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Abstract

Epidemiological, clinical and experimental studies have established a positive correlation between green tea consumption and cardiovascular health. Catechins, the major polyphenolic compounds in green tea, exert vascular protective effects through multiple mechanisms, including antioxidative, anti-hypertensive, anti-inflammatory, anti-proliferative, anti-thrombogenic, and lipid lowering effects. (1) Tea catechins present antioxidant activity by scavenging free radicals, chelating redox active transition-metal ions, inhibiting redox active transcription factors, inhibiting pro-oxidant enzymes and inducing antioxidant enzymes. (2) Tea catechins inhibit the key enzymes involved in lipid biosynthesis and reduce intestinal lipid absorption, thereby improving blood lipid profile. (3) Catechins regulate vascular tone by activating endothelial nitric oxide. (4) Catechins prevent vascular inflammation that plays a critical role in the progression of atherosclerotic lesions. The anti-inflammatory activities of catechins may be due to their suppression of leukocyte adhesion to endothelium and subsequent transmigration through inhibition of transcriptional factor NF-kB-mediated production of cytokines and adhesion molecules both in endothelial cells and inflammatory cells. (5) Catechins inhibit proliferation of vascular smooth muscle cells by interfering with vascular cell growth factors involved in atherogenesis. (6) Catechins suppress platelet adhesion, thereby inhibiting thrombogenesis. Taken together, catechins may be novel plant-derived small molecules for the prevention and treatment of cardiovascular diseases. This review highlights current developments in green tea extracts and vascular health, focusing specifically on the role of tea catechins in the prevention of various vascular diseases and the underlying mechanisms for these actions. In addition, the possible structure-activity relationship of catechins is discussed.

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... EGCG exerts cardiovascular protection via its antioxidant, anti-inflammatory, hypolipidemic, anti-thrombogenic, and antihypertensive actions [28]. Antioxidant properties of catechins include free radical scavenging [29], metal ion chelation [30], inhibition of redox responses, and induction of antioxidant enzymes [31]. ...
... EGCG-mediated inhibition of NF-κB via multiple mechanisms [20] contributes to its anti-inflammatory activities. Catechins in tea also improve blood lipid profiles, regulate vascular tone, and impede progression of atherosclerotic lesions, by inhibiting cytokine production, inflammatory cell transmigration, platelet adhesion, and vascular smooth muscle cell proliferation [reviewed in [28]]. Experimental and clinical studies identified protective roles of EGCG in CVDs [32], attracting attention toward developing novel therapeutic strategies targeting Nrf2 activation and NF-kB inhibition [33]. ...
Article
Tea contains antioxidant catechins thought to exert health-promoting protective effects against conditions involving chronic inflammation, such as cardiovascular diseases. The most abundant catechin in tea is Epigallocatechin Gallate (EGCG), thought to be a key contributor to tea’s health-promoting actions. EGCG exerts protective cardiovascular effects via its antioxidant, antiinflammatory, hypolipidemic, anti-thrombogenic, and anti-hypertensive actions. Because EGCG inhibits the strong proinflammatory gene-inducing transcription factor NF-κB, we analyzed the chemical and molecular details of the mechanism by which EGCG mediates NF-κB inhibition. We quantified and mapped key parameters of its chemical reactivity including its electrophilic Fukui ƒ+ function, in silico covalent binding, and identified its frontier Molecular Orbitals (MOs) and nucleophilic susceptibility. These physical and chemical reactivity parameters revealed that the bond-forming MOs are distributed on the B ring of the EGCG oxidized state with nucleophilic susceptibility, and that this B ring has properties that favor participating in a Cys-alkylating 1,4-addition reaction. Molecular modeling and docking analysis further revealed that EGCG bonds covalently with Cys-38 of NF-κB-p65, and thereby inhibits its DNA binding ability. We also generated a model pharmacophore based on the EGCG-NF-κB complex. We conclude that EGCG covalently binds to NF-κB-p65 and inhibits it by abolishing its DNA binding, by chemical mechanisms that may inform design of EGCG derivatives as novel anti-inflammatory agents.
... Compounds such as myricetin, kaempferol glucosides, catechin/ epicatechin, and procyanidins are associated with pancreatic lipase inhibition (BUCHHOLZ & MELZIG, 2015;CAMARGO et al., 2017;GENDARAM et al., 2017;YOSHIKAWA et al., 2009;ZHANG, B. et al., 2015). The antihyperlipidemic action of catechin is due to its inhibition of key enzymes involved in lipid biosynthesis, and its ability to reduce intestinal absorption of lipids (ANANDH BABU;LIU, 2008). Other studies have reported ellagic acid, quercetin (MARTINEZ-GONZALEZ et al., 2017), and anthocyanins to be lipase inhibitors (YOU et al., 2011). ...
... Compounds such as myricetin, kaempferol glucosides, catechin/ epicatechin, and procyanidins are associated with pancreatic lipase inhibition (BUCHHOLZ & MELZIG, 2015;CAMARGO et al., 2017;GENDARAM et al., 2017;YOSHIKAWA et al., 2009;ZHANG, B. et al., 2015). The antihyperlipidemic action of catechin is due to its inhibition of key enzymes involved in lipid biosynthesis, and its ability to reduce intestinal absorption of lipids (ANANDH BABU;LIU, 2008). Other studies have reported ellagic acid, quercetin (MARTINEZ-GONZALEZ et al., 2017), and anthocyanins to be lipase inhibitors (YOU et al., 2011). ...
Article
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“Araçá” has been reported with different biological activities such as antioxidant, antiproliferative and antimicrobial as well as inhibitors of digestive enzymes. The digestive pancreatic lipase enzyme plays a fundamental role in lipid metabolism, and its inhibition has been studied as a target for obesity treatment. This study quantified the bioactive compounds present in different parts of “araçá” fruit and evaluated their antioxidant activity and lipase inhibition properties. Three samples were analyzed for total anthocyanins, total phenolic content, antioxidant activity and pancreatic lipase inhibition. Anthocyanins were reported only in pulp-peel of red “araçá” sample. Phenolic compounds concentration was higher in pulp-peel than in seeds for all samples. The antioxidant activity followed the same trend. A positive correlation was observed between total phenolic content and both antioxidant activity and lipase inhibition. Lipase inhibition activity was higher for pulp-peel compared to the seeds. Overall, the results showed that “araçá” fruit extracts could be beneficial for the treatment of obesity.
... Our findings match those published by Shrestha et al. (2009) who cited that dietary Camellia sinensis extract can lower plasma and hepatic triglycerides with an increase in plasma HDLcholesterol. Also, the study of Velayutham et al. (2008) demonstrated that catechins can not only reduce the circulating LDL-cholesterol but also increase the levels of HDLcholesterol in the diabetic rats. Camellia sinensis catechin supplementation has also been shown to reduce apolipoprotein B, the primary apolipoprotein component in LDL, and upregulate LDL receptor expression, which enhances LDL particle uptake in liver from the circulation (Bursill et al. 2007). ...
... Camellia sinensis catechin supplementation has also been shown to reduce apolipoprotein B, the primary apolipoprotein component in LDL, and upregulate LDL receptor expression, which enhances LDL particle uptake in liver from the circulation (Bursill et al. 2007). Therefore, catechins modulate cholesterol metabolism by targeting its biosynthesis, absorption, and excretion that collectively implicate in the hypocholesterolemic effect of Camellia sinensis catechins (Velayutham et al. 2008). ...
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PurposeOur research aims to address and determine the effect of Camellia sinensis extract in the management of nonalcoholic steatohepatitis (NASH) in rats.Methods Forty adult female albino rats were divided into four groups. Group 1 (G1) served as the control group, while the other three groups received high-fat diet for 32 weeks to induce NASH and then were later assigned to the following groups: (G2) NASH-afflicted group which was left untreated, (G3) NASH-afflicted group treated with Camellia sinensis extract in a dose of 400 mg/kg, and (G4) NASH-afflicted group treated with Camellia sinensis extract in a dose of 200 mg/kg.ResultsSignificant elevation in serum alanine aminotransferase, albumin, bilirubin (total and direct), cholesterol, low density lipoprotein, triglycerides, leptin, Cox-2, and CD40 values was recorded. Moreover, overexpression of hepatic tumor necrosis factor alpha and hepatocyte growth factor genes were recorded, whereas blood platelet count and serum high density lipoprotein concentration revealed significant depletion, which was paralleled by significant downregulation of hepatic adiponectin gene expression level in NASH group versus the control group. On the opposite side, treatment of NASH groups with two different doses of Camellia sinensis extract reversed the values of the measured biochemical parameters and the targeted gene expression levels when compared with the NASH group. Optical micrograph of liver tissue sections of rats treated with Camellia sinensis extract showed the observed improvement in the studied biochemical and genetic markers.Conclusion This study provides a clear evidence for the promising therapeutic potential of Camellia sinensis extract against NASH. This could be ascribed to its hepatoprotective activity, hypolipidemic effect, and anti-inflammatory potency.
... Here we demonstrate that the polyphenol compound epigallocatechin gallate (EGCG) facilitates the synthesis of extracellular elastin fibers in vitro in tissue engineering grade hiPSC-VSMCs under conditions of elevated serum concentration. EGCG is a principal component of green tea, and has been shown to convey several vascular protective and cardiovascular benefits [30], including antioxidant [31][32][33][34], reduced lipid absorption [35,36], anti-inflammatory [37,38], anti-hypertensive [39,40], anti-thrombogenic [41,42], and antiproliferative effects [43][44][45][46], the last of which has led to additional research into EGCG as an anti-cancer agent [47][48][49]. Several of these effects are conducive to the synthesis and maturation of elastic fibers, including the activation of endothelial nitric oxide synthase [39], as nitric oxide has previously been shown to stimulate elastin expression in VSMCs [50]. ...
... Therefore, engineering hiPSC-derived vessels enriched with elastin fibers would be highly beneficial for vascular graft development in both disease contexts and for the general aging population ( Fig. 1A). As EGCG possesses numerous cardiovascular benefits [30,39,40], including anti-oxidant [31][32][33][34] and anti-inflammatory [37,38] activity, which would otherwise exacerbate the degradation of elastin, it serves as an optimal compound for facilitating elastin fiber formation in hiPSC-TEVGs. ...
Article
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Tissue engineered vascular grafts possess several advantages over synthetic or autologous grafts, including increased availability and reduced rates of infection and thrombosis. Engineered grafts constructed from human induced pluripotent stem cell derivatives further offer enhanced reproducibility in graft production. One notable obstacle to clinical application of these grafts is the lack of elastin in the vessel wall, which would serve to endow compliance in addition to mechanical strength. This study establishes the ability of the polyphenol compound epigallocatechin gallate, a principal component of green tea, to facilitate the extracellular formation of elastin fibers in vascular smooth muscle cells derived from human induced pluripotent stem cells. Further, this study describes the creation of a doxycycline-inducible elastin expression system to uncouple elastin production from vascular smooth muscle cell proliferative capacity to permit fiber formation in conditions conducive to robust tissue engineering.
... In addition, the major sources of non-alcoholic beverages in the present study were the green tea and coffee, which were associated with reduced risks of diabetes (31,32) and cardiovascular disease (33,24) . Polyphenolic compounds in green tea such as catechins, and caffeine with other polyphenols in coffee could have played preventive roles against oxidation, inflammation, thrombogenic prefiltration, and hypertension (34,35) as well. ...
Article
The association between the intake of non-alcoholic beverages and cardiovascular disease in Asians is uncertain. The intake of non-alcoholic beverages was estimated in 77,407 participants of the Japan public health center-based cohort study aged 45-74 years. The Cox regression calculated the HRs and 95% CIs for incident cardiovascular disease according to sex-specific quintiles of intake of non-alcoholic beverages. A total of 4578 incident cardiovascular disease (3,751 strokes and 827 coronary heart disease) were diagnosed during a 13.6-year median follow-up. The risks of stroke and total cardiovascular disease were lower for the highest versus lowest intake quintiles of non-alcoholic beverages in men and women: the multivariable HRs (95%CIs) were 0.82 (0.71-0.93, p-trend=0.005) and 0.86 (0.76-0.97, p-trend=0.02), respectively in men, and were 0.73 (0.63-0.86, p-trend=0.003) and 0.75 (0.65-0.87, p-trend=0.005) respectively in women. The reduced risk was evident for both ischemic and hemorrhagic strokes and was mainly attributable to green tea consumption. The intake of non-alcoholic beverages from coffee and other beverages was not associated with the risk of cardiovascular disease in both men and women. Also, there was no association between the intake of non-alcohol beverages and the risk of coronary heart disease in either sex. In conclusion, the risks of stroke and total cardiovascular disease were lower with a higher intake of non-alcoholic beverages in Japanese men and women.
... Recent scientific studies have reported the lutein has cardiac protective effects in vitro and in vivo. Epicatechin and procyanidins have been reported to have good cardioprotective health benefits [59]. ...
Chapter
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Since time immemorial, plants are used as the source of food and medicine. It can be traced back to the start of humanity. Bringing plant-based food, such as fruits, vegetables, and whole grains, rich in phytochemicals, with beneficial nutrients, opens the door for healthy living. The health benefits are partly attributed to the compounds which possess antioxidants. Several epidemiological observations have shown an opposite relationship between consumption of plant-based foods, rich in phytochemicals, and many diseases including cancer. The majority of the ailments are related to oxidative stress induced by free radicals. Free radicals are extremely unstable with a very short half-life, highly reactive molecule which leads to oxidative damage to macromolecules such as proteins, DNA, and lipids. Free radical induced cellular inflammation appears to be a major contributing factor to cause aging, and degenerative diseases such as cancer, cardiovascular diseases, diabetes, hepatic diseases, renal ailments, and brain dysfunction. Free radicals have been caught up in the pathogenesis of several diseases. Providentially, free radical formation is controlled naturally by phytochemicals, through their antioxidant potential which plays a key role in preventing many diseases including cancer by suppressing oxidative stress-induced DNA damage. Keeping these facts in mind, an attempt has been made to highlight the oxidative stress, enzymatic and non-enzymatic antioxidant, dietary phytochemicals and their role of in disease prevention and cure.
... Polyphenols also contribute to the antioxidant defense of endothelial cells by reducing NADPH oxidase expression [49]. Several in vitro studies have reported that phenolic compounds could effectively reduce oxidized LDL and increase the level of high-density lipoproteins (HDL), ultimately improving endothelial function [50,51]. Moreover, numerous phenolic compounds exert cardioprotective effects at a localized or systemic level by inducing antiplatelet effects [46], with such effects being majorly attributed to the O-dihydroxyl group in the A and/or B ring ( Figure 3) [52]. ...
Article
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Cardiovascular diseases (CVD) are one of the main causes of mortality in the world. The development of these diseases has a specific factor-alteration in blood platelet activation. It has been shown that phenolic compounds have antiplatelet aggregation abilities and a positive impact in the management of CVD, exerting prominent antioxidant, anti-inflammatory, antitumor, cardioprotective, antihyperglycemic, and antimicrobial effects. Thus, this review is intended to address the antiplatelet activity of phenolic compounds with special emphasis in preventing CVD, along with the mechanisms of action through which they are able to prevent and treat CVD. In vitro and in vivo studies have shown beneficial effects of phenolic compound-rich plant extracts and isolated compounds against CVD, despite that the scientific literature available on the antiplatelet aggregation ability of phenolic compounds in vivo is scarce. Thus, despite the current advances, further studies are needed to confirm the cardioprotective potential of phenolic compounds towards their use alone or in combination with conventional drugs for effective therapeutic interventions.
... Catechin also exhibits anticancer properties and is potentially utilized for its antioxidant and cardiovascular protective effects 9 . Green pods of the plant are rich in gallic acid, elagic acid, ferulic and epicatechin as reported by Singh et al. 71 Pods of A. nilotica are a rich source of polyphenolic compounds and contain different galloylated derivatives of catechin and gallocatechin. ...
Article
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Plant-derived medicines are long being used for the prevention and treatment of various human ailments. For the last few decades, plants are widely being explored for their active ingredients due to their immense potential in the treatment of critical illnesses. Thus, in recent years, exponential growth can be seen in the field of herbal medicines. Medicinal plants are a unique source of valuable phytochemicals. Their use in different medicine systems is gradually increasing due to their cost-effectiveness, easy availability and natural origin with fewer or no side effects. Acacia nilotica (L.) is a member of the family Fabaceae, commonly found in tropical and subtropical regions and the plant is widely known for its enormous medicinal values. Every plant part of A. nilotica is a source of many bioactive important secondary metabolites that are widely useful for the cure of various human diseases and the development of new drugs. An exhaustive literature survey revealed that tannins, flavonoids, alkaloids, polyphenols, fatty acids and carbohydrates are present as major classes of phytochemicals in different plant parts of A. nilotica. These phytochemicals exhibit significant antioxidant, anti-inflammatory, antibacterial, antifungal, antidiarrheal, antihypertensive, antispasmodic, anthelmintic, antiplatelet aggregation, anticancer and antiviral activities. The present review is aimed to organize the comprehensive information available on phytochemical composition and medicinal properties of different plant parts of A. nilotica viz. leaves, bark, flowers, seeds, pods, gum and roots. The study is useful to explore the therapeutic potential of different plant parts of A. nilotica which will further help in the development of new promising, safe, cost-effective drugs with a high therapeutic index from the different parts of the Acacia plant.
... Catechin was a major compound present in the optimized inajá cake extract (Table 5). Its effects and mechanisms of action are dependent on the concentration of the compound in the source material (Velayutham, Babu, & Liu, 2009;Bernatoniene & Kopustinskiene, 2018). ...
Article
Agro-industrial activities generate large amounts of solid residues, which are generally discarded or used as animal feed. Interestingly, some of these by-products could serve as natural sources of bioactive compounds with great potential for industrial exploitation. This study aimed to optimize the extraction of phenolic antioxidants from the pulp residue (oil processing by-product) of inajá (Maximiliana maripa, a native species found in the Brazilian Amazon). The antioxidant properties of the optimized extract and its phenolic profile by high-resolution mass spectrometry (LC-ESI-QTOF-MS) were further determined. Central composite rotatable design and statistical analysis demonstrated that the temperature of 70°C and 50% (v/v) ethanol concentration improved the extraction of phenolic compounds with antioxidant properties. The optimized extract also showed scavenging activity against the ABTS radical cation and reactive oxygen species (ROS; peroxyl and superoxide radical, and hypochlorous acid). Moreover, the optimized extract was able to reduce NF-κB activation and TNF-α release, which are modulated by ROS. Flavan-3-ols were the major phenolics present in the optimized extract. Collectively, our findings support the use of inajá cake as a new source of bioactive catechins and procyanidins. This innovative approach adds value to this agro-industrial by-product in the functional food, nutraceutical, pharmaceutical, and/or cosmetic industries and complies with the circular economy agenda.
... It is a relatively new finding that MP can be activated by potentiating MYPT1 dephosphorylation through the initiation of the 67LR/PKA/PP2A pathway by EGCG [26,27]. Indeed, EGCG has a variety of pharmacological actions including cardiovascular protective effects [42]. Some studies have suggested the effectiveness of EGCG in the treatment of atherosclerosis, but little is known about the underlying molecular mechanism [43]. ...
Article
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Monocyte to macrophage differentiation is characterized by the activation of various signal transduction pathways, which may be modulated by protein phosphorylation; however, the impact of protein kinases and phosphatases is not well understood yet. It has been demonstrated that actomyosin rearrangement during macrophage differentiation is dependent on Rho-associated protein kinase (ROCK). Myosin phosphatase (MP) target subunit-1 (MYPT1) is one of the major cellular substrates of ROCK, and MP is often a counter enzyme of ROCK; therefore, MP may also control macrophage differentiation. Changes in MP activity and the effects of MP activation were studied on PMA or l,25(OH)2D3-induced differentiation of monocytic THP-1 cells. During macrophage differentiation, phosphorylation of MYPT1 at Thr696 and Thr853 increased significantly, resulting in inhibition of MP. The ROCK inhibitor H1152 and the MP activator epigallocatechin-3-gallate (EGCG) attenuated MYPT1 phosphorylation and concomitantly decreased the extent of phosphorylation of 20 kDa myosin light chain. H1152 and EGCG pretreatment also suppressed the expression of CD11b and weakened the PMA-induced adherence of the cells. Our results indicate that MP activation/inhibition contributes to the efficacy of monocyte to macrophage differentiation, and this enzyme may be a target for pharmacological interventions in the control of disease states that are affected by excessive macrophage differentiation.
... Bee products caused decreased NF-κB activity in rats hypertensive with l-NAME. Anti-inflammatory activities of phenolics may be mediated by transcriptional factor NF-κB in cells (Babu & liu 2008). Bee products are known to be potent antioxidants. ...
Article
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Hypertension is a chronic disease affecting the whole world due to its clinical effects and complications. The reduction in the release and effect of NO is one of the mechanisms of hypertension formation. Hypertension disrupts the balance between oxidant and antioxidant mechanisms. In this study, we aimed to observe biochemical changes in the blood by treatment propolis, caffeic acid phenethyl ester (CAPE) and pollen in hypertensive rats via Nω-Nitro-L-arginine methyl ester (L-NAME). Rats were divided in five groups. Rats were given L-NAME (40 mg/kg, intraperitoneally) for 14 days to make hypertensive. L-NAME and bee products were administered together with rats for 14 days, then L-NAME for 14 days. All administrated ended 28 days. There was a statistically significant (P<0.05) decrease in blood pressure (BP) in the groups in which bee products were applied. Blood pressure was lower in the pollen treated group than in the CAPE and propolis treated group (P<0.05). Paraoxanase (PON1), total antioxidant status (TAS), total oxidant status (TOS), asymmetric dimethylarginine (ADMA), nuclear factor-κB (NF-κB) levels were measured in the blood samples in all groups. In the L-NAME group; PON1, TAS, HDL, and total protein levels were found to be lower than the groups applied bee products (P<0.05). TOS, oxidative stress index (OSI), ADMA, NF-κB, glucose, cholesterol, LDL, triglyceride, ALT, AST, ALP levels were found to be lower in groups plus of bee products were applied compared to the group that received L-NAME (P<0.05). The results showed that oxidative stress and homeostasis can be regulated with propolis, CAPE and pollen in hypertensive rats induced L-NAME.
... Penelitian lebih lanjut untuk senyawa ini pada D. burmannii tampaknya menarik untuk dilakukan mengingat katekin berperan penting dalam bidang medis. Sebagai contoh, Velayutham et al. (2008) telah merangkum fungsi katekin dari tanaman teh (Camellia sinensis (L.) Kuntze) yang berpotensi sebagai antikanker, antiinflamasi, antioksidan, menurunkan kadar lipid dan obat penyakit kardiovaskular. ...
Article
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One of the most unique plant groups in the world is carnivorous plants. Indonesia is home to many species of this plant group. Nepenthaceae, represented by single genus Nepenthes, is relatively well known, but the others are not. A literature study and several field trips were conducted to give a summary of the diversity and the potential uses of the non-Nepenthes carnivorous plants in Indonesia. Three families with a total number of 29 species have been reported for Indonesia, namely Lentibulariaceae (20 species), Droseraceae (8 species), and Byblidaceae (1 species). One species, Aldrovanda vesiculosa is listed as Endangered based on IUCN Red List. The results reveal that several species possess ethnobotanical and medicinal uses as well as other potential such as in phytoremediation and nanoparticle biosynthesis. Several bioactivities have been reported such as anticancer, antihypertensive, antitumor, antioxidant, antibacterial, or even hepatoprotective. Among the most important bioactivity is anticancer which is supported by the presence of secondary metabolites named plumbagin, which so far has been found in three species. Our result indicates that this plant group is highly potential and warrants further studies and or development.
... About 80-90% of the major flavonoids of green tea are various catechins, the four major catechins are mainly (-)-epicatechin (EC), (-)epigallocatechin (EGC), (-)-epicatechin-3gallate (ECG) and (-)-epigallocatechin-3gallate (EGCG). Among these, the most abundant is EGCG (~ 59%) followed by EGC (~ 19%), ECG (~14%) and EC (~ 6%) (Anandh and Liu, 2008;Jigisha et al., 2012). Green tea has far higher levels of catechins than black tea. ...
... The rate of fermentation will reduce the amount of polyphenol oxidase in the tea. In other words, green tea contains the maximum level of antioxidants, whereas oolong and black tea have comparatively lower levels [162,163]. However, black tea is the most consumed tea compared to green and oolong tea and there is insufficient evidence suggesting that green tea truly has better health-promoting properties than black tea [164]. ...
Article
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Tea is one of the most popular and widely consumed beverages worldwide, and possesses numerous potential health benefits. Herbal teas are well-known to contain an abundance of poly-phenol antioxidants and other ingredients, thereby implicating protection and treatment against various ailments, and maintaining overall health in humans, although their mechanisms of action have not yet been fully identified. Autophagy is a conserved mechanism present in organisms that maintains basal cellular homeostasis and is essential in mediating the pathogenesis of several diseases , including cancer, type II diabetes, obesity, and Alzheimer's disease. The increasing prevalence of these diseases, which could be attributed to the imbalance in the level of autophagy, presents a considerable challenge in the healthcare industry. Natural medicine stands as an effective, safe, and economical alternative in balancing autophagy and maintaining homeostasis. Tea is a part of the diet for many people, and it could mediate autophagy as well. Here, we aim to provide an updated overview of popular herbal teas' health-promoting and disease healing properties and in-depth information on their relation to autophagy and its related signaling molecules. The present review sheds more light on the significance of herbal teas in regulating autophagy, thereby improving overall health.
... Tea, dried leaves of Camellia sinensis, is classified into green, black, and Oolong tea according to its leaf treatment. It contains numerous catechins, mainly epicatechin, epicatechin-3-gallate, epigallocatechin, and epigallocatechin-3-gallate (EGCG) 5,6 . In recent years, green tea and its constituents have been massively studied for its beneficial health effects, including alleviation of metabolic syndrome. ...
Article
Background : Individually, green tea and green coffee have been extensively studied for mitigation of metabolic syndrome (MS) in both rats and humans; however, their combined effect requires further investigation. Thus, we compared the metabolic effect of combining green tea and decaffeinated light roasted green coffee on MS in rats. Methods: An MS animal model was constructed by feeding Sprague-Dawley rats with a high-fat-high-sucrose (HFHS) diet for eight weeks and a low dose of streptozotocin (STZ) injection at week 2. Rats fed with HFHS diets and injected with STZ successfully developed MS phenotypes, indicated by higher body weight, systolic blood pressure, plasma triglyceride level, plasma fasting blood glucose level, and lower plasma HDL-C level, compared to those fed with a normal chow diet. Subsequently, MS rats were continuously fed with HFHS and divided into four groups: MS rats, MS with 300 mg/bw.t green tea extract (GT), MS with 200 mg/bw.t green coffee extract (GC), and MS with combined green tea and green coffee extract (CM) for nine weeks. Results: Combining green tea and green coffee have synergistic effects on reducing plasma fasting blood glucose and triglyceride level. Inflammatory markers both in plasma and liver tissue robustly decreased in CM group rats. However, the reduction of systolic blood pressure was observed only in GT and CM groups. Moreover, all treatment resulted in an increase in plasma HDL-C level in MS rats. Conclusions : Our data highlighted that, in MS animal models, combined green tea and decaffeinated light roasted green coffee augment their several individual beneficial effects of improved metabolic parameters and modulated inflammatory genes.
... Green tea is an excellent source of catechins (Balentine et al., 1997). In green tea, catechins account for 80 to 90% of total flavonoids; EGCG is the most abundant catechin (48 -55%) followed by ECG (9 -12%), EGC (9 -12%), and EC (5 -7%) (Babu and Liu, 2008). The structural features of catechins that enable scavenging of DPPH radicals are an ortho-trihydroxyl group in the B ring, and a galloyl moiety at the 3-position. ...
Article
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The catechin content and antioxidant properties of various Camellia sinensis twig extracts, including a water extract (WE), 10% ethanol extract (10% EE), 50% ethanol extract (50% EE), and 95% ethanol extract (95% EE) were investigated. The 50% EE had the highest total phenolic content (161.3 ± 8.5 mg gallic acid equivalents/L) and total flavonoid content (278.9 ± 12.2 mg quercetin equivalents/L). High-performance liquid chromatography analysis suggested that epigallocatechin gallate and epigallocatechin were the predominant catechins in the twig extracts. The relative concentrations of six catechins isolated from the extracts were: 50% EE > 10% EE > WE > 95% EE. The 50% EE showed free radical-scavenging activity. The concentration of dry matter of 50% EE required to scavenge 50% of ABTS radicals was 102.8 ± 4.2 μg/mL. These results suggest that 50% EE can potentially be used as a source of catechins.
... Pu-erh tea is a traditional Chinese tea. There are two types of Pu-erh tea, namely raw (unfermented) and ripe (after microbial fermentation) [67]. In this review, one human trial and four murine studies were done on Pu-erh tea ( Table 2 and Table 3). ...
Preprint
A diet high in polyphenols is associated with a diversified gut microbiome. Tea is the second most consumed beverage in the world, after water. The health benefits of tea might be attributed to the presence of polyphenol compounds such as catechins, theaflavins, tannins, and flavonoids. Although many studies are on tea, little is known of its effects on trillions of gut microbiota. Hence, this review is aimed at systematically studying the effect of tea polyphenols on the stimulation or suppression of gut microbiota in humans and animals. It was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Articles were retrieved from PubMed and Scopus databases, and data were extracted from 6 human trials and 15 animal studies. Overall, huge variations were observed in terms of microbiota composition between humans and animals. A more consistent pattern of diversified microbiota was observed in animal studies. Tea alleviated the gut microbiota imbalance caused by high-fat diet-induced obesity, diabetes, and ultraviolet-induced damage. Overall changes in microbiota composition measured by beta diversity analysis showed that tea had shifted the microbiota from the pattern seen in animals that received tea-free intervention. In humans, the prebiotic-like effect was observed towards gut microbiota, but these results appear in lower-quality studies. Beta diversity in human microbiota remains intact despite tea intervention; supplementation with different teas affected different types of bacterial taxa in the gut. These studies suggest that tea polyphenols may have a prebiotic effect in disease-induced animals and in a limited number of human interventions. Further intervention is needed to identify the mechanisms of action underlying the effects of tea on gut microbiota.
... [13,14] Several studies also showed that catechins exert pharmacological properties such as antioxidant, anticancer, antihypertensive, anti-inflammatory, anti-hyperlipidemic, hypocholesterolemic, anti-diabetic, anti-obesity, and cardioprotective effects. [15][16][17][18][19] Moreover, the iron-binding property of catechin compounds in green tea may be responsible to exhibit antioxidant activity in iron-loaded rats. [20,21] Although Miang may contain chemical constituents like those of fresh tea leaf, studies focusing on its biological properties and possible toxicity have been done mostly only in the test tube level. ...
... Polyphenol oxidase is a heat-labile enzyme present in black tea [72]. The activity of this enzyme is reduced by steam-heating during the fermentation of black tea, consequently reducing its antioxidant properties compared to green tea [72,73]. In this review, one human study demonstrated the effect of black tea on the gut microbiota (Table 3). ...
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A diet high in polyphenols is associated with a diversified gut microbiome. Tea is the second most consumed beverage in the world, after water. The health benefits of tea might be attributed to the presence of polyphenol compounds such as flavonoids (e.g., catechins and epicatechins), theaflavins, and tannins. Although many studies have been conducted on tea, little is known of its effects on the trillions of gut microbiota. Hence, this review aimed to systematically study the effect of tea polyphenols on the stimulation or suppression of gut microbiota in humans and animals. It was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Articles were retrieved from PubMed and Scopus databases, and data were extracted from 6 human trials and 15 animal studies. Overall, large variations were observed in terms of microbiota composition between humans and animals. A more consistent pattern of diversified microbiota was observed in animal studies. Tea alleviated the gut microbiota imbalance caused by high-fat diet-induced obesity, diabetes, and ultraviolet-induced damage. The overall changes in microbiota composition measured by beta diversity analysis showed that tea had shifted the microbiota from the pattern seen in animals that received tea-free intervention. In humans, a prebiotic-like effect was observed toward the gut microbiota, but these results appeared in lower-quality studies. The beta diversity in human microbiota remains intact despite tea intervention; supplementation with different teas affects different types of bacterial taxa in the gut. These studies suggest that tea polyphenols may have a prebiotic effect in disease-induced animals and in a limited number of human interventions. Further intervention is needed to identify the mechanisms of action underlying the effects of tea on gut microbiota.
... The authors proposed that multiple mechanisms, including inhibition of conjugation, CYP450s and efflux transporters involved in the metabolism and excretion of biochanin A were responsible [81]. This is of importance as these flavonoids commonly occur within the diet and have been investigated for treating cardiovascular diseases, potentially increasing the risk of being combined with statins [92][93][94]. ...
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3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors, statins, are a primary treatment for hyperlipidemic cardiovascular diseases which are a leading global cause of death. Statin therapy is life saving and discontinuation due to adverse events such as myotoxicity may lead to unfavourable outcomes. There is no known mechanism for statin-induced myotoxicity although it is theorized that it is due to inhibition of downstream products of the HMG-CoA pathway. It is known that drug-drug interactions with conventional medicines exacerbate the risk of statin-induced myotoxicity, though little attention has been paid to herb-drug interactions with complementary medicines. Flavonoids are a class of phytochemicals which can be purchased as high dose supplements. There is evidence that flavonoids can raise statin plasma levels, increasing the risk of statin-induced myopathy. This could be due to pharmacokinetic interactions involving hepatic cytochrome 450 (CYP450) metabolism and organic anion transporter (OATP) absorption. There is also the potential for flavonoids to directly and indirectly inhibit HMG-CoA reductase which could contraindicate statin-therapy. This review aims to discuss what is currently known about the potential for high dose flavonoids to interact with the hepatic CYP450 metabolism, OATP uptake of statins or their ability to interact with HMG-CoA reductase. Flavonoids of particular interest will be covered and the difficulties of examining herbal products will be discussed throughout.
... Significant cooperation between NF-kB members and the Nrf2 signaling pathway was observed in various physiological disturbances. Additionally, it has been exposed that the Keap1 (Ahmad, Cheng, & Mukhtar, 2000;Babu & Liu, 2008;Bao & Peng, 2016;Bernatoniene & Kopustinskiene, 2018;Farkhondeh et al., 2020;Farkhondeh, Yazdi, & Samarghandian, 2018;Khan, Afaq, Saleem, Ahmad, & Mukhtar, 2006;Mak, 2012;Saeed et al., 2017;Samarghandian, Azimi Nezhad, & Farkhondeh, 2017;Sannella et al., 2007;Sinija & Mishra, 2008;Song & Seong, 2007;Thielecke & Boschmann, 2009;Yamagata, 2020). Green tea catechins are also used as flavoring and coloring agents in foods. ...
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Nuclear factor-erythroid 2-related factor 2 (Nrf2), is a transcriptional signaling pathway that plays a crucial role in numerous clinical complications. Pivotal roles of Nrf2 have been proved in cancer, autoimmune diseases, neurodegeneration, cardiovascular diseases, diabetes mellitus, renal injuries, respiratory conditions, gastrointestinal disturbances, and general disorders related to oxidative stress, inflammation, apoptosis, gelatinolysis, autophagy, and fibrogenesis processes. Green tea catechins as a rich source of phenolic compounds can deal with various clinical problems and manifestations. In this review, we attempted to focus on intervention between green tea catechins and Nrf2. Green tea catechins especially epigallocatechin gallate (EGCG) elucidated the protective role of Nrf2 and its downstream molecules in various disorders through Keap-1, HO-1, NQO-1, GPx, GCLc, GCLm, NF-kB cross-link, kinases, and apoptotic proteins. Subsequently, we compiled an updated expansions of the Nrf2 role as a gate to manage and protect different disorders and feasible indications of green tea catechins through this signaling pathway. The present review highlighted recent evidence-based data in silico, in vitro, and in vivo studies on an outline for future clinical trials.
... The most widely known compounds from this group are catechin, epicatechin, and their glycosides (Figure 7). Flavan-3-ols are widely known as antioxidants, as they have abilities to upregulate antioxidant enzymes and to scavenge ROS [107]. As reviewed by Aron and Kennedy [108], the generally accepted biological role of flavan-3-ols in plants relates to their protection against harmful intruders such as microbes, fungi, insects, and herbivorous animals. ...
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Abiotic stressors such as extreme temperatures, drought, flood, light, salt, and heavy metals alter biological diversity and crop production worldwide. Therefore, it is important to know the mechanisms by which plants cope with stress conditions. Polyphenols, which are the largest group of plant-specialized metabolites, are generally recognized as molecules involved in stress protection in plants. This diverse group of metabolites contains various structures, from simple forms consisting of one aromatic ring to more complex ones consisting of large number of polymerized molecules. Consequently, all these molecules, depending on their structure, may show different roles in plant growth, development, and stress protection. In the present review, we aimed to summarize data on how different polyphenol structures influence their biological activity and their roles in abiotic stress responses. We focused our review on phenolic acids, flavonoids, stilbenoids, and lignans.
... The inhibitory effects of EGCG is associated interfering with the hydrolysis of fats, luminal emulsification, uptake of lipids and micelle solubilization (Koo & Noh 2007). The catechins inhibit the vital enzymes which is involve in lipids biosynthesis and additionally minimize lipid absorption in intestine as a result enhancing blood lipid profile (Babu et al., 2008). ...
Chapter
Diabetes mellitus (DM) is a chronic disease caused by inherited or acquired deficiency in insulin secretion and by decreased insulin secretion by the organ. Insulin deficiency causes the DM. Synthetic drugs are widely used in the treatment of diabetes, but they have some side effects. The antihyperglycemic and antihyperlipedemic effects of the plants are related to their ability to maintain pancreatic function. Medicinal plants constituents such as glycosides, alkaloids, terpenoids, and flavonoids mitigate DM. B. ciliata inhibits the α-glucosidase and α-amylase. Cinnamon extracts improve insulin receptor function by activating insulin receptor kinase and inhibiting insulin receptor phosphatase, which lead to an increase in insulin sensitivity. Morinda lucida also had the highest antioxidant activity, and it also inhibited the α-glucosidase. Many plants have also been shown to antihyperlipedemic effects. Finally, it can be concluded that medicinal plants have that ability to treat or prevent DM.
... Epidemiological, in vitro, and animal studies have indicated that flavonoids have beneficial impact on cardiovascular disease, involving lipoprotein oxidation, blood platelet aggregation, and vascular reactivity [55] . The plant extract could exert its effect on blood pressure via multi-action pathway involving anti-oxidant, anti-thrombogenic, anti-inflammatory, and vaso-relaxant activities of flavonoids within the extract [56][57][58] . ...
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Baillonella toxisperma stem bark is used in Cameroonian traditional medicine to control many ailments such as diabetes mellitus. The present study was designed to evaluate the anti-diabetic potential of Baillonella toxisperma stem-barks aqueous extract on STZ-induced type 1 diabetes in rats. Experimental diabetes was induced by intravenous (penile vein) injection of 55 mg/kg of streptozotocin. Animal received distilled water (10 mL/kg), insulin (10 UI/kg) or the aqueous extract of B. toxisperma (100 mg/kg, 200 mg/kg and 300 mg/kg). Hypoglycemic effect was assessed by a single oral administration of the extract to normal and diabetic rats and anti-diabetic effect evaluated by administrating daily doses to diabetic rats for 28 days. At the end of experimental period, blood pressure was recorded and serum (blood glucose levels, total cholesterol, triglycerides, LDL-cholesterol, LDL-cholesterol, AST, ALT, creatinine, sodium, calcium and urea), urinary (creatinine, sodium, calcium, urea and protein) biochemical parameters were evaluated. Some oxidative stress parameters were evaluated, and histomorphometry of the pancreas performed. A single oral administration of the plant extract significantly reduced blood glucose levels in both normal and diabetic rat with a marked effect at higher dose. Injection of streptozotocin induced chronic hyperglycaemia accompanied by polyphagia, polydipsia, polyuria, weight loss, dyslipidemia, oxidative stress, rising on blood pressure, liver, kidney damages and degenerative changes in pancreas. The administration of Baillonella toxisperma stem-barks aqueous extract (200 mg/kg and 300 mg/kg) significantly decreased blood glucose levels and blood pressure parameters as compared to diabetic control 28 days post-treatment. Furthermore, the extract improved lipidemia, liver, renal parameters, and countered oxidative stress. Similarly, the plant extract improved morphological changes in pancreas by increased the area of islets cells of Langerhans as compared to diabetic control. These findings suggest that Baillonella toxisperma stem-barks aqueous extract exerts its anti-diabetic property by its hypolipidemic and anti-oxidative effects. These results justify the use of this extract in the management of diabetic condition.
... Epidemiological, in vitro, and animal studies have indicated that flavonoids have beneficial impact on cardiovascular disease, involving lipoprotein oxidation, blood platelet aggregation, and vascular reactivity [55] . The plant extract could exert its effect on blood pressure via multi-action pathway involving anti-oxidant, anti-thrombogenic, anti-inflammatory, and vaso-relaxant activities of flavonoids within the extract [56][57][58] . ...
... Armed with a plethora of cardiovascular health benefits, including anti-inflammatory and antioxidative properties, they demonstrate potential in attenuating atherogenesis and disease progression at a cheaper cost compared to other pharmaceutical agents. Particular examples include omega-3 polyunsaturated fatty acids (n À 3 PUFAs) [86][87][88] (e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), green tea catechins [89][90][91] and olive oil polyphenols [92][93][94] (e.g., hydroxytyrosol). The Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) demonstrated that daily intake of 4 g of icosapent ethyl (IPE; a purified EPA ethyl ester) by patients with established CVD/diabetes/other risk factors already on statin therapy significantly reduced the incidence of total cardiovascular events by 32% [95]. ...
Chapter
Atherosclerosis is the principal cause of cardiovascular disease that continues to be a substantial drain on healthcare systems, being responsible for about 31% of all global deaths. Atherogenesis is influenced by a range of factors, including oxidative stress, inflammation, hypertension, and hyperlipidemia, and is ultimately driven by the accumulation of low-density lipoprotein cholesterol within the arterial wall of medium and large arteries. Lipoprotein accumulation stimulates the infiltration of immune cells (such as monocytes/macrophages and T-lymphocytes), some of which take up the lipoprotein, leading to the formation of lipid-laden foam cells. Foam cell death results in increased accumulation of dead cells, cellular debris and extracellular cholesterol, forming a lipid-rich necrotic core. Vascular smooth muscle cells from the arterial media also migrate into the intima layer and proliferate, taking up the available lipids to become foam cells and producing extracellular matrix proteins such as collagen and elastin. Plaque progression is characterized by the formation of a fibrous cap composed of extracellular matrix proteins and smooth muscle cells, which acts to stabilize the atherosclerotic plaque. Degradation, thinning, and subsequent rupture of the fibrous cap leads to lumen-occlusive atherothrombosis, most commonly resulting in heart attack or stroke. This chapter describes the pathogenesis of atherosclerosis, current and emerging therapies, key challenges, and future directions of research.
... Catechin: The cardio protective property of honey is due to catechin which scavenges free radical species (ROS) liberated at uncoupled mitochondrial electron transport chain, encounter of inflammatory cells with pathogens and activity of oxidative enzymes e.g., xanthine oxidase (Babu and Liu 2008). Catechin chelates redox active transition metal ions, blocks the interaction of redox sensitive transcription factors, blocks prooxidative enzyme activity while stimulating antioxidative enzymes (Mihm et al. 2001;Frei and Higdon 2003). ...
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Honey comes with a legendary history of being used as an indigenous medicine to cure a number of diseases. Honey is an essential source of phenolic molecules such as flavonoids and phenolic acids. The most abundant flavonoids present in honey include flavones, flavanones, and flavonols. Flavonoids show diverse activities such as non-inflammatory, antiallergenic, antiviral, antimalignant, antimicrobial, however, the antioxidant activity has been studied widely. Honey also possess a diverse molecules of phenolic acids including p-coumaric, ferulic, caffeic acid, acetophenones, phenylacetic acids, syringic, vanillic, gallic acid, and so on which endow it with the therapeutic activities against pathogens, inflammation while at the same time shows antioxidant and healing properties. The phenolic compounds owing to their medical properties make honey a very critical and attractive prophylactic entity for the prevention of chronic diseases associated with oxidative stress including cancer, cardiovascular disease, diabetes, respiratory disease, hypertension, neurodegenerative diseases etc. In this chapter, a discussion has been made on classification, structure, and medicinal and health benefits of phenolic compounds.
... Such phenolic compounds consist of flavonoids that are broadly classified into anthocyanidins (e.g., cyanidin, delphinidin, malvidin), flavanols (e.g., catechin, epicatechin), flavonols (e.g., quercetin, fisetin, kaempferol, and rutin), flavones (e.g., luteolin), but also of phenolic acids (i.e. caffeic, gallic, and quinic acids), and other similar compounds characterized by the presence of phenol units with polar substrates such as the OH-group [24][25][26] . These compounds, even though they are usually water soluble, they are more than often co-extracted with other PLs during TL-extract preparations and separations, because they exhibit slightly more to similar polarity with the more polar molecules of PLs. ...
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Lipids are a very heterogeneous class of biomolecules with distinct structures and functions. Total lipids (TLs) obtained from natural sources are regularly further separated into lipid subclasses, with the two major ones being the polar lipids (PLs) and neutral lipids (NLs). Traditional analytical methods for fractionating TLs into NLs, PLs, and their subclasses, usually comprise difficult, costly and time-consuming steps. Instead, several benefits and applications are derived by implementing a novel one-step semi-preparative and reversed-phase HPLC-analysis for separating TLs into all kinds of lipid subclasses. This method allows a one-step separation/fractionation of several subclasses of bio-functional PLs (i.e. phospholipids, glycolipids, phenolic compounds, N-acyl-homoserine-lactones, etc.) and NLs (i.e. triacylglycerols, fatty acids, esters, etc.) from TL-extracts of a natural source, prior to further testing them for their bio-functionality (i.e. in bioassays/cell models) and structure-activity relationships (i.e. LC-MS/GC-MS). This method can be applied in several natural sources, such as animal and marine sources, plants, microorganisms of biotechnological and agricultural interest, foods, beverages and related products, and by-products. This method can also be applied for separating specific bio-functional lipids from complex medical and pharmaceutical samples (i.e. cells, tissues, blood, plasma, liposomes, etc.), either for evaluating their role in diseases (i.e. PAF/PAF-like molecules) or by elucidating their protective roles (i.e. PLs rich in ω3 PUFA) for supplements and nutraceuticals’ applications.
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Ethnopharmacological relevance Scientific evidence supports the antioxidant, anti-inflammatory and anti-lipidemic properties of Euterpe oleracea Mart. (açaí), which all converge to reduce cardiovascular risks. Macerating the pulp of açaí fruit produces a viscous aqueous extract (AE) rich in flavonoids that is commonly used in food production. In addition to nutritional aspects, cardiovascular benefits are attributed to AE by traditional medicine. Aim of the study Evaluation of AE impact on blood flow in vivo in rats and investigation of the mechanism underlying this response in vitro in rat endothelial cells (RECs). Materials and Methods For the measurement of acute blood flow, a perivascular ultrasound probe was used in Wistar rats. The in vitro assays employed REC to evaluate: concentration (1-1000 μg/mL) and time response (2-180 min) of AE in MTT cell viability assays; nitric oxide (NO) levels measurement and intracellular calcium handling using DAF-2DA and Fluo-4-AM, respectively; cellular biopterin content by HPLC; activation of Akt pathway using western blot analysis. For the chemical analyses of AE, stock solutions of the standards (+)catechin and quercetin were used for obtaining linear calibration curves. Identification and quantification of flavonoids in AE were based on comparisons with the retention times, increase in peak area determine by co-injection of AE with standards, UV-Vis scan and standard curves of known spectra. Results were expressed as mean ± standard deviation and data were analyzed using ANOVA followed by Tukey’s post-test (p<0.05). Results Although in vivo data have revealed the participation of NO in increasing of acute blood flow on abdominal aorta, in vitro analysis demonstrated that vasodilatation AE-induced is not related to its direct action on endothelial cells inducing eNOS activation. Besides, we demonstrated in isolated endothelial cells that highest concentrations of AE caused a reduction in NO levels, effect that could be partly justified by inhibition of Akt phosphorylation which, in turn, could decrease NOS activation. The involvement of cell transduction pathways involving variations in intracellular calcium and biopterins concentration were discarded. The participation of catechin and quercetin, identified in AE, was postulated to induce the responses of AE in REC. Conclusions Despite the responses in vitro, vasodilation prevailed in vivo, probably by activating intermediate pathways, validating a potential beneficial effect of AE in reducing cardiovascular risks.
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A doktori cím védésére született dolgozatban a CypD hatását vizsgálom az LPS indukálta szepszisre egérben és makrofág sejtekben. Emellett bemutatom még, hogy milyen egyéb anyagok (ferulaldehide, resveratrol) és PARP gátlók hathatnak még a CypD fehérjére, vagy az mPTP nyílására.
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Tea is a widely renowned functional beverage originating from processed tender leaves of the Camellia sinensis plant after brewing with hot water. This refreshing and revitalizing beverage has been recognized as an essential commodity since ancient times. Tea constituents have many health benefits and hence find usage in functional foods, beverages, and nutraceuticals. Nonetheless, the clinical usage of tea constituents is limited by the high molecular weight, poor stability, and low bioavailability of some active components. We review how fresh tea leaves are processed into different forms of tea such as green, oolong, white, and black teas. The major tea constituents, e.g., catechins, caffeine, and theanine, exhibit numerous health properties such as antioxidant, anti-inflammatory, anticancer, antidiabetic, cardioprotective, and antimicrobial. We discuss methods to enhance the efficacy and applicability of active tea constituents, such as micro- and nanoencapsulation techniques.
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Herbs have been used for centuries to treat various diseases, including cardiovascular disease. Herbs may be used by clients exclusively for disease management or in combination with conventional medications. This article increases provider awareness of certain herbs and their potential use by clients, as well as their impact on the cardiovascular system. It is important for the advanced practice nurse to collect information related to herb use during history retrieval. This information should prompt the nurse to discuss possible benefits and side effects that may occur taking herbs in isolation or in combination with cardiovascular prescription medications.
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Nowadays, destructive and immunosuppressive effects from long-term exposure to UV radiation have been fully investigated and documented in the literature. UV radiation is known as the main cause of skin ageing and carcinogenesis. Hence, skin protection against anti-oxidative and immunosuppressive processes is highly in demand. Now, plant polyphenols have been found as a versatile and natural tool for the prevention and treatment of various skin diseases. The presence of a large number of hydroxyl groups in the cyclic structure of polyphenols has induced valuable biological activities. Among them, their UV protective activity has attracted lots of attention due to promising efficacy and simple instruction to use.
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Background: Tea contains many polyphenols with biological properties such as antithrombosis and antioxidation. Recent observational studies on tea consumption concerning cerebral hemorrhage risk have reported inconsistent results. This meta-analysis aimed to summarize the accumulated evidence on the association between tea consumption and cerebral hemorrhage risk. Methods: Web of Science, PubMed, Embase, and Scopus databases were searched to identify relevant studies through December 2021. Relative risks (RRs) or odds ratios (ORs) from observational studies were synthesized. Results: Ten studies involving over 721,827 participants were included. Higher tea consumption was correlated with a 23% (RR = 0.77; 95% CI 0.66-0.89) lower risk of cerebral hemorrhage. Subgroup meta-analyses indicated higher tea consumption was beneficial in preventing cerebral hemorrhage risk for green tea, alcohol-adjusted, fruit/vegetables-adjusted, and physical activity-adjusted subgroups, respectively (P < 0.01). Dose-response analysis indicated each one-cup (120 ml/cup) increment in tea or green tea intake/day was correlated with an average of 2% (RR = 0.98, 95% CI 0.976-0.990), or 6% (RR = 0.94; 95% CI 0.92-0.97) lower cerebral hemorrhage risk. Conclusions: This study suggests that daily tea consumption is related to a lower risk of cerebral hemorrhage among adults. Green tea consumption appears to be more beneficial in preventing cerebral hemorrhage. Physical activity, fruit/vegetables, and alcohol may affect the relationship between tea consumption and hemorrhagic stroke. Future studies should investigate the interplay of tea with these factors.
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Em Suplementação Nutricional no Exercício e no Esporte – Fatos e Evidências, Dr. Tácito P. Souza Junior reuniu, com seus colegas, uma ampla variedade de tópicos de grande relevância para os interessados em aprender mais sobre Nutrição Esportiva, dis�tribuído em 12 capítulos: O Estado da Arte, Creatina, Cafeína, Beta-Alanina, Nitratos, Bicarbonato de Sódio, Suplementos Emergentes, Nutrigenômica, Probióticos, Antioxidantes e Alostase Redox no Treinamento de Força e Resistência, Proteínas e Aminoácidos, Carboidratos. Eu recomendo intensamente esta obra para aqueles apaixonados pelo tema ou até mesmo para o leitor casual. Stuart Phillips, Ph.D., FACSM, FCAHS Professor e Catedrático de Pesquisa Nível 1 - Canadá Departamento de Cinesiologia da Universidade McMaster (Canadá)
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Background Neonicotinoids are widely used insecticides, and tea is a popular nonalcoholic beverage in Taiwan. However, the levels of neonicotinoids in Taiwanese tea leaves remain unclear. Therefore, this study aims to understand the characteristics of neonicotinoid and metabolite residues in Taiwanese tea leaves. Methods In this study, 12 tea leaf samples were collected in Taiwan and extracted by solid-phase extraction before analysis by liquid chromatography-tandem mass spectrometry. In addition, the levels of neonicotinoids were compared with the maximum residue level standards from other countries. Results In Taiwanese tea leaves, 5 neonicotinoids and 7 metabolites were detected. Different tea species influenced the levels of neonicotinoids and their metabolites in the present study. Moreover, the levels of neonicotinoids and their metabolites in partially fermented leaves were higher than in completely fermented leaves. In Jin-Xuan tea, the levels of neonicotinoids and their metabolites in most winter-harvested teas were lower than in summer-harvested teas. Conclusion The residue levels of neonicotinoids and their metabolites were detectable in Taiwanese tea leaves. Moreover, different tea species, manufacturing processes, and harvest seasons might influence the levels of these pesticides. Therefore, the government should monitor the use of neonicotinoids. This article is protected by copyright. All rights reserved.
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Several polyphenol compounds commonly found in plant foods provide health benefits that promote their applications in food and pharmaceutical fields. The co-loading of proteins can improve the biological activity and synergy of combined polyphenols. Herein, multi-spectroscopic techniques and molecular docking were employed to investigate the interactions of native/heat treated β-lactoglobulin (β-LG/H-β-LG) with (−)-epicatechin gallate (ECG) and/or piceatannol (PIC). Furthermore, the synergistic antioxidant activity and cytotoxicity of ECG and PIC were demonstrated. The loading of β-LG/H-β-LG protected the antioxidant activity of ECG and PIC in the delivery systems and enhanced their cytotoxicity, stability, and bioaccessibility. Compared to the corresponding complexes, the nanoparticles of β-LG/H-β-LG had a greater impact on the functional properties and synergistic effects of ECG and PIC. The experimental results may provide a theoretical basis for the practical application of ECG and PIC co-loaded by H-β-LG, particularly H-β-LG nanoparticles in the food and pharmaceutical industries.
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Increasing interest has been focused on the antioxidant and anti-obesity effects of natural phenolic compounds (NPC). Based on generally used methodologies for the research of NPC anti-obesity effects including in vitro studies, in silico, cell models, animal model studies, and clinical research, the available scientific evidence has been summarized. The anti-obesity effect of NPC is a synergetic outcome of a series of mechanisms which can be classified in four main categories: (1) Inhibition of lipid absorption by binding bile salts and pancreatic lipase in digestion stage primarily in the duodenum, which results in fecal lipid excretion; (2) ‘prebiotic-like’ effect positively altering Gut microbes to enhance gut barrier function; (3) a series of anti-inflammation and modulation of fat metabolism in the cell; (4) Anti-atherosclerosis and suppression of plasma total triacylglycerol (TG) level through binding red blood cell (RBCs) and lipoproteins, and modulation of and HDL/LDL ratio link to atherosclerotic plaque in the cardiovascular system.
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Hyperspectral imagery was applied to estimating non-galloyl (EC, EGC) and galloyl (ECG, EGCG) types of catechins in new shoots of green tea. Partial least squares regression models were developed to consider the effects of commercial fertilizer (CF) and organic fertilizer (OF). The models could explain each type of catechin with a precision of more than 0.79, with a few exceptions. When the CF model was applied to the OF hyperspectral reflectance and the OF model was applied to the CF hyperspectral reflectance for mutual prediction, the prediction accuracy was better with the OF models than CF models. The prediction models using both CF and OF data (hyperspectral reflectances, and concentrations of catechins) had a precision of more than 0.76 except for the non-galloyl-type catechins as a group and EGC alone. These results provide useful data for maintaining and improving the quality of green tea.
Chapter
Plant-derived polyphenols catechins (flavan-3-ols) are the main chemical constituents of green tea and cocoa beans. Furthermore, they are found in lesser amounts in many fruits, vegetables, and their products. In numerous studies, catechins have been demonstrated to scavenge free oxygen radicals, to enhance cellular antioxidant defense, and to suppress inflammation processes. Oxidative stress, neuroinflammation, insufficient neurotrophic factor support, and mitochondrial dysfunction have been implicated in cognitive decline and progression of neurodegenerative diseases. This chapter reviews the chemical properties of catechins, their role in inflammation, neuroprotection, and modulation of brain mitochondria.
Chapter
Catechins are polyphenolic compounds belonging to the flavanol subfamily of flavonoids. The most abundant dietary sources of catechins are green tea, cocoa products, and wine. Catechins have been shown to possess beneficial effects in many pathological conditions including cardiovascular diseases which are currently one of the main causes of mortality in the world. Catechins are potent antioxidants, although under pathological conditions they act as prooxidants, modulating signal transduction, inflammation, and cell death regulation pathways. Furthermore, catechins may regulate metabolic processes via direct effects on mitochondria, which are responsible for energy supply in the cells. This chapter reviews the bioavailability of catechins, their cardioprotective activity, and their effects on the functions of cardiac mitochondria.
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The study aimed to isolate and characterize zinc ionophores from Terminalia bellirica fruit using a liposome assay and test its utility in H9c2 rat cardiomyoblasts cells subjected to hypoxia/reoxygenation. Ethyl acetate extract that exhibited zinc ionophore activity was resolved to yield three polyphenols that were characterized as epicatechin-3-gallate (ECG), epigallocatechin-3-gallate (EGCG) and epigallocatechin (EGC) by nuclear magnetic resonance and electrospray ionization-mass spectra. The polyphenols enhanced the uptake of zinc into the liposomes and increased FluoZin-3 fluorescence. These polyphenols in the presence of 10 μM ZnCl2 enhanced the zinc import into H9c2 cells, whose intracellular zinc levels were otherwise lowered upon hypoxia/reoxygenation. EGCG proved to be more potent than ECG, which indeed was more effective than EGC in improving cellular zinc levels and in attenuating the apoptosis of H9c2 cells after hypoxia/reoxygenation injury. The polyphenols required zinc for anti-apoptotic effect. The cardioprotective effect is indeed due to enhanced zinc uptake mediated by these polyphenols.
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Postprandial macro- and microvascular blood flow and metabolic dysfunction manifest with advancing age, so vascular transmuting interventions are desirable. In this randomised, single-blind, placebo-controlled, crossover trial, we investigated the impact of the acute administration of green tea extract (GTE; containing ~500 mg epigallocatechin-3-gallate) versus placebo (CON), alongside an oral nutritional supplement (ONS), on muscle macro- and microvascular, cerebral macrovascular (via ultrasound) and leg glucose/insulin metabolic responses (via arterialised/venous blood samples) in twelve healthy older adults (42% male, 74 ± 1 y). GTE increased m. vastus lateralis microvascular blood volume (MBV) at 180 and 240 min after ONS (baseline: 1.0 vs. 180 min: 1.11 ± 0.02 vs. 240 min: 1.08 ± 0.04, both p < 0.005), with MBV significantly higher than CON at 180 min (p < 0.05). Neither the ONS nor the GTE impacted m. tibialis anterior perfusion (p > 0.05). Leg blood flow and vascular conductance increased, and vascular resistance decreased similarly in both conditions (p < 0.05). Small non-significant increases in brachial artery flow-mediated dilation were observed in the GTE only and middle cerebral artery blood flow did not change in response to GTE or CON (p > 0.05). Glucose uptake increased with the GTE only (0 min: 0.03 ± 0.01 vs. 35 min: 0.11 ± 0.02 mmol/min/leg, p = 0.007); however, glucose area under the curve and insulin kinetics were similar between conditions (p > 0.05). Acute GTE supplementation enhances MBV beyond the effects of an oral mixed meal, but this improved perfusion does not translate to increased leg muscle glucose uptake in healthy older adults.
Article
Background Epigallocatechin gallate (EGCG) has attracted increasing attention due to its beneficial effect on cardiovascular health. The aim of this study was to investigate the underlying mechanism by which EGCG protects against myocardial ischaemia/reperfusion injury (I/RI). Methods Murine myocardial I/RI and H2O2-induced cardiomyocyte injury models were established to evaluate the therapeutic effects of EGCG. In the myocardial I/RI mouse model, the echocardiographic parameters of ejection fraction (EF) and fraction shortening (FS) levels, infarct size, histological evaluation and transmission electron microscopy (TEM) were used to evaluate cardiac tissue damage and autophagy. MTT assays, TUNEL staining, flow cytometry and immunofluorescence (IF) were used to monitor cell viability, apoptosis and autophagy in vitro. qRT-PCR and western blotting were used to determine the mRNA and protein levels of key molecules, respectively. The epigenetic regulation of DUSP5 was assessed via RNA immunoprecipitation (RIP), RNA pull-down and chromatin immunoprecipitation (ChIP) assays. Results EGCG significantly improved cardiac function, reduced infarct size, enhanced cell viability and inhibited autophagic activity in both myocardial I/RI mouse models and H2O2-induced cardiomyocyte injury models. Moreover, EGCG suppressed H2O2- or myocardial I/R-increased Gm4419 expression, and Gm4419 overexpression dramatically abolished EGCG-mediated protective effects against myocardial I/RI. Mechanistically, Gm4419 epigenetically suppressed DUSP5 by recruiting EZH2, thus activating ERK1/2 pathway-mediated autophagy. Furthermore, the in vivo experiments further verified that the Gm4419-mediated disruptive effects of EGCG on myocardial I/RI were potentiated by DUSP5 knockdown but attenuated by DUSP5 overexpression. Conclusions In conclusion, our findings demonstrated that EGCG protected against myocardial I/RI by modulating Gm4419/DUSP5/ERK1/2-mediated autophagy.
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Chapter
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Some epidemiological studies have associated tea drinking with several health benefits, while other such studies have been inconclusive. The liver enzyme, xanthine oxidase (XO) produces uric acid and reactive oxygen species (ROS) during the catabolism of purines. Excess of the former can lead to gout and of the latter to increased oxidative stress, mutagenesis and possibly cancer. Polyphenols are antioxidants, and it has been suggested that they can reduce oxidative stress by their antioxidant properties. We report here on the inhibition of XO by five tea catechins and two flavones. The Ki values (microM) and types of inhibition were catechin (C) (Ki = 303.95, uncompetitive), epicatechin (EC) (Ki = 20.48, mixed), epigallocatechin (EGC) (Ki = 10.66, mixed), epicatechin gallate (ECg) (Ki = 2.86, mixed) and epigallocatechin gallate (EGCg) (Ki = 0.76, competitive). The Ki of EGCg was similar to that of allopurinol (Ki = 0.30, mixed), the drug of choice for inhibition of XO in gout patients. Thus, tea catechins may act at.an earlier stage than has previously been suspected, by inhibiting ROS production, rather than only neutralizing the already formed ROS. This suggests a new mechanism whereby tea drinking may prevent oxidative stress related diseases, e.g. atherosclerosis and cancer.
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Structural analysis of the promoters of several endothelial genes induced at sites of inflammatory or immune responses reveals binding sites for the transcription factor nuclear factor kappa B (NF-kappa B). Endothelial cells express transcripts encoding the p50/p105 and p65 components of NF-kappa B and the rel-related proto-oncogene c-rel; steady state levels of these transcripts are transiently increased by tumor necrosis factor alpha (TNF-alpha). Western blotting revealed that stimulation of endothelial cells with TNF-alpha resulted in nuclear accumulation of the p50 and p65 components of NF-kappa B. Ultraviolet crosslinking and immunoprecipitation demonstrated binding of the p50 and p65 components of NF-kappa B to the E-selectin kappa B site. Endothelial cells express an inhibitor of NF-kappa B activation, I kappa B-alpha (MAD-3). Protein levels of this inhibitor fall rapidly after TNF-alpha stimulation. In parallel, p50 and p65 accumulate in the nucleus and RNA transcript levels for I kappa B-alpha are dramatically upregulated. Recombinant p65 stimulates expression of E-selectin promoter-reporter constructs. I kappa B-alpha inhibits p65 or TNF-alpha-stimulated E-selectin promoter-reporter gene expression in transfected endothelial cells. The NF-kappa B and I kappa B-alpha system may be an inducible regulatory mechanism in endothelial activation.
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An aqueous methanol extract from green tea showed potent acetyl-CoA carboxylase inhibitory activity. An active compound was isolated from the extract and identified as (-)-epigallocatechin gallate by instrumental analyses, The IC50 value of (-)-epigallocatechin gallate was 3.1 x 10(-4) M. Among tea catechins and related compounds, nearly equal activity was found in(-)-epigallocatechin gallate and (-)epicatechin gallate, whereas (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, gallic acid and methyl gallate each had no inhibitory activity. These results indicate that the 3-O-gallate group of the catechin structure was necessary for this activity. (-)-Epigallocatechin gallate inhibited triglyceride accumulation in 3T3-L1 cells at a concentration of 1.0 x 10(-7) M or higher.
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Monocytes contribute to the development of atherosclerotic lesions in mouse models. The chemoattractant proteins (chemokines), monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8), are found in human atheroma and mice lacking receptors for these chemokines are less susceptible to atherosclerosis and have fewer monocytes in vascular lesions. Although MCP-1 has a powerful effect on monocytes, IL-8 is thought to act predominantly on neutrophils and it is unclear how it could recruit monocytes. Here we investigate the ability of chemokines to control the interaction of monocytes under flow conditions with vascular endothelium that has been transduced to express specific leukocyte-adherence receptors. We find that MCP-1 and IL-8 can each rapidly cause rolling monocytes to adhere firmly onto monolayers expressing E-selectin, whereas related chemokines do not. These effects do not correlate with either the induction of a calcium transient or chemotaxis. We conclude that chemokines are important modulators of monocyte-endothelial interactions under flow conditions. Moreover, our finding that IL-8 is a powerful trigger for firm adhesion of monocytes to vascular endothelium reveals an unexpected role for this chemokine in monocyte recruitment.
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Background: New antiplatelet drugs are being developed and many clinical trials evaluating the benefits of antiplatelet drugs for the secondary prevention of ischemic events in patients with atherosclerotic vascular disease have been performed. Hypothesis: An updated systematic review and evidence-based guidelines for the appropriate selection of antiplatelet drugs may be beneficial to physicians and healthcare organizations attempting to create or update current clinical practice guidelines or clinical pathways aimed at caring for these patients. Methods: (1) A systematic review of the recent literature on the relative efficacy and safety of aspirin, ticlopidine, and clopidogrel was undertaken; (2) an evidence-based, expert panel approach using a modified Delphi technique to create explicit guidelines for prescribing antiplatelet therapy was instituted; and (3) the recommendations of an expert panel were summarized. Results: Consensus guidelines were developed for the utilization of aspirin, ticlopidine, or clopidogrel for the prevention of ischemic events in patients with manifestations of atherosclerotic vascular disease (prior myocardial infarction, prior ischemic stroke, or established peripheral arterial disease) who are at increased risk for recurrent ischemic events. Based on efficacy and safety, clopidogrel was recommended as the drug of choice for patients with established peripheral arterial disease; aspirin or clopidogrel should be considered in patients with prior myocardial infarction (with clopidogrel favored for patients who have had a recurrent event while on aspirin or in whom aspirin is contraindicated); aspirin or clopidogrel should be considered as first-line treatment in patients with prior ischemic (nonhemorrhagic) stroke--however, clopidogrel is the favored drug in patients in whom other antiplatelet drugs are either contraindicated or who have had recurrent events while on therapy. Conclusions: Myocardial infarction, ischemic stroke, and peripheral arterial disease are all clinical manifestations of the same underlying disease process (atherosclerosis), with thrombus formation on the disrupted atherosclerotic plaque (atherothrombosis) being a common precipitating factor of ischemic events in patients suffering from these disorders. An evidence-based approach was used to develop a practice guideline, based on available published evidence, for the appropriate utilization of antiplatelet agents (aspirin, ticlopidine, or clopidogrel). These guidelines may be of use to multidisciplinary teams wishing to create or update clinical guidelines or clinical pathways which address the care of patients with atherosclerotic vascular disease. New antiplatelet agents such as clopidogrel may be more effective and associated with lower risk of selected adverse effects (such as gastrointestinal distress, gastrointestinal hemorrhage, and neutropenia) than those previously used to prevent thrombus formation in the setting of atherosclerotic arterial disease. Combination antiplatelet therapy is being evaluated as an option for those patients who experience recurrent events on a single antiplatelet agent.
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A(−)-epicatechin (EC) and (−)-epigallocatechin (EGC) mixture and a mixture of their gallates (ECG and EGCG, respectively) markedly lowered lymphatic cholesterol absorption in rats with a cannulated thoracic duct. A mixture of ECG and EGCG was more effective in reducing cholesterol absorption than the EC and EGC mixture. These catechins also tended to decrease lymphatic absorption of triacylglycerols, although not so pronounced as in cholesterol absorption. An in vitro study on micellar solubility of cholesterol showed that these catechin mixtures precipitated cholesterol solubilized in mixed bile salt micelles in a dose-dependent manner. A mixture of ECG and EGCG more effectively precipitated micellar cholesterol than a mixture of EC and EGC. When purified EC, EGC, ECG and EGCG were used, EGCG was more effective in precipitating micellar cholesterol than ECG. The effect of EC and EGC was comparable and weaker than their gallate esters. The bile acid concentration in the micelles was not affected by these catechins. A positive correlation was observed between the amount of coprecipitated EGCG and cholesterol. These results clearly show that tea catechins, in particular their gallate esters, effectively reduce cholesterol absorption from the intestine by reducing solubility of cholesterol in mixed micelles. The observation accounts for the hypocholesterolemic effect of tea catechins.
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Endogenous oxidized cholesterols are potent atherogenic agents. Therefore, the antioxidative effects of green tea catechins (GTC) against cholesterol oxidation were examined in an in vitro lipoprotein oxidation system. The antioxidative potency of GTC against copper catalyzed LDL oxidation was in the decreasing order (−)-epigalocatechin gallate (EGCG)=(−)-epicatechin gallate (ECG)>(−)-epicatechin (EC)=(+)-catechin (C)>(−)-epigallocatechin (EGC). Reflecting these activities, both EGCG (74%) and ECG (70%) inhibited the formation of oxidized cholesterol, as well as the decrease of linoleic and arachidonic acids, in copper catalyzed LDL oxidation. The formation of oxidized cholesterol in 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH)-mediated oxidation of rat plasma was also inhibited when the rats were given diets containing 0.5% ECG or EGCG. In addition, EGCG and ECG highly inhibited oxygen consumption and formation of conjugated dienes in AAPH-mediated linoleic acid peroxidative reaction. These two species of catechin also markedly lowered the generation of hydroxyl radical and superoxide anion. Thus, GTC, especially ECG and EGCG, seem to inhibit cholesterol oxidation in LDL by combination of interference with PUFA oxidation, the reduction and scavenging of copper ion, hydroxyl radical generated from peroxidation of PUFA and superoxide anion.
Article
The green tea gallocatechins, (−)-epigallocatechin-3-O-gallate (EGCG) (IC50 = 0.69 μM), (−)-gallocatechin-3-O-gallate (GCG) (IC50 = 0.67 μM), (−)-epicatechin-3-O-gallate (ECG) (IC50 = 1.3 μM), and theasinensin A (IC50 = 0.13 μM), were found to be potent and selective inhibitors of rat squalene epoxidase (SE), a rate-limiting enzyme of cholesterol biogenesis. On the other hand, flavan-3-ols without galloyl group at C-3 did not show significant enzyme inhibition. It was demonstrated for the first time that the cholesterol lowering effect of green tea may be attributed to their potent SE inhibition activities. Inhibition kinetics revealed that EGCG inhibited SE in noncompetitive (KI = 0.74 μM), and non-time-dependent manner. The potent enzyme inhibition would be caused by specific binding to the enzyme, and by scavenging reactive oxygen species required for the monooxygenase reaction.
Article
METHODS. The relation between green tea consumption and serum lipid concentrations was examined using cross-sectional data on 1,306 males who received the retirement health examination at the Self-Defense Forces Fukuoka Hospital between October 1986 and December 1988. RESULTS. After adjustment for rank, smoking, alcohol use, physical activity, and body mass index, serum total cholesterol levels were found to be inversely related to the consumption of green tea while no association was noted with serum triglycerides and high-density lipoprotein cholesterol. Adjusted mean concentrations of total cholesterol were 8 mg/dl lower in men drinking nine cups or more per day than in those consuming zero to two cups per day. Serum cholesterol levels were inversely associated with traditional Japanese dietary habits (intake of rice and soy bean paste soup) and positively associated with Westernized habits. Additional adjustment for these dietary variables did not alter the inverse relation between green tea and total cholesterol.
Article
Highly toxic oxygen radicals and their metabolites have been implicated in the pathogenesis of ischaemia/ reperfusion injury. These reactive oxygen species include the superoxide anion, hydrogen peroxide, hydroxyl radical, and singlet oxygen. The central theme of this review is first to discuss the basic mechanisms of free radical generation from various potential sources, to point out and emphasise the growing importance of the role of singlet oxygen, and then to discuss in depth membrane-protein interactions that ultimately lead to myocardial damage and dysfunction. With this background, we highlight several novel therapeutic strategies aimed at interrupting the oxygen free radical mediated component of ischaemia/reperfusion injury. It is hoped that this thesis will then serve as a future impetus to challenge these hypotheses and further build on this truly unique system that has assumed such an important role in the pathophysiology of myocardial ischaemia/reperfusion and inflammation. “To those of us who are humbly exploring the mysteries of science, we must project our findings and model our systems. For if correct, we have made a small contribution and, if wrong, we have forced others to eventually think.” A V Hill, on the occasion of the 50th anniversary of E H Starling's Linacre lecture (University College, London, 1968).
The enzyme xanthine oxidase has been implicated in the tissue oxidative injury after ischemia-reperfusion. This enzyme, which is a source of oxygen free radicals, is formed from a dehydrogenase form during ischemia. The ratio dehydrogenase/oxidase of rat kidney homogenates decreases during the ischemia and the reperfusion. Two flavonoids, quercetin and silybin, characterized as free radical scavengers, exert a protective effect preventing the decrease in the dehydrogenase/oxidase ratio observed during ischemia-reperfusion. The mechanism of this effect and the role of flavonoids in the ischemia-reperfusion tissue damage is discussed.
Article
Following the oral feeding of a polyphenolic fraction isolated from green tea (GTP) in drinking water, an increase in the activities of antioxidant and phase II enzymes in skin, small bowel, liver, and lung of female SKH-1 hairless mice was observed. GTP feeding (0.2%, w/v) to mice for 30 days significantly increased the activities of glutathione peroxidase, catalase, and quinone reductase in small bowel, liver, and lungs, and glutathione S-transferase in small bowel and liver. GTP feeding to mice also resulted in considerable enhancement of glutathione reductase activity in liver. In general, the increase in antioxidant and phase II enzyme activities was more pronounced in lung and small bowel as compared to liver and skin. The significance of these results can be implicated in relation to the cancer chemopreventive effects of GTP against the induction of tumors in various target organs.
Article
The antiperoxidative effects of 35 phenolic compounds, most of them belonging to the flavonoid class, were investigated using CCl4-induced peroxidation of rat liver microsomes. This system was rather insensitive to gallic acid, methyl gallate and ellagic acid. Nevertheless it was inhibited by flavonoids and structure/activity relationships were established. The most potent compounds were gardenin D, luteolin, apigenin (flavones), datiscetin, morin, galangin (flavonols), eriodictyol (flavanone), amentoflavone (biflavone) and the reference compound, (+)-catechin. The natural polymethoxyflavone gardenin D has shown a potency comparable to that of (+)-catechin and higher than that of silybin. Thus, it may be considered as a new type of natural antioxidant with potential therapeutical applications.
Article
The objective of this study was to determine whether nitric oxide (NO) is responsible for the vascular smooth muscle relaxation elicited by endothelium-derived relaxing factor (EDRF). EDRF is an unstable humoral substance released from artery and vein that mediates the action of endothelium-dependent vasodilators. NO is an unstable endothelium-independent vasodilator that is released from vasodilator drugs such as nitroprusside and glyceryl trinitrate. We have repeatedly observed that the actions of NO on vascular smooth muscle closely resemble those of EDRF. In the present study the vascular effects of EDRF released from perfused bovine intrapulmonary artery and vein were compared with the effects of NO delivered by superfusion over endothelium-denuded arterial and venous strips arranged in a cascade. EDRF was indistinguishable from NO in that both were labile (t1/2 = 3-5 sec), inactivated by pyrogallol or superoxide anion, stabilized by superoxide dismutase, and inhibited by oxyhemoglobin or potassium. Both EDRF and NO produced comparable increases in cyclic GMP accumulation in artery and vein, and this cyclic GMP accumulation was inhibited by pyrogallol, oxyhemoglobin, potassium, and methylene blue. EDRF was identified chemically as NO, or a labile nitroso species, by two procedures. First, like NO, EDRF released from freshly isolated aortic endothelial cells reacted with hemoglobin to yield nitrosylhemoglobin. Second, EDRF and NO each similarly promoted the diazotization of sulfanilic acid and yielded the same reaction product after coupling with N-(1-naphthyl)-ethylenediamine. Thus, EDRF released from artery and vein possesses identical biological and chemical properties as NO.
Article
The in vitro effects of several flavonoids on nonenzymatic lipid peroxidation in the rat brain mitochondria was studied. The lipid peroxidation was indexed by measuring the MDA production using the 2-thiobarbituric acid TBA test. The flavonoids, apigenin, flavone, flavanone, hesperidin, naringin, and tangeretin promoted the ascorbic acid-induced lipid peroxidation, the extent of which depended upon the concentration of the flavonoid and ascorbic acid. The other flavonoids studied, viz., quercetin, quercetrin, rutin, taxifolin, myricetin, myricetrin, phloretin, phloridzin, diosmetin, diosmin, apiin, hesperetin, naringenin, (+)-catechin, morin, fisetin, chrysin, and 3-hydroxyflavone, all showed varying extents of inhibition of the nonenzymatic lipid peroxidation, induced by either ascorbic acid or ferrous sulfate. The flavonoid aglycones were more potent in their antiperoxidative action than their corresponding glycosides. Structure-activity analysis revealed that the flavonoid molecule with polyhydroxylated substitutions on rings A and B, a 2,3-double bond, a free 3-hydroxyl substitution and a 4-keto moiety, would confer upon the compound potent antiperoxidative properties.
Article
The mechanism of the anti-hypercholesteremic effect of (-)-epigallocatechin gallate (EGCG), a component of green tea, was explored in rats from the viewpoint of cholesterol metabolism.1) The in vitro incorporation of 14C-acetate into cholesterol was not affected by the presence of EGCG in liver slices from normal rats or by oral pretreatment of the animals with EGCG in liver slices from normal and Triton-induced hypercholesteremic rats.2) The kinetics of serum levels of 14C-cholesterol given orally and of 3H-cholesterol given intravenously revealed that EGCG, when orally administered, suppressed the absorption of 14C-cholesterol from the digestive tract and had an enhancing effect on elimination of serum 3H-cholesterol at higher doses.3) In situ uptake in the intestine of 14C-choresterol given in the lumen was suppressed by the presence of EGCG.In conclusion, these results indicated that the anti-hypercholesteremic effect EGCG in rats is mainly due to suppression of the absorption of exogenous cholesterol from the digestive tract, and partly due to the enhancement of the elimination of endogenous cholesterol.
Article
Serum cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-C) and apolipoprotein (apo) A-I, A-II and B concentrations were measured in 109 first-degree relatives of patients with angiographically defined coronary artery disease (CAD). Age- and sex-matched healthy factory employees were chosen as a control group. Male relatives of the CAD patients had significantly higher serum triglyceride and apoB levels, and significantly lower serum HDL-C and apoA-I levels than the controls. Female relatives of the CAD patients also showed similar differences in serum HDL-C, apoA-I and apoB levels. Discriminant analysis indicated that apolipoproteins were better discriminators than lipids in both patients with CAD and their relatives. In univariate analysis, the best discriminator was apoB between male relatives and the controls, and apoA-I between female relatives and the controls. The percentage of exact classification achieved using three variables (serum cholesterol, triglyceride and HDL-C) was 74% in male relatives and 70% in female relatives. By adding variables of apoA-I and apoB, the percentage of correctly classified subjects was increased to 82% and 80%, respectively. These results indicate that serum apolipoprotein abnormalities are prevalent in relatives of the CAD patients. These abnormalities may explain the familial aggregation of CAD.
Article
Structural analysis of the promoters of several endothelial genes induced at sites of inflammatory or immune responses reveals binding sites for the transcription factor nuclear factor kappa B (NF-kappa B). Endothelial cells express transcripts encoding the p50/p105 and p65 components of NF-kappa B and the rel-related proto-oncogene c-rel; steady state levels of these transcripts are transiently increased by tumor necrosis factor alpha (TNF-alpha). Western blotting revealed that stimulation of endothelial cells with TNF-alpha resulted in nuclear accumulation of the p50 and p65 components of NF-kappa B. Ultraviolet crosslinking and immunoprecipitation demonstrated binding of the p50 and p65 components of NF-kappa B to the E-selectin kappa B site. Endothelial cells express an inhibitor of NF-kappa B activation, I kappa B-alpha (MAD-3). Protein levels of this inhibitor fall rapidly after TNF-alpha stimulation. In parallel, p50 and p65 accumulate in the nucleus and RNA transcript levels for I kappa B-alpha are dramatically upregulated. Recombinant p65 stimulates expression of E-selectin promoter-reporter constructs. I kappa B-alpha inhibits p65 or TNF-alpha-stimulated E-selectin promoter-reporter gene expression in transfected endothelial cells. The NF-kappa B and I kappa B-alpha system may be an inducible regulatory mechanism in endothelial activation.
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Tea has been shown to inhibit chemically induced tumorigenesis in many animal models, but the effects of tea consumption on human carcinogenesis are not conclusive. In order to develop biomarkers for tea consumption, we developed methods for the analysis of tea polyphenols in human plasma and urine samples using HPLC with the coulochem electrode array detection system. (-)-Epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG), and (-)-epicatechin (EC) are the major polyphenols in green tea. Most of the tea polyphenols were in their conjugated forms in the plasma and urine. The samples were incubated with a mixture of beta-glucuronidase and sulfatase to generate the free form of tea polyphenols. After extraction into ethyl acetate and separation by reversed-phase chromatography, EGCG, EGC, and EC were identified on the basis of their retention times and electrochemical characteristics. Due to the high selectivity of the detection mode, interference was minimized. Good quantitative relationships were established for a large concentration range of tea polyphenols. The limits of detection for EGCG, EGC, ECG, and EC were from 0.5 to 1.5 ng/ml of plasma or urine sample. After ingestion of 1.2 g of decaffeinated green tea in warm water, the plasma samples collected at 1 h from 4 human volunteers contained 46-268 ng/ml of EGCG, 82-206 ng/ml of EGC, and 48-80 ng/ml of EC. ECG was not detected in plasma samples. The maximum urinary excretion of EGC and EC occurred at 3-6 h.(ABSTRACT TRUNCATED AT 250 WORDS)
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Tea polyphenols (flavan-3-ol derivatives) suppressed the oxidative modification of low density lipoprotein (LDL) which is assumed to be an important step in the pathogenesis of atherosclerosis lesions. Inhibitory experiments on the oxidative impairment of porcine serum LDL by flavan-3-ols were carried out by incubating them at 37 degrees C in the presence of 5 microM Cu2+. The oxidation of LDL was monitored either by an absorption increase at 234 nm due to the conjugated diene formation, or the formation of hydroperoxides and thiobarbituric acid reactive substances (TBARS). It was found that the oxidation was strongly inhibited by various flavan-3-ols, and a lag time over 100 min appeared, depending on the types of flavan-3-ols used. The activities based on the prolongation of the lag time were in the order of (-)-epigallocatechin (EGC) < (+)-catechin (C) < (-)-epicatechin (EC) < (-)-epicatechingallate (ECG) < (-)-epigallocatechingallate (EGCG). IC50 of flavan-3-ols on Cu2+ mediated hydroperoxides and TBARS formation of LDL were 0.90, 0.95 microM for ECG and 2.38, 2.74 microM for EGC, respectively. It was found that the Cu2+ mediated cholesterol ester degradation in LDL was almost completely inhibited by 5.0 microM C or EGCG. Cu2+ mediated apolipoprotein B-100 fragmentation was also inhibited (up to 60%) in the presence of C or EGCG.
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I kappa B-alpha inhibits transcription factor NF-kappa B by retaining it in the cytoplasm. Various stimuli, typically those associated with stress or pathogens, rapidly inactivate I kappa B-alpha. This liberates NF-kappa B to translocate to the nucleus and initiate transcription of genes important for the defense of the organism. Activation of NF-kappa B correlates with phosphorylation of I kappa B-alpha and requires the proteolysis of this inhibitor. When either serine-32 or serine-36 of I kappa B-alpha was mutated, the protein did not undergo signal-induced phosphorylation or degradation, and NF-kappa B could not be activated. These results suggest that phosphorylation at one or both of these residues is critical for activation of NF-kappa B.
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The cytoprotective effect of three flavonoids, catechin, quercetin and diosmetin, was investigated on iron-loaded hepatocyte cultures, considering two parameters: the prevention of iron-increased lipid peroxidation and the inhibition of intracellular enzyme release. These two criteria of cytoprotection allowed the calculation of mean inhibitory concentrations (IC50) which revealed that the effectiveness of these flavonoids could be classified as follows: catechin > quercetin > diosmetin. These IC50 values have been related to structural characteristics of the flavonoids tested. Moreover, the investigation of the capacity of these flavonoids to remove iron from iron-loaded hepatocytes revealed a good relationship between this iron-chelating ability and the cytoprotective effect. The cytoprotective activity of catechin, quercetin and diosmetin could thus be ascribed to their widely known antiradical property but also to their iron-chelating effectiveness. These findings increase further the prospects for the development and clinical application of these potent antioxidants.
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The recent explosion of interest in the bioactivity of the flavonoids of higher plants is due, at least in part, to the potential health benefits of these polyphenolic components of major dietary constituents. This review article discusses the biological properties of the flavonoids and focuses on the relationship between their antioxidant activity, as hydrogen donating free radical scavengers, and their chemical structures. This culminates in a proposed hierarchy of antioxidant activity in the aqueous phase. The cumulative findings concerning structure-antioxidant activity relationships in the lipophilic phase derive from studies on fatty acids, liposomes, and low-density lipoproteins; the factors underlying the influence of the different classes of polyphenols in enhancing their resistance to oxidation are discussed and support the contention that the partition coefficients of the flavonoids as well as their rates of reaction with the relevant radicals define the antioxidant activities in the lipophilic phase.
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The antioxidant properties of theaflavins and their gallate esters were studied by investigating their abilities to scavenge free radicals in the aqueous and lipophilic phases. The total relative antioxidant activities in the aqueous phase were assessed by measuring their direct ABTS.+ radical scavenging abilities, and by their efficacies in inhibiting the degradation of deoxyribose induced by iron. The propensities for enhancing the resistance of LDL to oxidation mediated by Cu2+ were also measured. The results show that the hierarchy of reactivity of these compounds as antioxidants is: theaflavin digallate > 3'-monogallate = 3-monogallate > theaflavin. Spectroscopic studies show that all the compounds chelate iron and copper; enhanced absorbance in the visible region is observed in the case of the iron-digallate complex, but not with copper.