Diabetic cardiomyopathy (DCM) pathogenesis is multifarious, and there are insufficient therapeutic options to treat DCM. The present research explored the effects of Citrus grandis peel ethanolic extract (CGPE) in alloxan-induced DCM in rats. Diabetes was triggered by intraperitoneal (i.p.) injection of alloxan (150 mg/kg) in Wistar rats (200-250 g). CGPE (100, 200, and 400 mg/kg) or glibenclamide (Glib, 10 mg/kg) were administered orally for 2 weeks. After the treatment schedule, prooxidants (thiobarbituric acid reactive substances), antioxidants (glutathione, catalase, and superoxide dismutase), and inflammatory markers (tumor necrosis factor-α) were determined in cardiac tissues. Biomarkers of cell death, viz., lactate dehydrogenase (LDH), creatine kinase MB (CK-MB) activity, glucose levels, total cholesterol (TC), and high-density lipoproteins (HDL), were assessed in the blood. Rats administered with alloxan showed a consistent increase in blood glucose level (days 7 and 14) that was lowered considerably (p < 0.001) by CGPE or Glib. Alloxan-induced increase in LDH, CK-MB, TC, and decline in HDL was attenuated (p < 0.001) in rats that were treated with CGPE or Glib. Alloxan significantly (p < 0.001) elevated oxidative stress, inflammation, and reduced antioxidants in the cardiac tissue of rats, and these pathogenic abnormalities were ameliorated (p < 0.001) by CGPE. Histopathological studies showed a decrease in morphological disruptions by alloxan in CGPE-treated rats. CGPE (400 mg/kg) significantly ameliorated biochemical parameters in comparison to the lower doses against alloxan cardiotoxicity. Citrus grandis peel extract can be an alternative in the management of DCM.

Mechanistic Insight into Oxidative Stress-Triggered Signaling Pathways and Type 2 Diabetes

Oxidative stress (OS) is a metabolic dysfunction mediated by the imbalance between the biochemical processes leading to elevated production of reactive oxygen species (ROS) and the antioxidant defense system of the body. It has a ubiquitous role in the development of numerous noncommunicable maladies including cardiovascular diseases, cancers, neurodegenerative diseases, aging and respiratory diseases. Diseases associated with metabolic dysfunction may be influenced by changes in the redox balance. Lately, there has been increasing awareness and evidence that diabetes mellitus (DM), particularly type 2 diabetes, is significantly modulated by oxidative stress. DM is a state of impaired metabolism characterized by hyperglycemia, resulting from defects in insulin secretion or action, or both. ROS such as hydrogen peroxide and the superoxide anion introduce chemical changes virtually in all cellular components, causing deleterious effects on the islets of β-cells, in turn affecting insulin production. Under hyperglycemic conditions, various signaling pathways such as nuclear factor-κβ (NF-κβ) and protein kinase C (PKC) are also activated by ROS. All of these can be linked to a hindrance in insulin signaling pathways, leading to insulin resistance. Hyperglycemia-induced oxidative stress plays a substantial role in complications including diabetic nephropathy. DM patients are more prone to microvascular as well as atherosclerotic macrovascular diseases. This systemic disease affects most countries around the world, owing to population explosion, aging, urbanization, obesity, lifestyle, etc. However, some modulators, with their free radical scavenging properties, can play a prospective role in overcoming the debilitating effects of OS. This review is a modest approach to summarizing the basics and interlinkages of oxidative stress, its modulators and diabetes mellitus. It may add to the understanding of and insight into the pathophysiology of diabetes and the crucial role of antioxidants to weaken the complications and morbidity resulting from this chronic disease.

Pharmacological actions and underlying mechanisms of Catechin: A review

BACKGROUND

Catechin is a phytochemical and is a major component of our daily use beverages, which has shown great potential in improving general health and fighting against several medical conditions. Clinical studies have confirmed its effectiveness in conditions ranging from acute upper respiratory tract infection, neuroprotection, to cardio-protection effects. Though most studies relate their potential to anti-oxidative action and radical scavenging action, still the mechanism of action is not clearly understood.

OBJECTIVE

The present review article is focused on addressing various pharmacological actions and underlying mechanisms of catechin. Additionally, we will try to figure out the major adverse effect and success in trials with catechin and lead to a conclusion for its effectiveness.

METHODS

This review article is based on the recent/ most cited papers of PubMed and Scopus databases.

DESCRIPTION

Catechin can regulate Nrf2 and NFkB pathways in ways that impact oxidative stress and inflammation by influencing gene expression. Other pathways like MAPKs and COMT and receptor tyrosine kinase are also affected by catechin and EGCG that alter their action and barge the cellular activity. This review article explored the structural aspect of catechin and its different isomers and analogs. It also evaluated its various therapeutic and pharmacological arrays .

CONCLUSION

Catechin and its stereo-isomers have shown their effectiveness as anti-inflammatory, anti-diabetic, anti-cancer, anti-neuroprotective, bactericidal, memory enhancer, anti-arthritis, and hepato-protective mainly through its activity to alter the pathway by NF-κB, Nrf-2, TLR4/NF-κB, COMT, and MAPKs.

EGCG, a Green Tea Catechin, as a Potential Therapeutic Agent for Symptomatic and Asymptomatic SARS-CoV-2 Infection

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emerged to be the greatest threat to humanity in the modern world and has claimed nearly 2.2 million lives worldwide. The United States alone accounts for more than one fourth of 100 million COVID-19 cases across the globe. Although vaccination against SARS-CoV-2 has begun, its efficacy in preventing a new or repeat COVID-19 infection in immunized individuals is yet to be determined. Calls for repurposing of existing, approved, drugs that target the inflammatory condition in COVID-19 are growing. Our initial gene ontology analysis predicts a similarity between SARS-CoV-2 induced inflammatory and immune dysregulation and the pathophysiology of rheumatoid arthritis. Interestingly, many of the drugs related to rheumatoid arthritis have been found to be lifesaving and contribute to lower COVID-19 morbidity. We also performed in silico investigation of binding of epigallocatechin gallate (EGCG), a well-known catechin, and other catechins on viral proteins and identified papain-like protease protein (PLPro) as a binding partner. Catechins bind to the S1 ubiquitin-binding site of PLPro, which might inhibit its protease function and abrogate SARS-CoV-2 inhibitory function on ubiquitin proteasome system and interferon stimulated gene system. In the realms of addressing inflammation and how to effectively target SARS-CoV-2 mediated respiratory distress syndrome, we review in this article the available knowledge on the strategic placement of EGCG in curbing inflammatory signals and how it may serve as a broad spectrum therapeutic in asymptomatic and symptomatic COVID-19 patients.

Protective effects of medicinal plant against diabetes induced cardiac disorder: A review

ETHNOPHARMACOLOGY RELEVANCE

Nowadays, there is an increase in global tendency to use medicinal plants as preventive and therapeutic agents to manage diabetes and its long-term complications such as cardiovascular disorders owing to their availability and valuable traditional background.

AIM OF STUDY

This review aims to introduce common medicinal plants, which have been demonstrated to have cardioprotective effects on diabetes and their mechanisms of action.

MATERIALS AND METHODS

Online literature databases, including Web of Sciences, PubMed, Science Direct, Scopus and Google Scholar were searched without date limitation by May 2020. The following keywords (natural products or medicinal plants or herbal medicine or herb or extract) and (diabetes or antidiabetic or hyperglycemic) and (cardiomyopathy or heart or cardioprotective or cardiac or cardio) were used, and after excluding non-relevant articles, 81 original English articles were selected.

RESULTS

The surveyed medicinal plants induced cardioprotective effects mostly through increasing antioxidant effects leading to attenuating ROS production as well as by inhibiting inflammatory signaling pathways and related cytokines. Moreover, they ameliorated the Na+/K + ATPase pump, the L-type Ca₂⁺ channel current, and the intracellular ATP. They also reduced cardiac remodeling and myocardial cell apoptosis through degradation of caspase-3, Bax, P53 protein, enhancement of Bcl-2 protein expression as well as downregulation of TGFβ1 and TNFα expression. In addition, the extracts improved cardiac function through increasing EF% and FS% as well as restoring hemodynamic parameters.

CONCLUSIONS

The reviewed medicinal plants demonstrated cardioprotective manifestations in diabetes through intervention with mechanisms involved in the diabetic heart to restore cardiovascular complications.

Preventing contrast-induced nephropathy (CIN) with herbal medicines: A review

OBJECTIVES

Currently, the use of iodinated contrast media in diagnostic imaging has been increased in clinical medicine. Contrast-induced nephropathy (CIN) is an important adverse effect of contrast media injection. According to the significant role of oxidative stress in the pathophysiology of CIN, different herbal antioxidants have been used for the prevention of nephropathy in different studies. In this review, we discussed the preventive effects of herbal medicine and natural products against CIN.

METHODS

We searched the electronic databases or search engines including PubMed, Scopus, ISI, Google Scholar with search terms such as "Contrast-induced nephropathy" and "Herbal medicine," "Contrast acute kidney injury" AND "natural products" and similar headings such as plant and extract.

RESULTS

Known medicinal plants and active ingredients such as green tea, ginger, garlic, silymarin, curcumin, resveratrol, and thymoquinone have been examined for prophylactic effects or treatment of contrast media nephropathy.

CONCLUSION

Herbal medicines have promising effects in the laboratory-based studies for the prevention and/or treatment of CIN. However, more practical and completed clinical trials are needed to investigate the clinical benefits of natural products against CIN.

Associations between tea and coffee beverage consumption and the risk of lung cancer in the Singaporean Chinese population

BACKGROUND

Tea and coffee are widely consumed beverages. Tea flavonoids have been shown to inhibit lung tumorigenesis using in vitro and in vivo models. Conversely, coffee contains complex mixtures of biochemically active compounds, some of which may have genotoxic and mutagenic properties. However, previous epidemiologic studies have shown inconsistent results on tea and coffee in relation to lung cancer risk.

METHODS

The Singapore Chinese Health Study is a population-based prospective cohort of 63,257 Singaporean Chinese men and women, with an average of 17.7 years of follow-up. Information on tea and coffee consumption and other lifestyle factors was collected through in-person interviews at baseline. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations with adjustment for potential confounders.

RESULTS

There were 1486 incident lung cancer cases. Compared to non-daily coffee drinkers, HRs (95% CIs) of lung cancer risk for those consuming one, two, and three or more cups of coffee per day were 1.18 (1.02-1.36), 1.21 (1.05-1.40), and 1.32 (1.08-1.62) respectively (P for trend = 0.0034). The highest category of black tea consumption (at least 2 cups per day) was inversely associated with risk of lung cancer [HR (95% CI) = 0.73 (0.53-0.99)], particularly among men [HR (95% CI) = 0.67 (0.47-0.95)], compared to less-than-weekly black tea drinkers, although the interaction by sex was not statistically significant.

CONCLUSIONS

Coffee beverage consumption was associated with higher risk of developing lung cancer. On the other hand, black tea intake was associated with lower risk of lung cancer among men in our cohort, and further studies are needed to confirm this association.

Effect of Rosmarinic Acid and Sinapic Acid on Oxidative Stress Parameters in the Cardiac Tissue and Serum of Type 2 Diabetic Female Rats

Cardiovascular diseases are one of the most common complications of type 2 diabetes. They are considered the leading cause of death among diabetics. One of the mechanisms underlying diabetic cardiovascular complications is oxidative stress. Many phenolic acids are regarded as antioxidants. The aim of the study was to investigate the effect of rosmarinic acid (RA) and sinapic acid (SA) on oxidative stress parameters in the cardiac tissue and serum of type 2 diabetic female rats. Additionally, the effect of these compounds on glucose homeostasis and lipid profile in the serum was evaluated. Type 2 diabetes was induced with high-fat diet and streptozotocin. RA at the doses of 10 and 50 mg/kg and SA at the doses of 5 and 25 mg/kg were administrated orally for 28 days. Untreated diabetic rats exhibited unfavorable changes in glucose metabolism and lipid profile. Changes in the enzymatic and non-enzymatic markers indicated the onset of oxidative stress in these animals. The results showed that the higher doses of the tested phenolic acids-50 mg/kg of RA and 25 mg/kg of SA-revealed beneficial effects on oxidative stress in the cardiac tissue of diabetic rats.

Dietary EPA Increases Rat Mortality in Diabetes Mellitus, A Phenomenon Which Is Compensated by Green Tea Extract

Diabetes is characterized by a high mortality rate which is often associated with heart failure. Green tea and eicosapentaenoic acid (EPA) are known to lessen some of the harmful impacts of diabetes and to exert cardio-protection. The aim of the study was to determine the effects of EPA, green tea extract (GTE), and a combination of both on the cardiac consequences of diabetes mellitus, induced in Wistar rats by injection of a low dose of streptozotocin (33 mg/kg) combined with a high fat diet. Cardiac mechanical function, coronary reactivity, and parameters of oxidative stress, inflammation, and energy metabolism were evaluated. In the context of diabetes, GTE alone limited several diabetes-related symptoms such as inflammation. It also slightly improved coronary reactivity and considerably enhanced lipid metabolism. EPA alone caused the rapid death of the animals, but this effect was negated by the addition of GTE in the diet. EPA and GTE combined enhanced coronary reactivity considerably more than GTE alone. In a context of significant oxidative stress such as during diabetes mellitus, EPA enrichment constitutes a risk factor for animal survival. It is essential to associate it with the antioxidants contained in GTE in order to decrease mortality rate and preserve cardiac function.

Larrea divaricata Cav. aqueous extract and nordihydroguariaretic acid modulate oxidative stress in submandibular glands of diabetic rats: a buccal protective in diabetes

Background

Oxidative stress is an imbalance between the levels of reactive oxygen species (ROS), reactive nitrogen species (RNS) and endogenous antioxidants. The aetiology and pathogenesis of several oral diseases are attributed to this process. The antioxidant enzymes secreted in the saliva by submandibular glands maintain oral health through the scavenging of ROS. The objective of this work was to study the capacity of an aqueous extract of L. divaricata (AE), and its majority compound, nordihydroguariaretic acid (NDGA), to modulate the pro-oxidant/antioxidant status in submandibular glands in a model of oxidative stress induced by streptozotocin (STZ) in rats.

Methods

To induce oxidative stress with STZ, a group of animals was treated i.p. with 1 X PBS (control group) and other group was injected i.p. once with STZ (60 mg/kg). Ten days after the treatment, blood samples were taken from the tail vain to determine the glucose levels. Animals with glucose values ≥300 mg/ml were selected.

The submandibular glands of control and STZ treated animals were incubated with either the AE (500 μg/ml) or with NDGA (1.5 μg/ml), and the content of malondialdehyde (MDA), protein carbonyl groups, ROS and RNS, and the activity and expression of peroxidase (Px), superoxide dismutase (SOD) and inducible nitric oxide synthase (iNOS) were assayed.

Results

AE decreased the levels of MDA (^##P < 0.01) and protein carbonyl groups (^#P < 0.05), and modulated the levels of ROS such as hydrogen peroxide (H₂O₂)(^##P < 0.01), superoxide anion (O₂^.-) (^#P < 0.05) and nitric oxide (NO) (^#P < 0.05) in relation to the modulation of Px and iNOS expression. NDGA was found to be involved in these effects.

Conclusions

The antioxidant activity of the AE in the submandibular glands would allow the maintenance of the antioxidant pool to prevent oral oxidative diseases.

The acute effect of a single dose of green tea on the quality and quantity of tears in normal eye subjects

Objective

The study aimed to investigate the acute effect of a single dose of green tea on the quality and quantity of tears in normal eye subjects.

Methods

Forty normal eye subjects (22 men and 18 women) aged 19–39 years were enrolled in the study. Also, an age matching control group (20 males and 20 females) was enrolled for comparison. McMonnies dry eye symptoms questionnaire and slit lamp were used for the exclusion criteria determination. Phenol red thread (PRT) test was performed on both eyes of each subject. A tear sample was collected from the lower tear meniscus of the right eye of each subject for the tear ferning (TF) test, which was performed before (30 minutes) and after (60 minutes) drinking green tea.

Results

The median PRT measurement after green tea consumption was lower (median [IQR]=23.50 [8.00] mm) compared to that before consumption (median [IQR]=27.00 [8.75] mm). In contrast, the median TF grade was significantly higher following green tea consumption than that before consumption (median [IQR]=2.65 [1.23] vs 1.50 [0.88] mm, respectively). The results show that TF grades increased in 97.5%, and the red phenol thread scores decreased in 80% of the subjects after green tea consumption compared to those before consumption. The PRT readings and TF grades were significantly different (P<0.05) before and after green tea consumption.

Conclusion

Drinking green tea could have a significant effect on the eye tear film quality. Tear quality appeared to decrease after green tea consumption.

Medicinal Plants with Multiple Effects on Diabetes Mellitus and Its Complications: a Systematic Review

PURPOSE OF REVIEW

This systematic review describes evidence concerning medicinal plants that, in addition to exerting hypoglycemic effects, decrease accompanying complications such as nephropathy, neuropathy, retinopathy, hypertension, and/or hyperlipidemia among individuals with diabetes mellitus (DM).

RECENT FINDINGS

Studies on the antidiabetic mechanisms of medicinal plants have shown that most of them produce hypoglycemic activity by stimulating insulin secretion, augmenting peroxisome proliferator-activated receptors (PPARs), inhibiting α-amylase or α-glucosidase, glucagon-like peptide-1 (GLP-1) secretion, advanced glycation end product (AGE) formation, free radical scavenging plus antioxidant activity (against reactive oxygen or nitrogen species (ROS/RNS)), up-regulating or elevating translocation of glucose transporter type 4 (GLUT-4), and preventing development of insulin resistance. Not only are medicinal plants effective in DM, but many of them also possess a variety of effects on other disease states, including the complications of DM. Such plants may be appropriate alternatives or adjuncts to available antidiabetic medications.

The Role of Catechins in Cellular Responses to Oxidative Stress

Catechins are polyphenolic compounds—flavanols of the flavonoid family found in a variety of plants. Green tea, wine and cocoa-based products are the main dietary sources of these flavanols. Catechins have potent antioxidant properties, although in some cases they may act in the cell as pro-oxidants. Catechins are reactive oxygen species (ROS) scavengers and metal ion chelators, whereas their indirect antioxidant activities comprise induction of antioxidant enzymes, inhibition of pro-oxidant enzymes, and production of the phase II detoxification enzymes and antioxidant enzymes. Oxidative stress and ROS are implicated in aging and related dysfunctions, such as neurodegenerative disease, cancer, cardiovascular diseases, and diabetes. Due to their antioxidant properties, catechins may be beneficial in preventing and protecting against diseases caused by oxidative stress. This article reviews the biochemical properties of catechins, their antioxidant activity, and the mechanisms of action involved in the prevention of oxidative stress-caused diseases.

Application of Metabolomics to Quality Control of Natural Product Derived Medicines

Metabolomics has been used as a powerful tool for the analysis and quality assessment of the natural product (NP)-derived medicines. It is increasingly being used in the quality control and standardization of NP-derived medicines because they are composed of hundreds of natural compounds. The most common techniques that are used in metabolomics consist of NMR, GC-MS, and LC-MS in combination with multivariate statistical analyses including principal components analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). Currently, the quality control of the NP-derived medicines is usually conducted using HPLC and is specified by one or two indicators. To create a superior quality control framework and avoid adulterated drugs, it is necessary to be able to determine and establish standards based on multiple ingredients using metabolic profiling and fingerprinting. Therefore, the application of various analytical tools in the quality control of NP-derived medicines forms the major part of this review. Veregen^® (Medigene AG, Planegg/Martinsried, Germany), which is the first botanical prescription drug approved by US Food and Drug Administration, is reviewed as an example that will hopefully provide future directions and perspectives on metabolomics technologies available for the quality control of NP-derived medicines.

Pterostilbene reduces oxidative stress, prevents hypertrophy and preserves systolic function of right ventricle in cor pulmonale model

BACKGROUND AND PURPOSE

In cor pulmonale, the increased afterload imposed on the right ventricle (RV) generates a maladaptive response, impairing the contractile cardiac function. Oxidative mechanisms play an important role in the pathophysiology and progression of this disease. The administration of pterostilbene (PTS), a phytophenol with antioxidant potential, may represent a therapeutic option. In the present study, we evaluated the effect of PTS complexed with hydroxypropyl-β-cyclodextrin (HPβCD) on hypertrophy, contractile function and oxidative parameters in the RV of rats with pulmonary hypertension, induced by the administration of monocrotaline (MCT).

EXPERIMENTAL APPROACH

The rats received daily doses of the PTS : HPβCD complex at 25, 50 or 100 mg·kg^-1 , p.o., for 14 days. The diastolic function, E/A ratio, and systolic function, shortening fraction, fractional area change (FAC) and tricuspid annular plane systolic excursion (TAPSE) of the RV were determined by echocardiography.

KEY RESULTS

The PTS : HPβCD complex reduced the production of NADPH oxidase-dependent superoxide anions and oxidative stress in the RV of MCT-treated rats in a dose-dependent manner. At higher doses it prevented the reduction in FAC and TAPSE in MCT-treated animals.

CONCLUSIONS AND IMPLICATIONS

The PTS : HPβCD complex prevented the maladaptative remodelling and protected systolic function in the RV of rats with pulmonary hypertension. These cardioprotective mechanisms may be related, in part, to the antioxidant potential of PTS, favoured by the increased p.o. bioavailability promoted by the presence of HPβCD in the complex.

Antidiabetic Effects of Tea

Diabetes mellitus (DM) is a chronic endocrine disease resulted from insulin secretory defect or insulin resistance and it is a leading cause of death around the world. The care of DM patients consumes a huge budget due to the high frequency of consultations and long hospitalizations, making DM a serious threat to both human health and global economies. Tea contains abundant polyphenols and caffeine which showed antidiabetic activity, so the development of antidiabetic medications from tea and its extracts is increasingly receiving attention. However, the results claiming an association between tea consumption and reduced DM risk are inconsistent. The advances in the epidemiologic evidence and the underlying antidiabetic mechanisms of tea are reviewed in this paper. The inconsistent results and the possible causes behind them are also discussed.

Green tea consumption and cause-specific mortality: Results from two prospective cohort studies in China

BACKGROUND

Green tea is one of the most widely consumed beverages in Asia. While a possible protective role of green tea against various chronic diseases has been suggested in experimental studies, evidence from human studies remains controversial.

METHODS

We conducted this study using data from Shanghai Men's Health Study (SMHS) and Shanghai Women's Health Study (SWHS), two population-based prospective cohorts of middle-aged and elderly Chinese adults in urban Shanghai, China. Hazard ratios (HR) and 95% confidence intervals (CI) for risk of all-cause and cause-specific mortality associated with green tea intake were estimated using Cox proportional hazards regression models.

RESULTS

During a median follow-up of 8.3 and 14.2 years for men and women, respectively, 6517 (2741 men and 3776 women) deaths were documented. We found that green tea consumption was inversely associated with risk of all-cause mortality (HR 0.95; 95% CI, 0.90-1.01), particularly among never-smokers (HR 0.89; 95% CI, 0.82-0.96). The inverse association with cardiovascular disease (CVD) mortality (HR 0.86; 95% CI, 0.77-0.97) was slightly stronger than that with all-cause mortality. No significant association was observed between green tea intake and cancer mortality (HR 1.01; 95% CI, 0.93-1.10).

CONCLUSIONS

Green tea consumption may be inversely associated with risk of all-cause and CVD mortality in middle-aged and elderly Chinese adults, especially among never smokers.

Effects of Dietary Strawberry Supplementation on Antioxidant Biomarkers in Obese Adults with Above Optimal Serum Lipids

Berries have shown several cardiovascular health benefits and have been associated with antioxidant functions in experimental models. Clinical studies are limited. We examined the antioxidant effects of freeze-dried strawberries (FDS) in adults [n = 60; age: 49 ± 10 years; BMI: 36 ± 5 kg/m² (mean ± SD)] with abdominal adiposity and elevated serum lipids. Participants were randomized to one of the following arms: low dose strawberry (25 g/day FDS), low dose control beverage (LD-C), high dose strawberry (50 g/d FDS), and high dose control beverage (HD-C) for 12 weeks. Control beverages were matched for calories and total fiber. Plasma antioxidant capacity, trace elements (copper, iron, selenium, and zinc), whole blood glutathione (GSH), and enzyme activity (catalase, glutathione peroxidase, and glutathione reductase) were examined at screening (0 week) and after 12 weeks' intervention. At 12 weeks, plasma antioxidant capacity and glutathione levels were higher in the strawberry versus control groups (low and high dose FDS: 45% and 42% for plasma antioxidant capacity and 28% and 36% for glutathione, resp.); glutathione was higher in the high versus low dose strawberry group (all p < 0.05). Serum catalase activity was higher in the low dose strawberry (43%) versus control group (p < 0.01). No differences were noted in plasma trace elements and glutathione enzyme activity. Dietary strawberries may selectively increase plasma antioxidant biomarkers in obese adults with elevated lipids.

Advanced glycation End-products (AGEs): an emerging concern for processed food industries

The global food industry is expected to increase more than US $ 7 trillion by 2014. This rise in processed food sector shows that more and more people are diverging towards modern processed foods. As modern diets are largely heat processed, they are more prone to contain high levels of advanced glycation end products (AGEs). AGEs are a group of complex and heterogeneous compounds which are known as brown and fluorescent cross-linking substances such as pentosidine, non-fluorescent cross-linking products such as methylglyoxal-lysine dimers (MOLD), or non-fluorescent, non-cross linking adducts such as carboxymethyllysine (CML) and pyrraline (a pyrrole aldehyde). The chemistry of the AGEs formation, absorption and bioavailability and their patho-biochemistry particularly in relation to different complications like diabetes and ageing discussed. The concept of AGEs receptor - RAGE is mentioned. AGEs contribute to a variety of microvascular and macrovascular complications through the formation of cross-links between molecules in the basement membrane of the extracellular matrix and by engaging the receptor for advanced glycation end products (RAGE). Different methods of detection and quantification along with types of agents used for the treatment of AGEs are reviewed. Generally, ELISA or LC-MS methods are used for analysis of foods and body fluids, however lack of universally established method highlighted. The inhibitory effect of bioactive components on AGEs by trapping variety of chemical moieties discussed. The emerging evidence about the adverse effects of AGEs makes it necessary to investigate the different therapies to inhibit AGEs.

Additional benefit of higher dose green tea in lowering postprandial blood glucose

Background: Green tea contains catechins that have inhibitory effects on amylase, sucrase, and sodium-dependent glucose transporter (SGLT) which result in lowering of postprandial blood glucose (PBG). This beneficial effect has been widely demonstrated using the usual dose (UD) of green tea preparation. Our study was aimed to explore futher lowering of PBG using high dose (HD) of green tea in healthy adolescents. Methods: 24 subjects received 100 mL infusion of either 0.67 or 3.33 grams of green tea with test meal. Fasting, PBG at 30, 60, 120 minutes were measured. Subjects were cross-overed after wash out. PBG and its incremental area under the curve (IAUC) difference between groups were analyzed with paired T-test. Cathecin contents of tea were measured using high-performance liquid chromatography (HPLC). Results: The PBG of HD group was lower compared to UD (at 60 minutes =113.70 ± 13.20 vs 124.16 ± 8.17 mg/dL, p = 0.005; at 120 minutes = 88.95 ± 6.13 vs 105.25 ± 13.85 mg/dL, p < 0.001). The IAUC of HD was also found to be lower compared to UD (2055.0 vs 3411.9 min.mg/dL, p < 0.001). Conclusion: Additional benefit of lowering PBG can be achieved by using higher dose of green tea. This study recommends preparing higher dose of green tea drinks for better control of PBG.

Impairment of calcium ATPases by high glucose and potential pharmacological protection

The review deals with impairment of Ca(2+)-ATPases by high glucose or its derivatives in vitro, as well as in human diabetes and experimental animal models. Acute increases in glucose level strongly correlate with oxidative stress. Dysfunction of Ca(2+)-ATPases in diabetic and in some cases even in nondiabetic conditions may result in nitration of and in irreversible modification of cysteine-674. Nonenyzmatic protein glycation might lead to alteration of Ca(2+)-ATPase structure and function contributing to Ca(2+) imbalance and thus may be involved in development of chronic complications of diabetes. The susceptibility to glycation is probably due to the relatively high percentage of lysine and arginine residues at the ATP binding and phosphorylation domains. Reversible glycation may develop into irreversible modifications (advanced glycation end products, AGEs). Sites of SERCA AGEs are depicted in this review. Finally, several mechanisms of prevention of Ca(2+)-pump glycation, and their advantages and disadvantages are discussed.

Catechin attenuates behavioral neurotoxicity induced by 6-OHDA in rats

This study was designed to investigate the beneficial effect of catechin in a model of Parkinson's disease. Unilateral, intrastriatal 6-hydroxydopamine (6-OHDA)-lesioned rats were pretreated with catechin (10 and 30 mg/kg) by intraperitoneal (i.p.) injection 2h before surgery and for 14 days afterwards. After treatments, apomorphine-induced rotations, locomotor activity, working memory and early and late aversive memories were evaluated. The mesencephalon was used to determine the levels of monoamines and measurement of glutathione (GSH). Immunohistochemical staining was also used to evaluate the expression of tyrosine hydroxylase (TH) in mesencephalic and striatal tissues. Catechin administration attenuated the increase in rotational behavior and the decrease in locomotor activity observed in lesioned rats. Although catechin did not rescue the impairment of late aversive memory, it protected the animals against 6-OHDA-induced working memory deficits. Furthermore, catechin treatment restored GSH levels, and significantly increased dopamine and DOPAC content, and TH-immunoreactivity in 6-OHDA-lesioned rats. Catechin protected 6-OHDA-lesioned rats due to its antioxidant action, indicating that it could be useful as an adjunctive therapy for the treatment of Parkinson's disease.

Green tea supplementation increases glutathione and plasma antioxidant capacity in adults with the metabolic syndrome

Green tea, a popular polyphenol-containing beverage, has been shown to alleviate clinical features of the metabolic syndrome. However, its effects in endogenous antioxidant biomarkers are not clearly understood. Thus, we tested the hypothesis that green tea supplementation will upregulate antioxidant parameters (enzymatic and nonenzymatic) in adults with the metabolic syndrome. Thirty-five obese participants with the metabolic syndrome were randomly assigned to receive one of the following for 8 weeks: green tea (4 cups per day), control (4 cups water per day), or green tea extract (2 capsules and 4 cups water per day). Blood samples and dietary information were collected at baseline (0 week) and 8 weeks of the study. Circulating carotenoids (α-carotene, β-carotene, lycopene) and tocopherols (α-tocopherol, γ-tocopherol) and trace elements were measured using high-performance liquid chromatography and inductively coupled plasma mass spectroscopy, respectively. Serum antioxidant enzymes (glutathione peroxidase, glutathione, catalase) and plasma antioxidant capacity were measured spectrophotometrically. Green tea beverage and green tea extract significantly increased plasma antioxidant capacity (1.5 to 2.3 μmol/L and 1.2 to 2.5 μmol/L, respectively; P < .05) and whole blood glutathione (1783 to 2395 μg/g hemoglobin and 1905 to 2751 μg/g hemoglobin, respectively; P < .05) vs controls at 8 weeks. No effects were noted in serum levels of carotenoids and tocopherols and glutathione peroxidase and catalase activities. Green tea extract significantly reduced plasma iron vs baseline (128 to 92 μg/dL, P < .02), whereas copper, zinc, and selenium were not affected. These results support the hypothesis that green tea may provide antioxidant protection in the metabolic syndrome.

Antiobesity Effects of the Ethanol Extract of Laminaria japonica Areshoung in High-Fat-Diet-Induced Obese Rat

Laminaria japonica Areshoung, a widely consumed marine vegetable, has traditionally been used in Korean maternal health. The present study investigated the antiobesity effects of Laminaria japonica Areshoung ethanol extract (LE) and its molecular mechanism in high-fat-diet-induced obese rats. Six-week-old Sprague-Dawley male rats were separately fed a normal diet or a high-calorie high-fat diet for 6 weeks; then they were treated with LE or tea catechin for another 6 weeks. LE administration significantly decreased the body weight gain, fat-pad weights, and serum and hepatic lipid levels in HD-induced obese rats. The histological analysis revealed that LE-treated group showed a significantly decreased number of lipid droplets and size of adipocytes compared to the HD group. To elucidate the mechanism of action of LE, the levels of genes and proteins involved in obesity were measured in the liver and skeletal muscle. LE treatment resulted in an increased expression of fatty acid oxidation and thermogenesis-related genes in obese rats. Conversely, the expression of the fat intake-related gene (ACC2) and lipogenesis-related genes was reduced by LE treatment. Additionally, LE treatment increased the phosphorylation of AMP-activated protein kinase and its direct downstream protein, acetyl coenzyme A carboxylase, which is one of the rate-limiting enzymes in fatty acid synthesis pathway. These findings demonstrate that LE treatment has a protective effect against a high-fat-diet-induced obesity in rats through regulation of expression of genes and proteins involved in lipolysis and lipogenesis.

Antidiabetic, anti-oxidant and antimicrobial activities of Fadogia ancylantha extracts from Malawi

ETHNOPHARMACOLOGICAL RELEVANCE

Communities in Chilumba, Malawi use herbal tea prepared from Fadogia ancylantha Schweinf (Rubiaceae) leaves for the management of diabetes, hypertension and alleviation of symptoms of gastrointestinal disorders and pneumonia. The objective of the study was to evaluate the in vitro antidiabetic, anti-oxidant and antimicrobial activities of the crude extracts of the leaves prepared by using three different extraction methods.

MATERIALS AND METHODS

Each of the organic, cold and hot aqueous extracts of the herbal tea was evaluated for its effect on glucose uptake in C2C12 muscle and Chang cell lines. Metformin and insulin were used as positive controls. The anti-oxidant activity, based on neutralisation of DPPH free radicals, was determined spectrophotometrically. The Agar serial dilution method was utilised to determine the minimum inhibitory concentration (MIC) of the extracts for the selected fungal and bacterial strains.

RESULTS AND DISCUSSION

The organic extract (12.5μg/ml) exhibited the highest in vitro glucose uptake increases in Chang cells (181.24±0.29%) and C2C12 muscle cells (172.29±0.32%) while the hot and cold aqueous extracts gave lower uptakes, 145.94±0.37% and 138.70±0.52% in Chang cells respectively. At 100μg/ml, aqueous extracts gave significantly higher (p<0.01) anti-oxidant activity (range 85.78-86.29%) than their organic counterpart (68.16%). The minimum inhibitory concentration (156μg/ml) was obtained in the organic extract against the fungus Aspergillus fumigatus and moderate growth inhibition was observed with other test micro-organisms. The hot aqueous extract inhibited the growth of all test organisms except Pseudomonas aeruginosa. The cold aqueous extract was inactive against Pseudomonas aeruginosa and Candida albicans. The differences in the MIC values between the aqueous extracts seem to suggest that raised temperatures, as traditionally practised, facilitate the extraction of secondary bioactive metabolites.

CONCLUSION

These results show that Fadogia ancylantha extracts have high antidiabetic and anti-oxidant properties.

Green tea catechins ameliorate adipose insulin resistance by improving oxidative stress

Epidemiological data have suggested that drinking green tea is negatively associated with diabetes, and adipose oxidative stress may have a central role in causing insulin resistance, according to recent findings. The aim of this work is to elucidate a new mechanism for green tea's anti-insulin resistance effect. We used obese KK-ay mice, high-fat diet-induced obese rats, and induced insulin resistant 3T3-L1 adipocytes as models. Insulin sensitivity and adipose reactive oxidative species (ROS) levels were detected in animals and adipocytes. The oxidative stress assay and glucose uptake ability assay were performed, and the effects of EGCG on insulin signals were detected. Green tea catechins (GTCs) significantly decreased glucose levels and increased glucose tolerance in animals. GTCs reduced ROS content in both models of animal and adipocytes. EGCG attenuated dexamethasone and TNF-α promoted ROS generation and increased glucose uptake ability. EGCG also decreased JNK phosphorylation and promoted GLUT-4 translocation. EGCG and GTCs could improve adipose insulin resistance, and exact this effect on their ROS scavenging functions.

The effects of green tea consumption on cardiometabolic alterations induced by experimental diabetes

We evaluated cardiac autonomic modulation by heart rate (HRV), and arterial pressure variability (APV), and metabolic response in streptozotocin diabetic rats treated with green tea. Male Wistar rats were separated in groups: control, drinking tap water (C), green tea-treated (GT) group, diabetic, drinking tap water (D), and diabetic, treated with green tea (DGT). Kidney mass was greater in D and DGT than in C and GT, but reduced in DGT compared to D. Green tea prevented the increase in creatinine clearance and reduced hyperglycemia in DGT compared to D. Arterial pressure was increased in GT and decreased in D compared to C. HRV was reduced in D compared with all groups. APV was decreased in D compared to C and recovery in DGT. Sympathetic modulation of APV was decreased in D compared with all groups. Green tea reduced hyperglycemia, prevented renal injury and autonomic dysfunction, suggesting reduced cardiovascular risk and target organ damage in diabetes.

Ameliorative effect of Aegle marmelos leaf extract on early stage alloxan-induced diabetic cardiomyopathy in rats

OBJECTIVE

The pathogenesis of diabetic cardiomyopathy (DCM) is complex, and the therapeutic options available to treat DCM are limited. The present study was designed to investigate the effect of Aegle marmelos (L.) Correa (Rutaceae) leaf extract on early stage DCM in alloxan-induced diabetic rats.

METHODS

Diabetes was induced in Wistar rats (150-200 g) by injecting alloxan (150 mg kg(-1); i.p.). Ethanol extract of A. marmelos leaves was administered at varying doses (100, 200, and 400 mg kg(-1)) and tolbutamide (100 mg kg(-1)) as standard. Fasting blood glucose (FBG), total cholesterol, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), lactate dehydrogenase (LDH) and creatine kinase (CK) were determined by standard methods.

RESULTS

A. marmelos extract (AME) was found to decrease the levels of FBG, total cholesterol, TBARS, LDH and CK, and increase the levels of GSH, CAT and SOD dose dependently as compared to diabetic control groups. The maximum dose-dependent decrease in TBARS (63.46%), LDH (34.04%), CK (53.14%), and increase in GSH (64.91%), CAT (59.34%), SOD (69.65%) was evident at an optimum dose of 200 mg kg(-1). Histopathological studies revealed salvage in the morphological derangements as indicated by absence of necrosis and marked decrease in inflammatory cells in AME-treated groups as compared to diabetic control.

CONCLUSIONS

The present investigations conclude that treatment with AME attenuates the severity and improves the myocardium in the early stages of alloxan-induced DCM at a dose of 200 mg kg(-1).

Dietary supplementation of grape skin extract improves glycemia and inflammation in diet-induced obese mice fed a Western high fat diet

Dietary antioxidants may provide a cost-effective strategy to promote health in obesity by targeting oxidative stress and inflammation. We recently found that the antioxidant-rich grape skin extract (GSE) also exerts a novel anti-hyperglycemic activity. This study investigated whether 3-month GSE supplementation can improve oxidative stress, inflammation, and hyperglycemia associated with a Western diet-induced obesity. Young diet-induced obese (DIO) mice were randomly divided to three treatment groups (n = 12): a standard diet (S group), a Western high fat diet (W group), and the Western diet plus GSE (2.4 g GSE/kg diet, WGSE group). By week 12, DIO mice in the WGSE group gained significantly more weight (24.6 g) than the W (20.2 g) and S groups (11.2 g); the high fat diet groups gained 80% more weight than the standard diet group. Eight of 12 mice in the W group, compared to only 1 of 12 mice in the WGSE group, had fasting blood glucose levels above 140 mg/dL. Mice in the WGSE group also had 21% lower fasting blood glucose and 17.1% lower C-reactive protein levels than mice in the W group (P < 0.05). However, the GSE supplementation did not affect oxidative stress in diet-induced obesity as determined by plasma oxygen radical absorbance capacity, glutathione peroxidase, and liver lipid peroxidation. Collectively, the results indicated a beneficial role of GSE supplementation for improving glycemic control and inflammation in diet-induced obesity.

WITHDRAWN: Attenuation of cardiac oxidative stress by (-)-epigallocatechin-gallate (EGCG) in CS exposed rats

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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.