Antihypertensive effect of Benifuuki tea containing O-methylated EGCG

Epigallocatechin-3-gallate and Epigallocatechin-3-O-(3-O-methyl)-gallate Enhance the Bonding Stability of an Etch-and-Rinse Adhesive to Dentin

This study evaluated epigallocatechin-3-gallate (EGCG) and epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG-3Me) modified etch-and-rinse adhesives (Single Bond 2, SB 2) for their antibacterial effect and bonding stability to dentin. EGCG-3Me was isolated and purified with column chromatography and preparative high performance liquid chromatography. EGCG and EGCG-3Me were incorporated separately into the adhesive SB 2 at concentrations of 200, 400, and 600 µg/mL. The effect of cured adhesives on the growth of Streptococcus mutans (S. mutans) was determined with scanning electron microscopy and confocal laser scanning microscopy; the biofilm of bacteria was further quantified via optical density 600 values. The inhibition of EGCG and EGCG-3Me on dentin-originated collagen proteases activities was evaluated with a proteases fluorometric assay kit. The degree of conversion (DC) of the adhesives was tested with micro-Raman spectrum. The immediate and post-thermocycling (5000 cycles) bond strength was assessed through Microtensile Bond Strength (MTBS) test. Cured EGCG/EGCG-3Me modified adhesives inhibit the growth of S. mutans in a concentration-dependent manner. The immediate MTBS of SB 2 was not compromised by EGCG/EGCG-3Me modification. EGCG/EGCG-3Me modified adhesive had higher MTBS than SB 2 after thermocycling, showing no correlation with concentration. The DC of the adhesive system was affected depending on the concentration of EGCG/EGCG-3Me and the depth of the hybrid layer. EGCG/EGCG-3Me modified adhesives could inhibit S. mutans adhesion to dentin–resin interface, and maintain the bonding stability. The adhesive modified with 400 µg/mL EGCG-3Me showed antibacterial effect and enhanced bonding stability without affect the DC of adhesive.

Metabolomic profiling delineate taste qualities of tea leaf pubescence

The amount of pubescence on leaf epidermis is an important morphological marker for the quality of green tea, and the tea with plenty of pubescence is generally recognized as having a better taste. However, there is no systematic study on chemical compositions of tea leaf pubescence. The contributions of pubescence to taste properties are far from clear. In this research, 114 components were identified from the tea leaf pubescence of yunkang 10, a broad-leaf tea cultivar with plenty leaf pubescence, for the first time with a non-targeted metabolomics approach using ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). Compared to the tea leaf with the pubescence removed (non-pubescent leaf), the pubescence obtained from the same shoots had relatively higher contents of amino acids and lower contents of polyphenols. It was also found that the umami of pubescence was elevated, while the bitterness and astringency were significantly declined. Partial least-squares (PLS) analysis suggested that the polyphenols and amino acids accounted for the taste quality. To the best of our knowledge, this is the first time that the metabolites in tea leaf pubescence were profiled. The results offer the direct concrete evidence on the contributions of pubescence to the tea taste properties.

Green tea cultivar 'Benifuuki' potentiates split vaccine-induced immunoglobulin A production

Influenza is a widespread disease caused by infection with the influenza virus. Vaccination is considered to be the main countermeasure against influenza. A split vaccine is widely used to avoid severe adverse events, and it induces strong humoral immunity. However, the split vaccine alone cannot elicit mucosal immunity, including IgA production, and its preventative effects are limited. Here, we show that the green tea cultivar 'Benifuuki' extract enhanced the effect of a split vaccine on mucosal immunity. The frequency of IgA⁺ cells was increased in lung and Peyer's patch that received Benifuuki diet. Secretion of hemagglutinin-specific mucosal IgA, which is closely linked to the prevention of viral infection, was significantly increased in the bronchoalveolar lavage fluid of split vaccine-immunized BALB/c mice that were administered green tea Benifuuki extract. Our findings suggest that Benifuuki intake enhanced the effects of the split vaccine on mucosal immunity.

Effect of olive oil phenolic compounds on the expression of blood pressure-related genes in healthy individuals

PURPOSE

To investigate whether the ingestion of olive oil having different phenolic contents influences the expression of blood pressure-related genes, involved in the renin-angiotensin-aldosterone system, in healthy humans.

METHODS

A randomized, double-blind, crossover human trial with 18 healthy subjects, who ingested 25 mL/day of olive oils (1) high (366 mg/kg, HPC) and (2) low (2.7 mg/kg, LPC) in phenolic compounds for 3 weeks, preceded by 2-week washout periods. Determination of selected blood pressure-related gene expression in peripheral blood mononuclear cells (PBMNC) by qPCR, blood pressure and systemic biomarkers.

RESULTS

HPC decreased systolic blood pressure compared to pre-intervention values and to LPC, and maintained diastolic blood pressure values compared to LPC. HPC decreased ACE and NR1H2 gene expressions compared with pre-intervention values, and IL8RA gene expression compared with LPC.

CONCLUSIONS

The introduction to the diet of an extra-virgin olive oil rich in phenolic compounds modulates the expression of some of the genes related to the renin-angiotensin-aldosterone system. These changes could underlie the decrease in systolic blood pressure observed.

Concord Grape Juice Polyphenols and Cardiovascular Risk Factors: Dose-Response Relationships

Pure fruit juices provide nutritional value with evidence suggesting some of their benefits on biomarkers of cardiovascular disease risk may be derived from their constituent polyphenols, particularly flavonoids. However, few data from clinical trials are available on the dose-response relationship of fruit juice flavonoids to these outcomes. Utilizing the results of clinical trials testing single doses, we have analyzed data from studies of 100% Concord grape juice by placing its flavonoid content in the context of results from randomized clinical trials of other polyphenol-rich foods and beverages describing the same outcomes but covering a broader range of intake. We selected established biomarkers determined by similar methods for measuring flow-mediated vasodilation (FMD), blood pressure, platelet aggregation, and the resistance of low density lipoprotein cholesterol (LDL) to oxidation. Despite differences among the clinical trials in the treatment, subjects, and duration, correlations were observed between the dose and FMD. Inverse dose-response relationships, albeit with lower correlation coefficients, were also noted for the other outcomes. These results suggest a clear relationship between consumption of even modest serving sizes of Concord grape juice, flavonoid intake, and effects on risk factors for cardiovascular disease. This approach to dose-response relationships may prove useful for testing other individual foods and beverages.

Antihypertensive effects of foods

Hypertension is one of the major risk factors for arteriosclerosis, which leads to cardiovascular disease and stroke. Several clinical trials revealed that control of the blood pressure is useful to reduce the morbidity and mortality associated with these diseases. However, the protective efficacy against these complications still remains at less than 50% even if the high blood pressure is treated by current medical drugs. Healthy diets are expected to not only prevent but also treat lifestyle-related diseases. Improvement of the dietary life, including low-salt diets, appropriate alcohol consumption, and calorie restriction, is important for the prevention of hypertension. In addition, green tea, which has been drunk on a daily basis in Japan and China since ancient times, possesses an antihypertensive effect, and it was revealed that its components with this effect are catechins. Many studies have been performed on the antihypertensive effects of foods. Therefore, functional foods and their ingredients, reported to possess antihypertensive effects in animal experiments and human clinical trials, are summarized in this review. Blood pressure might be controlled by improvement of the daily eating habits based on evidence regarding these functional foods, and a healthy longevity can be expected.

Epigallocatechin gallate attenuated non-alcoholic steatohepatitis induced by methionine- and choline-deficient diet

Nonalcoholic fatty liver disease (NAFLD) and its progressive form, nonalcoholic steatohepatitis (NASH), are the most common causes of chronic liver disease. In this study, we evaluated the effects of Epigallocatechin gallate (EGCG) on methionine- and choline-deficient (MCD) diet-induced NASH. Our data showed that EGCG significantly prevented MCD diet-induced liver and body weight loss. Histological analysis showed that EGCG inhibited MCD diet-induced steatohepatitis including fat accumulation and inflammatory cells infiltration. Biochemical analysis data showed that EGCG significantly reduced the elevation of plasma ALT and AST levels but increased plasma triglyceride and cholesterol contents. However, EGCG significantly inhibited hepatic triglyceride and cholesterol content in MCD diet fed mice. Consistent with histology results, EGCG treatment significantly inhibited MCD diet-induced IL-1β, IL-6, TNF-α and MCP-1 mRNA expression. As an antioxidant, EGCG treatment significant inhibited hepatic MDA contents and increased hepatic SOD contents. In addition, transforming growth factor (TGF)-β, collagen I-α1, tissue inhibitor of metalloproteinase 1 (TIMP-1) and α-smooth muscle actin (SMA) mRNA expression, which are markers of hepatic fibrosis, were markedly inhibited by EGCG treatment. Western blot data showed that EGCG inhibited Smad2 and Smad3 phosphorylation in the liver and LX-2 cells which were involved in TGF-β-induced pathway. Taken together, EGCG attenuated NASH induced by MCD diet associated with ameliorating fibrosis, oxidative stress, and hepatic inflammation. Our results indicate that EGCG has beneficial roles in the development of MCD diet-induced NASH.

Cloning of a caffeoyl-coenzyme A O-methyltransferase from Camellia sinensis and analysis of its catalytic activity

Epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me) present in leaves of Camellia sinensis has many beneficial biological activities for human health. However, EGCG3"Me occurs naturally in tea leaves in extremely limited quantities. Finding an enzyme from C. sinensis to catalyze the synthesis of EGCG3"Me is an alternative method to make up for the scarcity of EGCG3"Me in natural situations. In the present study, a complementary DNA (cDNA) encoding region and genomic DNA of the caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) gene were isolated from C. sinensis (designated CsCCoAOMT). Nucleotide sequence analysis of CsCCoAOMT revealed an open reading frame of 738 bp that encodes a polypeptide with a predicted molecular weight of 28 kDa, which correlated well with the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The full-length DNA sequence (2678 bp) contained five exons and four introns. The deduced amino acid sequence of CsCCoAOMT shared 92% identity with CCoAOMTs from Codonopsis lanceolata and Betula luminifera. The catalytic activity of CsCCoAOMT was analyzed. Three monomethylated epigallocatechin-3-O-gallate (EGCG) compounds (EGCG4"Me, EGCG3"Me, and EGCG3'Me) were produced by CsCCoAOMT with K(m) in the micromolar range. Real-time polymerase chain reaction (RT-PCR) experiments indicated that the CsCCoAOMT transcript was present at low levels during the early stages of leaf maturity (the first leaf and bud on a shoot) but the relative expression was augmented at advanced stages of leaf maturity (the third or fourth leaf on a shoot), which accorded well with changes in EGCG3"Me content in fresh leaves. Hence, we concluded that CsCCoAOMT catalyzes the syntheses of methylated EGCGs.

Small molecule-sensing strategy and techniques for understanding the functionality of green tea

Various low-molecular-weight phytochemicals in green tea (Camellia sinensis L.), especially (-)-epigallocatechin-3-O-gallate (EGCG), are known to be involved in health promotion and disease risk reduction. However, the underlying mechanism has remained elusive because of the absence of an analytical technique that can easily detect the precise behavior of such a small molecule. Recently, we have identified a cell-surface EGCG-sensing receptor and the related signaling molecules that control the physiological functions of EGCG. We also developed a novel in situ label-free imaging technique for visualizing spatially resolved biotransformations based on simultaneous mapping of EGCG and its phase II metabolites. Furthermore, we established a chemometric method capable of evaluating the functionality of multicomponent green tea extracts by focusing on their compositional balances. This review highlights our proposed small molecule-sensing techniques for detecting the complex behavior of green tea components and linking such information to an enhanced understanding of green tea functionality.

Effects of Oolong tea polyphenols, EGCG, and EGCG3″Me on pancreatic α-amylase activity in vitro

In order to investigate the inhibitory effects and possible mechanisms of Oolong tea polyphenols, (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin 3-O-(3-O-methyl) gallate (EGCG3″Me) on pancreatic α-amylase, the inhibition, enzyme kinetics, ultraviolet (UV) absorption spectrum and fluorescence spectrum of α-amylase were investigated. The results showed that Oolong tea polyphenols, EGCG, and EGCG3″Me all exhibited inhibitory effects against α-amylase, and their half inhibitory concentration (IC50) values were 0.375, 0.350, and 0.572 mg/mL, respectively. The results of Lineweaver-Burk double reciprocal plot indicated that the inhibitory types of Oolong tea polyphenols and EGCG were competitive, whereas EGCG3″Me was in a noncompetitive pattern. Oolong tea polyphenols, EGCG, and EGCG3″Me all induced red-shift of UV absorbance and quenching of fluorescence of α-amylase, suggesting possible changes in the conformation of α-amylase. The differences of inhibitory effects and inhibition types for EGCG and EGCG3″Me might be due to their structural difference (the hydroxyl group at C-3 in D ring of EGCG substituted by methoxy group, forming EGCG3″Me).

The role of nutrition and nutraceutical supplements in the treatment of hypertension

Vascular biology, endothelial and vascular smooth muscle and cardiac dysfunction play a primary role in the initiation and perpetuation of hypertension, cardiovascular disease and target organ damage. Nutrient-gene interactions and epigenetics are predominant factors in promoting beneficial or detrimental effects in cardiovascular health and hypertension. Macronutrients and micronutrients can prevent, control and treat hypertension through numerous mechanisms related to vascular biology. Oxidative stress, inflammation and autoimmune dysfunction initiate and propagate hypertension and cardiovascular disease. There is a role for the selected use of single and component nutraceutical supplements, vitamins, antioxidants and minerals in the treatment of hypertension based on scientifically controlled studies which complement optimal nutrition, coupled with other lifestyle modifications.

Nutrition and nutraceutical supplements for the treatment of hypertension: part III

Vascular biology, endothelial and vascular smooth muscle, and cardiac dysfunction play a primary role in the initiation and perpetuation of hypertension, cardiovascular disease, and target organ damage. Nutrient-gene interactions and epigenetics are predominant factors in promoting beneficial or detrimental effects in cardiovascular health and hypertension. Macronutrients and micronutrients can prevent, control, and treat hypertension through numerous mechanisms related to vascular biology. Oxidative stress, inflammation, and autoimmune dysfunction initiate and propagate hypertension and cardiovascular disease. There is a role for the selected use of single and component nutraceutical supplements, vitamins, antioxidants, and minerals in the treatment of hypertension based on scientifically controlled studies that complement optimal nutrition, coupled with other lifestyle modifications.

Non-alcoholic steatohepatitis and preneoplastic lesions develop in the liver of obese and hypertensive rats: suppressing effects of EGCG on the development of liver lesions

Non-alcoholic steatohepatitis (NASH), which involves hepatic inflammation and fibrosis, is associated with liver carcinogenesis. The activation of the renin-angiotensin system (RAS), which plays a key role in blood pressure regulation, promotes hepatic fibrogenesis. In this study, we investigated the effects of (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea catechins, on the development of glutathione S-transferase placental form (GST-P)-positive (GST-P(+)) foci, a hepatic preneoplastic lesion, in SHRSP.Z-Lepr(fa)/IzmDmcr (SHRSP-ZF) obese and hypertensive rats. Male 7-week-old SHRSP-ZF rats and control non-obese and normotensive WKY rats were fed a high fat diet and received intraperitoneal injections of carbon tetrachloride twice a week for 8weeks. The rats were also provided tap water containing 0.1% EGCG during the experiment. SHRSP-ZF rats presented with obesity, insulin resistance, dyslipidemia, an imbalance of adipokines in the serum, and hepatic steatosis. The development of GST-P(+) foci and liver fibrosis was markedly accelerated in SHRSP-ZF rats compared to that in control rats. Additionally, in SHRSP-ZF rats, RAS was activated and inflammation and oxidative stress were induced. Administration of EGCG, however, inhibited the development of hepatic premalignant lesions by improving liver fibrosis, inhibiting RAS activation, and attenuating inflammation and oxidative stress in SHRSP-ZF rats. In conclusion, obese and hypertensive SHRSP-ZF rats treated with a high fat diet and carbon tetrachloride displayed the histopathological and pathophysiological characteristics of NASH and developed GST-P(+) foci hepatic premalignant lesions, suggesting the model might be useful for the evaluation of NASH-related liver tumorigenesis. EGCG might also be able to prevent NASH-related liver fibrosis and tumorigenesis.

Hydroxylation of (-)-epigallocatechin-3-O-gallate at 3'', but not 4'', is essential for the PI3-kinase/Akt-dependent phosphorylation of endothelial NO synthase in endothelial cells and relaxation of coronary artery rings

(-)-Epigallocatechin-3-O-gallate (EGCg) has been shown to induce endothelium-dependent nitric oxide (NO)-mediated relaxation via the redox-sensitive Src/PI3-kinase/Akt-dependent phosphorylation of endothelial NO synthase (eNOS). Although the presence of 8 hydroxyl functions, mainly on B and D rings, is essential for the EGCg-induced activation of eNOS, the relative role of each individual hydroxyl function still remains unclear. This study examined the effect of selective replacement of hydroxyl functions by methoxy moieties on either the B or D ring on the EGCg-induced phosphorylation of Akt and eNOS, formation of reactive oxygen species (ROS) and NO in cultured coronary artery endothelial cells, and endothelium-dependent relaxation of coronary artery rings. Replacement of a single hydroxyl by the methoxy group on position 3', 4' or 4'' affected little the EGCg-induced phosphorylation of Akt and eNOS, formation of ROS and NO in endothelial cells, and induction of endothelium-dependent relaxations. In contrast, the single methylation at position 3'' and the double methylation at both positions 3' and 4' reduced markedly the phosphorylation of Akt and eNOS, the formation of ROS and NO in endothelial cells and the relaxation of artery rings. These findings suggest that the hydroxyl group at the 3'' position of the gallate ring is essential and, also, to some extent, the two hydroxyl groups at positions 3' and 4', for the EGCg-induced redox-sensitive activation of eNOS leading to the subsequent NO-mediated vascular relaxation.

Green and black tea for the primary prevention of cardiovascular disease

BACKGROUND

There is increasing evidence that both green and black tea are beneficial for cardiovascular disease (CVD) prevention.

OBJECTIVES

To determine the effects of green and black tea on the primary prevention of CVD.

SEARCH METHODS

We searched the following databases on 12 October 2012 without language restrictions: CENTRAL in The Cochrane Library, MEDLINE (OVID), EMBASE (OVID) and Web of Science (Thomson Reuters). We also searched trial registers, screened reference lists and contacted authors for additional information where necessary.

SELECTION CRITERIA

Randomised controlled trials (RCTs) lasting at least three months involving healthy adults or those at high risk of CVD. Trials investigated the intake of green tea, black tea or tea extracts. The comparison group was no intervention, placebo or minimal intervention. The outcomes of interest were CVD clinical events and major CVD risk factors. Any trials involving multifactorial lifestyle interventions or focusing on weight loss were excluded to avoid confounding.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, abstracted data and assessed the risk of bias. Trials of green tea were analysed separately from trials of black tea.

MAIN RESULTS

We identified 11 RCTs with a total of 821 participants, two trials awaiting classification and one ongoing trial. Seven trials examined a green tea intervention and four examined a black tea intervention. Dosage and form of both green and black tea differed between trials. The ongoing trial is examining the effects of green tea powder capsules.No studies reported cardiovascular events.Black tea was found to produce statistically significant reductions in low-density lipoprotein (LDL) cholesterol (mean difference (MD) -0.43 mmol/L, 95% confidence interval (CI) -0.56 to -0.31) and blood pressure (systolic blood pressure (SBP): MD -1.85 mmHg, 95% CI -3.21 to -0.48. Diastolic blood pressure (DBP): MD -1.27 mmHg, 95% CI -3.06 to 0.53) over six months, stable to sensitivity analysis, but only a small number of trials contributed to each analysis and studies were at risk of bias.Green tea was also found to produce statistically significant reductions in total cholesterol (MD -0.62 mmol/L, 95% CI -0.77 to -0.46), LDL cholesterol (MD -0.64 mmol/L, 95% CI -0.77 to -0.52) and blood pressure (SBP: MD -3.18 mmHg, 95% CI -5.25 to -1.11; DBP: MD -3.42, 95% CI -4.54 to -2.30), but only a small number of studies contributed to each analysis, and results were not stable to sensitivity analysis. When both tea types were analysed together they showed favourable effects on LDL cholesterol (MD -0.48 mmol/L, 95% CI -0.61 to -0.35) and blood pressure (SBP: MD -2.25 mmHg, 95% CI -3.39 to -1.11; DBP: MD -2.81 mmHg, 95% CI -3.77 to -1.86). Adverse events were measured in five trials and included a diagnosis of prostate cancer, hospitalisation for influenza, appendicitis and retinal detachment but these are unlikely to be directly attributable to the intervention.

AUTHORS' CONCLUSIONS

There are very few long-term studies to date examining green or black tea for the primary prevention of CVD. The limited evidence suggests that tea has favourable effects on CVD risk factors, but due to the small number of trials contributing to each analysis the results should be treated with some caution and further high quality trials with longer-term follow-up are needed to confirm this.

Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge)

BACKGROUND

The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin-rich tea cultivar 'Sunrouge' (Camellia sinensis x C. taliensis) by using high-performance liquid chromatography, and to study the effect of 'Sunrouge' extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK-N-SH cells.

RESULTS

The total anthocyanin content was higher in the third (3.09 mg g⁻¹) than in the second (2.24 mg g⁻¹) or first crop season (1.79 mg g⁻¹). The amount of anthocyanins contained in the stem was high (1.61 mg g⁻¹). In the third crop season, the concentrations of delphinidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside (DCGa), cyanidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside, delphinidin-3-O-β-D-galactopyranoside, delphinidin-3-O-β-D-(6-O-(Z)-p-coumaroyl)galactopyranoside, cyanidin-3-O-β-D-galactoside, and delphinidin-3-O-β-D-glucoside were 1.57 mg g⁻¹, 0.52 mg g⁻¹, 0.40 mg g⁻¹, 0.22 mg g⁻¹, 0.14 mg g⁻¹, and 0.11 mg g⁻¹, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of 'Sunrouge' water extract on AChE activity in human neuroblastoma SK-N-SH cells was the strongest among the three tea cultivars ('Sunrouge', 'Yabukita' and 'Benifuuki').

CONCLUSION

These results suggested that 'Sunrouge' might protect humans from humans from AChE-related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, 'Sunrouge' from the third crop season should be used.

Target molecules of food phytochemicals: food science bound for the next dimension

Phytochemicals are generally defined as secondary metabolites in plants that play crucial roles in their adaptation to a variety of environmental stressors. There is a great body of compelling evidence showing that these metabolites have pronounced potentials for regulating and modulating human health and disease onset, as shown by both experimental and epidemiological approaches. Concurrently, enormous efforts have been made to elucidate the mechanism of actions underlying their biological and physiological functions. For example, the pioneering work of Tachibana et al. uncovered the receptor for (-)-epigallocatechin-3-gallate (EGCg) as the 67 kDa laminin receptor, which was shown to partially mediate the functions of EGCg, such as anti-inflammatory, anti-allergic, and anti-proliferative activities. Thereafter, several protein kinases were identified as binding proteins of flavonoids, including myricetin, quercetin, and kaempferol. Isothiocyanates, sulfur-containing phytochemicals present in cruciferous plants, are well known to target Keap1 for activating the transcription factor Nrf2 for inducing self-defensive and anti-oxidative gene expression. In addition, we recently identified CD36 as a cell surface receptor for ursolic acid, a triterpenoid ubiquitously occurring in plants. Importantly, the above mentioned target proteins are indispensable for phytochemicals to exhibit, at least in part, their bioactivities. Nevertheless, it is reasonable to assume that some of the activities and potential toxicities of metabolites are exerted via their interactions with unidentified, off-target proteins. This notion may be supported by the fact that even rationally designed drugs occasionally display off-target effects and induce unexpected outcomes, including toxicity. Here we update the current status and future directions of research related to target molecules of food phytochemicals.

Metabolomics-driven nutraceutical evaluation of diverse green tea cultivars

Background

Green tea has various health promotion effects. Although there are numerous tea cultivars, little is known about the differences in their nutraceutical properties. Metabolic profiling techniques can provide information on the relationship between the metabolome and factors such as phenotype or quality. Here, we performed metabolomic analyses to explore the relationship between the metabolome and health-promoting attributes (bioactivity) of diverse Japanese green tea cultivars.

Methodology/Principal Findings

We investigated the ability of leaf extracts from 43 Japanese green tea cultivars to inhibit thrombin-induced phosphorylation of myosin regulatory light chain (MRLC) in human umbilical vein endothelial cells (HUVECs). This thrombin-induced phosphorylation is a potential hallmark of vascular endothelial dysfunction. Among the tested cultivars, Cha Chuukanbohon Nou-6 (Nou-6) and Sunrouge (SR) strongly inhibited MRLC phosphorylation. To evaluate the bioactivity of green tea cultivars using a metabolomics approach, the metabolite profiles of all tea extracts were determined by high-performance liquid chromatography-mass spectrometry (LC-MS). Multivariate statistical analyses, principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA), revealed differences among green tea cultivars with respect to their ability to inhibit MRLC phosphorylation. In the SR cultivar, polyphenols were associated with its unique metabolic profile and its bioactivity. In addition, using partial least-squares (PLS) regression analysis, we succeeded in constructing a reliable bioactivity-prediction model to predict the inhibitory effect of tea cultivars based on their metabolome. This model was based on certain identified metabolites that were associated with bioactivity. When added to an extract from the non-bioactive cultivar Yabukita, several metabolites enriched in SR were able to transform the extract into a bioactive extract.

Conclusions/Significance

Our findings suggest that metabolic profiling is a useful approach for nutraceutical evaluation of the health promotion effects of diverse tea cultivars. This may propose a novel strategy for functional food design.

Inhibition of angiotensin converting enzyme (ACE) activity by polyphenols from tea (Camellia sinensis) and links to processing method

The focus of this study was to investigate Angiotensin Converting Enzyme (ACE) inhibiting activity across 34 teas (Camellia sinensis) produced by 5 different processing methods including green (GT), oolong (OT), white (WT), black (BT) and dark (DT) teas. In vitro ACE inhibitory activity was affected by the tea processing method with IC(50) values for ACE inhibition: green < oolong < white < black < dark teas. Substrate-dependence of the reaction kinetics was studied for GT and BT polyphenolic size fractions either < or > 3 kDa and also Green Tea Polyphenolic Isolate (GTPI), and revealed that enzyme velocity curves fitted allosteric, not Michaelis-Menten, relationships. Inhibition was weakly dependent on substrate concentration for GT fraction >3 kDa and independent of substrate concentration for all other GT and BT size fractions and GTPI. Furthermore, evidence for direct inactivation of ACE by GTPI was demonstrated. Overall, the results suggest that tea polyphenolics exert a mixed mode of in vitro inhibition of ACE, mostly of a kinetically uncompetitive type. The results are discussed in the context of in vivo and epidemiological evidence for regulation of blood pressure by tea consumption.

Polyphenol-induced endothelium-dependent relaxations role of NO and EDHF

The Mediterranean diet has been associated with greater longevity and quality of life in epidemiological studies. Indeed, because of the abundance of fruits and vegetables and a moderate consumption of wine, the Mediterranean diet provides high amounts of polyphenols thought to be essential bioactive compounds that might provide health benefits in terms of cardiovascular diseases and mortality. Several polyphenol-rich sources, such as grape-derived products, cocoa, and tea, have been shown to decrease mean blood pressure in patients with hypertension. The improvement of the endothelial function is likely to be one of the mechanisms by which polyphenols may confer cardiovascular protection. Indeed, polyphenols are able to induce nitric oxide (NO)-mediated endothelium-dependent relaxations in a large number of arteries including the coronary artery; they can also induce endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxations in some of these arteries. Altogether, these mechanisms might contribute to explain the antihypertensive and cardio-protective effects of polyphenols in vivo. The aim of this review was to provide a nonexhaustive analysis of the effect of several polyphenol-rich sources and isolated compounds on the endothelium in in vitro, ex vivo, and in vivo models as well as in humans.