Tea and cardiovascular disease

Use of herbal medication in the perioperative period: Potential adverse drug interactions

Use of herbal medications and supplements has experienced immense growth over the last two decades, with retail sales in the USA exceeding $13 billion in 2021. Since the Dietary Supplement Health and Education Act (DSHEA) of 1994 reduced FDA oversight, these products have become less regulated. Data from 2012 shows 18% of U.S. adults used non-vitamin, non-mineral natural products. Prevalence varies regionally, with higher use in Western states. Among preoperative patients, the most commonly used herbal medications included garlic, ginseng, ginkgo, St. John's wort, and echinacea. However, 50-70% of surgical patients fail to disclose their use of herbal medications to their physicians, and most fail to discontinue them preoperatively. Since herbal medications can interact with anesthetic medications administered during surgery, the American Society of Anesthesiologists (ASA) and the American Association of Nurse Anesthetists (AANA) recommend stopping herbal medications 1-2 weeks before elective surgical procedures. Potential adverse drug effects related to preoperative use of herbal medications involve the coagulation system (e.g., increasing the risk of perioperative bleeding), the cardiovascular system (e.g., arrhythmias, hypotension, hypertension), the central nervous system (e.g., sedation, confusion, seizures), pulmonary (e.g., coughing, bronchospasm), renal (e.g., diuresis) and endocrine-metabolic (e.g., hepatic dysfunction, altered metabolism of anesthetic drugs). During the preoperative evaluation, anesthesiologists should inquire about the use of herbal medications to anticipate potential adverse drug interactions during the perioperative period.

Bioactive Flavonoids in Protecting Against Endothelial Dysfunction and Atherosclerosis

Atherosclerosis is a common cardiovascular disease closely associated with factors such as hyperlipidaemia and chronic inflammation. Among them, endothelial dysfunction serves as a major predisposing factor. Vascular endothelial dysfunction is manifested by impaired endothelium-dependent vasodilation, enhanced oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, endothelial senescence, and endothelial-mesenchymal transition (EndoMT). Flavonoids are known for their antioxidant activity, eliminating oxidative stress induced by reactive oxygen species (ROS), thereby preventing the oxidation of low-density lipoprotein (LDL) cholesterol, reducing platelet aggregation, alleviating ischemic damage, and improving vascular function. Flavonoids have also been shown to possess anti-inflammatory activity and to protect the cardiovascular system. This review focuses on the protective effects of these naturally-occuring bioactive flavonoids against the initiation and progression of atherosclerosis through their effects on endothelial cells including, but not limited to, their antioxidant, anti-inflammatory, anti-thrombotic, and lipid-lowering properties. However, more clinical evidences are still needed to determine the exact role and optimal dosage of these compounds in the treatment of atherosclerosis.

The Systematic Assessment of the Membrane-Stabilizing and Antioxidant Activities of Several Kazakhstani Plants in the Asteraceae Family

The objective of our research was to examine the antioxidant and membrane-protective characteristics of a few medicinal plant extracts belonging to the Asteracea family, along with their flavonoid and polyphenolic content, in order to identify strategies for enhancing beverage composition and boosting the antioxidant capacity of green and black tea. The activity of aqueous-ethanolic extracts from the dried parts of plants, such as Arictum tomentosum Mill., Ghnapilum kasachstanicum Kirp. & Kuprian. ex Kirp., Artemisia schrenkiana Ledeb., A. rutifolia Steph. ex Spreng., A. cina O.Berg, and A. vulgaris L., were examined using a model of Wistar rats. Thiobarbituric acid-reacting substances (TBARS), a marker of malondialdehyde concentration, were used to measure the amount of lipid peroxidation (LPO) in liver microsomes. Considering the outcomes, the extracts from A. tomentosum, G. kasachstanicum, and A. vulgaris exhibit the strongest membrane-stabilizing action among those examined. At a concentration of 5 g/mL, the extracts of these plants demonstrated a significant anti-hemolitic impact, whereas the remaining extracts displayed a similar effect at doses above 10 g/mL. Accordingly, among the extracts studied, the A. tomentosum, G. kasachstanicum, A. schrenkiana, A. rutifolia, A. cina, and A. vulgaris extracts have significant antioxidant properties. The integrated antioxidant and antihemolytic qualities of A. tomentosum and green tea extracts were comparable to those of the individual plant extracts. When the extracts of A. schrenkiana and green tea were combined, similar outcomes were seen, suggesting that there was no appreciable synergistic interaction.

Bioactive molecules from terrestrial and seafood resources in hypertension treatment: focus on molecular mechanisms and targeted therapies

Hypertension (HTN), a complex cardiovascular disease (CVD), significantly impacts global health, prompting a growing interest in complementary and alternative therapeutic approaches. This review article seeks to provide an up-to-date and thorough summary of modern therapeutic techniques for treating HTN, with an emphasis on the molecular mechanisms of action found in substances found in plants, herbs, and seafood. Bioactive molecules have been a significant source of novel therapeutics and are crucial in developing and testing new HTN remedies. Recent advances in science have made it possible to understand the complex molecular mechanisms underlying blood pressure (BP)-regulating effects of these natural substances better. Polyphenols, flavonoids, alkaloids, and peptides are examples of bioactive compounds that have demonstrated promise in influencing several pathways involved in regulating vascular tone, reducing oxidative stress (OS), reducing inflammation, and improving endothelial function. The article explains the vasodilatory, diuretic, and renin-angiotensin-aldosterone system (RAAS) modifying properties of vital plants such as garlic and olive leaf. Phytochemicals from plants are the primary in traditional drug development as models for novel antihypertensive drugs, providing diverse strategies to combat HTN due to their biological actions. The review also discusses the functions of calcium channel blockers originating from natural sources, angiotensin-converting enzyme (ACE) inhibitors, and nitric oxide (NO) donors. Including seafood components in this study demonstrates the increased interest in using bioactive chemicals originating from marine sources to treat HTN. Omega-3 fatty acids, peptides, and minerals obtained from seafood sources have anti-inflammatory, vasodilatory, and antioxidant properties that improve vascular health and control BP. Overall, we discussed the multiple functions of bioactive molecules and seafood components in the treatment of HTN.

The medicinal value of tea drinking in the management of COVID-19

Corona Virus Disease 2019 (COVID-19) is presently the largest international public health event, individuals infected by the virus not only have symptoms such as fever, dry cough, and lung infection at the time of onset, but also possibly have sequelae in the cardiovascular system, respiratory system, nervous system, mental health and other aspects. However, numerous studies have depicted that the active ingredients in tea show good antiviral effects and can treat various diseases by regulating multiple pathways, and the therapeutic effects are associated with the categories of chemical components in tea. In this review, the differences in the content of key active ingredients in different types of tea are summarized. In addition, we also highlighted their effects on COVID-19 and connected sequelae, further demonstrating the possibility of developing a formulation for the prevention and treatment of COVID-19 and its sequelae through tea extracts. We have a tendency to suggest forestalling and treating COVID-19 and its sequelae through scientific tea drinking.

The therapeutic potential of matcha tea: A critical review on human and animal studies

Matcha is a powdered form of Japanese green tea that has been gaining global popularity recently. Matcha tea has various health benefits, including an enhancing effect on cognitive function, cardio-metabolic health, and anti-tumorogenesis. To date, randomized clinical trials (RCT) showed that matcha decreases stress, slightly enhances attention and memory, and has no effect on mood. Results regarding the effect of matcha on cognitive function are contradictory and more RCTs are warranted. The cardio-metabolic effects of matcha have only been studied in animals, but findings were more homogenous. Consuming matcha with a high-fat diet resulted in decreased weight gain velocity, food intake, improved serum glucose and lipid profile, reduced inflammatory cytokines and ameliorated oxidative stress. Evidence regarding the anti-tumor function of matcha is very limited. Findings showed that matcha can affect proliferation, viability, antioxidant response, and cell cycle regulation of breast cancer cells. Nonetheless, more studies are needed to examine this effect on different types of cancer cells, and there is also a need to verify it using animal models. Overall, the evidence regarding the effect of matcha tea on cognitive function, cardio-metabolic function, and anti-tumor role is still limited, and conclusions cannot be drawn.

Characteristics of catechin loading rice porous starch/chitosan functional microsphere and its adsorption towards Pb2+

In this paper, we explore the adsorption potential of catechin (CT) loaded composite microspheres and provide a new micron scale carrier of functional factor. Chitosan (CS) modified rice porous starch (RPS/CS) was used as a CT adsorption carrier to prepare bioactive CT-loaded composite microspheres (CT@RPS/CS). The adsorption kinetics, storage characteristics, and biological activity maintenance of CT@RPS/CS were studied in an aqueous solution, and the sustained-release characteristics of CT@RPS/CS were studied in vitro during simulated gastrointestinal digestion. An aqueous solution further studied the removal characteristics of adsorbed heavy metal ion Pb²⁺. RPS/CS can significantly improve the ability to adsorb CT. RPS/CS can also significantly improve CT's storage stability, antioxidant stress, and slow-release characteristics, and the sustained release effect in gastric and intestinal juice. CT@RPS/CS can be removed Pb²⁺ by adsorbing in the solution, and their adsorption was physical adsorption and chemisorption, but the primary interaction is chemisorption. CT@RPS/CS can be used as a micron carrier of new food functional factors, which has potential space for improving and expanding the functional characteristics of its loaded functional factors and the endowing of new functions.

Role of medicinal plants in inhibiting SARS-CoV-2 and in the management of post-COVID-19 complications

BACKGROUND

The worldwide corona virus disease outbreak, generally known as COVID-19 pandemic outbreak resulted in a major health crisis globally. The morbidity and transmission modality of COVID-19 appear more severe and uncontrollable. The respiratory failure and following cardiovascular complications are the main pathophysiology of this deadly disease. Several therapeutic strategies are put forward for the development of safe and effective treatment against SARS-CoV-2 virus from the pharmacological view point but till date there are no specific treatment regimen developed for this viral infection.

PURPOSE

The present review emphasizes the role of herbs and herbs-derived secondary metabolites in inhibiting SARS-CoV-2 virus and also for the management of post-COVID-19 related complications. This approach will foster and ensure the safeguards of using medicinal plant resources to support the healthcare system. Plant-derived phytochemicals have already been reported to prevent the viral infection and to overcome the post-COVID complications like parkinsonism, kidney and heart failure, liver and lungs injury and mental problems. In this review, we explored mechanistic approaches of herbal medicines and their phytocomponenets as antiviral and post-COVID complications by modulating the immunological and inflammatory states.

STUDY DESIGN

Studies related to diagnosis and treatment guidelines issued for COVID-19 by different traditional system of medicine were included. The information was gathered from pharmacological or non-pharmacological interventions approaches. The gathered information sorted based on therapeutic application of herbs and their components against SARSCoV-2 and COVID-19 related complications.

METHODS

A systemic search of published literature was conducted from 2003 to 2021 using different literature database like Google Scholar, PubMed, Science Direct, Scopus and Web of Science to emphasize relevant articles on medicinal plants against SARS-CoV-2 viral infection and Post-COVID related complications.

RESULTS

Collected published literature from 2003 onwards yielded with total 625 articles, from more than 18 countries. Among these 625 articles, more than 95 medicinal plants and 25 active phytomolecules belong to 48 plant families. Reports on the therapeutic activity of the medicinal plants belong to the Lamiaceae family (11 reports), which was found to be maximum reported from 4 different countries including India, China, Australia, and Morocco. Other reports on the medicinal plant of Asteraceae (7 reports), Fabaceae (8 reports), Piperaceae (3 reports), Zingiberaceae (3 reports), Ranunculaceae (3 reports), Meliaceae (4 reports) were found, which can be explored for the development of safe and efficacious products targeting COVID-19.

CONCLUSION

Keeping in mind that the natural alternatives are in the priority for the management and prevention of the COVID-19, the present review may help to develop an alternative approach for the management of COVID-19 viral infection and post-COVID complications from a mechanistic point of view.

No causal effect of tea consumption on cardiovascular diseases: A two-sample Mendelian randomization study

Background

Numerous studies have been conducted to investigate the relationship between tea consumption and the risk of cardiovascular diseases (CVD); however, no conclusive results have been achieved. We conducted a Mendelian randomization (MR) study to elucidate the causal associations between tea consumption and several CVD outcomes, including coronary artery disease (CAD), myocardial infarction (MI), atrial fibrillation (AF), and heart failure (HF).

Methods

Independent single-nucleotide polymorphisms (SNPs) genome-wide significantly associated with tea consumption were used as instrumental variables (IVs). Summary statistics for CVD outcomes were obtained from the corresponding genetic consortia and the FinnGen consortium. The inverse-variance weighted (IVW) method was the primary analytical method, and MR estimates from different data sources were combined using fixed-effects meta-analysis. Supplementary MR analyses, including the weighted median, MR-Egger, and the MR pleiotropy residual sum and outlier methods, were conducted to evaluate the robustness of the results. Further MR analyses were repeated by including more genetic variants at a higher P-value threshold.

Results

We found that genetically predicted tea consumption was not causally associated with any CVD outcomes in the IVW method using data from large genetic consortia [CAD: odds ratio (OR) = 1.00, 95% confidence interval (CI), 0.91, 1.10, P = 0.997; MI: OR = 0.98, 95% CI, 0.90, 1.08, P = 0.751; AF: OR = 0.97, 95% CI, 0.92, 1.03, P = 0.350; HF: OR = 0.96, 95% CI, 0.88, 1.05, P = 0.401] or the FinnGen consortium (CAD: OR = 1.06, 95% CI, 0.96, 1.17, P = 0.225; MI: OR = 1.01, 95% CI, 0.89, 1.15, P = 0.882; AF: OR = 1.00, 95% CI, 0.88, 1.14, P = 0.994; HF: OR = 0.96, 95% CI, 0.88, 1.04, P = 0.362). The results were robust and consistent across meta-analysis, supplementary MR analyses, and analyses with more IVs included.

Conclusion

This MR study revealed no causal association between tea consumption and four CVD outcomes, suggesting that tea consumption may not be beneficial for the primary prevention of CVD.

Quickly and efficiently remove multiple pesticides in tea infusions by low-cost carbonized bacterial cellulose

Soaking tea leaves make tea consumers exposure to pesticide residues more easily. However, there are few studies on the removal of pesticides in tea infusions. Therefore, a low-cost carbonized bacterial cellulose material was prepared by direct calcination method, and used to remove multiple pesticides in tea infusions quickly and efficiently. CBC-350 has the best removal efficiency for 9 pesticides and then screened the best adsorption conditions. The adsorption isotherm experiment was carried out and indicated that the adsorption process was in consist with the Freundlich model. The thermodynamic parameters are also calculated. Moreover, the adsorption mechanism was discussed, which suggests that π-π interaction and hydrophobic action are the driving force during the adsorption process. Exhilaratingly, the CBC-350 also has excellent adsorption capacity compared to other adsorbents and can be reused at least five times.

The mechanisms of calcium mobilization by procyanidins, flavonols and flavonoids from Cecropia glaziovii Sneth in pulmonary endothelial cell cultures endorse its popular use as vasodilator phytomedicine

The hypotensive and antihypertensive activities of the aqueous extract (AE) and butanolic fraction (ButF) isolated from Cecropia glaziovii Sneth have been demonstrated in previous studies in animal models. This study aimed to evaluate the molecular mechanism of action responsible for the vasodilatory effect of procyanidins, flavanols, and flavonoids found in C. glaziovii in endothelial cell culture. For this purpose, we analyzed the effect of procyanidin B2 and B3 compounds, catechin, epicatechin, orientin, isoorientin, and isovitexin in the mobilization of Ca2+ in rat endothelial cell cultures. Parallel associations with different antagonists were examined by considering the following in vivo hypotensive mechanisms: blockage of L-type calcium channels, action on β-2 adrenergic receptors, and vasodilation via the nitric oxide pathway. All measurements of calcium mobilization were carried out by using the fluorescence measurement methodology in a Flexstation M3 spectrophotometer. The results indicate that some of the compounds have mixed actions, acting through different calcium mobilization pathways. The mobilization induced by such compounds significantly decreased when they were incubated with their corresponding antagonists. Taken together, our data suggest that the beneficial effects seen with the popular use of Cecropia glaziovii Sneth in pathological conditions, such as systemic arterial hypertension, seem to be related to the plant's hypotensive effect, very probably promoted by the actions of flavonols, flavonoids, and procyanidins, by different pathways of calcium mobilization.

Epigallocatechin gallate (EGCG) attenuates myocardial hypertrophy and fibrosis induced by transverse aortic constriction via inhibiting the Akt/mTOR pathway

CONTEXT

Epigallocatechin gallate (EGCG) is the most abundant catechin from tea. Previous studies have indicated EGCG has a cardioprotective effect.

OBJECTIVE

This manuscript mainly explores the role of EGCG in pressure-overload cardiac hypertrophy and its mechanism related to the Akt/mTOR pathway.

METHODS AND METHODS

Transverse aortic constriction (TAC) was utilized to establish the cardiac hypertrophy mice model. C57BL/6 mice were assigned into 6 groups. Starting from the first day after surgery, mice received different doses of EGCG (20, 40, 80 mg/kg) or vehicle orally for four weeks. Heart weight to body weight (HW/BW) ratio and heart weight to tibia length (HW/TL) ratio as well as hematoxylin-eosin staining were utilized to evaluate cardiac hypertrophy. Masson's trichrome and Sirius red staining were used to depict cardiac fibrosis. The expressions of fibrosis and hypertrophy-related markers and Akt/mTOR pathway were quantified by western blot and qRT-PCR.

RESULTS

EGCG significantly attenuated cardiac function shown by decreased HW/BW (TAC, 6.82 ± 0.44 vs. 20 mg/kg EGCG, 5.53 ± 0.45; 40 mg/kg EGCG, 4.79 ± 0.32; 80 mg/kg EGCG, 4.81 ± 0.38) and HW/TL (TAC, 11.94 ± 0.69 vs. 20 mg/kg EGCG, 11.44 ± 0.49; 40 mg/kg EGCG, 8.83 ± 0.58; 80 mg/kg EGCG, 8.98 ± 0.63) ratios as well as alleviated cardiac histology. After treatment, hemodynamics was improved, cardiac fibrosis was attenuated. The activated Akt/mTOR pathway was inhibited by EGCG.

DISCUSSION AND CONCLUSIONS

EGCG plays a protective role in the TAC model by regulating the Akt/mTOR pathway, which provides a theoretical basis for its clinical treatment.

Potential role of tea extract in oocyte development

Tea is the second most popular beverage in the world and beneficial to health. It has been demonstrated that tea polyphenols can reduce the risk of diseases, such as cancers, diabetes, obesity, Alzheimer's disease, etc. But the knowledge of tea extract on the female germline is limited. Folliculogenesis is a complicated process and prone to be affected by ROS. Tea polyphenols can reduce the accumulation of ROS in folliculogenesis and affect oocyte maturation. Tea extract also influences granulosa cell proliferation and expansion during oocyte growth and maturation. However, the studies about the benefits of tea extract on female germline are few, and the underlying mechanisms are obscure. In the present study, we will mainly discuss the effects of tea extract on ovarian function, oocyte maturation, and the underlying possible mechanisms, and according to the discussion, we suggest that tea extract may have benefits for oocytes at an appropriate dose.

Association of lipid accumulation product with chronic kidney disease in Chinese community adults: a report from the REACTION study

Background

Limited studies regarding the correlation of lipid accumulation product (LAP) with a decreased estimated glomerular filtration rate (eGFR) have yielded conflicting findings, and no report has demonstrated the relationship of LAP with chronic kidney disease (CKD), defined as the presence of albuminuria and/or a decreased eGFR. The purpose of this study was to estimate the possible correlation of LAP with CKD prevalence in Chinese community adults.

Method

In this cross-sectional study, LAP level of 7202 participants (age ≥ 40 years) was determined, and its possible association with CKD was evaluated by a multiple logistic regression model.

Results

Compared with subjects with non-CKD, non-albuminuria, and high eGFR, LAP levels significantly increased in female not male subjects with CKD, albuminuria, and low eGFR, respectively (all P < 0.001). The univariate logistic regression analysis revealed that LAP level of female not male subjects were significantly and positively associated with the prevalence of CKD (P < 0.001). The multivariate logistic regression analysis showed that the risk of CKD prevalence in female not male subjects progressively increased across LAP quartiles (P for trend < 0.01), and the risk of CKD prevalence of subjects in Q4 significantly increased compared to those in Q1 after adjustment for potential confounding factors in Models 4 (odds ratio [OR]: 1.382, 95% confidence intervals [CI] 1.002–1.906, P < 0.05). Stratified analysis revealed positive associations of LAP quartiles with risk of CKD prevalence in people with the following characteristics: women, older, overweight, with hypertension, normal glucose tolerance, appropriate low-density lipoprotein cholesterol, nonsmokers, nondrinkers, and no cardiovascular disease events.

Conclusions

High LAP levels might be significantly associated with risk of CKD prevalence in community-dwelling Chinese female adults, which may inform both public health recommendations and clinical practice.

Evaluation of Roasting Effect on Selected Green Tea Volatile Flavor Compound and Pyrazine Content by HS-SPME GC-MS

The present study aims at the development and validation of a quali-quantitative headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME GC-MS) method for the analysis of odorants in different Chinese and Japanese green teas. A 65 µm PDMS/DVB fiber was used, and GC-MS was performed on a ZB-5 (30 m × 0.25 mm ID, 0.25 μm film) column. The main odorants in green tea samples were identified and the method was fully validated. Linearity (r2 0.981–0.999), sensitivity (LOQ 0.005–0.04 µg/mL), reproducibility (CV% 3.12–10.37), accuracy (recovery% 79.08–99.17) and matrix effect (ME% −9.5 to +4.5) were determined. Quantitation of 2,4-heptadienal, β-damascenone, β-ionone, linalool, indole, 2-ethyl-6-methyl-pyrazine, 2-ethyl-5-methyl-pyrazine, 2-ethyl-3,6-dimethylpirazine, 2-ethyl-3,5-dimethyl-pyrazine and 2-acetyl-pyrazine was carried out in the presence of isotopically labeled compounds as the internal standards. The proposed method was applied to the comparison of the profile of the volatile flavor compounds (VFCs) of green tea subjected to roasting treatment at three different temperatures (160, 180 and 200 °C for 30 min). In particular, the roasting process was monitored by following the quantitative variations of the selected odorant content, considered as the most important contributory components to the Hojicha or black tea (roasted tea) flavor. A temperature of 160 °C was found to be the best roasting temperature.

Plants Used as Antihypertensive

Hypertension is a critical health problem and worse other cardiovascular diseases. It is mainly of two types: Primary or essential hypertension and Secondary hypertension. Hypertension is the primary possibility feature for coronary heart disease, stroke and renal vascular disease. Herbal medicines have been used for millions of years for the management and treatment of hypertension with minimum side effects. Over aim to write this review is to collect information on the anti-hypertensive effects of natural herbs in animal studies and human involvement as well as to recapitulate the underlying mechanisms, from the bottom of cell culture and ex-vivo tissue data. According to WHO, natural herbs/shrubs are widely used in increasing order to treat almost all the ailments of the human body. Plants are the regular industrial units for the invention of chemical constituents, they used as immunity booster to enhance the natural capacity of the body to fight against different health problems as well as herbal medicines and food products also. Eighty percent population of the world (around 5.6 billion people) consume medicines from natural plants for major health concerns. This review provides a bird's eye analysis primarily on the traditional utilization, phytochemical constituents and pharmacological values of medicinal herbs used to normalize hypertension i.e. Hibiscus sabdariffa, Allium sativum, Andrographis paniculata, Apium graveolens, Bidenspilosa, Camellia sinensis, Coptis chinensis, Coriandrum sativum, Crataegus spp., Crocus sativus, Cymbopogon citrates, Nigella sativa, Panax ginseng,Salviaemiltiorrhizae, Zingiber officinale, Tribulus terrestris, Rauwolfiaserpentina, Terminalia arjuna etc.

Systematic Analysis of Combined Antioxidant and Membrane-Stabilizing Properties of Several Lamiaceae Family Kazakhstani Plants for Potential Production of Tea Beverages

One of the most important compounds that exhibit a wide range of biological activities with especially strong antioxidant action are plant polyphenols. In the course of the experiment, the dose-dependent effects of polyphenols-rich extracts isolated from the Lamiaceae family Kazakhstani plants were studied on the processes of lipid peroxidation and on the degree of erythrocytes hemolysis. The activity of aqueous-ethanolic extracts from dried parts of plants, such as Origanum vulgare, Ziziphora bungeana, Dracocephalum integrifolium, Mentha piperita, Leonurus turkestanicus, Thymus serpyllum, and Salvia officinalis, was studied in a Wistar rat model. Lipid peroxidation (LPO) in liver microsomes was assessed by measuring malondialdehyde content in the form of thiobarbituric acid-reacting substances (TBARS). Estimation of osmotic resistance of isolated erythrocytes was evaluated based on hemoglobin absorbance. The amount of total phenolics in the extracts was measured using the Folin-Ciocalteu reagent method. Based on the results, Thymus serpyllum extract exhibited a significantly higher antioxidant activity (IC50 = 3.3 ± 0.7) compared to other plant extracts. Accordingly, among the extracts studied, those from Salvia officinalis, Thymus serpyllum, and Origanum vulgare show the most pronounced membrane-stabilizing activity. Antioxidant and antihemolytic properties of green tea and Origanum vulgare extract mixtures were similar to that of each individual plant extract. Similar results were obtained when the green tea extract was mixed with Mentha piperita, Ziziphora bungeana, and Dracocephalum integrifolium extracts, indicating no discernible synergistic interaction.

Addition of flavonols and polysaccharides as excipient ingredients into epicatechin rich green tea extract inhibited free radical formation and glucose uptake

It was revealed that excipient ingredients such as flavonols (FVN) or polysaccharides (GTP) which could be derived from green tea enhanced catechin absorption. We hypothesized that the addition of FVN or GTP as excipient ingredients into epicatechin rich green tea extracts (GTE) may improve the health benefits that accompany its consumption. When FVN8.7 (8.7% of GTE, w/w) was added to the GTE (20 mg) as an excipient ingredient, the bioaccessibility and intestinal absorption of total epicatechins was 1.2 and 1.5 times higher than that of only GTE, respectively. This was due to the free radical scavenging capacity of flavonols, showing 114.23 ± 3.07 μmol TE per g for GTE 100 + FVN8.7 and 113.64 ± 1.61 μmol TE per g for GTE 100 + FVN2, respectively. This was significantly higher than the GTE or GTE 100 + OW2 (onion peel and whangchil extracts, 2% of GTE, w/w) which have the same amount of total flavonols. Regarding potential hypoglycemic effects, co-digestion of GTE (20 mg) + green tea polysaccharides (2 mg) + FVN (5 mg) with wheat starch significantly reduced glucose intestinal absorption by 41.85 ± 1.75% compared to only the wheat starch. The results from the current study suggest that whole green tea components rich in flavonols and polysaccharides could be potential hypoglycemic excipient ingredients for green tea catechins.

Tea consumption and its effects on primary and secondary prevention of coronary artery disease: Qualitative synthesis of evidence from randomized controlled trials

BACKGROUND AND AIMS

There is a general interest in understanding how the consumption of tea impacts cardiovascular function in individuals at risk of developing cardiovascular disease (CVD). The current review focuses on evidence from randomized controlled trials (RCTs) reporting on associations between tea consumption and endothelial function, in the primary and secondary prevention of coronary artery disease (CAD).

METHODS

PubMed, EMBASE, and Google Scholar databases/search engines were used to identify eligible studies. Included studies had to report on the impact of tea supplementation of endothelial function or CAD related markers. In addition to flow-mediated dilation (FMD), makers of oxidative stress and inflammation such as oxidized low-density lipoprotein and C-reactive protein were considered as determinants of endothelial function. A total of 34 RCTs met the inclusion criteria, and these reported on the impact of tea consumption on endothelial function in individuals at risk of CVD or patients with CAD.

RESULTS

The current qualitative synthesis of literature demonstrates that beyond enhancing nitric oxide bioavailability and lowering blood pressure, regular consumption of tea and its active ingredients such as epigallocatechin gallate may be beneficial in reducing markers of oxidative stress and inflammation. Moreover, the reduction of oxidized low-density lipoprotein and C-reactive protein levels, could be a sign of improved endothelial function in individuals at increased risk of developing CVD.

CONCLUSIONS

The cumulative evidence also suggests that the development of epigallocatechin gallate as a nutraceutical or enriching foods with this bioactive compound could be a feasible strategy to improve endothelial function and lower CVD-risk. However, well-designed RCTs are still necessary to confirm long-term benefits of tea consumption on vascular health.

Black and Green Tea as Well as Specialty Teas Increase Osteoblast Mineralization with Varying Effectiveness

Many human studies suggest a benefit of tea consumption on bone health. The study objective was to compare the ability of different tea types to promote mineralization. Saos-2 cells underwent mineralization (5 days) in the presence of tea (white: WT, green: GT, black: BT, green rooibos: GR, or red rooibos: RR; 1 μg/mL of polyphenols) or control. Total polyphenol content (TPC, Folin-Ciocalteu's reagent), antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl [DPPH] scavenging), mineralization (Alizarin Red staining), gene expression quantitative reverse transcription PCR (RT-qPCR), and cell activity (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay) were determined. TPC was highest in GT and BT. The ability of each tea to inhibit DPPH also differed (WT, GT > RR) after normalizing for polyphenol quantity. Each tea increased mineralization and differences were observed among types (GT/BT/GR/RR > WT, GT = BT = GR, RR > BT/GT). mRNA expression of alkaline phosphatase (ALP) and ectonucleotide pyrophosphatase/phosphodiesterase (NPP1) remained unchanged, whereas osteopontin (OPN) and sclerostin (SOST) were reduced in cells treated with tea, regardless of type. At 24- and 48-h postexposure to tea, cell activity was greater in cells receiving any of the teas compared with vehicle control. Supplementation increased mineralization regardless of tea type with both rooibos teas and black tea stimulating greater mineralization than WT, whereas green tea is similar to the others. While future study is needed to confirm in vivo effects, the results suggest that consuming any of the teas studied may benefit bone health.

Associations between habitual tea consumption and 5-year longitudinal changes of systolic blood pressure in older Chinese

BACKGROUND AND OBJECTIVES

Tea consumption may contribute to the management of blood pressure; however, evidence from longitudinal studies is lacking. This study aimed to examine the relationship between habitual tea consumption and trajectories of systolic blood pressure in a community-based sample of Chinese adults aged 60 years or older.

METHODS

A prospective cohort of 3870 participants was investigated from 2014 to 2018. Trajectories of systolic blood pressure were identified using latent mixture modeling with the Proc Traj procedure. Multiple logistic regression models were fitted to explore associations between tea consumption habits and trajectories of systolic blood pressure.

RESULTS

In the overall sample, participants were less likely to be habitual tea drinkers if they were in the "moderate-stable" (144.4-149.9 mm Hg), "moderate-increasing" (157.2-180.0 mm Hg), and "elevated-increasing" (184.7-209.8 mm Hg) groups as compared to those in the "low-stable" group (125.3-130.0 mm Hg). The "elevated-decreasing" group (170.7 - 167.2 mmHg) consistently showed no significant difference in the likelihood of habitual tea drinking as compared to the "low-stable" group.

CONCLUSIONS

This community-based prospective study indicated that habitual tea consumption was associated with relatively favorable long-term systolic blood pressure statuses.

Evaluation inhibitory activity of catechins on trypsin by capillary electrophoresis-based immobilized enzyme microreactor with chromogenic substrate

In this study, a capillary electrophoresis-based online immobilized enzyme microreactor was developed for evaluating the inhibitory activity of green tea catechins and tea polyphenol extracts on trypsin. The immobilized trypsin activity and other kinetic parameters were evaluated by measuring the peak area of the hydrolyzate of chromogenic substrate S-2765. The results indicated that the activity of the immobilized trypsin remained approximately 90.0% of the initial immobilized enzyme activity after 30 runs. The value of Michaelis-Menten constant (K_m ) was (0.47 ± 0.08) mM, and the half-maximal inhibitory concentration (IC₅₀ ) and inhibition constant (K_i ) of benzamidine were measured as 3.34 and 3.00 mM, respectively. Then, the inhibitory activity of four main catechins (epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate) and three tea polyphenol extracts (green tea, white tea, and black tea) on trypsin were investigated. The results showed that four catechins and three tea polyphenol extracts had potential trypsin inhibitory activity. In addition, molecular docking results illustrated that epigallocatechin gallate, epicatechin gallate, epicatechin, and epigallocatechin were all located not only in the catalytic cavity, but also in the substrate-binding pocket of trypsin. These results indicated that the developed method is an effective tool for evaluating inhibitory activity of catechins on trypsin.

Endothelial TRPV1 as an Emerging Molecular Target to Promote Therapeutic Angiogenesis

Therapeutic angiogenesis represents an emerging strategy to treat ischemic diseases by stimulating blood vessel growth to rescue local blood perfusion. Therefore, injured microvasculature may be repaired by stimulating resident endothelial cells or circulating endothelial colony forming cells (ECFCs) or by autologous cell-based therapy. Endothelial Ca²⁺ signals represent a crucial player in angiogenesis and vasculogenesis; indeed, several angiogenic stimuli induce neovessel formation through an increase in intracellular Ca²⁺ concentration. Several members of the Transient Receptor Potential (TRP) channel superfamily are expressed and mediate Ca²⁺-dependent functions in vascular endothelial cells and in ECFCs, the only known truly endothelial precursor. TRP Vanilloid 1 (TRPV1), a polymodal cation channel, is emerging as an important player in endothelial cell migration, proliferation, and tubulogenesis, through the integration of several chemical stimuli. Herein, we first summarize TRPV1 structure and gating mechanisms. Next, we illustrate the physiological roles of TRPV1 in vascular endothelium, focusing our attention on how endothelial TRPV1 promotes angiogenesis. In particular, we describe a recent strategy to stimulate TRPV1-mediated pro-angiogenic activity in ECFCs, in the presence of a photosensitive conjugated polymer. Taken together, these observations suggest that TRPV1 represents a useful target in the treatment of ischemic diseases.

The Effect of L-Theanine Incorporated in a Functional Food Product (Mango Sorbet) on Physiological Responses in Healthy Males: A Pilot Randomised Controlled Trial

Consumption of L-Theanine (L-THE) has been associated with a sensation of relaxation, as well as a reduction of stress. However, these physiological responses have yet to be elucidated in humans where L-THE is compared alongside food or as a functional ingredient within the food matrix. The aim of this study was to determine the physiological responses of a single intake of a potential functional food product (mango sorbet) containing L-THE (ms-L-THE; 200 mgw/w) in comparison to a flavour and colour-matched placebo (ms). Eighteen healthy male participants were recruited in this randomised, double-blind, placebo-controlled trial. The participants were required to consume ms-L-THE or placebo and their blood pressure (BP) (systolic and diastolic), heart rate (HR), and heart rate variability (HRV) were monitored continuously over 90 minutes. Eleven males (age 27.7 ± 10.8 years) completed the study. Changes in area under the curve for systolic and diastolic blood pressure and HRV over the 90 minute observation period indicated no differences between the three conditions (all p > 0.05) or within individual groups (all p > 0.05). The values for heart rate were also not different in the placebo group (p = 0.996) and treatment group (p = 0.066), while there was a difference seen at the baseline (p = 0.003). Based on the findings of this study, L-THE incorporated in a food matrix (mango sorbet) demonstrated no reduction in BP or HR and showed no significant parasympathetic interaction as determined by HRV high-frequency band and low-frequency/high-frequency ratio. Further studies should be focussed towards the comparison of pure L-THE and incorporation within the food matrix to warrant recommendations of L-THE alongside food consumption.

Red Rooibos Tea Stimulates Osteoblast Mineralization in a Dose-Dependent Manner

Most studies show a positive association between higher tea intake and bone mineral density (BMD), while associations with fracture are inconclusive. Although a few studies have investigated the potential effects of rooibos tea on the bone cell metabolism, only 1 or 2 doses were tested or specific flavonoids were evaluated in isolation. A dose-response study is needed to comprehensively identify whether a level that modulates bone cell activity is associated with dietary or supplemental levels of red rooibos (RR) tea. We investigated if RR tea stimulates mineralization in a dose-dependent manner. Mineralization was induced in Saos-2 cells in the presence of RR tea (0.1–10 µg/mL of polyphenols) or control (dH2O) for 5 days. Cell activity, mRNA, protein expression and activity of key regulators of mineralization were measured. A positive dose-dependent relationship was observed between RR tea concentration and mineralization accompanied with similar trends in cell activity. With high concentrations of tea, protein expression of enzymes directly regulating mineralization (ALP and NPP1) were unchanged but ALP activity was significantly elevated. Osteopontin (OPN) was significantly downregulated midway through mineralization while sclerostin (SOST) was upregulated in response to higher concentrations of RR tea. In conclusion, RR tea stimulated osteoblast mineralization in a dose-dependent manner and were accompanied with downregulation of OPN, increased ALP activity, and increased cell activity.

A Study of Diet and Lifestyle and the Risk of Urolithiasis in 1,519 Patients in Southern China

Background

This study aimed to evaluate the risk factors associated with the development of urolithiasis in a population in Southern China.

Material/Methods

A questionnaire-based study was conducted between March 2017 to April 2018 that included 1,519 patients in Southern China and included questions on patient demographics, diet, and lifestyle. Patients were divided into the urolithiasis group who had urinary calculi and the control group.

Results

There were 829 patients (54.6%) in the urolithiasis group and 690 patients (45.4%) in the control group. Using a chi-squared (χ²) test, 13 variables were found to be significantly associated with urolithiasis, including age, physical activity, and dietary factors that included high sodium, protein, fat, lean meat, vegetables, pickled food, fluid intake, drinking habits and tea consumption, and frequency and duration of physical exercise. Multivariate logistic regression analysis showed that dietary factors, including vegetables (OR, 0.856; 95% CI, 0.769–0.948), pickled foods (OR, 1.271; 95% CI, 1.030–1.357), and animal protein intake (OR, 1.138; 95% CI, 1.031–1.258), drinking strong tea (OR, 0.793; 95% CI, 0.702–0.897), fluid intake (OR, 0.758; 95% CI, 0.644–0.816), and duration of physical exercise (OR, 0.840; 95% CI, 0.808–0.973) were significantly associated with the occurrence of urolithiasis and were independent risk factors.

Conclusions

High consumptions of pickled foods and animal protein were the main risk factors for the development of urolithiasis in a population of southern China, but high fluid intake with a preference for strong tea, a diet of vegetables, and physical exercise were protective factors.

Studies on the Prevention of Cancer and Cardiometabolic Diseases by Tea: Issues on Mechanisms, Effective Doses, and Toxicities

This article presents a brief overview of studies on the prevention of cancer and cardiometabolic diseases by tea. The major focus is on green tea catechins concerning the effective doses used, the mechanisms of action, and possible toxic effects. In cancer prevention by tea, the laboratory results are strong; however, the human data are inconclusive, and the effective doses used in some human trials approached toxic levels. In studies of the alleviation of metabolic syndrome, diabetes, and prevention of cardiovascular diseases, the results from human studies are stronger in individuals who consume 3-4 cups of tea (600-900 mg of catechins) or more per day. The tolerable upper intake level of tea catechins has been set at 300 mg of (-)-epigallocatechin-3-gallate in a bolus dose per day in some European countries. The effects of doses and dosage forms on catechin toxicity, the mechanisms involved, and factors that may affect toxicity are discussed.

Effectiveness of black tea versus placebo in subjects with hypercholesterolemia: A PRISMA systematic review and meta-analysis

AIM

To determine if the black tea is more effective in serum lipid profile that placebo in subjects with hypercholesterolemia.

DESIGN

Systematic review with meta-analysis of randomized clinical trials (RCTs).

DATA SOURCES

The databases Medline, Central, Embase, Lilacs, Cinahl, SPORTDiscus, and Web of Science were searched from inception up to January 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

RCTs that compared black tea versus placebo, that included serum lipid profile outcomes in subjects older than 18 years of age with hypercholesterolemia.

RESULTS

Seven RCTs met the eligibility criteria, and for the quantitative synthesis, six studies were included. Mean difference for total cholesterol was 1.67 mg/dl 95% CI = -5.47 to 8.80 (p = 0.65), mean difference 0.28 mg/dl, 95% CI = -3.89 to 4.45 (p = 0.90) for triglycerides, mean difference 3.21 mg/dl, 95% CI = -11.02 to 4.60 (p = 0.42) for low density lipoprotein-cholesterol, mean difference 0.38 mg/dl, 95% CI = -1.12 to 1.87 (p = 0.62) for high density lipoprotein-cholesterol.

CONCLUSION

In the short term, no significant differences were found in lipid serum profile comparing black tea consumption with placebo.

Effect of particle size on the bioaccessibility of polyphenols and polysaccharides in green tea powder and its antioxidant activity after simulated human digestion

The bioaccessibilities of polyphenols and polysaccharides in green tea powders (GTPs) with different particle sizes of 564.24 µm, 74.85 µm, 34.62 µm and 15.10 µm and their antioxidant activities were investigated using an in vitro simulated gastrointestinal digestion model. The results showed that particle size significantly affected the bioaccessibilities of polyphenols and polysaccharides before and after digestion, except for the bioaccessibility of polysaccharides after gastric plus intestinal (GI) digestion, thus significantly affecting the antioxidant activity of GTPs. Compared with the undigested initial amount, the bioaccessibilities of polyphenols in all GTPs were approximately 59.98-71.00% after gastric digestion and 9.69-15.57% after GI digestion, and the bioaccessibilities of polysaccharides were approximately 71.10-79.51% after gastric digestion and 113.78-190.38% after GI digestion. With the decrease in particle size, the FRAP value of GTP before digestion was significantly increased and that of 15.10 µm was the largest (4.96 mmol Fe²⁺/g). Both the FRAP and DPPH values after digestion showed a trend of first increasing and subsequently decreasing; 74.85 µm GTP had the largest FRAP (4.11 mmol Fe²⁺/g) and DPPH (156.61 mg VCE/g) values after gastric digestion, and 34.62 µm GTP had the largest FRAP (0.16 mmol Fe²⁺/g) and DPPH (1.43 mg VCE/g) values after GI digestion. This study suggested that the bioaccessibilities of polyphenols and polysaccharides in GTPs and their antioxidant activity can be improved by properly reducing the particle size such that TGPs can exert more beneficial health effects.

Epigallocatechin-3-gallate inhibits angiotensin II-induced cardiomyocyte hypertrophy via regulating Hippo signaling pathway in H9c2 rat cardiomyocytes

Angiotensin II (AII) has been well known to induce cardiomyocyte hypertrophy. Epigallocatechin-3-gallate (EGCG) is the main active component of green tea and it has been shown to exhibit strong cardioprotective potential, although the underlying molecular mechanisms remain unclear. In this study, we investigated the role and mechanism of EGCG in preventing AII-induced cardiomyocyte hypertrophy using rat H9c2 cardiomyocytes cells. Reactive oxygen species assay, cell size, and mRNA expression of cardiac hypertrophy markers ANP and BNP were assessed in response to AII treatment. In addition, expression of proteins involved in Hippo signaling pathway were determined by western blot analysis. We found that AII treatment resulted in significant upregulation of ANP and BNP expression levels and increase in H9c2 cell size, which were markedly attenuated by EGCG treatment. Furthermore, our results suggested that EGCG inhibited AII-induced cardiac hypertrophy via regulating the Hippo signaling pathway. Therefore, EGCG may be an effective agent for preventing cardiac hypertrophy.

Phytochemicals for Improving Aspects of Cognitive Function and Psychological State Potentially Relevant to Sports Performance

Subjective alertness and optimal cognitive function, including in terms of attention, spatial/working memory and executive function, are intrinsic to peak performance in many sports. Consumption of a number of plant-derived 'secondary metabolite' phytochemicals can modulate these psychological parameters, although there is a paucity of evidence collected in a sporting context. The structural groups into which these phytochemicals fall-phenolics, terpenes and alkaloids-vary in terms of the ecological roles they play for the plant, their toxicity and the extent to which they exert direct effects on brain function. The phenolics, including polyphenols, play protective roles in the plant, and represent a natural, benign component of the human diet. Increased consumption has been shown to improve cardiovascular function and is associated with long-term brain health. However, whilst short-term supplementation with polyphenols has been shown to consistently modulate cerebral blood-flow parameters, evidence of direct effects on cognitive function and alertness/arousal is currently comparatively weak. Terpenes play both attractant and deterrent roles in the plant, and typically occur less frequently in the diet. Single doses of volatile monoterpenes derived from edible herbs such as sage (Salvia officinalis/lavandulaefolia) and peppermint (Mentha piperita), diterpene-rich Ginkgo biloba extracts and triterpene-containing extracts from plants such as ginseng (Panax ginseng/quinquefolius) and Bacopa monnieri have all been shown to enhance relevant aspects of cognitive function and alertness. The alkaloids play toxic defensive roles in the plant, including via interference with herbivore brain function. Whilst most alkaloids are inappropriate in a sporting context due to toxicity and legal status, evidence suggests that single doses of nicotine and caffeine may be able to enhance relevant aspects of cognitive function and/or alertness. However, their benefits may be confounded by habituation and withdrawal effects in the longer term. The efficacy of volatile terpenes, triterpene-rich extracts and products combining low doses of caffeine with other phytochemicals deserves more research attention.

Lipophilization of EGCG and effects on antioxidant activities

A green, fast, and efficient method for synthesizing lipophilic epigallocatechin gallate (EGCG) derivatives was set up for the first time. EGCG was lipophilized by esterification in order to promote its application in lipid products and to possibly enhance its bioactivity. A high conversion of EGCG was achieved. Three monoesters of the EGCG derivatives were confirmed by high performance liquid chromatography-mass spectrometry, and the predominant one was identified as 4'-O-palmitoyl EGCG by nuclear magnetic resonance. The EGCG derivatives exhibited good radical scavenging capacities. In lard the solubility of EGCG derivatives was enhanced 470 times compared to EGCG, and they exhibited excellent antioxidative activity in the oil. These results indicate that the palmitoylated EGCG derivatives may be used as potent antioxidants in lipophilic medium, such as edible oils and fatty foods. In addition, this method can be applied to commercial application, producing antioxidants to substitute for synthetic ones like tert-butylhydroquinone.

Plasma tea catechins and risk of cardiovascular disease in middle-aged Japanese subjects: The JPHC study

BACKGROUND AND AIMS

Although a potential benefit of drinking green tea has been suggested to reduce the development of cardiovascular disease, no study has investigated the relationship between plasma tea catechin and risk of cardiovascular disease.

METHODS

A prospective, nested case-control study was conducted to examine the association between plasma tea catechin and risk of stroke and coronary heart disease (CHD) in a cohort of 29,876 men and women aged 40-69 years without history of heart disease, stroke or cancer. Participants completed a survey and donated blood samples between 1990 and 1994, and were followed-up through 2008. A total of 1132 stroke cases and 209 CHD cases, matched 1:1 to controls (n = 1132) for stroke and 1:2 to controls (n = 418) for CHD, were included in the analysis.

RESULTS

We found no significant association between plasma tea catechin and the incidence of stroke or CHD in either men or women. However, we found that high plasma levels of epigallocatechin gallate (EGCG) were associated with reduced risk of stroke in non-smoking men; the adjusted odds ratio (95% CI) for the highest vs. non-detectable levels was 0.53 (0.29-0.98). The respective OR in male smokers was 1.23 (0.75-2.16). A significant interaction by smoking status was found for the highest vs. non-detected plasma EGCG in relation to stroke (p-for-interaction: p = 0.09).

CONCLUSIONS

Plasma tea catechin was not associated with reduced risks of either stroke or CHD, while a protective effect of certain tea catechin on stroke risk is suggested for male non-smokers.

Potential Role of Seaweed Polyphenols in Cardiovascular-Associated Disorders

The beneficial effects of various polyphenols with plant origins on different cardiovascular-associated disorders, such as hypertension, diabetes mellitus type 2 and metabolic syndrome are well known. Recently, marine crude-drugs are emerging as potential treatments in many noncommunicable conditions, including those involving the cardiovascular system. Among the active compounds responsible for these activities, seaweed polyphenols seem to play a key role. The aim of the present review is to summarise the current knowledge about the beneficial effects reported for edible seaweed polyphenols in the amelioration of these prevalent conditions, focusing on both preclinical and clinical studies. This review will help to establish the basis for future studies in this promising field.

UV-C Irradiation on the Quality of Green Tea: Effect on Catechins, Antioxidant Activity, and Cytotoxicity

Short-wavelength ultraviolet (UV-C) irradiation is a nonthermal processing technique that is a possible alternative to the heat-pasteurization of tea beverages. This study investigated the effect of UV-C irradiation on the polyphenolic and total phenolic contents of a green tea beverage and analyzed cytotoxicity of irradiated green tea using a novel continuous flow-through UV system. UV-C fluence levels ranging from 0 to 240 mJ/cm² were delivered to green tea, and polyphenols were chemically profiled. Continuous-flow UV-C irradiation of the green tea beverage at a fluence of 68 mJ/cm²  induced a minor reduction in the concentration of the most abundant catechin in green tea, (-)-epigallocatechin gallate (EGCG), from 145 to 131.1 μg/mL. The total phenolic content of the green tea beverage was 0.19 μg GAE/uL and remained constant at all UV fluence levels. The UV-treated green tea beverage showed no cytotoxic effects on normal intestinal cells with healthy colonic cells (CCD-18Co) maintained at 90% viability for the UV-treated green tea beverages and the control. The treated and nontreated green tea have comparable inhibitory effects on the survival of human colon cancer cells. Overall, these results demonstrate that the UV-C irradiation did not significantly deplete catechins or produce cytotoxic byproducts.

PRACTICAL APPLICATION

Short wavelength ultraviolet (UV-C) irradiation is a nonthermal processing technique that is a possible alternative to the heat pasteurization of tea beverages. This study investigated the effect of UV-C irradiation on the antioxidant concentration of green tea and analyzed cytotoxicity of irradiated a green tea beverage using a novel continuous flow-through UV system. The results demonstrated that the UV-C irradiation did not significantly deplete catechins or produce cytotoxic byproducts.

Diabetes and Alzheimer's Disease: Can Tea Phytochemicals Play a Role in Prevention?

Dementia and diabetes mellitus are prevalent disorders in the elderly population. While recognized as two distinct diseases, diabetes has more recently recognized as a significant contributor to risk for developing dementia, and some studies make reference to type 3 diabetes, a condition resulting from insulin resistance in the brain. Alzheimer's disease, the most common form of dementia, and diabetes, interestingly, share underlying pathological processes, commonality in risk factors, and, importantly, pathways for intervention. Tea has been suggested to possess potent antioxidant properties. It is rich in phytochemicals including, flavonoids, tannins, caffeine, polyphenols, boheic acid, theophylline, theobromine, anthocyanins, gallic acid, and finally epigallocatechin-3-gallate, which is considered to be the most potent active ingredient. Flavonoid phytochemicals, known as catechins, within tea offer potential benefits for reducing the risk of diabetes and Alzheimer's disease by targeting common risk factors, including obesity, hyperlipidemia, hypertension, cardiovascular disease, and stroke. Studies also show that catechins may prevent the formation of amyloid-β plaques and enhance cognitive functions, and thus may be useful in treating patients who have Alzheimer's disease or dementia. Furthermore, other phytochemicals found within tea offer important antioxidant properties along with innate properties capable of modulating intracellular neuronal signal transduction pathways and mitochondrial function.

Influence of flavonol-rich excipient food (onion peel and Dendropanax morbifera) on the bioavailability of green tea epicatechins in vitro and in vivo

The impacts of onion peel (OP) and Dendropanax morbifera (DM), as excipient foods rich in flavonols, on the digestive recovery, intestinal absorption, and pharmacokinetics of GT epicatechins were studied via an in vitro digestion model system with Caco-2 cells and an in vivo study. The digestive stability of total epicatechins recovered from GT upon the addition of 2% DM was up to 1.12 times higher than that observed with OP. The combined effects of OP and DM, which were observed with 2% OP + DM in a ratio of 1 : 4 (w : w), significantly increased (by a factor of 1.31) the digestive recovery of total epicatechins (p < 0.05). Remarkable cellular uptakes of EC (185.36%) and ECG (188.08%) were found with 4% OP + DM (4 : 1, w : w), and those of EGC (112.30%) and EGCG (136.27%) were obtained with 2% OP + DM (4 : 1, w : w) and 1% OP + DM (1 : 1, w : w), respectively. The peak plasma concentrations of total epicatechins from GT, GT + 5% OP, GT + 5% DM, and GT + 2% OP + 2% DM were 1044.78 ± 609.10, 2267.18 ± 3734.38, 1270.35 ± 547.59, and 714.53 ± 499.27 ng mL^-1, respectively. The C_max value of total epicatechins in rats orally administrated with GT with 5% OP was found to be approximately twice of that obtained with GT alone. The co-ingestion of GT with flavonol-rich excipient foods possibly enhances the absorption of epicatechins because flavonols act as not only enhancers of digestive stability but also modulators of the biotransformation of epicatechins. The results obtained from the current study suggest that the absorption of GT catechins can vary depending upon the kinds and doses of excipient foods co-ingested.

Identification of Intestinal UDP-Glucuronosyltransferase Inhibitors in Green Tea (Camellia sinensis) Using a Biochemometric Approach: Application to Raloxifene as a Test Drug via In Vitro to In Vivo Extrapolation

Green tea (Camellia sinensis) is a popular beverage worldwide, raising concern for adverse interactions when co-consumed with conventional drugs. Like many botanical natural products, green tea contains numerous polyphenolic constituents that undergo extensive glucuronidation. As such, the UDP-glucuronosyltransferases (UGTs), particularly intestinal UGTs, represent potential first-pass targets for green tea-drug interactions. Candidate intestinal UGT inhibitors were identified using a biochemometrics approach, which combines bioassay and chemometric data. Extracts and fractions prepared from four widely consumed teas were screened (20-180 μg/ml) as inhibitors of UGT activity (4-methylumbelliferone glucuronidation) in human intestinal microsomes; all demonstrated concentration-dependent inhibition. A biochemometrics-identified fraction rich in UGT inhibitors from a representative tea was purified further and subjected to second-stage biochemometric analysis. Five catechins were identified as major constituents in the bioactive subfractions and prioritized for further evaluation. Of these catechins, (-)-epicatechin gallate and (-)-epigallocatechin gallate showed concentration-dependent inhibition, with IC₅₀ values (105 and 59 μM, respectively) near or below concentrations measured in a cup (240 ml) of tea (66 and 240 μM, respectively). Using the clinical intestinal UGT substrate raloxifene, the K_i values were ∼1.0 and 2.0 μM, respectively. Using estimated intestinal lumen and enterocyte inhibitor concentrations, a mechanistic static model predicted green tea to increase the raloxifene plasma area under the curve up to 6.1- and 1.3-fold, respectively. Application of this novel approach, which combines biochemometrics with in vitro-in vivo extrapolation, to other natural product-drug combinations will refine these procedures, informing the need for further evaluation via dynamic modeling and clinical testing.