European Journal of Clinical Nutrition (2010) 64, 660–668 & 2010 Macmillan Publishers Limited All rights reserved 0954-3007/10 www.nature.com/ejcn

REVIEW Anti-atherogenic effects of

VR Ramprasath and PJH Jones

Richardson Centre for Functional and Nutraceuticals, University of Manitoba, Winnipeg, Canada

Resveratrol (RS), a compound found in grapes and grape products, including wine, peanuts and , exists in cis- and trans-isomeric forms. RS is believed to decrease circulating low-density lipoprotein cholesterol levels and reduce (CVD) risk. However, it is possible that RS has other mechanisms to reduce the risk of CVD without altering levels. The objective of this review is to critically examine results from recent research concerning potential effects of RS on CVD. RS exerts several health benefits including anti-atherogenic, anti-inflammatory and anti- effects. RS may also prevent lipid oxidation, platelet aggregation, arterial vasodilation and modulates the levels of and lipoproteins. As a potent, anti-oxidant RS reduces and regenerates a-, which further strengthens the anti-oxidant defense mechanism. RS has been considered safe as no significant toxic effects have been identified, even when consumed at higher concentrations. This evidence identified RS as an effective anti-atherogenic agent, which could be used in the prevention and treatment of CVD. European Journal of Clinical Nutrition (2010) 64, 660–668; doi:10.1038/ejcn.2010.77; published online 19 May 2010

Keywords: resveratrol; ; lipids; anti-inflammatory; anti-oxidant

Introduction mechanisms have been proposed for RS in reducing the CVD risk including alteration in lipid . Resveratrol (RS) naturally occurs as a polyphenol found in The objective of this review is to critically examine the grapes and grape products, including wine, as well as other results from recent research concerning potential effects of sources including nuts (Cavallaro et al., 2003). RS is also RS on CVD. This review considers the evidence supporting found in the root of Polygonum cuspidatum (Polygonaceae) the effects of RS on atherosclerosis and in reducing CVD risk (Jang and Pezzuto, 1999). In grapes, RS is present in the skin by various mechanisms including modulation of lipid as both free RS and piceid (3-O-mono-D-glucoside of RS; metabolism, free scavenging and anti-oxidant effects, Figure 1). RS has been demonstrated to exert a variety of anti-inflammatory effects and platelet aggregation. health benefits including anti-atherogenic, anti-inflamma- tory and anti-cancer effects (Das and Maulik, 2006; Sun et al., 2008; Udenigwe et al., 2008). RS has also been shown to offer Structure and metabolism of RS protection against ischemic injuries (Wang et al., 2002a) and neurodegenerative diseases (Fremont, 2000; Hung et al., RS, a non-flavonoid polyphenolic compound, exists in 2000; Sun et al., 2002). A number of studies exist regarding cis- and trans-isomeric forms (3,40,5-trihydroxy-stilbene, the beneficial effects of RS on cardiovascular disease (CVD) MW ¼ 228.2) and of piceid (Figure 1). Bioavailability and with the positive effects being attributed to its anti-oxidant metabolism of RS have previously been reviewed in detail (Fauconneau et al., 1997; Martinez and Moreno, 2000; (Udenigwe et al., 2008). RS gets rapidly metabolized in liver Sato et al., 2000) and anti-coagulative properties (Bertelli and intestine by glucuronidation and sulphonation (Bertelli et al., 1996b; Soleas et al., 1997). Various anti-atherogenic et al., 1996a). Over 90% of metabolized RS might be present in plasma of rats (Meng et al., 2004). In a pharmacokinetic study of RS in mice, rats and human, it was shown that Correspondence: Dr PJH Jones, Richardson Centre for Functional Foods and within 24 h after administration of RS at a dose of 0.03 mg/kg Nutraceuticals, University of Manitoba, 196 Innovation Drive, Winnipeg, body weight, nearly 50% of RS gets excreted through urine. Canada R3T 6C5. However, as o25% of the RS was found in the urine with the E-mail: [email protected] Received 28 July 2009; revised 24 January 2010; accepted 27 January 2010; dose of 1 mg/kg, these results suggest the rapid gastro- published online 19 May 2010 intestinal absorption of RS in all the three species studied Anti-atherogenic effects of resveratrol VR Ramprasath and PJH Jones 661 showed that RS supplementation effectively reduced total and LDL cholesterol values, while increasing HDL levels in plasma. RS was also found to reduce atherosclerotic lesions and activity of hepatic HMG-CoA reductase. Rivera et al. (2009) in a long-term study administering RS orally at 10 mg/kg for 8 weeks to obese Zucker rats have found reductions in plasma levels of triglycerides, total cholesterol and free fatty acids and hepatic total lipids. Treatment of RS to nephritic rats at 50 mg/kg body weight Figure 1 Structures of trans and cis isomers of resveratrol and per day for 14 days substantially reduced hyperlipidemia and piceid. suppressed hepatic synthesis of lipids (Nihei et al., 2001). In a study by Miura et al. (2003), hepatoma bearing rats were treated with RS at a dosage of 10 and 50 p.p.m. for 20 days. Results showed a reduction in hyperlipidemia by RS treat- (Meng et al., 2004). In another study, the half of RS in ment by increasing fecal excretion of bile acids and sterols. plasma was reported to be 12–15 min after oral administra- But in an study, RS supplementation to rabbits with tion in rats (Gescher and Steward, 2003). hypercholesterolemia resulted in an absence in reducing circulating cholesterol levels or atherosclerosis (Wilson et al., 1996). Since the early 1980s, RS has been reported to inhibit Effect of RS on lipids and lipoprotein levels hepatic triglyceride synthesis and reduce hepatic cholesterol It is well known that hypercholesterolemia and other lipid and triglyceride accumulation in rats (Arichi et al., 1982). abnormalities are important indicators and risk factors for studies have also shown promising beneficial CVD. High low-density lipoprotein (LDL) and low high- effects of RS on (Kollar et al., 2000). RS at density lipoprotein (HDL) levels form the major risk markers 5 mM concentration led to a 50% reduction in LDL secretion that are directly and positively correlated with CVD risk. by human liver cells in vitro after 24 h treatment (Pal et al., Penumathsa et al. (2007) have examined the effect of RS 2003). However, RS caused only a modest reduction in the administration at 20 mg/kg body weight for 14 days on activity of squalene monooxygenase, a rate-limiting high cholesterol -induced hypercholesterolemia in rats. in cholesterol synthesis (Laden and Porter, 2001). In HepG2 Results showed that treatment with RS reduced not only human hepatocarcinoma cells, RS effectively and dose lipid levels including LDL cholesterol, and triglycerides but dependently reduced apolipoprotein-B production and also the myocardial complications by influencing infarct secretion of triglycerides and cholesterol esters and hence, size, apoptosis and angiogenesis. Recently Rocha et al. (2009) reducing LDL production. These results suggest that RS have shown a significant reduction in total and LDL effectively modulates hepatic lipid metabolism (Goldberg cholesterol levels in high diet-fed rats after treatment et al., 1995). Reduction in synthesis of fatty acid and TG was with RS in drinking water at 1 mg/kg body weight. Other observed in isolated normal rat hepatocytes treated with studies have shown effects of RS in reducing total, LDL and 25 mM concentration of RS (Gnoni and Paglialonga, 2009). VLDL cholesterol levels in vivo (Miura et al., 2003). Treatment This observation represents a possible mechanism for RS of RS at 0.025% diet for 8 weeks to hamsters fed with high fat in reducing TG and other lipoprotein levels in circulation. diets improved lipid profiles by reducing levels of total Hepatic cells on in vitro treatment with RS decreased cholesterol and triglycerides, apolipoprotein-B, lipoprotein-a secretion of esterified cholesterol and triglycerides, which and cholesterol ester transport (Cho et al., 2008). RS indicates the inhibition of lipoprotein metabolism in liver by also reduced endogenous cholesterol synthesis by down- RS (Gaziano, 1994; Goldberg et al., 1995). regulating hepatic HMG-CoA reductase mRNA expression, However, various other studies have failed to show a the rate-limiting enzyme in sterol biosynthesis (Cho et al., change in lipids and lipoprotein profile after treatment with 2008). Ahn et al. (2008) studied effects of supplementation of RS in vivo (Wilson et al., 1996; Soleas et al., 1997; Turrens RS at 0.0125% provided in diet on lipid metabolism and et al., 1997, 1999; Fremont, 2000; Wang et al., 2002b). Table 1 related gene expression. Results showed that RS reduced shows a list of studies analysing the effects of RS on lipid plasma levels of total and free cholesterol. Treatment with RS and lipoprotein levels in various experimental conditions. also decreased levels of hepatic total lipids and triglycerides, The discrepancies between different studies could be the as well as their accumulation. In addition, the authors difference in various experimental models used; however, it observed that RS feeding prevented steatohepatitis induced is of concern that such a level of disparity exists among by atherogenic diets through modulation of expression of results of studies conducted to date. Although RS has been genes involved in and . known to reduce CVD risk by altering blood lipid levels and Long-term effects of RS supplementation on lipid levels reducing the synthesis of cholesterol, other mechanisms and atherosclerosis at 0.02 and 0.06% diet for 20 weeks in independent of circulating lipid levels have also been apoE-deficient mice were studied by Do et al. (2008). Results proposed (Figure 2).

European Journal of Clinical Nutrition Anti-atherogenic effects of resveratrol VR Ramprasath and PJH Jones 662 Table 1 Effects of RS on lipid metabolism

Reference Model Dosage of RS and route Duration Outcome of administration

Rivera et al., Obese and lean male Zucker rats 10 mg/kg b.w. oral 8 weeks Reduction in plasma levels of triglycerides, total 2009 cholesterol and free fatty acids and hepatic total lipids Rocha et al., Hypercholesterolemic diet-fed 1 mg/kg body orally 45 days Decreased oxidized LDL, no effects on total 2009 male Wistar rats through drinking water cholesterol, HDL and LDL-cholesterol Ahn et al., Hypercholesterolemic diet-fed 0.0125% diet 8 weeks Reduced the level of plasma total and free cholesterol, 2008 male C57BL6/J mice hepatic total lipids and triglycerides and their accumulation. Prevented the steatohepatitis by modulating the expression of genes involved in lipogenesis and lipolysis Cho et al., Hypercholesterolemic diet-fed 0.025% diet 8 weeks Reduced the levels of total cholesterol and 2008 male Syrian Golden hamsters triglycerides, apoB, lipoprotein-a, cholesterol ester transport protein. Decreased endogenous cholesterol synthesis by downregulating hepatic HMG-CoA reductase mRNA expression Do et al., Male apoE-deficient mice 0.02 and 0.06% diet 20 weeks Reduced total cholesterol and LDL; increased plasma 2008 HDL; reduced hepatic HMG-CoA reductase Penumathsa Hypercholesterolemic diet-fed 20 mg/kg b.w. oral 2 weeks Reduced total cholesterol, triglycerides, LDL levels et al., 2007 male Sprague-Dawley rats Wang et al., Hypercholesterolemic diet-fed 3 mg/kg b.w. oral 12 week No change in lipid levels 2005 male New Zealand rabbits Miura et al., Hepatoma-induced male Donryu 10 or 50 p.p.m. 20 days Reduction in triglycerides LDL and VLDL cholesterol 2003 rats through diet Wang et al., Hypercholesterolemic diet-fed 4 mg/kg b.w. oral 4 weeks No significant change in lipid levels 2002b male New Zealand rabbits Nihei et al., Nephritis-induced male Wistar rats 50 mg/kg b.w. oral 14 days Insignificantly reduced hyperlipidemia and improved 2001 hepatic synthesis of lipid and fatty oxidation Turner et al., Weanling female Sprague-Dawley 1, 4, 10, 40, 100, 6 days No change in serum cholesterol 1999 rats 1000 mg/day oral Turrens et al., Female CD rats 20 or 40 mg/kg 21 days No significant change in lipid profile; insignificant 1997 injected i.p. decrease in triglyceride and increase in HDL Wilson et al., Hypercholesterolemic diet-fed 0.6 mg/kg during the first 60 days No significant change in lipid levels 1996 New Zealand white rabbits 5 days and 1.0 mg/kg b.w. from days 6 to 60 oral

Abbreviations: HDL, high-density lipoprotein; LDL, low-density lipoprotein; RS, resveratrol; VLDL, very low-density lipoprotein.

Cardioprotection through anti-oxidant activity rats treated with RS for 45 days at a dose of 1 mg/kg per day. of RS and its role in oxidative stress management All of the above results suggest that RS effectively inhibits the in vivo. The anti-oxidative properties of It has been widely accepted that natural and dietary anti- RS were suggested as the mechanism underlying its diverse oxidants have a vital role in preventing various diseases effects including anti-atherogenic effects (Fremont, 2000). caused by oxidative stress. Oxidative stress impacts CVD risk, including atherosclerosis, through halting the production of free radicals and the oxidation process of LDL (Kovanen and Inhibitory effect of RS on ROS production and lipid peroxidation Pentika¨inen, 2003). Reactive species (ROS) leads to Numerous investigations have reported that RS inhibits production and accumulation of oxidized LDL at the site of oxidative stress by scavenging ROS and attenuating peroxyl atherosclerotic lesions (Yla-Herttuala, 1999). Oxidative stress radicals and (Jang and Surh, 2001; also progressively leads to the development of atherosclerosis Liu et al., 2003; Shigematsu et al., 2003; Chen et al., 2004; by contributing to the formation of macrophage foam cells Leiro et al., 2004). Inhibition of both intracellular and extra- and causing endothelial dysfunction (Mietus-Snyder et al., cellular production of ROS by RS has been demonstrated 2000). RS was found to significantly decrease oxidative stress with a concentration ranging from 1 to 100 mmol/l (Jang and markers including serum glycated albumin and urinary Surh, 2001). RS has demonstrated strong anti-oxidant 8-hydroxyguanosine in stroke prone, spontaneously hyper- properties by reducing the rate of cytochrome C oxidation tensive rats (Mizutani et al., 2001). RS also enhances the by hydroxyl radicals, produced by irradiation

activities of and reduces ROS production in cardiac of hydrogen peroxide (H2O2) (Turrens et al., 1997). RS has tissue of guinea pigs (Floreani et al., 2003). Rocha et al. (2009) also shown to scavenge hydroxyl radicals (Soares et al., 2003)

have shown a reduction in oxidized LDL in high fat diet-fed and inhibit radical and H2O2 produced by

European Journal of Clinical Nutrition Anti-atherogenic effects of resveratrol VR Ramprasath and PJH Jones 663

Figure 2 Possible anti-atherogenic mechanisms of resveratrol. m Increase, k Decrease, ApoB, Apolipoprotein-B; CETP, Cholesterol ester transport protein; COX, Cyclo-oxygenase; FC, Free cholesterol; FFA, Free fatty acids; HDL, High density lipoprotein; IL, Interleukin; LDL, Low density lipoprotein; Lpn(a), Lipoprotein-A; LPG, Lipid peroxodation; PGE, Prostaglandin-E; ROS, ; RNS, Reactive species; TC, Total cholesterol; TD, Triglyceride; TNF-a, Tumour factor alpha; VCAM, vascular adhesion molecule; VLDL, Very low density lipoprotein. macrophages stimulated by lipopolysaccharides (LPS) or prevents the oxidation of polyunsaturated fatty acids found phorbol esters. RS effectively reduces 3H-arachidonic acid in LDL (Miller and Rice-Evans, 1995) and inhibits the release induced by LPS, phorbol esters or exposure to oxidized LDL uptake in the vascular wall in a concentra- superoxide or H2O2 (Martinez and Moreno, 2000) and tion-dependent manner (Fremont, 2000), as well as prevents significantly lowers levels of in platelets damage caused to lipids through peroxidation (Frankel and isolated from humans (Olas et al., 2004). Leonard et al. Waterhouse, 1993; Leighton et al., 1999). (2003) have demonstrated RS to be a strong anti-oxidant by RS suppresses oxidative stress by increasing the synthesis scavenging hydroxyl and superoxide radicals and protect the of nitric oxide in ischemic re-perfused tissues (Hattori et al., cells by preventing lipid peroxidation in the cell membranes 2002). RS has been shown to prevent the production of as well as DNA damage. RS has been shown to prevent lipid ROS stimulated by LPS (Martinez and Moreno, 2000) and to peroxidation and inhibit uptake of oxidized LDL (Fremont inhibit the ROS and lipid peroxidation induced by tumor et al., 1999; Leighton et al., 1999; Bhavnani et al., 2001). This necrosis factor (TNF) in a wide variety of cells including inhibition of lipid peroxidation by RS could arise from RS’ myeloid, lymphoid and epithelial cells (Manna et al., 2000). strong anti-oxidant effect and its ability to inhibit ROS gene- RS inhibits lipid peroxidation by effectively scavenging ration (Fremont et al., 1999; Olas and Wachowicz, 2002). various free radicals including peroxyl and hydroxyl radicals Oxidation of LDL cholesterol is strongly associated with in the post-ischemic re-perfused myocardium (Ray et al., risk of CVD (Holvoet, 2004). In rat liver microsomes, 1999). Inhibition of inducible nitric oxide synthase and RS inhibited -induced as well as ultraviolet-irradiated prevention of cytotoxic effects were also observed after lipid peroxidation and prevented LDL oxidation by copper treatment of RS (Tsai et al., 1999; Matsuda et al., 2000). (Fauconneau et al., 1997; Miura et al., 2000). RS could Bradamante et al. (2004) have explained in detail the effectively prevent oxidative LDL modification by inhibiting of RS in inhibiting lipid peroxidation. lipoxygenase enzyme activity (Maccarrone et al., 1999; Various mechanisms through which RS exerts anti-oxidant Kovanen and Pentika¨inen, 2003). in red wine effects are suggested (Zini et al., 1999). First, RS may compete including RS have been reported to inhibit LDL oxidation; with coenzyme Q and decreases the oxidative chain this effect was found to be stronger than the well-known complex III. Second, RS has been found to enhance the intra- anti-oxidant a-tocopherol (Frankel et al., 1993). RS also cellular free radical , as RS maintains

European Journal of Clinical Nutrition Anti-atherogenic effects of resveratrol VR Ramprasath and PJH Jones 664 cell viability and inhibits oxidation (Savaskan et al., 2003). by inhibiting the secretion of histamine and tumor necrosis Third, RS may increase endogenous anti-oxidants and factor-a (Carluccio et al., 2003). phase 2 in cardiomyocytes, and these increased Inhibition of vascular endothelial growth factor-induced cellular defenses provide protection against oxidative injury angiogenesis appears to occur by RS impairing the (Cao and Li, 2004). RS and its analogues are demonstrated as ROS-dependent pathway in human umbilical vein endo- effective anti-oxidants against linoleic acid peroxidation in thelial cells. (Lin et al., 2003). Reduction in pro-inflamma- sodium dodecyl sulphate and cetyltrimethylammonium tory cytokine -a was also shown by bromide micelles (Fang et al., 2002; Fang and Zhou, 2008). Rivera et al. (2009) after treatment of Zucker rats with RS at a The results suggested that the anti-oxidative actions involve dosage of 10 mg/kg body weight for 8 weeks. Pervaiz (2003) trapping the propagating peroxyl radicals on the surface of has demonstrated the influence of RS on the effect of nuclear the micelle and regenerating a-tocopherol. factor-kB, an important transcription factor that regulates various mediators or inflammation including cytokines, growth factors and adhesion molecules. RS possesses strong Modulation of anti-oxidant enzymes by RS anti-inflammatory effect by inhibiting leukocyte adhesion in Treatment with RS has been found to reduce the oxidative ischemia–reperfusion rat model at a dose of 0.7 mg/kg stress and prevent various diseases by increasing the (Shigematsu et al., 2003). activities of several anti-oxidant enzymes including super- Endothelial dysfunction is also reported to be an impor- oxide dismutase, catalase, glutathione, glutathione reduc- tant risk factor for CVD (Rodriguez-Porcel et al., 2001). tase, and glutathione-S-transferase Fukuda et al. (2006) have found that RS significantly in rat aortic smooth muscle cells (Yen et al., 2003; Li et al., increases myocardial angiogenesis in experimental 2006). RS has been demonstrated to maintain levels of myocardial infarction-induced rats through a vascular glutathione in oxidatively stressed human peripheral blood endothelial growth factor-mediated mechanism. Saiko et al. mononuclear cells, and to elevate glutathione levels in (2008) reviewed the beneficial effects of RS on arachidonic human lymphocytes activated by hydrogen peroxide (Losa, acid metabolism, where it was found that RS inhibits the 2003; Olas et al., 2004). A strong dose-dependent induction conversion of phospholipids to arachidonic acid. Further- of phase II drug metabolizing enzymes and anti-oxidant more, RS suppresses inflammation by inhibiting cyclooxy- genes was demonstrated when rats were supplemented with genase-1, -2; lipoxygenases, epoxygenases and synthesis of 0.3, 1 and 3 g/kg body weight per day of RS for 28 days prostaglandins and eicosanoids (Saiko et al., 2008). Hattori (Hebbar et al., 2005). Significant reductions in oxidative et al. (2002) and Hung et al. (2000) demonstrated the stress after treatment with RS by decreasing lipid hydroper- inhibition of inflammation and atheromatous plaque oxide and increasing anti-oxidant enzymes including super- formation by RS through altering the nitric oxide generation oxide dismutase in high fat diet-fed rats have been shown by from vascular endothelium. RS modulates the production Rocha et al. (2009). and secretion of inflammatory mediators and thereby suppresses the thrombogenic function of polymorpho- Anti-inflammatory effects of RS nuclear cells (Rotondo et al., 1998). The role of inflammation in the process of atherosclerosis has been increasingly well recognized over the past decade. Inflammation has a significant role at all stages of Role of RS on production of vasodilators and vasoconstrictors atherosclerosis including initiation, progression and plaque Endothelial cells are known to regulate and maintain a formation. (Libby et al., 2002; Jawien, 2008). Both in vivo and balance between vasodilators such as nitric oxide and in vitro anti-inflammatory effects of RS and the underlying vasoconstrictors such as endothelin-1, as well as reduce mechanism have been suggested (Udenigwe et al., 2008). the risk of atherosclerosis by preventing atherogenesis RS inhibits the activity of cyclooxygenase-2, which is the (Davignon and Ganz, 2004). RS has been reported to enzyme producing PGE2, a vital component to mediate influence and maintain a balance between production of inflammation (Donnelly et al., 2004). Interleukin-6 has been vasodilators and vasoconstrictors, respectively (Fan et al., implicated as an important marker in the process of 2008). Reduction in nitric oxide production results in inflammation and the progression of atherosclerotic vasoconstriction, platelet aggregation and oxidative stress. plaques (Ikeda et al., 2001). Cultured murine macrophages, Furthermore, RS inhibits the enzyme cyclooxygenase-1, after treatment with RS, have been shown to reduce gene which is a strong vasoconstrictor and has an important role expression, synthesis and secretion of interleukin-6 (Zhong in platelet aggregation (Szewczuk et al., 2004). Increased et al., 1999). The inflammatory process was found to be activity of nitric oxide synthase was found in pulmonary suppressed by RS, through mediating various inflammatory artery endothelial cells when treated with RS, which markers such as inhibition of secretion of interleukin-8 and indicates the direct association of nitric oxide in vasorelaxa- granulocyte macrophage colony-stimulating factors (Culpitt tion (Klinge et al., 2003). RS has been shown to increase the et al., 2003; Donnelly et al., 2004), endothelial-leukocyte expression of nitric oxide synthase and hence, potentially adhesion molecules, vascular cell adhesion molecule-1, and protect perfused working hearts (Hattori et al., 2002),

European Journal of Clinical Nutrition Anti-atherogenic effects of resveratrol VR Ramprasath and PJH Jones 665 although RS failed to show such protective effect in nitric levels, inhibiting hepatic triglyceride synthesis and reducing oxide synthase knockout mice (Imamura et al., 2002). cholesterol and triglycerides accumulation in liver. However, These results confirm the effect of RS in balancing vaso- contradicting results emerging from some studies fail to constrictors and vasodilators, thereby preventing platelet show a change in lipids and lipoprotein profile after aggregation and oxidative stress, which leads to reduction treatment with RS. Such discrepancies among the results of in CVD risk. various studies may reflect differences in the various experimental models used. Promising findings by several groups have demonstrated the potential cardioprotection of Suppression of platelet aggregation by RS RS by reducing atherosclerotic plaque formation and Platelet aggregation has an important role in mediating preventing oxidation of LDL cholesterol. Also, persuasive atherosclerosis, whereby platelets adhere to cell surfaces, data suggest that RS prevents arterial vasodilation and releasing platelet-derived growth factor and induces athero- influences infarct size, as well as apoptosis and angiogenesis. sclerosis. Enhanced or impaired platelet aggregation results Another principal mechanism of action of RS in cardiopro- in various complications including myocardial infarction, tection is through reduction of oxidative stress. RS possesses ischemia and stroke. However, RS has been shown to inhibit strong anti-oxidant potential, reducing ROS production, as the aggregation of platelets (Bertelli et al., 1996b; Bhat et al., well as attenuating peroxyl radicals and hydrogen peroxide. et al 2001; Fan ., 2008). Suppression of platelet aggregation by Consumption of RS also induces various anti-oxidant genes RS in rabbits supplemented with hypercholesterolemic diet and enzymes and phase II drug metabolizing enzymes. RS and reduced atherosclerosis in genetic hypercholesterolemic downregulates pro-inflammatory cytokines thereby et al et al mice were also demonstrated (Zini ., 1999; Wang ., suppressing inflammation through nitric oxide-dependent 2002b). However, RS failed to demonstrate such effects in mechanisms. RS also regulates and maintains the balance whole blood as the mechanism might be through inhibition between vasodilators and vasoconstrictors and reduces et al of mitogen-activated protein kinases in platelets (Kirk ., the risk of atherosclerosis by preventing atherogenesis. RS 2000). Various mechanisms of action of RS have been shown has been shown to increase the expression of nitric oxide to inhibit platelet aggregation including the inhibition of synthase and inhibit cyclooxygenase-1 and hence, have an platelet adhesion to type I , the principal step in important role in balancing vasodilation and constriction platelet activation. Olas et al. (2002) demonstrated that as well as platelet aggregation. In conclusion, promising pretreatment of platelets with RS prevents LPS or thrombin evidence depicting beneficial effects of RS supports the stimulated platelet adhesion to collagen and fibrinogen. health claim that RS could be used in the prevention and These findings provide more insight to the suppressive effect treatment of several diseases including CVD. of RS on platelet aggregation.

Safety aspects of RS treatment Conflict of interest Several investigations with human and various animal models have demonstrated an absence of significant toxic The authors declare no conflict of interest. effects after supplementation with RS across a wide range of dosages. No toxic effects were found in rats after oral administration of 20 mg/kg per day for 28 days (Juan et al., References 2002). Doses used in these studies were 1000-fold higher than the amount consumed by humans drinking one glass of Ahn J, Cho I, Kim S, Kwon D, Ha T (2008). Dietary resveratrol alters lipid metabolism-related gene expression of mice on an athero- red wine per day. Furthermore, no adverse effects were seen genic diet. J Hepatol 49, 1019–1028. in rats supplemented with RS at 300 mg per day for 4 weeks Arichi H, Kimura Y, Okuda H, Baba K, Kozawa M, Arichi S et al. (Crowell et al., 2004). Boocock et al. (2007) reported no (1982). Effects of stilbene components of the roots of Polygonum toxicity in humans administered with a single dose of RS up cuspidatum Sieb. et Zucc. on lipid metabolism. Chem Pharm Bull 30, 1766–1770. to 5 g. The results of these studies signal that RS could be Bertelli AA, Giovanni L, Stradi R, Urien S, Tillement JP, Bertelli A consumed for its beneficial effects without any apparent (1996a). Kinetics of trans- and cis-resveratrol (3,40,5-trihydroxy- toxicity. stilbene) after red wine oral administration in rats. Int J Clin Pharmacol Res 16, 77–81. Bertelli AA, Giovannini L, Bernini W, Migliori M, Fregoni M, Bavaresco L et al. (1996b). Antiplatelet activity of cis-resveratrol. Summary and conclusion Drug Exp Clin Res 22, 61–63. Bhat KPL, Kosmeder 2nd JW, Pezzuto JM (2001). Biological effects of RS has been shown to have an important role in maintaining resveratrol. Antioxid Signal 3, 1041–1064. human health and preventing various diseases including Bhavnani BR, Cecutti A, Gerulath A, Woolever AC, Berco M (2001). atherosclerosis. The anti-atherogenic actions of RS have been Comparison of the antioxidant effects of equine estrogens, red wine components, E, and probucol on low-density shown to involve various mechanisms (Figure 2). RS appears lipoprotein oxidation in postmenopausal women. Menopause 8, to be beneficially modulating the lipid and lipoproteins 408–419.

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