Effects of red grape skin and seed extract supplementation on atherosclerosis in Watanabe heritable hyperlipidemic rabbits

Grape Seed Procyanidins Inhibit the Growth of Breast Cancer MCF-7 Cells by Down-Regulating the EGFR/VEGF/MMP9 Pathway

Breast cancer is the most common invasive cancer in women and the second leading cause of cancer death in women. However, it is not clear about its effective treatments. As a potential anticancer agent, grape seed procyanidins (GSPs) have been shown to inhibit the proliferation of various cancer cells in vitro and in vivo. In this study, it was shown that GSPs significantly inhibit MCF-7 cell proliferation in a concentration/time-dependent manner. The flow cytometric data clearly demonstrated that GSPs cause cell cycle arrest in the G2/M phase, followed by cell apoptosis. Moreover, it also confirmed that growth inhibition mediated by treatment with GSPs is related to the induction of apoptosis due to p53 elevation, purportedly by inhibition of the epidermal growth factor receptor (EGFR)/vascular endothelial growth factor (VEGF)/matrix metalloproteinase 9 (MMP9) pathway. Taken together, these findings suggest that GSPs inhibit MCF-7 cells proliferation and induce cell apoptosis by suppressing EGFR/VEGF/MMP9 pathway.

Sea Buckthorn and Grape Antioxidant Effects in Hyperlipidemic Rats: Relationship with the Atorvastatin Therapy

Background

Medications to reduce oxidative stress are preventing cellular damage associated with hyperlipidemia. In this regard, statins (e.g., atorvastatin) act primarily by decrease in low-density lipoprotein-c but, in the last decade, hepatotoxicity, associated with liver injuries in the next months after treatments' initiation, was reported. In this case, associated phytotherapy can be a solution.

Purpose

To investigate the antioxidant potential and response to free radicals, in the case of hyperlipidemic rats treated with atorvastatin. Sea buckthorn (Hippophae rhamnoides) and a grape extract (antioxivita) efficiency in the oxidative stress were investigated, also being ascertained the rats' organs cytoarchitecture.

Methods

Eighty-four hyperlipidemic Wistar rats were divided into seven groups and orally treated as follows: ATS, atorvastatin (20 mg/kg·bw); ATS + Hr, atorvastatin + H. rhamnoides; ATS + Aox, atorvastatin + grape extract; Hr, H. rhamnoides; and Aox, grape extract (both as 100 mg/kg·bw). HFD and Control received high fat diet and normal fodder only. After two and six months, respectively, rats were euthanized and the heart, liver, and kidneys were gathered. The tissue samples were prepared by homogenization of 0.5 g tissue, in ethanol, kept for 48 hours at 4°C–10°C and then filtered, in order to assess organs' cytoarchitecture and the TAC's values (by using cupric ion reducing antioxidant capacity (CUPRAC) assay). The test tubes were incubated, at room temperature, for 30 minutes, and then analyzed using a spectrophotometer at 450–650 nm.

Results

The statistics (ANOVA) revealed that sea buckthorn diminished notably (p < 0.001) the oxidative stress in the heart, liver, and kidney. After six months, the TAC's reduced levels for the heart were significant (p < 0.001) in ATS + Aox. In the case of histology, the liver's cytoarchitecture in ATS revealed abnormal cytoarchitecture. In ATS + Hr, ATS + Aox, Hr, and Aox, cell regeneration improved in different stages, especially for ATS + Hr and ATS + Aox, in comparison with HFD, which exhibited fat degeneration. Kidney's cytoarchitecture revealed cellular healing, especially in ATS + Hr and ATS + Aox.

The effect of red grape seed extract on serum paraoxonase activity in patients with mild to moderate hyperlipidemia

CONTEXT AND OBJECTIVE

Red grape seed extract (RGSE) contains oligomeric proanthocyanidin complexes as a class of flavonoids. These compounds are potent antioxidants and exert many health-promoting effects. This study aimed to determine the effects of RGSE on serum levels of triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein AI (apo-AI) levels and paraoxonase (PON) activity in patients with mild to moderate hyperlipidemia (MMH).

DESIGN AND SETTINGS

A randomized double-blind placebo-controlled clinical trial was conducted at Shahid-Modarres Hospital (Tehran, Iran) and Tabriz University of Medical Sciences. Seventy MMH patients were randomly assigned to receive treatment (200 mg/day of RGSE) or placebo for eight weeks.

RESULTS

Significant elevation in serum levels of apo-AI (P = 0.001), HDL-C (P = 0.001) and PON activity (P = 0.001) and marked decreases in concentrations of TC (P = 0.015), TG (P = 0.011) and LDL-C (P = 0.014) were found in the cases. PON activity was significantly correlated with apo-AI (r = 0.270; P < 0.01) and HDL-C (r = 0.45; P < 0.001). Significant differences between the RGSE and control groups (before and after treatment) for TC (P = 0.001), TG (P = 0.001), PON (P = 0.03), apo-AI (P = 0.001) and LDL-C (P = 0.002) were seen.

CONCLUSION

It is possible that RGSE increases PON activity mostly through increasing HDL-C and apo-AI levels in MMH patients. It may thus have potential beneficial effects in preventing oxidative stress and atherosclerosis in these patients.

Effects of dietary Corinthian currants (Vitis vinifera L., var. Apyrena) on atherosclerosis and plasma phenolic compounds during prolonged hypercholesterolemia in New Zealand White rabbits

Corinthian currants are a rich source of phenolic compounds, which are known to exert beneficial effects on cardiovascular disease. The hypothesis tested is whether dietary supplementation with currants attenuates atherosclerosis and affects plasma phenolics during prolonged hypercholesterolemia in rabbits. Thirty New Zealand White rabbits were fed one of four diets (normal and supplemented with 10% currants, with 0.5% cholesterol, and with 0.5% cholesterol plus 10% currants) for eight weeks. Plasma lipids, glucose and hepatic enzymes were determined. Individual phenolic compounds were identified and quantified in plasma during the dietary intervention. At the end of the study, histological examinations of aorta and liver were performed. The high-cholesterol diet resulted in hypercholesterolemia and oxidative stress, increased aspartate aminotransferase (AST) activity and induced aortic and hepatic lesion formation. Corinthian currant supplementation attenuated atherosclerotic lesions, maintained AST within the normal range and reduced oxidative stress without affecting glucose concentrations. The p-OH-benzoic and p-OH-phenylacetic acids predominated at high concentrations in plasma and remained almost constant during the study in the group that received the normal rabbit chow and the groups given food with added cholesterol either alone or supplemented with currants. Currant supplementation to the normal diet resulted in the reduced absorption of phenolic compounds, as revealed by the measurement of their plasma metabolites, suggesting a regulatory mechanism at the gut level under normal conditions.

A pilot, randomized controlled trial to examine the health outcomes of raisin consumption in patients with diabetes

OBJECTIVES

Dried fruits, like their fresh homologues, contain relatively high concentrations of antioxidants. The aim of this study was to determine the health outcomes of raisin consumption on patients with diabetes.

METHODS

We examined the effects of dried grapes (Vitis vinifera) cultivated in Greece, namely Corinthian Raisins (CR) on blood pressure, fasting glucose, glucated hemoglobin (HbA1c), lipid peroxidation, high-sensitivity C-reactive protein, antioxidant status, and cytokines in patients with type 2 diabetes mellitus (T2DM). Forty-eight well-controlled patients with T2DM from the diabetes outpatient clinic of our hospital were recruited to a two-armed, randomized, controlled, 24-wk prospective intervention trial in order to examine the health outcomes of CR consumption. All participants were reported to consume less fruits and vegetables than the recommended amount of five servings daily. Participants in the intervention were instructed to consume CR equal to two fruit servings (36 g/d), replacing snacks with similar energy density twice during the day. Anthropometric and blood pressure measurements, assessment of dietary intake, and fasting blood draws were conducted at baseline and at week 24. Also, phenolic compounds present in CR were analyzed in plasma of the patients. t Test for parametric data and Mann-Whitney test or Wilcoxon test for non-parametric data were performed. Significance was set at P < 0.05.

RESULTS

Body weight, glycemic control, and lipid profile were not affected in either arm. Patients in the CR arm reduced their diastolic blood pressure and increased their total antioxidant potential significantly compared with baseline. The differences between the two groups at week 24 were significant. No change in high-sensitivity C-reactive protein was observed. A significant difference in plasma circulating p-hydroxybenzoic acid was observed between groups at the end of the trial.

CONCLUSIONS

Our study shows that naturally CR may improve health features in patients with well-controlled T2DM.

Inhibition of advanced glycation end products by red grape skin extract and its antioxidant activity

BACKGROUND

The objective of the present study was to determine the phytochemical content and the protective effect of red grape skin extract (RGSE) against fructose-mediated protein oxidation. In addition, RGSE was screened for its potential as an antioxidant using various in vitro models.

METHODS

Antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical scavenging activity, superoxide radical scavenging activity, trolox equivalent antioxidant capacity, ferric reducing antioxidant power (FRAP), ferrous ion chelating power. The total phenols content was measured by Folin-Ciocalteu assay, the flavonoids content by the AlCl3 colorimetric method. Antiglycation activity was determined using the formation of AGE fluorescence intensity, Nε-(carboxymethyl)lysine, and the level of fructosamine. The protein oxidation was examined using the level of protein carbonyl content and thiol group.

RESULTS

The results showed that the content of total phenolics, flavonoids and total anthocyanins in RGSE was 246.3 ± 0.9 mg gallic acid equivalent/g dried extract, 215.9 ± 1.3 mg catechin equivalent/g dried extract, and 36.7 ± 0.8 mg cyanidin-3-glucoside equivalent/g dried extract, respectively. In the DPPH radical scavenging activity, hydroxyl radical scavenging activity, and superoxide radical scavenging activity, RGSE had the IC50 values of 0.03 ± 0.01 mg/ml, 5.40 ± 0.01 mg/ml, and 0.58 ± 0.01 mg/ml, respectively. In addition, RGSE had trolox equivalent antioxidant capacity assay (395.65 ± 1.61 mg trolox equivalent/g dried extract), ferric reducing antioxidant power (114.24 ± 0.03 mM FeSO4/g dried extract), and ferrous ion chelating power (3,474.05 ± 5.55 mg EDTA/g dried extract), respectively. The results showed that RGSE at different concentrations (0.031-0.500 mg/ml) has significantly inhibited the formation of AGEs in terms of the fluorescence intensity of glycated BSA during 4 weeks of study. The RGSE markedly decreased the level of fructosamine, which is directly associated with the reduction of AGE formation and Nε-(carboxymethyl)lysine (CML). The results demonstrated the significant effect of RGSE on preventing protein oxidative damages, including effects on the thiol and protein carbonyl oxidation.

CONCLUSIONS

The present study revealed that RGSE would exert beneficial effects by virtue of its antioxidants and antiglycation. The findings could provide a new insight into the naturally occurring antiglycation properties of RGSE for preventing AGE-mediated diabetic complication.

Grape-seed procyanidins inhibit the in vitro growth and invasion of pancreatic carcinoma cells

OBJECTIVES

Grape-seed procyanidins (GSPs) can inhibit cell proliferation and invasiveness in various human cancers. However, the effect of GSP on pancreatic carcinoma cells has not been investigated.

METHODS

Pancreatic carcinoma cell lines MIA PaCa-2 and BxPC-3 treated with GSP were assessed for viability by trypan blue exclusion, for cell cycle distribution by flow cytometry, for increased apoptosis by annexin V labeling, for their adhesion and invasion potential by evaluating their ability to penetrate through a matrix gel-coated Boyden chamber, and for changes in the levels of proteins involved in cellular events by immunoblotting.

RESULTS

Grape-seed procyanidin inhibited MIA PaCa-2 and BxPC-3 proliferation in a dose-dependent manner and induced G1-phase arrest of the cell cycle in BxPC-3 or mitochondria-mediated apoptosis in MIA PaCa-2. Grape-seed procyanidin also inhibited the adhesion and invasion potential of both cell lines in a dose-dependent manner, which are associated with the suppression of metalloproteases matrix metalloproteinase 9 or 2 (MMP-9 or -2) expression.

CONCLUSIONS

Grape-seed procyanidin inhibited the proliferation of pancreatic carcinoma cells by cell cycle blockage or apoptotic induction. The invasiveness was also suppressed by GSP through down-regulation of MMP-2 or MMP-9 in pancreatic carcinoma cells. Grape-seed procyanidin is a potential chemotherapeutic or preventive agent for pancreatic carcinoma.

The chemoadjuvant potential of grape seed procyanidins on p53-related cell death in oral cancer cells

BACKGROUND

To clarify the efficacy of grape seed procyanidin (GSP) on antiproliferative effects related to p53 functional status of oral squamous cell carcinoma (OSCC) for its chemoadjuvant potential.

METHODS

We used GSP to investigate SCC-25 cells with wild-type p53 gene and OEC-M1 cells with mutant p53 gene for the assessment of antiproliferative effects including cell viability, cell cycle, apoptosis, migration and invasion potential, and alterations of associated oncoproteins involved in cellular and molecular events.

RESULTS

The findings suggest that GSP on OEC-M1 cells leads to cell cycle arrest by increasing the expression of p21(Cip1) /p27(Kip1) protein without functioning mitochondria-mediated apoptosis, whereas GSP on SCC-25 cells inhibits cell proliferation via both G1-phase arrest and mitochondria-mediated apoptosis in a dose-dependent manner as a result of alterations of Bcl-2. GSP also inhibits the migration and invasion of both cells, which are associated with the suppression of matrix metalloproteinases (MMPs), MMP-2 and MMP-9.

CONCLUSION

Antiproliferative effectiveness of GSP is closely associated with the p53 status of OSCC cells. GSP displays chemoadjuvant potential via cell cycle blockage and apoptotic induction. Our findings clearly suggest that GSP may play a role as a novel chemopreventive or therapeutic agent for OSCC.

Synthetic and natural iron chelators: therapeutic potential and clinical use

Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade(®)) and deferiprone (Ferriprox(®)), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry.

Bioactive dietary polyphenols inhibit heme iron absorption in a dose-dependent manner in human intestinal Caco-2 cells

Although heme iron is an important form of dietary iron, its intestinal absorption mechanism remains elusive. Our previous study revealed that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) markedly inhibited intestinal heme iron absorption by reducing the basolateral iron export in Caco-2 cells. The aim of this study was to examine whether small amounts of EGCG, GSE, and green tea extract (GT) could inhibit heme iron absorption, and to test whether the inhibitory action of polyphenols could be offset by ascorbic acid. A heme-⁵⁵Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT to Caco-2 cells in the absence and presence of ascorbic acid. Polyphenolic compounds significantly inhibited heme-⁵⁵Fe absorption in a dose-dependent manner. The addition of ascorbic acid did not modulate the inhibitory effect of dietary polyphenols on heme iron absorption when the cells were treated with polyphenols at a concentration of 46 mg/L. However, ascorbic acid was able to offset or reverse the inhibitory effects of polyphenolic compounds when lower concentrations of polyphenols were added (≤ 4.6 mg/L). Ascorbic acid modulated the heme iron absorption without changing the apical heme uptake, the expression of the proteins involved in heme metabolism and basolateral iron transport, and heme oxygenase activity, indicating that ascorbic acid may enhance heme iron absorption by modulating the intracellular distribution of ⁵⁵Fe. These results imply that the regular consumption of dietary ascorbic acid can easily counteract the inhibitory effects of low concentrations of dietary polyphenols on heme iron absorption but cannot counteract the inhibitory actions of high concentrations of polyphenols.

PRACTICAL APPLICATION

Bioactive dietary polyphenols inhibit heme iron absorption in a dose-dependent manner. The small amounts of polyphenolic compounds present in foods are capable of reducing heme iron transport across the intestinal enterocyte. However, the inhibitory effects of dietary polyphenolic compounds on heme iron absorption can be offset by ascorbic acid and can possibly be avoided by decreasing the consumption of polyphenols while simultaneously taking ascorbic acid.

Ascorbic acid offsets the inhibitory effect of bioactive dietary polyphenolic compounds on transepithelial iron transport in Caco-2 intestinal cells

We previously reported that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) at high concentration nearly blocked intestinal iron transport across the enterocyte. In this study, we aimed to determine whether small amounts of EGCG, GSE, and green tea extract (GT) are capable of inhibiting iron absorption, to examine if ascorbic acid counteracts the inhibitory action of polyphenols on iron absorption, and to explore the mechanisms of polyphenol-mediated apical iron uptake and basolateral iron release. An(55)Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT using Caco-2 intestinal cells. Polyphenols were found to inhibit the transepithelial (55)Fe transport in a dose-dependent manner. The addition of ascorbic acid offset the inhibitory effects of polyphenols on iron transport. Ascorbic acid modulated the transepithelial iron transport without changing the apical iron uptake and the expression of ferroportin-1 protein in the presence of EGCG. The polyphenol-mediated apical iron uptake was inhibited by membrane impermeable Fe(2+) chelators (P < 0.001), but at a low temperature (4°C), the apical iron uptake was still higher than the control values at 37°C (P < 0.001). These results suggest that polyphenols enhance the apical iron uptake partially by reducing the conversion of ferric to ferrous ions and possibly by increasing the uptake of polyphenol-iron complexes via the energy-independent pathway. The present results indicate that the inhibitory effects of dietary polyphenols on iron absorption can be offset by ascorbic acid. Further studies are needed to confirm the current findings in vivo.

Bioactive dietary polyphenols decrease heme iron absorption by decreasing basolateral iron release in human intestinal Caco-2 cells

Because dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron, it is prudent to test whether the regular consumption of dietary bioactive polyphenols impair the utilization of dietary iron. Because our previous study showed the inhibitory effect of (-) -epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) on nonheme iron absorption, we investigated whether EGCG and GSE also affect iron absorption from heme. The fully differentiated intestinal Caco-2 cells grown on microporous membrane inserts were incubated with heme (55)Fe in uptake buffer containing EGCG or GSE in the apical compartment for 7 h. Both EGCG and GSE decreased (P < 0.05) transepithelial transport of heme-derived iron. However, apical heme iron uptake was increased (P < 0.05) by GSE. Despite the increased cellular levels of heme (55)Fe, the transfer of iron across the intestinal basolateral membrane was extremely low, indicating that basolateral export was impaired by GSE. In contrast, EGCG moderately decreased the cellular assimilation of heme (55)Fe, but the basolateral iron transfer was extremely low, suggesting that the basolateral efflux of heme iron was also inhibited by EGCG. Expression of heme oxygenase, ferroportin, and hephaestin protein was not changed by EGCG and GSE. The apical uptake of heme iron was temperature dependent and saturable in fully differentiated Caco-2 cells. Our data show that bioactive dietary polyphenols inhibit heme iron absorption mainly by reducing basolateral iron exit rather than decreasing apical heme iron uptake in intestinal cells.

Grape skin improves antioxidant capacity in rats fed a high fat diet

This study was conducted to investigate the effect of dietary grape skin on lipid peroxidation and antioxidant defense system in rats fed high fat diet. The Sprague-Dawley rats were fed either control (5% fat) diet or high fat (25% fat) diet which was based on AIN-93 diet for 2 weeks, and then they were grouped as control group (C), control + 5% grape skin group (CS), high-fat group (HF), high fat + 5% grape skin group (HFS) with 10 rats each and fed corresponding diets for 4 weeks. The hepatic thiobarbituric acid reacting substances (TBARS) were increased in high fat group as compared with control group, but reduced by grape skin. The serum total antioxidant status, and activities of hepatic catalase and superoxide dismutase, xanthine oxidase and glucose-6-phosphatase were increased by supplementation of grape skin. Glutathione peroxidase activity was significantly higher in CS group than in C group. Grape skin feeding tended to increase the concentration of total glutathione, especially in control group. The ratio of reduced glutathione to oxidized glutathione was lower in high fat groups than in control groups. The ratio was increased by dietary supplementation of grape skin in control group. These results suggest that dietary supplementation of grape skin would be effective on protection of oxidative damage by lipid peroxidation through improvement of antioxidant defense system in rats fed high fat diet as well as rats with low fat diet.

Cardioprotective actions of grape polyphenols

The aim of this review is to discuss the accumulating evidence that suggests that grape extracts and purified grape polyphenols possess a diverse array of biological actions and may be beneficial in the prevention of some inflammatory-mediated diseases including cardiovascular disease. The active components from grape extracts, which include the grape seed, grape skin, and grape juice, that have been identified thus far include polyphenols such as resveratrol, phenolic acids, anthocyanins, and flavonoids. All possess potent antioxidant properties and have been shown to decrease low-density lipoprotein-cholesterol oxidation and platelet aggregation. These compounds also possess a range of additional cardioprotective and vasoprotective properties including antiatherosclerotic, antiarrhythmic, and vasorelaxation actions. Although not exclusive, antioxidant properties of grape polyphenols are likely to be central to their mechanism(s) of action, which also include cellular signaling mechanisms and interactions at the genomic level. This review discusses some of the evidence favoring the consumption of grape extracts rich in polyphenols in the prevention of cardiovascular disease. Consumption of grape and grape extracts and/or grape products such as red wine may be beneficial in preventing the development of chronic degenerative diseases such as cardiovascular disease.

Differential effects of red and white wines on inhibition of the platelet-derived growth factor receptor: impact of the mash fermentation

AIMS

Moderate wine consumption is associated with a significant reduction of cardiovascular mortality. The molecular basis of this phenomenon remains unknown. Platelet-derived growth factor (PDGF) is an important contributor to atherogenesis. We investigated the effects of selected red and white wines on PDGF receptor (PDGFR) signalling in rat and human vascular smooth muscle cells (VSMCs).

METHODS AND RESULTS

All red wines concentration dependently inhibited the ligand-induced tyrosine phosphorylation of the PDGFR, downstream signalling events such as mitogen activated protein (MAP) kinase activation (Erk 1/2) and induction of immediate early genes (Egr-1, c-fos), and PDGF-induced cellular responses, whereas all white wines had no effect. At concentrations achieved after wine consumption in humans, all red wines completely abolished PDGF-dependent VSMC proliferation and migration. Red wines also inhibited PDGFR phosphorylation in vascular tissue, and in human coronary smooth muscle cells. Quantitative analyses of all tested wines and of samples collected at various time points (Days 0-16) of the 'mash fermentation', which is only performed for red wine, revealed that flavonoids of the catechin family, which potently inhibit PDGFR signalling, are extracted from grape seeds and skins during this process and therefore accumulate specifically in red wine. The accumulation of flavonoids correlated with the inhibitory potency of red wines on PDGFR signalling. Furthermore, this procedure could be imitated by incubation of wines with shredded grape seeds, and flavonoid-enriched white wine inhibited the PDGFR as potently as red wines.

CONCLUSION

Only red wines abrogate a critical pathogenic mechanism during atherogenesis, PDGFR signalling, in VSMCs. This effect is mediated by non-alcoholic constituents, which accumulate during the mash fermentation. Our findings offer a molecular explanation for the vasoprotective effects particularly of red wine. Therefore, future epidemiological studies should consider differential protective effects of red and white wine in vivo.

Grape products and cardiovascular disease risk factors

Many in vivo trials have evaluated the effects of grape products on different CVD risk factors. Most published studies have dealt with some specific aspects of mechanisms of grape flavonoid action or have focused only on one product, such as wine. The aim of the present paper is to review trials dealing with grape products and CVD published during the last 13 years (seventy-five trials). Polyphenols, alcohol and dietary fibre are the main constituents of the tested products. In animal and human studies, grape products have been shown to produce hypotensive, hypolipidaemic and anti-atherosclerotic effects, and also to improve antioxidant status as measured in terms of plasma antioxidant capacity, oxidation biomarkers, antioxidant compounds or antioxidant enzymes. Differences in the design of the studies and in the composition of the tested products (not always provided) could explain the different results of these studies.

Grape seed proanthocyanidines and skin cancer prevention: inhibition of oxidative stress and protection of immune system

Overexposure of the skin to UV radiation has a variety of adverse effects on human health, including the development of skin cancers. There is a need to develop nutrition-based efficient chemopreventive strategies. The proanthocyanidins present in grape seeds (Vitis vinifera) have been shown to have some biological effects, including prevention of photocarcinogenesis. The present communication discusses the in vitro and in vivo studies of the possible protective effect of grape seed proanthocyanidins (GSPs) and the molecular mechanism for these effects. In SKH-1 hairless mice, dietary supplementation with GSPs is associated with a decrease of UVB-induced skin tumor development in terms of tumor incidence, tumor multiplicity, and a decrease in the malignant transformation of papillomas to carcinomas. It is suggested that the chemopreventive effects of dietary GSPs are mediated through the attenuation of UV-induced: (i) oxidative stress; (ii) activation of mitogen-activated protein kinases and nuclear factor-kappa B (NF-kappaB) signaling pathways; and (iii) immunosuppression through alterations in immunoregulatory cytokines. Collectively, these studies indicate protective potential of GSPs against experimental photocarcinogenesis in SKH-1 hairless mice, and the possible mechanisms of action of GSPs, and suggest that dietary GSPs could be useful in the attenuation of the adverse UV-induced health effects in human skin.

Cholesterol-lowering nutraceuticals and functional foods

Epidemiological studies have demonstrated that elevated levels of plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) are the major risk factors for coronary heart disease (CHD), whereas high concentrations of plasma high-density lipoprotein cholesterol (HDL-C) and a low ratio of TC to HDL-C are protective against CHD. A relationship between plasma TC and the risk of CHD is well established at concentrations above 240 mg/dL. In addition to the use of three main classes of cholesterol-lowering medications, including HMG-CoA reductase inhibitors, anion-exchange resins, and fibrates, a nutritionally balanced diet that reduces saturated fat and cholesterol intake has traditionally been the first goal of dietary therapy in lowering plasma TC. In recent years, nutraceuticals and functional foods have attracted much interest as possible alternative therapies for lowering plasma TC, especially for hypercholesterolemia patients, whose blood cholesterol level is marginally high (200-240 mg/dL) but not high enough to warrant the prescription of cholesterol-lowering medications. This review summarizes the findings of recent studies on the production, application, efficacy, and mechanisms of popular cholesterol-lowering nutraceuticals and functional foods.

Bioactive dietary polyphenolic compounds reduce nonheme iron transport across human intestinal cell monolayers

There is persuasive epidemiological evidence that regular intake of dietary bioactive polyphenolic compounds promotes human health. Because dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron, it is prudent to test whether the regular consumption of bioactive polyphenolic components impair the utilization of dietary iron. We examined the influence of the dietary polyphenols (-) -epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) on transepithelial iron transport in Caco-2 intestinal cells. The range of EGCG and GSE concentrations used in this study was within physiological levels and did not affect the integrity of differentiated Caco-2 cell monolayers. Both EGCG and GSE decreased (P < 0.001) transepithelial iron transport. However, apical iron uptake was increased (P < 0.001) by the addition of EGCG and GSE. The increased uptake of iron might be due in part to the reducing activity of EGCG and GSE. Both EGCG and GSE reduced approximately 15% of the applied Fe(3+) to Fe(2+) in the uptake buffer. Despite the increased cellular levels of (55)Fe, the transfer of iron across the basolateral membrane of the enterocyte was extremely low, indicating that basolateral exit via ferroportin-1 was impaired, possibly through formation of a nontransportable polyphenol-iron complex. Our data show that polyphenols inhibit nonheme iron absorption by reducing basolateral iron exit rather than by decreasing apical iron import in intestinal cells.

Biological models for phytochemical research: from cell to human organism

Nutrigenomics represents a shift of nutrition research from epidemiology and physiology to molecular biology and genetics. Nutrigenomics seeks to understand nutrition influences on homeostasis, the mechanism of genetic predispositions for diseases, to identify the genes influencing risk of diet related diseases. This review presents somein vitromodels applicable in nutrigenomic studies, and discuses the use of animal models, their advantages and limitations and relevance for human situation.In vitroandin vivomodels are suitable for performance of DNA microarrays, proteomic and transcriptomic analyses.In vitromodels (intracellular organelles and suborganellar compartments, cell cultures, or tissue samples/cultures) give insight in metabolic pathways and responses to test stimuli on cellular and molecular levels. Animal models allow evaluation of the biological significance of the effects recordedin vitroand testing of the hypothesis on how a specific factor affects specific species under specific circumstances. Therefore, the evaluation of the data in relation to human organism should be done carefully, considering the species differences. The use ofin vitroandin vivomodels is likely to continue as the effects of nutrition on health and disease cannot be fully explained without understanding of nutrients action at nuclear level and their role in the intra- and intercellular signal transduction. Through advances in cell and molecular biology (including genomic and proteomic), the use of these models should become more predictively accurate. However, this predictive value relies on an underpinning knowledge of the advantages and limitations of the model in nutrigenomic research as in other fields of biomedical research.