Tea flavonoids and cardiovascular health

Polylactide-Based Films Incorporated with Berberine-Physicochemical and Antibacterial Properties

A series of new polymeric materials consisting of polylactide (PLA), polyethylene glycol (PEG) and berberine chloride (B) was evaluated. PEG was incorporated into the polymer matrix with the aim of obtaining a plasticizing effect, while berberine was added in order to obtain antibacterial properties in formed packaging materials. Materials were formed using the solvent-casting procedure. Fourier transform infrared spectroscopy and scanning electron microscopy were used so as to establish the structural changes resulting from the introduction of berberine. Thermogravimetry and differential scanning calorimetry were applied to study the thermal properties. Further, mechanical properties and differences in colour and transparency between the control sample and films containing berberine were also studied. The recorded data indicates that berberine formed a network on the surface of the PLA-based materials. Introduction of an active compound significantly improved thermal stability and greatly affected the Young's modulus values of the studied polymeric films. Moreover, it should be stressed that the addition of the studied active compound leads to an improvement of the antibacterial properties, resulting in a significant decrease in growth of E. coli and the S. aureus bacteria cultures.

Effects of green tea polyphenol extract and epigallocatechin-3-O-gallate on diabetes mellitus and diabetic complications: Recent advances

Diabetes mellitus is one of the major non-communicable diseases accounting for millions of death annually and increasing economic burden. Hyperglycemic condition in diabetes creates oxidative stress that plays a pivotal role in developing diabetes complications affecting multiple organs such as the heart, liver, kidney, retina, and brain. Green tea from the plant Camellia sinensis is a common beverage popular in many countries for its health benefits. Green tea extract (GTE) is rich in many biologically active compounds, e.g., epigallocatechin-3-O-gallate (EGCG), which acts as a potent antioxidant. Recently, several lines of evidence have shown the promising results of GTE and EGCG for diabetes management. Here, we have critically reviewed the effects of GTE and EGCC on diabetes in animal models and clinical studies. The concerns and challenges regarding the clinical use of GTE and EGCG against diabetes are also briefly discussed. Numerous beneficial effects of green tea and its catechins, particularly EGCG, make this natural product an attractive pharmacological agent that can be further developed to treat diabetes and its complications.

Classification of Tea Leaves Based on Fluorescence Imaging and Convolutional Neural Networks

The development of the smartphone and computer vision technique provides customers with a convenient approach to identify tea species, as well as qualities. However, the prediction model may not behave robustly due to changes in illumination conditions. Fluorescence imaging can induce the fluorescence signal from typical components, and thus may improve the prediction accuracy. In this paper, a tea classification method based on fluorescence imaging and convolutional neural networks (CNN) is proposed. Ultra-violet (UV) LEDs with a central wavelength of 370 nm were utilized to induce the fluorescence of tea samples so that the fluorescence images could be captured. Five kinds of tea were included and pre-processed. Two CNN-based classification models, e.g., the VGG16 and ResNet-34, were utilized for model training. Images captured under the conventional fluorescent lamp were also tested for comparison. The results show that the accuracy of the classification model based on fluorescence images is better than those based on the white-light illumination images, and the performance of the VGG16 model is better than the ResNet-34 model in our case. The classification accuracy of fluorescence images reached 97.5%, which proves that the LED-induced fluorescence imaging technique is promising to use in our daily life.

SPOCK1 with unexpected function. The start of a new career

SPOCK1, 2 and 3 are considered as matricellular proteoglycans without structural role. Their functions are only partly elucidated. SPOCK1 was detected in the brain as a member of the neural synapses, then in the neuromuscular junctions. It plays a role in the regulation of blood-brain barrier. Its best characterized activity was its oncogenic potential discovered in 2012. Its deleterious effect on tumor progression was detected on 36 different types of tumors by the end of 2020. However, its mode of actions is still not completely understood. Furthermore, even less was discovered about its physiological function. The fact that it was found to localize in the mitochondria and interfered with the lipid metabolism indicated, that the full discovery of SPOCK1 still waiting for us.

Different Withering Times Affect Sensory Qualities, Chemical Components, and Nutritional Characteristics of Black Tea

The present study emphasizes the effect of withering time set at 4 ± 0.5 h (WT4), 6 ± 0.5 h (WT6), 8 ± 0.5 h (WT8), 10 ± 0.5 h (WT10), and 12 ± 0.5 h (WT12) on the sensory qualities, chemical components, and nutritional characteristics of black tea. The sensory evaluation revealed high total quality scores at WT8 and WT10. Polysaccharides, amino acids, and soluble sugars significantly increased with an increase in withering time, and an apparent peak value was obtained at WT10. However, polyphenols, flavonoids, glycosides, organic acids, catechins, alkanoids, and theaflavins decreased with an increase in withering time. With an increase in withering time, the content of aromatic substances showed a trend of increasing first and then decreasing. The peaks of alcohols, aldehydes, and acids appeared at 10 ± 0.5 h, 10 ± 0.5 h, and 8 ± 0.5 h, respectively. The content of esters, ketones, and hydrocarbons showed a downward trend with an increase in withering time. Aroma analysis revealed that withering time could not exceed 10 ± 0.5 h. Black tea withered up to WT10 showed enhanced inhibition of α-glucosidase and α-amylase activity with good sensorial attributes. Glucose uptake inhibition capacity increased up 6 ± 0.5 h and then decreased, while antioxidant capacity decreased with an increase in withering time. The overall results show that the 8 ± 0.5 h to 10 ± 0.5 h withering time could improve black tea quality and nutritional characteristics.

Efficient Chemical Synthesis of (Epi)catechin Glucuronides: Brain-Targeted Metabolites for Treatment of Alzheimer's Disease and Other Neurological Disorders

Grape seed extract (GSE) is rich in flavonoids and has been recognized to possess human health benefits. Our group and others have demonstrated that GSE is able to attenuate the development of Alzheimer's disease (AD). Moreover, our results have disclosed that the anti-Alzheimer's benefits are not directly/solely related to the dietary flavonoids themselves, but rather to their metabolites, particularly to the glucuronidated ones. To facilitate the understanding of regioisomer/stereoisomer-specific biological effects of (epi)catechin glucuronides, we here describe a concise chemical synthesis of authentic standards of catechin and epicatechin metabolites 3-12. The synthesis of glucuronides 9 and 12 is described here for the first time. The key reactions employed in the synthesis of the novel glucuronides 9 and 12 include the regioselective methylation of the 4'-hydroxyl group of (epi)catechin (≤1.0/99.0%; 3'-OMe/4'-OMe) and the regioselective deprotection of the tert-butyldimethylsilyl (TBS) group at position 5 (yielding up to 79%) over the others (3, 7 and 3' or 4').

(−)-Epicatechin mitigates high fat diet-induced neuroinflammation and altered behavior in mice

(−)-Epicatechin improves memory in high fat diet-induced obese mice in association with prevention of endotoxemia and mitigation of neuroinflammation.

A Novel Candidate for Prevention and Treatment of Atherosclerosis: Urolithin B Decreases Lipid Plaque Deposition in apoE-/- Mice and Increases Early Stages of Reverse Cholesterol Transport in ox-LDL Treated Macrophages Cells

SCOPE

HDL cholesterol is inversely related to the incidence of atherosclerosis. Polyphenols including ellagitannins have been shown to exert antiatherogenic properties. Urolithin B is formed from ellagitannins by components of the gut microbiota, and urolithins might be involved in beneficial effects against cardiovascular diseases in vitro. In this study, the influence of urolithin B on several parameters involved in the lipid plaque deposition and the reverse cholesterol transport is investigated.

METHODS AND RESULTS

In apoE^-/- mice and two different macrophage cell lines, the influence of urolithin B and its phase II conjugated metabolite on lipid plaque deposition, cholesterol uptake, and expression of ABCA1 and SR-BI is tested. It is shown that urolithin B decreases lipid plaque deposition, both urolithin B and urolithin B sulfate modulate expression of SR-BI and ABCA1, and cholesterol efflux increases from cholesterol laden macrophages to HDL particles as well as to reverse lipid uptake by stimulated THP-1 macrophages.

CONCLUSIONS

Urolithin B can decrease lipid plaque deposition, and urolithin B and urolithin B sulfate are able to induce reverse cholesterol transport by influencing expression of key proteins of this pathway. Urolithin B may represent the basis for development of new drugs for prevention and treatment of atherosclerosis in humans.

Influence of leaf age, species and soil depth on the authenticity and geographical origin assignment of green tea

RATIONALE

Stable isotope fractionation occurring during leaf growth provides internal characteristics for identifying the geographical origin, traceability and authentication of tea. Studying the influence of leaf age, species and the relationship with the cultivated soil may reveal previously undocumented stable isotope fractionation mechanisms, and provide a deeper understanding of the physiological isotopic effects on the tractability and authentication accuracy of green tea to combat mislabeling and fraudulent conduct.

METHODS

A total of 36 pairs of young (one bud with one leaf) and mature growth (older leaf) samples from two species of Longjing tea (Longjing #43 and Colonial cultivar) and corresponding cultivation soil samples from two different depth layers (0-20 cm and 20-40 cm) were collected in Westlake district, Hangzhou, Zhejiang province, China. Four stable isotope ratios (δ¹³ C, δ¹⁵ N, δ² H, and δ¹⁸ O values) were measured using an elemental analyzer coupled with an isotope ratio spectrometer. Linear correlation and one-way analysis of variance (ANOVA) statistical analyses were performed to investigate isotopic fractionation mechanisms during plant growth, and reflect the dynamic physiological processes from soil to leaf.

RESULTS

The carbon and nitrogen isotope ratios (δ¹³ C and δ¹⁵ N values) reflected the absorption, migration and fractionation of carbon dioxide and nitrogenous nutrients during photosynthesis, nutrient uptake, nitrogen fixation and leaf respiration. The water isotope ratios (δ² H and δ¹⁸ O values) reflected the use and fractionation of water by tea plants at different growth stages.

CONCLUSIONS

Considerable differences were found for hydrogen and oxygen isotope ratios according to leaf age, revealing complex isotopic fractionation mechanisms and possible interference factors. Leaf maturity effects should be considered, as they will influence the precision and accuracy of models when assigning the geographical origin, traceability and authentication of tea.

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.

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.

A Randomized Controlled Trial of Green Tea Beverages on the in vivo Radical Scavenging Activity in Human Skin

BACKGROUND

Oxidative stress plays an important role in the pathogenesis of various skin diseases. Thus, the antioxidant network of the skin relies on the uptake of exogenous antioxidants to ensure cell protection against radical formation. Green tea is one of the main sources of polyphenolic antioxidant compounds, but only few data are available on its cutaneous antioxidant effects.

METHODS

The radical scavenging properties of Benifuuki and Yabukita green tea were investigated in the human skin. Thirty-two participants who met the inclusion criteria were randomized to consume 3 cups per day of either Benifuuki tea, Yabukita tea, or water (control group) for 2 weeks. Electron paramagnetic resonance (EPR) spectroscopy was applied to measure the radical scavenging capacity of the skin in vivo before and after the intervention.

RESULTS

Both Yabukita and Benifuuki tea led to an increase in the radical scavenging activity of the skin by 28 and 29%, respectively, and the difference was significant when compared to the control group. Benifuuki tea, previously reported to be superior in bioavailability due to a highly absorbable methylated catechin, did not prove to be more effective than the common Yabukita tea.

CONCLUSION

The results show that green tea enhances the radical scavenging capacity of the skin and support the hypothesis that green tea may offer protection against cutaneous oxidative stress.

Salts Influence Cathechins and Flavonoids Encapsulation in Liposomes: A Molecular Dynamics Investigation

Cathechins and flavonoids are responsible of numerous health benefits. Two of the most representatives' compounds for their antioxidant and therapeutic effects are Epigallocatechin 3-Gallate (EGCG), from green tea extracts, and morelloflavone (MF), from Garcinia dulcis. Here we explore, by atomistic Molecular Dynamics simulations, how EGCG and MF interact with lipid bilayers and we show the salts' influence on their encapsulation degree in neutral liposomes. As a result, we found out that EGCGs naturally bind to the hydrophilic regions of phospholipids, positioning themselves mostly at the interface between water and lipid phases. The presence of a salt clearly influences the EGCG molecules' absorption and the total effect depends strongly on the salt nature and concentration. Beside, for MF, we observed a high stability of the intermolecular MFs aggregates in water that strongly penalizes the flavonoid's interaction with the lipid polar heads. However, salts can influence MF's liposomal penetration, even if they are not able to promote completely its absorption inside the bilayer. For both compounds, the increase of penetration is more marked in presence of magnesium chloride, whilst calcium chloride showed the opposite effect.

A review on the analysis of ingredients with health care effects in health food in Taiwan

This review article discusses the analysis of ingredients with health care effects in health food in Taiwan. The top 10 items on the list of registered health food products up to 2014 in Taiwan are described, including monocolin K, ω-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid), β-glucans, inulin, catechins, oligosaccharides, resistant maltodextrin, amino acids, medium chain fatty acids, and polysaccharides. Some analytical methods for the analysis of ingredients with health care effects are announced to the public on the website of health food section of the Taiwan Food and Drug Administration for the application and the postmarket surveillance of health food. Each application of health food should include the appropriate analytical method for the analysis of the ingredient or specific compound that has the health care effect, for the sake of quality assurance. Self-management of each applicant is required for regulation, the reputation of its own, and social responsibility to the consumers.

Effect of black tea intake on blood cholesterol concentrations in individuals with mild hypercholesterolemia: a diet-controlled randomized trial

Habitual intake of black tea has been associated with relatively lower serum cholesterol concentrations in observational studies. However, clinical trial results evaluating the effects of black tea on serum cholesterol have been inconsistent. Several factors could explain these mixed results, in particular, uncontrolled confounding caused by lifestyle factors (eg, diet). This diet-controlled clinical trial estimates the effect of black tea flavonoid consumption on cholesterol concentrations in 57 borderline hypercholesterolemic individuals (total cholesterol concentrations between 190 and 260 mg/dL [4.9 and 6.7 mmol/L]). A double-blind, randomized crossover trial was conducted in Minneapolis, MN, from April 2002 through April 2004 in which key conditions were tightly controlled to minimize possible confounding. Participants consumed a controlled low-flavonoid diet plus 5 cups per day of black tea or tea-like placebo during two 4-week treatment periods. The flavonoid-free caffeinated placebo matched the tea in color and taste. Differences in cholesterol concentrations at the end of each treatment period were evaluated via linear mixed models. Differences among those treated with tea vs placebo were 3.43 mg/dL (0.09 mmol/L) (95% CI -7.08 to 13.94) for total cholesterol, -1.02 mg/dL (-0.03 mmol/L) (95% CI -11.34 to 9.30) for low-density lipoprotein cholesterol, 0.58 mg/dL (0.02 mmol/L) (95% CI -2.98 to 4.14) for high-density lipoprotein cholesterol, 15.22 mg/dL (0.17 mmol/L) (95% CI -40.91 to 71.35) for triglycerides, and -0.39 mg/dL (-0.01 mmol/L) (95% CI -11.16 to 10.38) for low-density lipoprotein plus high-density lipoprotein cholesterol fraction. The low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio decreased by -0.1 units (95% CI -0.41 to 0.21). No results were statistically or clinically significant. The intake of 5 cups of black tea per day did not alter the lipid profile of borderline hypercholesterolemic subjects significantly.

Effect of green tea supplementation on blood pressure among overweight and obese adults: a protocol for a systematic review

INTRODUCTION

Emerging randomised controlled trials (RCTs) exploring the effect of green tea (GT) supplementation or GT extract (GTE) on blood pressure (BP) among overweight and obese adults yielded inconclusive results. We aim to conduct a systematic review to summarise the evidence of RCTs until now, to clarify the efficacy of GT supplementation or GTE in BP in overweight and obese populations.

METHODS AND ANALYSIS

The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and ClinicalTrials.gov will be searched to retrieve potential RCTs. Unpublished studies will be identified by searching the abstract books or websites of the three major conference proceedings: the International Society of Hypertension, the Nutrition & Health Conference and the World Congress of Nutrition and Health. A random-effects meta-analysis will be performed to pool the mean difference for the change in BP from baseline (ie, postintervention BP minus baseline BP) between intervention groups and placebo groups of the included studies, presenting the pooled results with 95% CIs. Subgroups analyses will be conducted according to different doses of GT or GTE, trial duration, geographic regions, overweight versus obese participants, and participants with versus without change in body weight after intervention. Sensitivity analysis will be performed by excluding studies classified as having a high risk of bias, applying a fixed-effects model, using the postintervention BP for analyses and excluding trials with non-study cointerventions.

ETHICS AND DISSEMINATION

This systematic review will be published in a peer-reviewed journal. It will be disseminated electronically and in print. Summarising the RCT evidence to clarify the efficacy in BP among overweight and obese adults will aid in making the dietary recommendation of GT and improving the clinical management of hypertension.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42014007273.

Effects of season and plantation on phenolic content of unfermented and fermented Sri Lankan tea

The effects of season and plantation on the polyphenol content of Camellia sinensis (tea) leaves were determined. Aqueous and organic extracts of freeze-dried fresh (unfermented) and black (fully-fermented) tea leaves were prepared for a structured set of samples (fermented and unfermented teas from six high-, mid- and low-grown plantations; fermented and unfermented teas from two harvesting seasons from four highland plantations), collected from the main tea-growing regions in Sri Lanka. Total catechin content and amounts of individual catechins, flavonols and theaflavins were determined by HPLC. Mean values for the phenolic constituents were generally significantly higher (p<0.05) with solvent extraction. The mean values for total catechins, total flavonols and caffeine in the aqueous extracts from unfermented teas were 10.6%, 1.5% and 2.9%, respectively. For both unfermented and fermented tea leaves, a significant (p<0.05) interaction between plantation and season was observed for phenolic constituents. Ferric reducing antioxidant power was positively (p<0.05) correlated with (-)-epicatechin gallate and total phenolic contents.

Green tea pain modulating effect in sciatic nerve chronic constriction injury rat model

We investigated the effect of green tea (GT) in unilateral chronic constriction injury (CCI) to the rat scaitic nerve. Five groups (n = 6 rats/group) sham group: rats which underwent operation but with no ligation to the scaitic nerve, and received tap water for two weeks before and for five weeks after the surgery. Four experimental groups underwent CCI to the right sciatic nerve, divided randomly as follows: group E were given tap water throughout the study. Group B received GT before and after CCI. Group C was given GT following CCI. Group D received GT for two weeks prior to CCI. Groups which consumed GT showed significant improvement in the toe spread (P < 0.001) and foot positioning (P < 0.001) tests compared to the experimental control group. In addition, these groups showed a significant decrease in the behavioral mechanical hyperalgesia (P < 0.0001) and allodynia (P < 0.0002). Consumption of GT improves both reflexes and sensation which are often affected in the course of peripheral neuropathy.

A computational exploration of the interactions of the green tea polyphenol (-)-Epigallocatechin 3-Gallate with cardiac muscle troponin C

Thanks to its polyphenols and phytochemicals, green tea is believed to have a number of health benefits, including protecting from heart disease, but its mechanism of action at the molecular level is still not understood. Here we explore, by means of atomistic simulations, how the most abundant of the green tea polyphenols, (-)-Epigallocatechin 3-Gallate (EGCg), interacts with the structural C terminal domain of cardiac muscle troponin C (cCTnC), a calcium binding protein that plays an important role in heart contractions. We find that EGCg favourably binds to the hydrophobic cleft of cCTnC consistently with solution NMR experiments. It also binds to cCTnC in the presence of the anchoring region of troponin I (cTnI(34-71)) at the interface between the E and H helices. This appears to affect the strength of the interaction between cCTnC and cTnI(34-71) and also counter-acts the effects of the Gly159Asp mutation, related to dilated cardiomyopathy. Our simulations support the picture that EGCg interacting with the C terminal domain of troponin C may help in regulating the calcium signalling either through competitive binding with the anchoring domain of cTnI or by affecting the interaction between cCTnC and cTnI(34-71).

Molecular basis for the action of a dietary flavonoid revealed by the comprehensive identification of apigenin human targets

Flavonoids constitute the largest class of dietary phytochemicals, adding essential health value to our diet, and are emerging as key nutraceuticals. Cellular targets for dietary phytochemicals remain largely unknown, posing significant challenges for the regulation of dietary supplements and the understanding of how nutraceuticals provide health value. Here, we describe the identification of human cellular targets of apigenin, a flavonoid abundantly present in fruits and vegetables, using an innovative high-throughput approach that combines phage display with second generation sequencing. The 160 identified high-confidence candidate apigenin targets are significantly enriched in three main functional categories: GTPase activation, membrane transport, and mRNA metabolism/alternative splicing. This last category includes the heterogeneous nuclear ribonucleoprotein A2 (hnRNPA2), a factor involved in splicing regulation, mRNA stability, and mRNA transport. Apigenin binds to the C-terminal glycine-rich domain of hnRNPA2, preventing hnRNPA2 from forming homodimers, and therefore, it perturbs the alternative splicing of several human hnRNPA2 targets. Our results provide a framework to understand how dietary phytochemicals exert their actions by binding to many functionally diverse cellular targets. In turn, some of them may modulate the activity of a large number of downstream genes, which is exemplified here by the effects of apigenin on the alternative splicing activity of hnRNPA2. Hence, in contrast to small-molecule pharmaceuticals designed for defined target specificity, dietary phytochemicals affect a large number of cellular targets with varied affinities that, combined, result in their recognized health benefits.

Pharmaceutical properties and toxicology of Dioclea grandiflora

CONTEXT

Since the beginning of civilization, herbal medicines have been an important source for human beings to treat their ailments. Despite the large number of synthetic remedies available in the market, the use of plants is seen as a great challenge in the search for new substances endowed with therapeutic properties. One example is Dioclea grandiflora Mart. ex Benth. (Leguminosae) employed in traditional medicine to treat prostate disorders and kidney stones.

OBJECTIVES

This work presents a brief overview of D. grandiflora, including a description of the plant, its chemical composition and pharmacological properties.

METHODS

This review gathers information available in the scientific literature compiled from databases such as Science Direct, PubMed, Dr. Dukes Phytochemical and Ethnobotany, Missouri Botanical Garden and The International Plant Names Index.

RESULTS

The information found in the literature showed that flavonoids are the major constituents of D. grandiflora that account for most of the pharmacological properties so far disclosed. Several studies have revealed that D. grandiflora possesses antinociceptive, cardiovascular, antioxidant and anti-inflammatory activities.

CONCLUSION

Research shows that D. grandiflora is a potential source of compounds pertaining medicinal applications. It provides an interesting subject in the search for new drugs of natural origin.

Dietary plant phenolic improves survival of bacterial infection in Manduca sexta caterpillars

Plant phenolics are generally thought to play significant roles in plant defense against herbivores and pathogens. Many plant taxa, including Solanaceae, are rich in phenolic compounds and some insect herbivores have been shown to acquire phenolics from their hosts to use them as protection against their natural enemies. Here we demonstrate that larvae of an insect specialist on Solanaceae, the tobacco hornworm, Manduca sexta L. (Lepidoptera: Sphingidae), acquire the plant phenolic chlorogenic acid (CA), and other caffeic acid derivatives as they feed on one of their hosts, Nicotiana attenuata L. (Solanaceae), and on artificial diet supplemented with CA. We test the hypothesis that larvae fed on CA-supplemented diet would have better resistance against bacterial infection than larvae fed on a standard CA-free diet by injecting bacteria into the hemocoel of fourth instars. Larvae fed CA-supplemented diet show significantly higher survival of infection with Enterococcus faecalis (Andrewes & Horder) Schleifer & Kilpper-Bälz, but not of infection with the more virulent Pseudomonas aeruginosa (Schroeter) Migula. Larvae fed on CA-supplemented diet possess a constitutively higher number of circulating hemocytes than larvae fed on the standard diet, but we found no other evidence of increased immune system activity, nor were larvae fed on CA-supplemented diet better able to suppress bacterial proliferation early in the infection. Thus, our data suggest an additional defensive function of CA to the direct toxic inhibition of pathogen proliferation in the gut.

Green Tea Polyphenol Epigallocatechin Gallate Inhibits Adipogenesis and Induces Apoptosis in 3T3-L1 Adipocytes

OBJECTIVE

Green tea catechins have been shown to promote loss of body fat and to inhibit growth of many cancer cell types by inducing apoptosis. The objective of this study was to determine whether epigallocatechin gallate (EGCG), the primary green tea catechin, could act directly on adipocytes to inhibit adipogenesis and induce apoptosis.

RESEARCH METHODS AND PROCEDURES

Mouse 3T3-L1 preadipocytes and mature adipocytes were used. To test the effect of EGCG on viability, cells were incubated for 3, 6, 12, or 24 hours with 0, 50, 100, or 200 microM EGCG. Viability was quantitated by MTS assay. To determine the effect of EGCG on apoptosis, adipocytes were incubated for 24 hours with 0 to 200 microM EGCG, then stained with annexin V and propidium iodide and analyzed by laser scanning cytometry. Both preadipocytes and adipocytes were also analyzed for apoptosis by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. To determine the effect of EGCG on adipogenesis, maturing preadipocytes were incubated during the 6-day induction period with 0 to 200 microM EGCG, then stained with Oil-Red-O and analyzed for lipid content.

RESULTS

EGCG had no effect on either viability or apoptosis of preconfluent preadipocytes. EGCG also did not affect viability of mature adipocytes; however, EGCG increased apoptosis in mature adipocytes, as demonstrated by both laser scanning cytometry and terminal deoxynucleotidyl transferase dUTP nick-end labeling assays. Furthermore, EGCG dose-dependently inhibited lipid accumulation in maturing preadipocytes.

DISCUSSION

These results demonstrate that EGCG can act directly to inhibit differentiation of preadipocytes and to induce apoptosis of mature adipocytes and, thus, could be an important adjunct in the treatment of obesity.

Evaluation of antitumour activity of tea carbohydrate polymers in hepatocellular carcinoma animals

Box-Behnken design criterion was applied to identify the significant effects of various extraction parameters such as temperature, time, and solvent-solid ratio on extraction of tea carbohydrate. Among the three variables tested extraction temperature, and solvent-solid ratio were found to have significant effect on tea carbohydrate extraction. The most suitable condition for extraction of tea carbohydrate was found to be a single step extraction at extraction temperature 90°C, extraction time 30 min, and solvent-solid ratio 5:1. At these optimum extraction parameters, the maximum yield of tea carbohydrate obtained experimentally was found to be very close to its predicted value of 3.47% dry weight of root. Then, we have studied the influence of tea carbohydrate on biochemical parameters in hepatocellular carcinoma (HCC) animals. Hepatocellular carcinoma was induced by the injection of 1×10(5) H22 hepatocarcinoma cells into right hind thigh muscle in experimental animals. Tea carbohydrate could inhibit tumour growth and decrease microvessel density in tumour tissue. The altered amount of serum white blood cells (WBC), Interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) in HCC animals were dose-dependently increased, whereas activities of serum alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) were dose-dependently decreased in the drug treated animals. In addition, tea carbohydrate administration could decrease expression of vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) in H22 tumor tissue. It can be concluded that tea carbohydrate displayed strong antitumour activity in animals.

Epigallocatechin gallate delays the onset of type 1 diabetes in spontaneous non-obese diabetic mice

Type 1 diabetes (T1D) results from the autoimmune-mediated destruction of pancreatic β-cells, leading to deficiency of insulin production. Successful islet transplantation can normalise hyperglycaemia in T1D patients; however, the limited availability of the islets, loss of islet cell mass through apoptosis after islet isolation and potential autoimmune destruction of the transplanted islets prevent the widespread use of this procedure. Therefore, the search for novel and cost-effective agents that can prevent or treat T1D is extremely important to decrease the burden of morbidity from this disease. In the present study, we discovered that ( - )-epigallocatechin gallate (EGCG, 0·05 % in drinking-water), the primary polyphenolic component in green tea, effectively delayed the onset of T1D in non-obese diabetic (NOD) mice. At 32 weeks of age, eight (66·7 %) out of twelve mice in the control group developed diabetes, whereas only three (25 %) out of twelve mice in the EGCG-treated group became diabetic (P < 0·05). Consistently, mice supplemented with EGCG had significantly higher plasma insulin levels and survival rate but lower glycosylated Hb concentrations compared with the control animals. EGCG had no significant effects on food or water intake and body weight in mice, suggesting that the glucose-lowering effect was not due to an alteration in these parameters. While EGCG did not modulate insulitis, it elevated the circulating anti-inflammatory cytokine IL-10 level in NOD mice. These findings demonstrate that EGCG may be a novel, plant-derived compound capable of reducing the risk of T1D.

Immunoregulatory effects of the flavonol quercetin in vitro and in vivo

PURPOSE

Atherosclerosis is known to be an inflammatory disease. Dendritic cells (DCs) are essential for the regulation of the immune system. Up to 10% of the cells in atherosclerotic plaques are DCs. The cardiovascular protective effects of flavonoids (tea, wine) may be mediated by anti-inflammatory mechanisms that affect DC regulation. We aimed to characterize the impact of the flavonol quercetin on DC activity and differentiation in vitro and in vivo.

METHODS

For the in vitro experiments, we used murine DCs and endothelial cells to study adhesion properties. For all other experiments (DC phagocytosis capacity, DC maturation, DC differentiation (BDCA-1/-2) and NF-kB-activation), human monocyte-derived DCs were used. The cells were incubated with quercetin (10 μmol/L) ± oxLDL (10 μg/mL) between 24 and 48 h. For in vivo experiments, eight healthy male volunteers took 500 mg of quercetin twice daily over 4 weeks, five healthy male volunteers served as control. Before and after intake, blood samples were collected. Peripheral blood leukocytes were isolated (analyses of DC differentiation), and plasma was immediately frozen.

RESULTS

Quercetin reduced DC adhesion (-42%; p < 0.05) and expression of CD11a (-21%; p < 0.05). OxLDL-induced DC differentiation was partially inhibited by quercetin (BDCA-1-29%; BDCA-2-33%; p < 0.05). These effects were achieved by compensation of oxLDL-induced up-regulation of NF-kB by quercetin. The 4-week treatment with quercetin resulted in relevant plasma levels (2.47 μmol/L) and reduced BDCA-2 + DCs in the peripheral blood by 42% (p < 0.05) as well as systemic levels of the NO-synthase inhibitor asymmetric dimethylarginine (-31%, p < 0.05).

CONCLUSION

In vitro, quercetin reduced DC adhesion and oxLDL-induced DC differentiation. In vivo, quercetin reduced circulating plasmacytoid DCs and systemic ADMA-levels. The immunoregulatory effects of quercetin may contribute to the anti-atherosclerotic potential of flavonols.

Tea and coffee consumption and cardiovascular morbidity and mortality

OBJECTIVE

To examine the associations of coffee and tea consumption with risk of morbidity and mortality of stroke and coronary heart disease (CHD) and with all-cause mortality.

METHODS AND RESULTS

Coffee and tea consumption were assessed with a validated food-frequency questionnaire, and 37 514 participants were observed for 13 years for the occurrence of cardiovascular morbidity and mortality. A U-shaped association between coffee and CHD was found, with the lowest hazard ratio (HR [95% CI]) for 2.1 to 3.0 cups per day (0.79 [0.65 to 0.96]; P(trend)=0.01). Tea was inversely associated with CHD, with the lowest HR (95% CI) for more than 6.0 cups per day (0.64 [0.46 to 0.90]; P(trend)=0.02). No associations between tea or coffee and stroke were found (P(trend)=0.63 and P(trend)=0.32, respectively). Although not significant, coffee slightly reduced the risk for CHD mortality (HR, 0.64; 95% CI, 0.37 to 1.11; P(trend)=0.12) for 3.1 to 6.0 cups per day. A U-shaped association between tea and CHD mortality was observed, with an HR of 0.55 (95% CI, 0.31 to 0.97; P(trend)=0.03) for 3.1 to 6.0 cups per day. Neither coffee nor tea was associated with stroke (P(trend)=0.22 and P(trend)=0.74, respectively) and all-cause mortality (P(trend)=0.33 and P(trend)=0.43, respectively).

CONCLUSIONS

High tea consumption is associated with a reduced risk of CHD mortality. Our results suggest a slight risk reduction for CHD mortality with moderate coffee consumption and strengthen the evidence on the lower risk of CHD with coffee and tea consumption.

Protection of fibroblasts (NIH-3T3) against oxidative damage by cyanidin-3-rhamnoglucoside isolated from fig fruits (Ficus carica L.)

Anthocyanins, plant secondary metabolites, have been recognized for their health-promoting properties when consumed by humans. In this study, the antioxidant properties of a major anthocyanin in fresh fig fruits, cyanidin-3-rhamnoglucoside (C3R), were evaluated by various assays in vitro and correlated with the protection afforded by C3R to cultured NIH-3T3 fibroblast cells. C3R inhibited lipid peroxidation from producing peroxy radicals (ROO(*)) and MDA in a dose-dependent manner, and a high calculated stoichiometric coefficient [n] for peroxy radicals was demonstrated. In addition to its scavenging of reactive oxygen species (ROS), C3R showed a strong chelating activity toward the Fe(2+) ion. Finally, pretreatment with C3R inhibited proapoptotic processes that were initiated by the oxidation of lysosome membranes in fibroblast cells. The high antioxidant potential, with several modes of action of purified C3R, may contribute to health benefits gained by the consumption of fresh fig fruits.

EGCG protects against oxidized LDL-induced endothelial dysfunction by inhibiting LOX-1-mediated signaling

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), originally identified as the major receptor for oxidized low-density lipoprotein (oxLDL) in endothelial cells, plays a major role in the pathology of vascular diseases. Green tea consumption is associated with reduced cardiovascular mortality in some epidemiological studies. In the present study, we hypothesized that the most abundant polyphenolic compound in tea, epigallocatechin-3-gallate (EGCG), can downregulate parameters of endothelial dysfunction by modulating LOX-1-regulated cell signaling. In cultured human umbilical vein endothelial cells (HUVECs), exposure to oxLDL (130 microg/ml), which led to an increase in LOX-1 expression at the RNA and protein levels, was abrogated by addition of EGCG or DPI, a well-known inhibitor of flavoproteins, suggesting the involvement of NADPH oxidase. Furthermore, oxLDL rapidly activated the membrane translocation of Rac-1 and p47phox and the subsequent induction of ROS generation, which was suppressed markedly by pretreatment with EGCG or anti-LOX-1 monoclonal antibody. OxLDL also increased p38 MAPK phosphorylation and decreased phosphorylation of the amino-terminal region of Akt, with maximal induction at about 30 min, and NF-kappaB phosphorylation within 1 h, resulting in redox-sensitive signaling. In addition, oxLDL diminished the expression of endothelial nitric oxide synthase (eNOS), enhanced the expression of endothelin-1 and adhesion molecules (ICAM, E-selectin, and monocyte chemoattractant protein-1), and increased the adherence of monocytic THP-1 cells to HUVECs. Pretreatment with EGCG, however, exerted significant cytoprotective effects in all events. These data suggest that EGCG inhibits the oxLDL-induced LOX-1-mediated signaling pathway, at least in part, by inhibiting NADPH oxidase and consequent ROS-enhanced LOX-1 expression, which contributes to further ROS generation and the subsequent activation of NF-kappaB via the p38 MAPK pathway. Results from this study may provide insight into a possible molecular mechanism by which EGCG suppresses oxLDL-mediated vascular endothelial dysfunction.

Effects of green tea extract administration on the pharmacokinetics of clozapine in rats

The pharmacokinetic interaction between clozapine, an atypical antipsychotic with metabolic complications, including weight gain, and green tea consumption has not been evaluated, although green tea is responsible for beneficial effects, including weight reduction, and is widely consumed in the world. Commercial green tea extract (175 mg kg−1) or saline was administered orally for 4 days before the oral administration of clozapine (20 mg kg−1) to rats. Plasma concentrations of clozapine were measured up to 5 h after clozapine administration, and then hepatic CYP1A2 expression and activity were determined. There was no significant difference in the elimination half-life of clozapine between the green tea extract and saline groups. However, the time to reach peak concentration (Tmax) was significantly increased by green tea extract. The mean total area under the plasma concentration-time curve (AUC0-∞) and maximal peak plasma concentration (Cmax) of clozapine in the green tea extract group were significantly lower than those of controls. Green tea extract induced a ∼2-fold increase in hepatic CYP1A2 levels, while the activity increased slightly (by 10% of control). Because of this reduction in AUC and Tmax of clozapine by green tea extract pretreatment, we suggest that both the rate and amount of absorption of clozapine may be reduced by green tea extract, although the hepatic elimination phase may not be significantly altered. Therefore, the clinical implications of the effects of green tea on the bioavailability of clozapine in patients should be further evaluated.

Increased responsiveness of human coronary artery endothelial cells in inflammation and coagulation

The effects of anti-inflammatory plant extracts, such as black tea extract (BTE) and resveratrol (RSV) could modulate cell activation leading to atherosclerosis, however there is little comparative information about how different endothelial cell types are affected by these compounds. In order to compare human endothelial cells derived from different origins (umbilical vein or HUVEC, coronary artery or HCAEC, microvascular or HMVEC) and their interleukin-1β (IL-1β) responsiveness, IL-6 ELISA, RT-PCR, tissue factor assay, and prostacyclin responses using 6-keto PGF_1α ELISA were determined. The IL-1β-induced IL-6 levels were dose-dependent with highest responses seen in HCAEC. Significant inhibition of IL-1β responses was achieved with BTE and RSV, with the largest decrease of IL-6 and TF seen in HCAEC. Prostacyclin levels were highest in HUVEC and were inhibited by RSV in all cell types. The differences between the endothelial cell types could account for greater susceptibility of coronary arteries to inflammation and atherogenesis.

Phenolic compounds in red wine digestedin vitroin the presence of iron and other dietary factors

Quantitative and qualitative changes in the phenolic composition of red wine may occur during digestion in the lumen, particularly when other dietary components are present. In this study, mixtures of red wine, iron, and ascorbic acid, meat or casein were subjected to a simulated gastrointestinal digestion. This process involves incubation of samples for 4.5 h at 37 degrees C, at different pH values, in the presence of peptic enzymes and fractionation of digests through a dialysis membrane with a molecular weight cut-off of 6000-8000. Selected phenolic compounds were determined in undigested samples and in their dialysable digests by reversed-phase high-performance liquid chromatography. A dramatic decrease in the concentration of the selected phenolic compounds was observed in all samples after they were digested in vitro. Moreover, when iron and/or protein were added to red wine samples, changes in the phenolic profile of the undigested and of the in vitro digested samples were detected. These results suggest that interactions between red wine phenolic compounds and iron, protein and/or digestion components are important determinants of the physicochemical properties and the concentration of these phenolic compounds in the lumen. The in vitro methodology employed herein offers a tool for the study of phenolic compounds under conditions of simulated gastrointestinal digestion, incorporating lumenal events that may affect phenolic compounds.

Does regular consumption of green tea influence expression of vascular endothelial growth factor and its receptor in aged rat erectile tissue? Possible implications for vasculogenic erectile dysfunction progression

Erectile dysfunction (ED) is a highly prevalent disease affecting millions of men worldwide with a tendency for widespread increase. ED is now considered an early manifestation of atherosclerosis and, consequently, a precursor of systemic vascular disease. Atherosclerosis and ED share potentially modifiable risk factors, as smoking or high-fat food intake, but it is unclear how regular consumption of anti-oxidant rich drinks, which exhibit recognised anti-atherosclerotic features, affects ED progression. The objective of this study was to evaluate the modulating effects of chronic consumption of catechin-rich beverages on the vascular structure of the rat corpus cavernosum, and how this could contribute to delay or prevention of the onset of ED. Male Wistar rats aged 12 months were treated with green tea (GT) or a green tea extract solution (GTE) as the only liquid source for 6 months. Consumption of GT and GTE led to decreased plasma androgen levels without any significant change in plasma lipid levels. A reduction in corpus cavernosum intracellular storage of lipids, associated with decreased expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR2 in endothelial cells, was observed. Taken together, these results suggest diminished atherosclerotic progression in cavernous tissue. However, functional studies will be necessary to elucidate if catechin-rich beverages are useful compounds in the prevention of deleterious vascular events associated with ED. It was also demonstrated that regular consumption of catechins reduces atherosclerotic progression and mortality due to cardiovascular disease. The results reported here suggest diminished atherosclerotic progression in cavernous tissue in aged rats following chronic ingestion of catechin-rich beverages.

Complexation with beta-cyclodextrin confers oral activity on the flavonoid dioclein

Dioclein is a flavonoid reported to have many beneficial effects on the cardiovascular system such as vasorelaxant, hypotensive, antioxidant and antiarrythmogenic activities. However, use as pharmaceuticals is limited due to the lack of oral activity and low water solubility. In this work, intending to improve its oral activity, we performed a 1:1 inclusion complex (IC) between dioclein and beta-cyclodextrin (beta-CD). The IC was characterized by nuclear magnetic resonance and infrared spectroscopy and its vasodilator and hypotensive effects were evaluated in mice. The inclusion of dioclein in beta-CD increased the water solubility 44% compared to free dioclein. The IC (2.5mgkg(-1)) produced a higher and long lasting change in systolic blood pressure (SBP) after intraperitoneal administration compared to free dioclein. When given orally, free dioclein (10mgkg(-1)) showed no hypotensive effect while the IC induced a pronounced decrease in SBP. The in vitro vasodilator effect of dioclein was unchanged by its inclusion in beta-CD showing that the IC does not change the interaction between dioclein and its cellular targets. In conclusion, our results show that the new complex prepared by inclusion of dioclein in beta-CD improves the hypotensive effect of the flavonoid by increasing its bioavailability and enables dioclein to be effective after oral administration. The mechanism underling the increase in bioavailability is probably a consequence of a protective effect of beta-CD against in vivo biodegradation by enzymes and possibly increased water solubility.