Article

Bioflavonoids Effectively Inhibit Smooth Muscle Cell-Mediated Contraction of Collagen Matrix Induced by Angiotensin II

Authors:
  • Independent Researcher
  • Independent Researcher
  • Independent Researcher
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Plant-derived bioflavonoids have been recognized to support arterial wall structural integrity and interfere with a variety of proatherosclerotic stimuli. In this study we tested the effects of bioflavonoids on the contractile activity of cultured human aortic smooth muscle cells (SMC) embedded in a 3-dimensional type I collagen matrix. Collagen I solution mixed with human aortic SMC in 24-well plates were allowed to form gels. Tested compounds were added to the wells, and the gels were set afloat by gentle tapping. Digital photographs of the gels were taken after 24 hours of incubation at 37 degrees C. The area of contracted gel was measured and expressed as a percentage of the control gel area from 3 or more replicates. Expression of matrix metalloproteinase (MMP-2) in conditioned media was assessed by gel zymography. Different classes of bioflavanoids showed variable efficiency in inhibiting angiotensin II (ATII)-dependent collagen gel contraction by SMCs. An increase in the number of gallate groups per catechin molecule was associated with increased inhibition of angiotensin II-dependent collagen gel contraction by SMC. Antioxidants (N-acetyl cysteine and ascorbic acid) did not inhibit collagen gel contraction. Bioflavonoid inhibition of collagen gel contraction by SMC correlated with inhibition of matrix metalloproteinase-2 expression. Bioflavonoids participate in the regulation of SMC-mediated contraction and have a strong potential in counteracting pathophysiological effects of ATII. Bioflavonoid activity depends on structural characteristics and can be related to extracellular matrix integrity.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Approximately 65 million adults in the United States have hypertension (Fields et al., 2004). Worldwide, approximately 972 million adults were diagnosed with hypertension in 2000 and by 2025 the number of cases is predicted to increase by about 60% to a total of 1.56 billion (Ivanov et al., 2005). Diet substantial impact on hypertension. ...
... Ang II is regarded as the leading mediator of clinical systemic hypertension and it plays a role in the restructuring arterial walls in both atherosclerosis (Peng et al., 2010) and hypertension (Kurita et al., 2010). Various studies have shown that either an increased Ang II level by its relevant metabolism or an impaired response of Ang II production to dietary salt intake are associated with a salt-sensitive component of blood pressure regulation (Declue et al., 1978;Ivanov et al., 2005;Crowley et al., 2006;Papparella et al., 2008). Green tea extract and its catechins are reported to effectively inhibit smooth muscle cell collagen gel contraction (Ivanov et al., 2005), reactive oxygen species production (Papparella et al., 2008) and C-reaction protein secretion (Peng et al., 2010) induced by ANG II. ...
... Various studies have shown that either an increased Ang II level by its relevant metabolism or an impaired response of Ang II production to dietary salt intake are associated with a salt-sensitive component of blood pressure regulation (Declue et al., 1978;Ivanov et al., 2005;Crowley et al., 2006;Papparella et al., 2008). Green tea extract and its catechins are reported to effectively inhibit smooth muscle cell collagen gel contraction (Ivanov et al., 2005), reactive oxygen species production (Papparella et al., 2008) and C-reaction protein secretion (Peng et al., 2010) induced by ANG II. The present study suggests that suppressive effect of green tea on blood pressure might be mediated through its regulation of Ang II. ...
Article
Full-text available
Effects of green tea on blood pressure, level of plasma angiotensin II (Ang II) and ultrastructure of left ventricular tissue in spontaneous hypertensive rats (SHR) were investigated. Intragastric administration at dosages 0.2 and 1.0 g kg -1 d -1 green tea significantly decreased blood pressure and plasma Ang II level, accompanying the improvement of ultra structures of left ventricular mitochondrion and myofibrillae. It is considered that the effect of green tea on hypertension might be related to its inhibition of angiotensin converting enzyme.
... The clear correlation of sheet formation in AF-S clones with the expression of P4HA1, P4HA2, P4HA3, PLOD1 and LOX, demonstrates their involvement in Collagen fiber formation and matrix contraction. Matrix contraction is rarely investigated: one study used smooth muscle cells in combination with a Collagen type I coating to induce matrix contraction within 24 hours [52]. MMP inhibition prevented matrix contraction while ascorbic acid and other anti-oxidants were unable to prevent contraction [52]. ...
... Matrix contraction is rarely investigated: one study used smooth muscle cells in combination with a Collagen type I coating to induce matrix contraction within 24 hours [52]. MMP inhibition prevented matrix contraction while ascorbic acid and other anti-oxidants were unable to prevent contraction [52]. Hence, we speculate that sheet formation occurs rapidly, perhaps in conjunction with a certain critical Collagen fiber mass or cell density, under the influence of Collagen modifying enzymes. ...
Article
Full-text available
Introduction Loss of annulus fibrosus (AF) integrity predisposes to disc herniation and is associated with IVD degeneration. Successful implementation of biomedical intervention therapy requires in-depth knowledge of IVD cell biology. We recently generated unique clonal human nucleus pulposus (NP) cell lines. Recurring functional cellular phenotypes from independent donors provided pivotal evidence for cell heterogeneity in the mature human NP. In this study we aimed to generate and characterize immortal cell lines for the human AF from matched donors. Methods Non-degenerate healthy disc material was obtained as surplus surgical material. AF cells were immortalized by simian virus Large T antigen (SV40LTAg) and human telomerase (hTERT) expression. Early passage cells and immortalized cell clones were characterized based on marker gene expression under standardized culturing and in the presence of Transforming Growth factor β (TGFβ). Results The AF-specific expression signature included COL1A1, COL5A1, COL12A1, SFRP2 and was largely maintained in immortal AF cell lines. Remarkably, TGFβ induced rapid 3D sheet formation in a subgroup of AF clones. This phenotype was associated with inherent differences in Procollagen type I processing and maturation, and correlated with differential mRNA expression of Prolyl 4-hydroxylase alpha polypeptide 1 and 3 (P4HA1,3) and Lysyl oxidase (LOX) between clones and differential P4HA3 protein expression between AF cells in histological sections. Conclusion We report for the first time the generation of representative human AF cell lines. Gene expression profile analysis and functional comparison of AF clones revealed variation between immortalized cells and suggests phenotypic heterogeneity in the human AF. Future characterization of AF cellular (sub-)populations aims to combine identification of additional specific AF marker genes and their biological relevance. Ultimately this knowledge will contribute to clinical application of cell-based technology in IVD repair.
... 19,50 A collagen matrix containing smooth muscle cells overlaid the 3D gel containing neuronal progenitor cells. The ability of smooth muscle cells from various tissue sources (including GI) to restructure collagen gels is well established [51][52][53] as is the involvement of matrix metalloproteinase activity in this process. 51,52 As the smooth muscle cells reformed the composite 3D hydrogel, the neuronal progenitor cells were brought into close association. ...
... The ability of smooth muscle cells from various tissue sources (including GI) to restructure collagen gels is well established [51][52][53] as is the involvement of matrix metalloproteinase activity in this process. 51,52 As the smooth muscle cells reformed the composite 3D hydrogel, the neuronal progenitor cells were brought into close association. The progenitor cells then differentiated to functionally innervate the smooth muscle. ...
Article
Full-text available
Muscle replacement for patients suffering from extensive tissue loss or dysfunction is a major objective of regenerative medicine. To achieve functional status, bioengineered muscle replacement constructs require innervation. Here we describe a method to bioengineer functionally innervated gut smooth muscle constructs using neuronal progenitor cells and smooth muscle cells isolated from adult human donors. These constructs expressed markers for contractile smooth muscle, glial cells and mature neuronal populations. The constructs responded to physiologically relevant neurotransmitters, and neural network integration was demonstrated by response to electrical field stimulation. The ability of enteric neuroprogenitor cells to differentiate into neuronal populations provides enormous potential for functional innervation of a variety of bioengineered muscle constructs. Functionally innervated muscle constructs offer a regenerative medicine based therapeutic approach to neurodegenerative disorders.
... The vasodilatory effect on microcirculation enhances local oxygen delivery to peripheral tissues, and thus decreases morbidity and mortality even in established hepatotoxicity. 1 A unique nutrient formulation (NM) containing among other nutrients, NAC, ascorbic acid and green tea extract has previously been demonstrated to exhibit a broad spectrum of pharmacological, therapeutic, cardio vascular and chemoprotective properties. [3][4][5][6] This study was undertaken to determine whether NM is useful in prevention of APAPinduced hepatic and renal damage. ...
... Our previous studies with a wide variety of cell types have shown that NM inhibits MMP-2 and MMP-9 secretions and cellular invasion through the ECM. [3][4][5][6] ECM integrity is dependent upon adequate collagen formation and its stability. In this aspect ascorbic acid and the amino acids lysine and proline are necessary for the formation and optimum structure of collagen fibers. ...
Article
Full-text available
Acetaminophen (APAP) overdose is often fatal, leading to fulminant hepatic and renal tubular necrosis in humans and animals. We studied the effect of a nutrient mixture (NM) containing, among other nutrients, lysine, proline, ascorbic acid, N-acetyl cysteine, and green tea extract, which has previously been demonstrated to exhibit a broad spectrum of therapeutic properties on APAP-induced hepatic and renal damage in ICR (Imprinting Control Region) mice. Seven-week-old male ICR mice were divided into four groups (A-D) of five animals each. Groups A and C mice were fed a regular diet for 2 weeks, while groups B and D mice were supplemented with 0.5% NM (w/w) during that period. Groups A and B received saline i.p., while groups C and D received APAP (600 mg/kg) i.p. All animals were killed 24 h after APAP administration, serum was collected to assess the liver and kidney functions, and the livers and kidneys were excised for histology. Mean serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, BUN (Blood Urea Nitrogen), creatinine, and BUN/creatinine ratios were comparable in groups A and B, increased markedly in group C and significantly lower in group D compared with group C. APAP caused significant centrilobular necrosis and glomerular damage in unsupplemented animals, while NM prevented these alterations. The results indicate that NM has potential to protect against APAP-induced liver and kidney damage.
... Indeed, horse chestnut extract contracts (through serotonin receptors, at least partly) both veins and arteries, but it is more potent in inducing venocontraction [40] . A pharmacological vasoactive agent, diosmin, is capable of inhibiting inflammatory pathways since it simultaneously influences proangiogenic/anti-angiogenic balance by an increase of anti-angiogenic factors and reducing the level of proangiogenic factors in blood plasma (TNF-alpha, VEGF-A and VEGF-C, angiostatin, IL-6, FGF2 and PLG) [41] . Bioflavonoids found in citrus bioflavonoid extract, grape seed extract, pine bark extract and green tea extract participate in the regulation of human aortic smooth muscle cell-mediated contraction and have a strong potential for counteracting pathophysiological effects of angiotensin II-the leading mediator of clinical systemic hypertension [42] . ...
Article
Full-text available
This perspective focuses primarily on the fundamental part of phlebology, where most attention is paid to the genetic aspects of the pathogenesis of varicose vein disease and where the main breakthrough advances in this area of research are discussed. We propose a direction for further actions to replenish molecular genetic knowledge about the main drivers of pathological processes in varicose vein disease and to complete the creation of an entire picture of pathogenesis, which, in turn, may serve as a key for the development of treatment options in the future in order to translate research evidence into clinical practice.
... 1-3 Pathological vascular remodeling is an adoptive response during multiple stresses, and associated with various vascular diseases, including pulmonary hypertension, atherosclerosis, post-angioplasty restenosis, and aneurysm. 1,2,31 Paeonol was reported to inhibit proliferation of SMC through Ras-Raf-ERK1/2 signaling pathway. 6 Previous studies showed that paeonol inhibits cell proliferation and suppresses inflammatory response. ...
Article
Full-text available
Objective Smooth muscle cell (SMC) phenotypic switching is associated with development of a variety of occlusive vascular diseases. Paeonol has been reported to be involved in suppressing SMC proliferation. However, it is still unknown whether paeonol can regulate SMC phenotypic switching, and which eventually result in suppressing vasculogenesis. Methods Murine left common carotid artery was injured by completely ligation, and paeonol was administrated by intraperitoneal injection. Hematoxylin and eosin (H&E) staining was performed to visualize vascular neointima formation. Rat aortic SMCs were used to determine whether paeonol suppresses cell proliferation and migration. And murine hind limb ischemia model was performed to confirm the function role of paeonol in suppressing vasculogenesis. Results Complete ligation of murine common carotid artery successfully induced neointima formation. Paeonol treatment dramatically reduced the size of injury-induced neointima. Using rat aortic primary SMC, we identified that paeonol strongly suppressed cell proliferation, migration, and decreased extracellular matrix deposition. And paeonol treatment dramatically suppressed vasculogenesis after hind limb ischemia injury. Conclusion Paeonol could regulate SMC phenotypic switching through inhibiting proliferation and migration of SMC, which results in inhibiting ischemia-induced vasculogenesis.
... Angiotensin II-induced contractile activity of cultured human ASMC embedded in a collagen matrix was inhibited by catechins, dependent on the number of gallate groups, and this correlated with inhibition of matrix metalloproteinase-2 expression [153]. ...
Article
Full-text available
The hypothesis that dietary (poly)phenols promote well-being by improving chronic disease-risk biomarkers, such as endothelial dysfunction, chronic inflammation and plasma uric acid, is the subject of intense current research, involving human interventions studies, animal models and in vitro mechanistic work. The original claim that benefits were due to the direct antioxidant properties of (poly)phenols has been mostly superseded by detailed mechanistic studies on specific molecular targets. Nevertheless, many proposed mechanisms in vivo and in vitro are due to modulation of oxidative processes, often involving binding to specific proteins and effects on cell signalling. Here we review the molecular mechanisms for 3 actions of (poly) phenols on oxidative processes where there is evidence in vivo from human intervention or animal studies. (1) Effects of (poly) phenols on pathways of chronic inflammation leading to prevention of some of the damaging effects associated with the metabolic syndrome (2) Interaction of (poly)phenols with endothelial cells and smooth muscle cells, leading to effects on blood pressure and endothelial dysfunction, and consequent reduction in cardiovascular disease risk. (3) The inhibition of xanthine oxidoreductase leading to modulation of intracellular superoxide and plasma uric acid, a risk factor for developing type 2 diabetes. This article is protected by copyright. All rights reserved.
Article
Fruits and vegetables form the major source of polyphenols in human diet. Extensiveuse of these phytochemicals in alleviating various human health diseases and disordersare in practice throughout the world since time immemorial in traditional medicinalsystems like Ayurveda and Unani. It is important to establish the scientific rationale todefend their use in nutraceutical and functional foods as potential nutritionally activeingredients. However, it must be emphasized that a distinction needs to be drawnbetween the polyphenols from fruits and vegetables and their inherent efficacy toalleviate different degenerative diseases. The present chapter elucidates the diverse formsof polyphenols available from fruits and vegetables and their chemical and biologicalsignificance of polyphenols in imparting health benefits, which may emerge as: substratesfor biochemical reactions; cofactors of enzymatic reactions; inhibitors of enzymaticreactions; absorbents/sequestrates that bind to and eliminate undesirable constituents inthe intestine; scavengers of reactive or toxic chemicals; compounds that enhance theabsorption and or stability of essential nutrients; selective growth factors for beneficialgastrointestinal bacteria; and selective inhibitors of deleterious intestinal bacteria. The manifold antioxidant activities and beneficial effects of polyphenols on diabetic andcardiovascular system along with the other modes of actions are discussed in this chapter.
Article
Full-text available
We examined the effect of a nutrient mixture (NM) that contains lysine, proline, ascorbic acid, and green tea extract in mice treated with carbon tetrachloride (CCl4), a model of liver injury in which free radical, oxidative stress, and cytokine production are closely linked. Seven-week-old male Imprinting Control Region (ICR) mice were divided into four groups (A-D) of five animals each. Groups A and C mice were fed a regular diet for 2 weeks, whereas groups B and D mice were supplemented with 0.5% NM (w/w) during that period. Groups A and B received corn oil i.p., whereas groups C and D received CCl4 (25 microL/kg, in corn oil, i.p.). All animals were killed 24 h after CCl4 administration, serum was collected to assess liver and kidney functions, and livers and kidneys were excised for histology. Mean serum aspartate aminotransferase and alanine aminotransferase were comparable in groups A and B, increased markedly in group C, and significantly lowered in group D compared with group C. CCl4 had no significant effect on renal markers (blood urea nitrogen [BUN], creatinine, and BUN/creatinine ratio). CCl4 administration caused an intense degree of liver necrosis that was less severe in the NM fed group D. These results indicate that NM could be a useful supplement in preventing acute chemical-induced liver toxicity.
Article
The guanine nucleotide exchange factor (GEF), SmgGDS, promotes nucleotide exchange by several GTPases in both the Ras and Rho families, especially by RhoA. Because RhoA plays an important role in regulating the contraction of vascular smooth muscle cells (VSMC), we examined the expression and function of SmgGDS in VSMC. SmgGDS is expressed in primary rat aortic smooth muscle (ASM) cells, primary bovine coronary artery smooth muscle (BCASM) cells, and the immortalized A7r5 line of rat ASM cells. Down regulation of SmgGDS expression by siRNA transfection resulted in a decrease of RhoA-GTP levels, enhanced cell spreading, and loss of the characteristic elongated morphology of VSMC. A similar morphology was also observed following treatment with the Rho-kinase inhibitor, Y27632. In contrast, cells with reduced RhoA expression exhibit an elongated shape. Subsequent immunofluorescent staining revealed a disruption of the myosin filament organization in the cells with reduced SmgGDS expression. Further studies analyzed the effect of SmgGDS siRNA transfection on the contraction of A7r5 cells and BCASM cells, which is also a Rho-regulated pathway. Transfection of SmgGDS siRNA or RhoA siRNA resulted in an impaired ability of the A7r5 and BCASM cells to undergo contraction in a collagen gel matrix. However, phosphorylation of the myosin-binding subunit of myosin phosphatase (MYPT1) or the light chain of myosin II (MLC) was not altered by downregulating expression of either SmgGDS or RhoA GTPase. Taken together these results identify SmgGDS as a novel regulator of myosin organization and contraction in VSMC.
Article
Full-text available
Angiotensin II (AII) is a critical factor in cardiac remodeling which involves hypertrophy, fibroblast proliferation, and extracellular matrix production. However, little is known about the mechanism by which AII accelerates these responses. Osteopontin is an acidic phosphoprotein with RGD (arginine-glycine-aspartate) sequences that are involved in the vascular smooth muscle cell remodeling process. We identified the presence of osteopontin mRNA and protein in cultured rat cardiac fibroblasts and its prominent regulation by AII (10(-11) M). Osteopontin message levels were increased fourfold (P < 0.01) and protein fivefold (P < 0.05) at 24 h after addition of AII (10(-7) M). This response was inhibited by the AT1 receptor blocker, losartan. Osteopontin mRNA levels were increased in hypertrophied ventricles from animals with renovascular hypertension (1.6-fold, P < 0.05) and aortic banding (2.9-fold, P < 0.05). To examine the function of osteopontin, we determined its effects on (a) the ability of cardiac fibroblasts to contract three-dimensional collagen gels and (b) cardiac fibroblast growth. A monoclonal antibody against osteopontin partially blocked AII-induced three-dimensional collagen gel contraction by cardiac fibroblasts (64+/-4 vs. 86+/-5% in the presence of antibody, P < 0.05), while osteopontin itself promoted contraction of the gels by fibroblasts (71+/-5%, P < 0.05 compared with control). Either a monoclonal antibody against beta3 integrin which is a ligand for osteopontin or the RGD peptide blocked both AII and osteopontin-induced collagen gel contraction. Thus, the osteopontin RGD sequence binds to beta3 integrins on the fibroblast to promote fibroblast binding to collagen. All induced a threefold increase in DNA synthesis of cardiac fibroblasts, which was completely blocked by antibodies against osteopontin and beta3 integrin, or by RGD peptide, but not by controls. Thus, All-induced growth of cardiac fibroblasts also requires osteopontin engagement of the beta3 integrin. Taken together, these results provide the first evidence that osteopontin is a potentially important mediator of AII regulation of cardiac fibroblast behavior in the cardiac remodeling process.
Article
Full-text available
Pulmonary hypertension is characterized by increased vascular resistance due to smooth muscle cell hyper-activity and excess deposition of extracellular matrix (ECM) in the vessel wall. We investigated the possibility that changes in cell-ECM interactions may play an active role in this process by modifying the contractile response of pulmonary vascular smooth muscle (PVSM) cells. Contractility was measured within individual cultured PVSM cells, when resting or stimulated with vasoactive agents, by quantitating changes in stiffness of the cytoskeleton (CSK) using magnetic twisting cytometry (N. Wang, J. P. Butler, and D. E. Ingber. Science 260: 1124-1127, 1993). Control studies confirmed that changes in CSK stiffness closely paralleled alterations in cell contraction and relaxation as measured in response to endothelin-1 (ET-1) and dibutyryl guanosine 3',5'-cyclic monophosphate (cGMP), respectively, in a collagen gel contraction assay. CSK stiffness and contractile tone in cultured PVSM cells increased in direct proportion as the density of fibronectin (FN) coating was raised from 10 to 500 ng/well in 96-well plates. Dibutyryl cGMP had no effect in cells on low FN, although it completely inhibited the FN-dependent increase in CSK stiffness on higher ECM densities. In contrast, ET-1 induced the greatest increase in CSK stiffness on the intermediate FN density (100 ng/well). The reduced sensitivity to ET-1 on high FN was not due to dysfunction of the contractile apparatus nor to changes in protein tyrosine phosphorylation. Taken together, these results show that ECM can modulate PVSM cell contractility and suggest that the changes in ECM observed in hypertensive vessels could play an important role in the etiology of this disease.
Article
Full-text available
The flavonoids constitute a large group of polyphenolic phytochemicals with antioxidant properties in vitro. The interactions of four structurally related flavonoids (quercetin, kaempferol, rutin and luteolin) with Cu2+ ions were investigated in terms of the extent to which they undergo complex formation through chelation or modification through oxidation, as well as in their structural dependence. The ortho 3',4'-dihydroxy substitution in the B ring is shown to be important for Cu2+-chelate formation, thereby influencing the antioxidant activity. The presence of a 3-hydroxy group in the flavonoid structure enhances the oxidation of quercetin and kaempferol, whereas luteolin and rutin, each lacking the 3-hydroxy group, do not oxidize as readily in the presence of Cu2+ ions. The results also demonstrate that the reactivities of the flavonoids in protecting low-density lipoprotein (LDL) against Cu2+ ion-induced oxidation are dependent on their structural properties in terms of the response of the particular flavonoid to Cu2+ ions, whether chelation or oxidation, their partitioning abilities between the aqueous compartment and the lipophilic environment within the LDL particle, and their hydrogen-donating antioxidant properties.
Article
Full-text available
The aim of the present study was to investigate whether angiotensin II (Ang II), angiotensin III (Ang III) or Ang II (2-8), angiotensin IV (Ang IV) or Ang II (3-8) and Ang II (1-7), Ang II (4-8), Ang II (5-8) and Ang II (1-4) can stimulate collagen gel contraction in cardiac fibroblasts in serum-free conditions. Cardiac fibroblasts (from male adult Wistar rats) from passage 2 were cultured to confluency and added to a hydrated collagen gel in a Dulbecco's Modified Eagle's Medium, with or without foetal bovine serum, for one, two or three days. The area of the collagen gels embedded with cardiac fibroblasts was determined by a densitometric analysis. Collagen gel contraction was characterised by a decrease in the gel area. Ang II dose-dependently stimulated the contraction of collagen mediated by cardiac fibroblasts after one, two or three days of incubation in a serum-free medium. Telmisartan completely blocked the Ang II-induced collagen contraction by cardiac fibroblasts. PD 123319 and des-Asp(1)-Ile(8)-Ang II had no effect on the Ang II-induced collagen contraction by cardiac fibroblasts. Ang III also stimulated the contraction of collagen mediated by cardiac fibroblasts after one, two or three days of incubation in a serum-free medium. des-Asp(1)-Ile(8)-Ang II and telmisartan completely blocked the Ang III-induced collagen gel contraction by cardiac fibroblasts. des-Asp(1)-Ile(8)-Ang II, however, had no effect on the Ang II-induced collagen gel contraction by cardiac fibroblasts. Ang IV and Ang II (4-8), (5-8), (1-7) and (1-4), however, had no effect on collagen gel contraction by cardiac fibroblasts. Addition of telmisartan, PD 123319 or des-Asp(1)-Ile(8)-Ang II alone did not affect collagen gel contraction by cardiac fibroblasts. Our data demonstrate that the effects of Ang II on the collagen gel contraction by adult rat cardiac fibroblasts in serum-free conditions are Ang II type 1(AT(1))-receptor- mediated, because they are abolished by the specific AT(1)-receptor antagonist, telmisartan, and not by the AT(2)-receptor antagonist PD 123319 or by the Ang III antagonist des-Asp(1)-Ile(8)-angiotensin. The Ang III- stimulated contraction of collagen by cardiac fibroblasts is completely blocked by the Ang III receptor antagonist, des-Asp(1)-Ile(8)-angiotensin II, and by telmisartan.
Article
Full-text available
Endothelium-dependent relaxations are impaired in carotid artery of apolipoprotein E-deficient (apoE-/-) mice. This impairment seems to be due to increased formation of superoxide anions and inactivation of endothelial nitric oxide (NO). In the present study, we tested hypothesis that chronic treatment with vitamin C may prevent endothelial dysfunction by increasing release of NO from endothelial cells. C57BL/6 and apoE-/- mice were treated for 26 weeks with Western-type fat diet with and without 1% vitamin C. Vasomotor function of isolated carotid arteries was studied by video dimension analyzer. Expression of endothelial NO synthase (eNOS) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) protein were evaluated by Western blotting. Levels of cGMP and cAMP were measured by radioimmunoassay. In apoE-/- mice, vitamin C significantly augmented relaxations to acetylcholine (10-9-10-5 mol/l), but did not affect relaxations to NO donor diethylammonium-(Z)-1-(N,N-diethylamino) diazen-1-1,2-diolate (DEA-NONOate; 10-9-10-5 mol/l). In contrast, vitamin C reduced relaxations to acetylcholine and DEA-NONOate in C57BL/6 mice. Interestingly, vitamin C significantly increased basal cGMP levels in C57BL/6 mice but did not affect cGMP formation in apoE-/-. Vitamin C treatment did not affect expression of eNOS protein, whereas elevated expression of PECAM-1 protein in apoE-/- mice was returned to normal level. Our findings demonstrate that chronic treatment with vitamin C prevents endothelial dysfunction of carotid artery induced by hypercholesterolemia. This effect seems to be mediated by preservation of NO bioavailability in endothelial cells.
Article
Full-text available
"The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure" provides a new guideline for hypertension prevention and management. The following are the key messages(1) In persons older than 50 years, systolic blood pressure (BP) of more than 140 mm Hg is a much more important cardiovascular disease (CVD) risk factor than diastolic BP; (2) The risk of CVD, beginning at 115/75 mm Hg, doubles with each increment of 20/10 mm Hg; individuals who are normotensive at 55 years of age have a 90% lifetime risk for developing hypertension; (3) Individuals with a systolic BP of 120 to 139 mm Hg or a diastolic BP of 80 to 89 mm Hg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD; (4) Thiazide-type diuretics should be used in drug treatment for most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes (angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, calcium channel blockers); (5) Most patients with hypertension will require 2 or more antihypertensive medications to achieve goal BP (<140/90 mm Hg, or <130/80 mm Hg for patients with diabetes or chronic kidney disease); (6) If BP is more than 20/10 mm Hg above goal BP, consideration should be given to initiating therapy with 2 agents, 1 of which usually should be a thiazide-type diuretic; and (7) The most effective therapy prescribed by the most careful clinician will control hypertension only if patients are motivated. Motivation improves when patients have positive experiences with and trust in the clinician. Empathy builds trust and is a potent motivator. Finally, in presenting these guidelines, the committee recognizes that the responsible physician's judgment remains paramount.
Article
Full-text available
We examined the ability of polyphenols from tomatoes and soy (genistein, quercetin, kaempferol, biochanin A, daidzein and rutin) to modulate insulin-like growth factor-I (IGF-I)-induced in vitro proliferation and apoptotic resistance in the AT6.3 rat prostate cancer cell line. IGF-I at 50 micro g/L in serum-free medium produced maximum proliferation and minimized apoptosis. Polyphenols exhibited different abilities to modulate IGF-I-induced proliferation, cell cycle progression (flow cytometry) and apoptosis (Annexin V/propidium iodide and terminal deoxynucleotidyltransferase-mediated deoxyuridine 5'-triphosphate nick end labeling). Genistein, quercetin, kaempferol and biochanin A exhibited dose-dependent inhibition of growth with a 50% inhibitory concentration (IC(50)) between 25 and 40 micro mol/L, whereas rutin and daidzein were less potent with an IC(50) of >60 micro mol/L. Genistein and kaempferol potently induced G(2)/M cell cycle arrest. Genistein, quercetin, kaempferol and biochanin A, but not daidzein and rutin, counteracted the antiapoptotic effects of IGF-I. Human prostate epithelial cells grown in growth factor-supplemented medium were also sensitive to growth inhibition by polyphenols. Genistein, biochanin A, quercetin and kaempferol reduced the insulin receptor substrate-1 (IRS-1) content of AT6.3 cells and prevented the down-regulation of IGF-I receptor beta in response to IGF-I binding. IGF-I-stimulated proliferation was dependent on activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) and phosphatidylinositide 3-kinase pathways. Western blotting demonstrated that ERK1/2 was constitutively phosphorylated in AT6.3 cells with no change in response to IGF-I, whereas IRS-1 and AKT were rapidly and sensitively phosphorylated after IGF-I stimulation. Several polyphenols suppressed phosphorylation of AKT and ERK1/2, and more potently inhibited IRS-1 tyrosyl phosphorylation after IGF-I exposure. In summary, polyphenols from soy and tomato products may counteract the ability of IGF-I to stimulate proliferation and prevent apoptosis via inhibition of multiple intracellular signaling pathways involving tyrosine kinase activity.
Article
Full-text available
Oxidative stress was reported to be involved not only in cardiovascular diseases, but also in hypertension. Epidemiologic studies indicated that tea consumption slightly reduces blood pressure. We conducted two studies to determine whether black and green tea can lower blood pressure (BP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP (n=15) were allowed to recover for 2 wk after a transmitter for measuring BP was implanted in the peritoneal cavity. The rats were divided into three groups: the control group consumed tap water (30 mL/d); the black tea polyphenol group (BTP) consumed water containing 3.5 g/L thearubigins, 0.6 g/L theaflavins, 0.5 g/L flavonols and 0.4 g/L catechins; and the green tea polyphenol group (GTP) consumed water containing 3.5 g/L catechins, 0.5 g/L flavonols and 1 g/L polymetric flavonoids. The telemetry system was used to measure BP, which were recorded continuously every 5 min for 24 h. During the daytime, systolic and diastolic BP were significantly lower in the BTP and GTP groups than in the controls. Protein expressions of catalase and phosphorylated myosin light chain (MLC-p) were measured in the aorta by Western blotting. GTP significantly increased catalase expression, and BTP and GTP significantly decreased MLC-p expression in the aorta. These data demonstrate that both black and green tea polyphenols attenuate blood pressure increases through their antioxidant properties in SHRSP. Furthermore, because the amounts of polyphenols used in this experiment correspond to those in approximately 1 L of tea, the regular consumption of black and green tea may also provide some protection against hypertension in humans.
Article
Full-text available
Regular consumption of moderate amounts of red wine is associated with a reduced risk of coronary disease. Matrix metalloproteinases (MMPs) that participate in extracellular matrix degradation have been involved in atherosclerotic plaque growth and instability. The present study examined whether red wine polyphenolic compounds (RWPCs) inhibit activation of MMP-2, a major gelatinase, in vascular smooth muscle cells (VSMCs). Expression of pro-MMP-2 was assessed by Western and Northern blot analyses; MMP-2 activity was assessed by zymography and cell invasion by a modified Boyden's chamber assay. High levels of pro-MMP-2 and low levels of MMP-2 activity were found in conditioned medium from unstimulated VSMCs. Thrombin induced cell-associated pro-MMP-2 protein expression and MMP-2 activity in conditioned medium of VSMCs. The stimulatory effect of thrombin on MMP-2 activation was prevented by RWPCs in a concentration-dependent and reversible manner. Thrombin markedly increased cell-associated membrane type 1 (MT1)-MMP activity, the physiological activator of pro-MMP-2, and this response was not affected by RWPCs. However, addition of RWPCs directly to MT1-MMP abolished its metalloproteinase activity in a reversible manner. Finally, matrix invasion of VSMCs was stimulated by thrombin, and this response was prevented by RWPCs as efficiently as a broad-spectrum MMP inhibitor. The present findings demonstrate that RWPCs effectively inhibit thrombin-induced matrix invasion of VSMCs, most likely by preventing the expression and activation of MMP-2 via direct inhibition of MT1-MMP activity. The inhibitory effect of RWPCs on the activation of pro-MMP-2 and matrix degradation might contribute to their beneficial effects on the cardiovascular system.
Article
Full-text available
Data on the impact of the many dietary and lifestyle factors on the prevalence of hypertension in Western societies are lacking. This study quantified the contributions of body weight, physical inactivity and dietary factors to the prevalence of hypertension in Finland, Italy, the Netherlands, United Kingdom (UK) and USA. Distributions of blood pressure (BP) and risk factors in Western populations were obtained from nationwide surveys. The effect of risk factors on BP was assessed by meta-regression analysis of randomized trials, published between 1966 and March 2001. Population attributable risk percentages (PAR%) for hypertension (i.e. systolic BP > or =140 mmHg) were computed for all risk factors in the five countries. Being overweight made the largest contribution to hypertension, with PAR% between 11% (Italy) and 25% (USA). PAR% were 5-13% for physical inactivity, 9-17% for high sodium intake, 4-17% for low potassium intake and 4-8% for low magnesium intake. The impact of alcohol was small (2-3%) in all populations. PAR% varied among populations for inadequate intake of calcium (2-8%), magnesium (4-8%), coffee (0-9%) and fish fatty acids (3-16%). Diet and lifestyle have a substantial impact on hypertension in Western societies, with being overweight, physical inactivity, high sodium intake and low potassium intake being the main contributors. The relative significance of different risk factors varies among populations, which is important for preventative strategies.
Article
Background: Data on the impact of the many dietary and lifestyle factors on the prevalence of hypertension in Western societies are lacking. This study quantified the contributions of body weight, physical inactivity and dietary factors to the prevalence of hypertension in Finland, Italy, the Netherlands, United Kingdom (UK) and USA. Methods: Distributions of blood pressure (BP) and risk factors in Western populations were obtained from nationwide surveys. The effect of risk factors on BP was assessed by meta-regression analysis of randomized trials, published between 1966 and March 2001. Population attributable risk percentages (PAR%) for hypertension (i.e. systolic BP ≥140 mmHg) were computed for all risk factors in the five countries. Results: Being overweight made the largest contribution to hypertension, with PAR% between 11% (Italy) and 25% (USA). PAR% were 5–13% for physical inactivity, 9–17% for high sodium intake, 4–17% for low potassium intake and 4–8% for low magnesium intake. The impact of alcohol was small (2–3%) in all populations. PAR% varied among populations for inadequate intake of calcium (2–8%), magnesium (4–8%), coffee (0–9%) and fish fatty acids (3–16%). Conclusions: Diet and lifestyle have a substantial impact on hypertension in Western societies, with being overweight, physical inactivity, high sodium intake and low potassium intake being the main contributors. The relative significance of different risk factors varies among populations, which is important for preventative strategies. Received 29 August 2002. Accepted 6 February 2003.
Article
The interaction between peroxynitrite and dopamine and the inhibition of this reaction by plant-derived antioxidants have been investigated. Peroxynitrite promoted the oxidation of dopamine to 6-hydroxyindole-5-one as characterised by HPLC and photodiode array spectra, akin to the products of the tyrosinase-dopamine reaction, but no evidence of dopamine nitration was obtained. Although peroxynitrite did not cause nitration of dopamine in vitro, the catecholamine is capable of inhibiting the formation of 3-nitrotyrosine from peroxynitrite-mediated nitration of tyrosine. The plant-derived phenolic compounds, caffeic acid and catechin, inhibited peroxynitrite-mediated oxidation of dopamine. This effect is attributed to the ability of catechol-containing antioxidants to reduce peroxynitrite through electron donation, resulting in their oxidation to the corresponding o-quinones. The antioxidant effect of caffeic acid and catechin was comparable to that of the endogenous antioxidant, glutathione. In contrast, the structurally related monohydroxylated hydroxycinnamates, p-coumaric acid and ferulic acid, which inhibit tyrosine nitration through a mechanism of competitive nitration, did not inhibit peroxynitrite-induced dopamine oxidation. The findings of the present study suggest that certain plant-derived phenolics can inhibit dopamine oxidation.
Article
Phenols in tea are responsible for its antioxidant activity. The pure catechins and phenolic acids found in tea are more powerful than the antioxidant vitamins C, E and β-carotene in an in vitro lipoprotein oxidation model. Comparison of the tea fractions indicated that both catechins and theaflavins contribute to the teas' antioxidant characteristics. Black and green teas were not significantly different in phenol content, in antioxidant strength as measured by IC50, or in antioxidant potential as measured by the phenol antioxidant index (PAOXI). The PAOXI of teas was significantly higher than grape juices and wines. Tea catechins and both green and black tea exhibited potent lipoprotein-bound antioxidant activity. Phenol antioxidants from tea were calculated to be a large source of antioxidants in the U.S. diet.
Article
Flavonoids are polyphenolic antioxidants naturally present in vegetables, fruits, and beverages such as tea and wine. In vitro, flavonoids inhibit oxidation of low-density lipoprotein and reduce thrombotic tendency, but their effects on atherosclerotic complications in human beings are unknown. We measured the content in various foods of the flavonoids quercetin, kaempferol, myricetin, apigenin, and luteolin. We then assessed the flavonoid intake of 805 men aged 65-84 years in 1985 by a cross-check dietary history; the men were then followed up for 5 years. Mean baseline flavonoid intake was 25.9 mg daily. The major sources of intake were tea (61%), onions (13%), and apples (10%). Between 1985 and 1990, 43 men died of coronary heart disease. Fatal or non-fatal myocardial infarction occurred in 38 of 693 men with no history of myocardial infarction at baseline. Flavonoid intake (analysed in tertiles) was significantly inversely associated with mortality from coronary heart disease (p for trend = 0.015) and showed an inverse relation with incidence of myocardial infarction, which was of borderline significance (p for trend = 0.08). The relative risk of coronary heart disease mortality in the highest versus the lowest tertile of flavonoid intake was 0.42 (95% CI 0.20-0.88). After adjustment for age, body-mass index, smoking, serum total and high-density-lipoprotein cholesterol, blood pressure, physical activity, coffee consumption, and intake of energy, vitamin C, vitamin E, beta-carotene, and dietary fibre, the risk was still significant (0.32 [0.15-0.71]). Intakes of tea, onions, and apples were also inversely related to coronary heart disease mortality, but these associations were weaker. Flavonoids in regularly consumed foods may reduce the risk of death from coronary heart disease in elderly men.
Article
To study the association between dietary intake of flavonoids and subsequent coronary mortality. A cohort study based on data collected at the Finnish mobile clinic health examination survey from 1967-72 and followed up until 1992. 30 communities from different parts of Finland. 5133 Finnish men and women aged 30-69 years and free from heart disease at baseline. Dietary intake of flavonoids, total mortality, and coronary mortality. In women a significant inverse gradient was observed between dietary intake of flavonoids and total and coronary mortality. The relative risks between highest and lowest quarters of flavonoid intake adjusted for age, smoking, serum cholesterol concentration, blood pressure, and body mass index were 0.69 (95% confidence interval 0.53 to 0.90) and 0.54 (0.33 to 0.87) for total and coronary mortality, respectively. The corresponding values for men were 0.76 (0.63 to 0.93) and 0.78 (0.56 to 1.08), respectively. Adjustment for intake of antioxidant vitamins and fatty acids weakened the associations for women; the relative risks for coronary heart disease were 0.73 (0.41 to 1.32) and 0.67 (0.44 to 1.00) in women and men, respectively. Intakes of onions and apples, the main dietary sources of flavonoids, presented similar associations. The relative risks for coronary mortality between highest and lowest quarters of apple intake were 0.57 (0.36 to 0.91) and 0.81 (0.61 to 1.09) for women and men, respectively. The corresponding values for onions were 0.50 (0.30 to 0.82) and 0.74 (0.53 to 1.02), respectively. The results suggest that people with very low intakes of flavonoids have higher risks of coronary disease.
Article
Peroxynitrite is a cytotoxic species generated by the reaction between superoxide and nitric oxide. The ability of catechins and their gallate esters to decrease peroxynitrite-induced nitration of tyrosine and to limit surface charge alteration of low density lipoprotein (LDL) was investigated. All compounds tested were found to be potent peroxynitrite scavengers preventing the nitration of tyrosine. The ability of the catechin polyphenols at 10 microM to minimise tyrosine nitration induced by peroxynitrite (500 microM) was ECG (38.1 +/- 3.6%) approximately EGCG (32.1 +/- 7.5%) approximately gallic acid (32.1 +/- 1.9%) > catechin (23.9 +/- 5.4%) approximately epicatechin (22.9 +/- 3.3%) approximately EGC (19.9 +/- 2.0%). Trolox (10 microM) was used as the standard for comparative purposes and was found to be less effective than the polyphenols in inhibiting tyrosine nitration (13.6 +/- 2.9%). The catechin polyphenols were also found to offer protection from peroxynitrite-induced modification of critical amino acids of apolipoprotein B-100 of LDL which contribute towards its surface charge.
Article
In a randomised, double-blind, placebo-controlled study we showed that treatment of hypertensive patients with ascorbic acid lowers blood pressure. Further studies of ascorbic acid to treat hypertension, with clinical endpoints, are warranted.
Article
To determine the effect of oral vitamin C supplements on ambulatory blood pressure and plasma lipids. A 6-month double-blind randomized placebo-controlled cross-over study with a 1 -week washout between cross-over periods. Vitamin C 500 mg daily or matching placebo was given to 40 men and women aged between 60 and 80 years for 3 months each in a cross-over fashion. Clinic and 24-h ambulatory blood pressure, plasma ascorbate and lipids were measured at baseline and at the end of each cross-over phase. Clinic blood pressure did not change between placebo and vitamin C phases. Daytime ambulatory blood pressure showed a small but significant fall in systolic blood pressure (2.0 +/- 5.2 mmHg; 95% confidence interval 0-3.9 mmHg) but not in diastolic blood pressure. Regression analysis showed that with increasing baseline daytime blood pressure the fall in blood pressure with vitamin C supplementation increased. Regression analysis of the change in high-density lipoprotein (HDL) cholesterol showed a significant effect of sex on the change in HDL cholesterol. In women, but not men, HDL cholesterol increased significantly by 0.08 +/- 0.11 mmol/l, P=0.007. There was no change in low-density lipoprotein cholesterol between treatment periods. In older adults high intakes of ascorbic acid have modest effects on lowering high systolic blood pressure, which could contribute to the reported association between higher vitamin C intake and lower risk of cardiovascular disease and stroke.
Article
Ascorbic acid appears to have vasodilatory properties, but the underlying mechanisms are not well understood. The aims of this study were to define the acute effects of locally infused ascorbic acid in human veins and to explore underlying mechanisms by using pharmacological tools in vivo. Ascorbic acid was infused in dorsal hand veins submaximally preconstricted with the alpha(1)-adrenoceptor agonist phenylephrine or with prostaglandin F(2alpha) in 23 healthy male nonsmokers, and the venodilator response was measured. Ascorbic acid produced dose-dependent dilation with maximum reversal of constriction of 38+/-4% in phenylephrine-preconstricted veins and of 51+/-13% in prostaglandin F(2alpha)-preconstricted veins. Oral pretreatment with the cyclooxygenase inhibitor acetylsalicylic acid or local coinfusion of ascorbic acid and the nitric oxide synthase inhibitor N:(G)-monomethyl-L-arginine had no effect, but coinfusion of ascorbic acid and methylene blue (to inhibit cGMP generation) abolished venodilation. Coinfusion of ascorbic acid and the nonselective potassium channel blocker quinidine abolished venodilation, whereas the inhibitor of ATP-dependent potassium channels glibenclamide had no effect. In cultured bovine endothelial cells, ascorbic acid did not affect intracellular calcium concentration but blunted the response to ATP or digitonin exposure. Ascorbic acid, in millimolar concentrations, dilates human hand veins, presumably by activation of vascular smooth muscle potassium channels through cGMP. This activation is independent of eNOS-mediated nitric oxide synthesis and cyclooxygenase products and does not involve ATP-dependent potassium channels.
Article
Myofibroblasts are ultrastructurally and metabolically distinctive fibroblasts that express smooth muscle (SM)-alpha actin and are associated with various fibrotic lesions. The present study was undertaken to investigate the myofibroblast phenotype that appears after activation of normal lung fibroblasts by thrombin. We demonstrate that thrombin induces smooth muscle-alpha actin expression and rapid collagen gel contraction by normal lung fibroblasts via the proteolytically activated receptor-1 and independent of transforming growth factor-beta pathway. Using antisense oligonucleotides we demonstrate that a decreased level of PKCepsilon abolishes SM-alpha actin expression and collagen gel contraction induced by thrombin in normal lung fibroblasts. Inhibition of PKCepsilon translocation also abolishes thrombin-induced collagen gel contraction, SM-alpha actin increase, and its organization by normal lung fibroblasts, suggesting that activation of PKCepsilon is required for these effects. In normal lung fibroblasts PKCepsilon binds to SM-alpha actin after thrombin treatment, but in activated fibroblasts derived from scleroderma lung they associate even in untreated cells. This suggests that SM-alpha actin may serve as a substrate for PKCepsilon in lung fibroblasts when activated by thrombin. We propose that thrombin differentiates normal lung fibroblasts to a myofibroblast phenotype via a PKC-dependent pathway. Thrombin-induced differentiation of normal lung fibroblasts to a myofibroblast phenotype resembles the phenotype observed in scleroderma lung fibroblasts. Therefore, we conclude that chronic exposure to thrombin after microvascular injury leads to activation of normal lung fibroblasts and to the appearance of a myofibroblast phenotype in vivo. Our study provides novel, compelling evidence that thrombin is an important mediator of the interstitial lung fibrosis associated with scleroderma.
Article
Flavonoids comprise the most common group of plant polyphenols and provide much of the flavor and color to fruits and vegetables. More than 5000 different flavonoids have been described. The six major subclasses of flavonoids include the flavones (e.g., apigenin, luteolin), flavonols (e.g., quercetin, myricetin), flavanones (e.g., naringenin, hesperidin), catechins or flavanols (e.g., epicatechin, gallocatechin), anthocyanidins (e.g., cyanidin, pelargonidin), and isoflavones (e.g., genistein, daidzein). Most of the flavonoids present in plants are attached to sugars (glycosides), although occasionally they are found as aglycones. Interest in the possible health benefits of flavonoids has increased owing to their potent antioxidant and free-radical scavenging activities observed in vitro. There is growing evidence from human feeding studies that the absorption and bioavailability of specific flavonoids is much higher than originally believed. However, epidemiologic studies exploring the role of flavonoids in human health have been inconclusive. Some studies support a protective effect of flavonoid consumption in cardiovascular disease and cancer, other studies demonstrate no effect, and a few studies suggest potential harm. Because there are many biological activities attributed to the flavonoids, some of which could be beneficial or detrimental depending on specific circumstances, further studies in both the laboratory and with populations are warranted.
Article
Tea catechins inhibited TBARS accumulation in HepG2 cells, the order of effectiveness being (-)-epigallocatechin gallate (EGCG) > (-)-epigallocatechin (EGC) > or = (-)-epicatechin gallate (ECG) > (-)-epicatechin (EC). EGCG and EGC protected the depletion of alpha-tocopherol in the cells, and the glutathione content was enhanced by all four catechins. Moreover, all four catechins suppressed the formation of glutathione disulfide and the activation of glutathione peroxidase induced by tert-butylated hydroperoxide.
Article
In the present study, we investigated the free radical scavenging effects of green tea extract and green tea tannin mixture and its components using a nitric oxide (NO) and superoxide (O(2)(-)) generating system in vitro. Green tea extract showed direct scavenging activity against NO and O(2)(-) and green tea tannin mixture, at the same concentration, showed high scavenging activity. Comparison of the activities of seven pure compounds isolated from green tea tannin mixture showed that (-)-epigallocatechin 3-O-gallate (EGCg), (-)-gallocatechin 3-O-gallate (GCg) and (-)-epicatechin 3-O-gallate (ECg) had higher scavenging activities than (-)-epigallocatechin (EGC), (+)-gallocatechin (GC), (-)-epicatechin (EC) and (+)-catechin (C), showing the importance of the structure of flavan-3-ol linked to gallic acid for this activity. Among the gallate-free tannins, EGC and GC were more effective O(2)(-) scavengers than EC and C, indicating the O-trihydroxy structure in the B ring is an important determinant of such activity. However, this structure did not affect the NO scavenging activity. These findings confirm that green tea tannin has excellent antioxidant properties, which may be involved in the beneficial effect of this compound.
Article
Experimental evidence suggests that acute parenteral administration of high-dose ascorbic acid has beneficial vascular effects in type 2 diabetes. We studied the hemodynamic effects of chronic oral supplementation in this condition. Thirty patients, 45 to 70 years of age, with type 2 diabetes, were randomly assigned in a double-blind manner to receive 500 mg ascorbic acid daily by mouth or placebo. Patients were studied at baseline and after 4 weeks of assigned treatment. The central aortic augmentation index (AgIx) and the time to wave reflection (Tr) were derived from radial artery pulse wave analysis data. AgIx and Tr were used as measures of systemic arterial stiffness and aortic stiffness, respectively. Ascorbic acid decreased brachial systolic blood pressure from 142.1+/-12.6 (SD) to 132.3+/-12.1 mm Hg (difference [95% CI] 9.9 [4.7, 15.0]; P<0.01), brachial diastolic pressure from 83.9+/-4.8 to 79.5+/-6.0 mm Hg (4.4 [1.8, 7.0]; P<0.01), and AgIx from 26.8+/-5.5% to 22.5+/-6.8% (4.3 [1.5, 7.1]; P<0.01). Tr increased from 137.1+/-12.6 to 143.4+/-9.2 ms (-6.3 [-10.1, -2.5]; P<0.01). Placebo had no hemodynamic effects, and this difference between treatments was significant (P<0.01 for blood pressure and Tr, P=0.03 for AgIx). We have therefore shown that after 1 month, oral ascorbic acid lowered arterial blood pressure and improved arterial stiffness in patients with type 2 diabetes. As strict control of blood pressure reduces cardiovascular risk in diabetes, ascorbic acid supplementation may potentially be a useful and inexpensive adjunctive therapy. Larger and longer studies now need to be performed.
Article
Antioxidant vitamins C and E have protective properties in genetic hypertension associated with enhanced oxidative stress. This study investigated whether vitamins C and/or E modulate vascular function by regulating enzymatic activities of endothelial nitric oxide synthase (eNOS) and NAD(P)H oxidase using thoracic aortas of 20- to 22-week-old male spontaneously hypertensive rats (SHR) and their matched normotensive counterparts, Wistar-Kyoto rats (WKY). SHR aortas had impaired relaxant responses to acetylcholine but not to sodium nitroprusside, despite an approximately 2-fold increase in eNOS activity and NO release. The levels of superoxide anion (O2-), a potent NO scavenger, and NAD(P)H oxidase activity were also 2-fold higher in SHR aortas. Mechanical but not pharmacological inactivation of endothelium (by rubbing and 100 micromol/L L-NAME, respectively) significantly abrogated O2- in both strains. Treatments of SHR aortas with NAD(P)H oxidase inhibitors, namely diphenyleneiodinium and apocynin, significantly diminished O2- production. The incubation of SHR aortas with different concentrations of vitamin C (10 to 100 micromol/L) and specifically with high concentrations of vitamin E (100 micromol/L) improved endothelial function, reduced superoxide production as well as NAD(P)H oxidase activity, and increased eNOS activity and NO generation in SHR aortas to the levels observed in vitamin C- and E-treated WKY aortas. Our results reveal endothelial NAD(P)H oxidase as the major source of vascular O2- in SHR and also show that vitamins C and E are critical in normalizing genetic endothelial dysfunction through regulation of eNOS and NAD(P)H oxidase activities.
Article
Quercetin is a typical flavonoid ubiquitously present in fruits and vegetables, and its antioxidant effect is implied to be helpful for human health. The bioavailability of quercetin glycosides should be clarified, because dietary quercetin is mostly present as its glycoside form. Although quercetin glycosides are subject to deglycosidation by enterobacteria for the absorption at large intestine, small intestine acts as an effective absorption site for glucose-bound glycosides (quercertin glucosides). This is because small intestinal cells possess a glucoside-hydrolyzing activity and their glucose transport system is capable of participating in the glucoside absorption. A study using a cultured cell model for intestinal absorption explains that the hydrolysis of the glucosides accelerates their absorption in the small intestine. Small intestine is also recognized as the site for metabolic conversion of quercetin and other flavonoids as it possesses enzymatic activity of glucuronidation and sulfation. Modulation of the intestinal absorption and metabolism may be beneficial for regulating the biological effects of dietary quercetin.
Article
Cardiovascular disease and cancer are ranked as the first and second leading causes of death in the United States and in most industrialized countries. Regular consumption of fruit and vegetables is associated with reduced risks of cancer, cardiovascular disease, stroke, Alzheimer disease, cataracts, and some of the functional declines associated with aging. Prevention is a more effective strategy than is treatment of chronic diseases. Functional foods that contain significant amounts of bioactive components may provide desirable health benefits beyond basic nutrition and play important roles in the prevention of chronic diseases. The key question is whether a purified phytochemical has the same health benefit as does the whole food or mixture of foods in which the phytochemical is present. Our group found, for example, that the vitamin C in apples with skin accounts for only 0.4% of the total antioxidant activity, suggesting that most of the antioxidant activity of fruit and vegetables may come from phenolics and flavonoids in apples. We propose that the additive and synergistic effects of phytochemicals in fruit and vegetables are responsible for their potent antioxidant and anticancer activities, and that the benefit of a diet rich in fruit and vegetables is attributed to the complex mixture of phytochemicals present in whole foods.
Article
Clinical and experimental evidence suggests that the pathways by which hypertension and dyslipidemia lead to vascular disease may overlap and that angiotensin II (Ang II) is involved in restructuring of the arterial wall in both atherosclerosis and hypertension. Ang II represents a potent proinflammatory agent promoting recruitment of monocytes into the vascular intima. Ang II also indirectly facilitates transformation of macrophages and smooth muscle cells into foam cells by promoting superoxide radical formation (via NADP/NADPH oxidase stimulation). The oxidative stress produced by Ang II leads to enhanced low-density lipoprotein oxidation and degradation of nitric oxide, an important vascular protective molecule capable of retarding atherosclerosis progression. The importance of the renin-angiotensin system (RAS) in atherogenesis is highlighted by studies in animal models as well as human beings indicating that inhibition of angiotensin-converting enzyme or blockade of type 1 Ang II receptors retards the development of atherosclerotic lesions. In light of a causal and central role of Ang II in atherogenesis, blockade of the RAS represents an important therapeutic consideration in the prevention and treatment of atherosclerotic disease.
Article
Antioxidative effects of the flavonols and their glycosides, i.e., quercetin (Q), quercetin galactopyranoside (QG), quercetin rhamnolpyranoside (QR), rutin (R), morin (MO), myrecetin (MY), kaempferol (K) and kaempferol glucoside (KG), against free radical initiated peroxidation of human low density lipoprotein (LDL) were studied. The peroxidation was initiated either by a water-soluble initiator 2,2'-azobis(2-amidino propane hydrochloride) (AAPH), or by cupric ion (Cu2+). The reaction kinetics were monitored either by the uptake of oxygen and the depletion of alpha-tocopherol (TOH) presented in the native LDL, or by the formation of thiobarbituric acid reactive substances (TBARS). Kinetic analysis of the antioxidation process demonstrates that these flavonols and their glycosides are effective antioxidants against AAPH- and Cu(2+)-initiated LDL peroxidation, the flavonols bearing ortho-dihydroxyl groups possess significantly higher antioxidant activity than those bearing no such functionalities, and the glycosides are less active than their parent aglycones.
Article
We studied the effects of tea catechins, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) on the P-glycoprotein (P-gp) function in multidrug-resistant P-gp over-expressing KB-C2 cells. EC did not have any effects on cellular accumulation of P-gp substrates, rhodamine-123 and daunorubicin, but the other catechins increased the accumulation in the order of EGC < ECG < EGCG. The effects of EGCG were larger than those of verapamil and quercetin. Since these catechins inhibited the efflux of P-gp substrates, the elevation of substrate accumulation seemed to be induced by the inhibition of the efflux transporter. The results showed that the inhibitory effects of the catechins did not depend on their total hydrophobicity, but significantly depended on their chemical structure. The presence of the galloyl moiety on the C-ring markedly increased the n-octanol/PBS partition coefficients of the catechins and their activity on P-gp. On the other hand, the presence of the trihydric pyrogallol group as the B-ring decreased the partition coefficients but increased the activity on P-gp, compared with the action of the corresponding catechins with a dihydric catechol B-ring.
Article
The effects of a red wine polyphenolic extract (RWPE), ethanol, or both combined were evaluated in insulin resistant rats. Rats were fed for 6 weeks with fructose (60%)-enriched food and force-fed with (a) water only (F group), (b) aqueous solution of RWPE (100 mg/kg, FP group), (c) 10% (v/v) mixture of ethanol and water (FE group), or (d) solution containing the same amount of the RWPE and ethanol (FPE group). Animals fed a standard chow (C group) were used for comparison purpose. After 6 weeks, blood pressure was higher in F (130.0 x b1 1.7 mm Hg) than in C animals (109.6 x b1 0.9 mm Hg) and similar to the C group in all other fructose-fed treatment groups. Relative heart weight was higher in F (3.10 x b1 0.05) than in C (2.78 x b1 0.07) and significantly lower in FP (2.92 x b1 0.04) and FPE (2.87 x b1 0.08 mg/g) than in F animals. Left ventricle and aorta productions of reactive oxygen species (O2*-) were higher in F than in C groups and lowered by the RWPE but not by the ethanol treatment. Ethanol but not the RWPE treatment reduced the degree of insulin resistance in the fructose-fed rats. In summary, our study showed that polyphenols are able to prevent cardiac hypertrophy and production of reactive oxygen species in the insulin resistant fructose-fed rat.
Article
The Dietary Approaches to Stop Hypertension (DASH) diet substantially lowers blood pressure and reduces blood lipid levels. The DASH diet menus were designed to reach beneficial levels of fiber, potassium, magnesium, and calcium, and therefore contain more fruits, vegetables, and whole grains relative to the control menus, and consequently more phytochemicals. Using the US Department of Agriculture food composition databases, the polyphenol, carotenoid, and phytosterol contents of the diets used in the DASH study were estimated. When compared with the control diet, the DASH diet is higher in flavonols, flavanones, flavan-3-ols, beta-carotene, beta-cryptoxanthin, lycopene, lutein+zeaxanthin, and phytosterols. Flavone levels are similar, whereas isoflavones are present in a small amount in the DASH diet. The roles of these compounds in disease risk reduction are becoming recognized. It therefore is possible that the health benefits of the DASH diet are partially attributable to the phytochemicals and might extend beyond cardiovascular disease risk reduction.
Article
Intimal thickening, the accumulation of cells and extracellular matrix within the inner vessel wall, is a physiological response to mechanical injury, increased wall stress, or chemical insult (e.g., atherosclerosis). If excessive, it can lead to the obstruction of blood flow and tissue ischemia. Together with expansive or constrictive remodeling, the extent of intimal expansion determines final lumen size and vessel wall thickness. Plaque rupture represents a failure of intimal remodeling, where the fibrous cap overlying an atheromatous core of lipid undergoes catastrophic mechanical breakdown. Plaque rupture promotes coronary thrombosis and myocardial infarction, the most prevalent cause of premature death in advanced societies. The matrix metalloproteinases (MMPs) can act together to degrade the major components of the vascular extracellular matrix. All cells present in the normal and diseased blood vessel wall upregulate and activate MMPs in a multistep fashion driven in part by soluble cytokines and cell-cell interactions. Activation of MMP proforms requires other MMPs or other classes of protease. MMP activation contributes to intimal growth and vessel wall remodeling in response to injury, most notably by promoting migration of vascular smooth muscle cells. A broader spectrum and/or higher level of MMP activation, especially associated with inflammation, could contribute to pathological matrix destruction and plaque rupture. Inhibiting the activity of specific MMPs or preventing their upregulation could ameliorate intimal thickening and prevent myocardial infarction.
Article
Reliable information about the prevalence of hypertension in different world regions is essential to the development of national and international health policies for prevention and control of this condition. We aimed to pool data from different regions of the world to estimate the overall prevalence and absolute burden of hypertension in 2000, and to estimate the global burden in 2025. We searched the published literature from Jan 1, 1980, to Dec 31, 2002, using MEDLINE, supplemented by a manual search of bibliographies of retrieved articles. We included studies that reported sex-specific and age-specific prevalence of hypertension in representative population samples. All data were obtained independently by two investigators with a standardised protocol and data-collection form. Overall, 26.4% (95% CI 26.0-26.8%) of the adult population in 2000 had hypertension (26.6% of men [26.0-27.2%] and 26.1% of women [25.5-26.6%]), and 29.2% (28.8-29.7%) were projected to have this condition by 2025 (29.0% of men [28.6-29.4%] and 29.5% of women [29.1-29.9%]). The estimated total number of adults with hypertension in 2000 was 972 million (957-987 million); 333 million (329-336 million) in economically developed countries and 639 million (625-654 million) in economically developing countries. The number of adults with hypertension in 2025 was predicted to increase by about 60% to a total of 1.56 billion (1.54-1.58 billion). Hypertension is an important public-health challenge worldwide. Prevention, detection, treatment, and control of this condition should receive high priority.
Article
1. Oxidative stress is recognized as a major contributing factor for the development of late complications of diabetes. 2. Tea contains polyphenolic compounds (catechins), which have many important biological properties, including strong anti-oxidant activity. 3. The present study was undertaken to evaluate the effect of tea catechins (epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC)) on markers of oxidative stress (malondialdehyde (MDA), reduced glutathione (GSH) and membrane -SH group) in erythrocytes from type 2 diabetics. 4. Oxidative stress was induced in normal and type 2 diabetic erythrocytes by incubating with tert-butyl hydroperoxide (t-BHP). 5. Diabetic erythrocytes have higher MDA and decreased GSH and membrane -SH groups compared with normal erythrocytes. 6. Our results show that tea catechins protect erythrocytes from t-BHP-induced oxidative stress, the effect being more pronounced in diabetic erythrocytes. The relative effectiveness of individual catechins are in the order of EGCG > ECG > EGC > EC. 7. We hypothesise that a higher intake of catechin-rich food by diabetic patients may provide some protection against the development of long-term complications of diabetes.
Article
Tea catechins (EGCG, EGC, ECG and EC) possess many important biological properties. We evaluated the effect of tea catechins on erythrocyte membrane Na(+)/K(+)-ATPase and sodium/hydrogen exchanger (NHE) activity in normal (control) and NIDDM subjects. Erythrocyte membrane Na(+)/K(+)-ATPase and NHE activity were determined in normal and non-insulin dependent diabetes mellitus (NIDDM) patients. In vitro effect of tea catechins was studied by incubating membrane/intact erythrocytes in assay medium prior to Na(+)/K(+)-ATPase/NHE activity determination. A 24.2% decrease in the activity of Na(+)/K(+)-ATPase (p<0.001) and 39.37% increase in activity of NHE (p<0.02) were observed in NIDDM subjects compared to normal. Tea catechins inhibited the activity of Na(+)/K(+)-ATPase and NHE in both normal and NIDDM erythrocytes, the effect was concentration-dependent. The inhibitory effect of EGCG and ECG at micromolar concentrations was greater compared to EGC and EC on Na(+)/K(+)-ATPase. On NHE the inhibition of tea catechins was in the order: EC>EGC>ECG>EGCG at concentrations up to 10 micromol/l. This data may help to explain the anti-carcinogenic and cardioprotective effects of tea catechins. The effect of tea catechins on Na(+)/K(+)-ATPase and NHE may be explained due to a direct effect of these compounds on plasma membrane leading to a change in membrane fluidity.
Article
The reaction rates (k(r)) of 5,7-diisopropyl-tocopheroxyl radical (Toc) with catechins (epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), epigallocatechin gallate (EGCG)) and related compounds (methyl gallate (MG), 4-methylcatechol (MC), and 5-methoxyresorcinol (MR)) have been measured by stopped-flow spectrophotometer. The k(r) values increased in the order of MR < < MG < EC < MC approximately ECG < EGC < EGCG in ethanol and 2-propanol/H(2)O (5/1, v/v) solutions, indicating that the reactivity of the OH groups in catechins increased in the order of resorcinol A-ring < < gallate G-ring < catechol B-ring < pyrogallol B-ring. The catechins which have lower oxidation potentials show higher reactivities. The rate constants for catechins in micellar solution showed notable pH dependence with one or two peaks around pH 9-11, because of the dissociation of various phenolic hydroxyl protons in catechins. The structure-activity relationship in the free-radical-scavenging reaction by catechins has been clarified by the detailed analyses of the pH dependence of k(r) values. The reaction rates increased remarkably with increasing the anionic character of catechins, that is, the electron-donating capacity of catechins. The mono anion form at catechol B-and resorcinol A-rings and dianion form at pyrogallol B-and gallate G-rings show the highest activity for free-radical-scavenging. It was found that catechins (EC, ECG, EGC, and EGCG) have activity similar to or higher than that of vitamin C in vitamin E regeneration at pH 7-12 in micellar solution.
Article
A polyphenol extract from a Corbières (France) red wine (P, 200 mg/kg), ethanol (E, 1 mL/kg), or a combination of both (PE) was administered by daily gavage for 6 weeks to healthy control or streptozotocin (60 mg/kg i.v.)-induced diabetic rats (180-200 g). Treatment groups included C or D (untreated control or diabetic) and CP, CE, or CPE (treated control) or DP, DE, or DPE (treated diabetic). P treatment induced a reduction in body growth, food intake, and glycemia in both CP and DP groups. In DP, hyperglycemia was reduced when measured 1 h after daily treatment but not at sacrifice (no treatment on that day). The hyperglycemic response to the oral glucose tolerance test (OGTT) and plasma insulin at sacrifice were impaired similarly in DP and D groups. In contrast, in DE or DPE, body growth was partially restored while hyperglycemia was reduced both during treatment and at sacrifice. In addition, hyperglycemia response to OGTT was reduced and plasma insulin was higher in DE or DPE than in D animals, indicating a long-term correction of diabetes in ethanol-treated animals. Morphometric studies showed that ethanol partially reversed the enlarging effect of diabetes on the mesenteric arterial system while the polyphenolic treatment enhanced it in the absence of ethanol. In summary, our study shows that (i). a polyphenol extract from red wine ("used at a pharmacological" dose) reduces glycemia and decreases food intake and body growth in diabetic and nondiabetic animals and (ii). ethanol ("nutritional" dose) administered alone or in combination with polyphenols is able to correct the diabetic state. Some of the effects of polyphenols were masked by the effects of ethanol, notably in diabetic animals. Further studies will determine the effect of "nutritional" doses of polyphenols as well as their mechanism of action.
Article
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in the United States and worldwide. In this review, we examine the scientific evidence in support of current dietary recommendations to increase fruit and vegetable intake for CVD prevention. Available evidence indicates that persons who consume more fruits and vegetables often have lower prevalence of important risk factors for CVD, including hypertension, obesity, and type 2 diabetes mellitus. Recent large, prospective studies also show a direct inverse association between fruit and vegetable intake and the development of CVD incidents such as coronary heart disease and stroke. However, the biologic mechanisms whereby fruits and vegetables may exert their effects are not entirely clear and are likely to be multiple. Many nutrients and phytochemicals in fruits and vegetables, including fiber, potassium, and folate, could be independently or jointly responsible for the apparent reduction in CVD risk. Functional aspects of fruits and vegetables, such as their low dietary glycemic load and energy density, may also play a significant role. Although it is important to continue our quest for mechanistic insights, given the great potential for benefits already known, greater efforts and resources are needed to support dietary changes that encourage increased fruit and vegetable intake.
Article
The genomics of atherosclerosis can arise as a result of cross-talk between the genes coding for the LDL-receptor (LDL-R), LXR-alpha, PPARs (alpha, gamma), CD36 and C-myc because these genes control lipid metabolism, cytokine production and cellular activity within the arterial wall. The effect of green tea polyphenols (GTPs) upon such genomics revealed their ability to down-regulate genes coding for PPAR-gamma, CD36, LXR-alpha, C-myc coupled with up-regulation of genes coding for LDL-R and PPAR-alpha at the transcriptional level. Based upon these results, it is proposed that GTPs have the inherent capacity to inhibit the development of atherosclerotic lesions.
A nutrient mixture containing ascorbic acid, lysine, proline, arginine, cysteine, and green tea extract suppresses autocrine inflammatory response in cultured human aortic smooth muscle cells.
  • Ivanov
Dietary antioxidant flavonoid and risk of coronary heart disease: the Zutphen Elderly Study.
  • Hertog
Flavonoid intake and coronary mortality in Finland: a cohort study.
  • Knect
Dietary intake of fruits and vegetables and risk of cardiovascular disease.
  • Bazzano