Antioxidant effects and mechanism of silymarin in oxidative stress induced cardiovascular diseases

Biomedicine & Pharmacotherapy 102 (2018) 689–698

Contents lists available at ScienceDirect

Biomedicine & Pharmacotherapy journal homepage: www.elsevier.com/locate/biopha

Review

Antioxidant effects and mechanism of silymarin in oxidative stress induced cardiovascular diseases

T

Abdoh Taleba, Khalil Ali Ahmada, Awais Ullah Ihsanb, Jia Qua, Na Lina, Kamal Hezamc, ⁎ Nirmala Kojua, Lei Huia, Ding Qilonga, a

Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Longmian Avenue, 639, Nanjing, Jiangsu 211198, China Department of Clinical Pharmacy, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu Province, 211198, China c Antibody Engineering Laboratory, School of Life Science and Technology, China Pharmaceutical University, Longmian Avenue, 639, Nanjing, Jiangsu 211198, China b

A R T I C LE I N FO

A B S T R A C T

Keywords: Antioxidants CVDs Oxidative stress ROS Silymarin

Cardiovascular diseases (CVDs) are considered as the major reason for mortality and morbidity worldwide. Substantial evidence suggests that increased oxidative stress plays a significant role in the pathogenesis of CVDs, including atherosclerosis, hypertension, vascular endothelial dysfunction and ischemic heart disease. Cellular oxidative stress results in the release of toxic free radicals by endothelial cells and vascular smooth muscle cells that interact with cell components such as protein, DNA or lipid resulting in cardiovascular pathology. Silymarin has antioxidant activities against CVDs and offers protection against oxidative stress-induced hypertension, atherosclerosis and cardiac toxicity. We present a comprehensive review regarding the oxidative stress and protective effects of silymarin in CVDs management. We also aim to provide mechanistic insight of the mechanisms of silymarin action in oxidative stress-induced CVDs.

1. Introduction Cardiovascular diseases (CVDs) are the diseases of heart and blood vessels that include the blood vessel diseases, rheumatic heart, and congenital heart diseases. Patients with heart diseases are more susceptible to the development of diabetes and renal diseases. CVDs stay the leading cause of death globally accounting for 17.3 million deaths per year. The estimated cost of CVDs is more than $316.1 billion. Thus novel therapies are required to limit the burden of CVDs [1]. Risk factors for CVDs include imbalance diet, physical inactivity, age, gender, tobacco use, total cholesterol, and high-density lipoprotein cholesterol [2–5]. These factors are monitored in the primary care centres to limit the risk of developing heart diseases [6]. Different strategies such as lifestyle modifications and nutritional habits are considered for management of CVDs risk factors [7]. The primary step in the pathogenesis of CVDs is the endothelial damage in which the underlying cell layers expose to harmful inflammatory process that ultimately leads to the formation of lesions [8]. Cellular oxidative stress is the prime pathogenic factor for CVDs due to the release of toxic free radicals by endothelial cells and vascular smooth muscle cells [9,10]. Free radicals are reactive oxygen species (ROS) with an unpaired free electron in their outer most orbital. They interact with cell components such as protein, DNA or lipid and strip

⁎

their electrons to become stabilize [11]. For example, Superoxide and nitric oxide are prime oxidants that play an important role in cardiovascular pathology [12,13]. Antioxidants are substances that quench reactive oxygen species and reduce the oxidative stress damage [14]. Flavonoids are widespread polyphenolic antioxidants, available in a variety of fruits and vegetables. Silymarin is one of the polyphenolic antioxidants [15] and belongs to family Asteraceae. It is an annual herb with large leaves, hard spikes and tubular flowers [16] and native to the Mediterranean region of Europe but naturalized in California and the eastern United States [17]. Silymarin is used by herbalists and physicians for the treatment of different types of liver diseases, tumors, cardiovascular and neurodegenerative diseases [18,19]. It is extracted from the seeds of milk thistle plant as a mixture of three structural isomers (i) silybin & isosilybin (ii) silydianin & isosilydianin and (iii) silychristin &isosilychristin and minor components of quercetin and taxifolin [15,20]. Silybin or Silibinin being the main component in the silymarin mixture has antioxidant and anti-inflammatory activities [21]. Absorption of silymarin after oral administration is rather low and peak plasma concentrations are achieved in 6 hours, in animal and humans. However, some authors reported plasma level of 500 mg/L (as silibinin) 90 minutes after oral administration of 200 mg/kg of silymarin in mice [22,23]. It is quickly metabolized via phase II enzymes, and elimination

Corresponding author. E-mail address: [email protected] (D. Qilong).

https://doi.org/10.1016/j.biopha.2018.03.140 Received 11 January 2018; Received in revised form 22 March 2018; Accepted 22 March 2018 0753-3322/ © 2018 Elsevier Masson SAS. All rights reserved.

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

Fig. 1. Schematic presentation of the sources of ROS (NADPH oxidase, Xanthine, Mitochondria) and the resulting oxidative damage to cellular Protein, DNA and Lipids [11,51]. Silymarin shows mechanisms of actions as a scavenger of free radicals (OH%, O2%−), enhances antioxidant enzymes (CAT, SOD, GPx) thereby increasing the antioxidant cell defense and increases mitochondrial enzymes activity. It also inhibits expression of eNOS and MAPK (ERK1, 2, JNK), activates Nrf2 and inhibits NF-kB, thereby regulates gene expressions [189]. Silymarin increases the regenerative ability of cardiovascular tissues by activating ribosomes and increases protein synthesis. It has been shown to stabilize the cellular membrane through modifying the transporters and receptors of cell membranes such as ABC transporters and organic anion uptake transporter peptides [193]. Silymarin has protective and cell-regenerating actions in a cell membrane, scavenges free radicals in the cytoplasm, and promotes ribosomal RNA synthesis, consequently improving the cardiovascular dysfunction and dyslipidemia [23].

2. Reactive oxygen species and CVDs

half-life ranges from 6 to 8 hours. Silibinin and other components of silymarin are rapidly conjugated with sulfate and glucuronic acid in the liver. The conjugates pass into the plasma and into the bile, where they are found in amounts corresponding to 80% of the total dose administered [23]. Poor bioavailability of silymarin extract is mainly due to accompanying substances or the concentration of the extract itself. Thus solubilizing agents are added to the extract to achieve therapeutic plasma level [24,25]. Silymarin is commercially available as capsules and caplets in doses of 120 mg, 160 mg, 250 mg, and 300 mg under the brand name legalon. Its dose ranges from 280 to 800 mg/kg of body weight, and usual dosage is 1-2 tablets twice daily with a meal [26]. Consumption of acute doses of silymarin has been reported as safe and non-toxic to animals and humans. Rare side effects include mild gastrointestinal disturbance, nausea, and headache in clinical trials [27,28]. Silymarin has antioxidant activities against CVDs and offers protection against oxidative stress-induced hypertension, atherosclerosis, and cardiac toxicity. The purpose of this review is to highlight the current knowledge regarding the role of reactive oxygen species in inducing CVDs and antioxidant effects and mechanism of silymarin in preventing oxidative stress-induced CVDs (Fig. 1).

Oxidative stress is defined as an imbalance between the formation of reactive oxygen species (ROS) and the capacity of the body to detoxify them [29,30]. They are signaling molecules produced in cells as byproducts of normal cellular oxidation-reduction reaction[31,32]. ROS include superoxide (O2ˉ), hydrogen peroxide (H2O2), hydroxyl radical (OH˙) and lipid peroxy radical (LOO˙) [31]. Besides, it also includes reactive nitrogen species such as nitric oxide (NO), nitrogen dioxide radical (NO2), nitrosonium cation (NO+) and peroxynitrite (ONOO−). These reactive species can modify and alter the function of lipids and proteins by reacting with cellular components [33,34]. Peroxidation of membrane lipids is toxic and alters the biological properties of the cell membrane leading to inactivation of membrane-bound receptors or enzymes and impairing normal cellular function [35]. Reduction in Na + /K+ -ATPase activity in cell membrane correlates with elevation of lipid peroxidation products in pre-hypertensive patients, suggesting that ROS underlie some of the pathophysiological aspects linked to this condition [36]. Cardiac and vascular tissues are rich sources of ROS that play an

690

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

was more marked in NOX2-deficient patients [66,67] suggesting that a partial reduction of NOX2 may lead to enhance endothelial function. The mechanism underlying an improved artery dilatation was attributed to increasing NO production, resulting in vasodilation detected in the animal knockout for NOX [68,69]. Nox4 isoform is highly expressed in endothelial cells, and its byproduct includes O2−% which rapidly dismutases to H2O2 [70]. Nox4 produces the low concentration of H2O2rather than O2−%. It is incapable of NO scavenging and acts as an endogenous anti-atherosclerotic enzyme[71]. ROS production due to NADPH oxidase is regulated by nuclear factor Nrf2 that has a crucial transcription factor mediating protection against oxidants [72]. Increased NADPH oxidase expression has been observed in the vascular endothelium during the pre-atherosclerotic state. In blood vessels, angiotensin II acts via angiotensin type I (AT1) receptor to elicit a powerful stimulus for ROS generation from NADPH oxidase [73]. Moreover, several components of the renin-angiotensin system (RAS) including angiotensinogen, angiotensin-converting enzyme, and AT1 receptors are present in the human adipose tissue. Angiotensinogen is overproduced in increased visceral fat, and RAS may be able to activate in individuals with metabolic syndrome [74]. A rise in adipose RAS may result in toxic local and systemic effects in obese persons and contributes to insulin resistance and hypertension. Some drugs such as statins have antioxidant properties and reduce ROS production by reducing vascular NADPH oxidase activity and lipid generation in the vascular cells [75].

important role in CVDs [37]. Moreover, increased ROS concentration and altered redox signaling have been suspected in inducing endothelial dysfunction in vessels [38]. Numerous studies support the involvement of oxidative stress in the pathogenesis and development of CVDs like hypertension, atherosclerosis, ischemia, vascular dysfunction, Cardiotoxicity, cardiomyopathies and heart failure [14,39–42].Oxidative stress results in higher blood pressure in the presence of other prohypertensive factors (salt, renin-angiotensin system, sympathetic hyperactivity) [43]. Oxidative stress is linked to arrhythmic risk which alters multiple cardiac ionic currents and causes the molecular mechanism of ROS-induced arrhythmia [44]. ROS accumulation in the vascular wall leads to low-density lipoprotein (LDL) oxidation that results in early-stage atherosclerosis [45]. ROS overproduction is also associated with increasing age that may lead to CVDs [46]. Pro-oxidant pathways stimulate the process of aging. Oxidative stress can stimulate phosphorylation of the redox-sensitive transcription factor p53 by activating p38 mitogen-activated protein kinases (p38 MAPK) and Protein-kinase C (PKC), that are involved in stimulation of mitochondrial-mediated patterns implicated in reducing lifespan [47]. Oxidative stress in the aging process makes the human more susceptible to CVDs, e.g. Atherothrombosis in elderly. Cellular metabolism in the heart causes the reduction in antioxidants and enhanced production of oxy-radicals leading to increased oxidative stress in sarcolemma, sarcoplasmic reticulum, mitochondria, myofibrils, and nucleus. All these changes cause Ca2+ handling abnormalities, decrease energy stores, and reduce sensitivity to Ca2+ and DNA fragmentation. These defects in subcellular organelles finally lead to Myocyte dysfunction [40]. Superoxide and nitric oxide radicals in cardiovascular system react and form peroxynitrite free radical to facilitate CVDs [48]. Peroxynitrite is extremely active intermediate in the process of increasing vascular tone, which reduces cardiac output and increases myocardial oxygen demand and finally exacerbates the heart failure syndrome [49].

3.2. Mitochondria Mitochondria are the most significant endogenous origin of ROS production by oxidative phosphorylation. Damaged mitochondria produce more oxidative stress and less cellular energy than normal mitochondria. ROS are usually generated on the inner side of the mitochondrial membrane through the mitochondrial electron transport chain machinery [76–78]. In mitochondria, electron movements from the Krebs cycle FADH2 or NADH molecules by four complexes catalyze the reduction of molecular oxygen to water through four single-electron transfer reactions. These electrons are capable of reducing molecular oxygen or other electron acceptors and generate free radicals, e.g. O2−% [79]. Mitochondrial electron transport reduces 95% of O2 by tetravalent reduction to H2O without any free radical intermediates. It causes reduction of remaining 5% of oxygen via the univalent pathway and produces free radicals such as superoxide, which dismutases to hydrogen peroxide in the presence of Superoxide dismutase(SOD), leading to ROS generation [80].

3. Sources of ROS in cardiovascular system ROS in cardiovascular organs are derived from both endogenous sources (NADPH oxidase, Mitochondria, Xanthine oxidase and uncoupled nitric oxide synthases) and exogenous sources (environmental toxins, chemical toxins, radiations, ultraviolet light, smoking, some pharmaceuticals agents) [50–53]. These sources generate an elevated concentration of ROS and subsequent cardiovascular tissue injury. 3.1. NADPH oxidase NADPH oxidases (NOXs) are the major enzymatic source of ROS in cardiovascular system[54]. They are membrane-bound proteins [54,55] and generate ROS either within the cellular milieu or in the extra-cellular space in the cellular membrane, nucleus, endoplasmic reticulum and mitochondria [56]. NADPH oxidases isoforms consist of a number of catalytic subunits (Nox1, Nox2, Nox3,Nox4, Nox5, Duox1and Duox2), and accessory subunits (p22phox, p47phox, p67phox and Rac1–2) [57,58]. They catalyze superoxide anion (O2−) production by the 1 electron reduction of molecular oxygen with the help of NADPH as the electron donor. In response to specific upstream stimuli, the NOXs transfer electrons from the substrate NADPH to the molecular Oxygen, leading to either superoxide (O2-) or H2O2 production [59]. NADPH oxidases can exert damaging as well as protective effects in the vascular system. NOX2, NOX4, NOX5, and NOX1 are mainly implicated in the pathogenesis of atherosclerosis [60,61]. NOX2 is frequently expressed in endothelial cells [62], and cardiomyocytes [63] and its activation is involved in the development of atherosclerosis [64]. However, the preventive effects of NOX2 deficiency against atherosclerosis development have also been reviewed [65]. Flowmediated dilatation (FMD) is a marker of atherosclerosis and has been evaluated in NOX2 deficient individuals. Results indicated that FMD

3.3. Xanthine oxidase Xanthine oxidases are a form of xanthine oxidoreductase, located in the endothelial cells. This enzyme is considered as an important source of ROS production in ischemia-reperfusion injury associated with heart attacks [81]. Xanthine oxidase donates the electron to molecular oxygen and generates ROS that stimulate the oxidation of hypoxanthine into xanthine, and finally into uric acid [82]. Xanthine oxidase is reduced by allopurinol which is used in the treatment of gout [83,84]. 3.4. Uncoupled nitric oxide synthases Nitric oxide is a transmitter produces by endothelial nitric oxide synthase (eNOS) and plays a significant role in vasodilatation of blood vessels [85,86]. The tetrahydrobiopterin is an important cofactor to regulate the activity of nitric oxide enzyme (coupled NO). In the absence of this cofactor, nitric oxide is converted to uncoupled NO and produces ROS (O2−) instead of nitric oxide transmitter [86–88] in the vascular system that causes endothelial dysfunction leading to hypertension[89]. 691

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

4. Protective effects of antioxidants and silymarin in CVDs

tone of blood vessels. Endothelial dysfunction is defined as the systemic disorder characterized by an abnormal vascular function that may lead to initiation and progression of atherosclerosis [109]. Silymarin exerts a positive effect on various types of vascular diseases. E.g., rats were administered with 250 mg/kg/day of silymarin for eight days that improved lung ischemia-reperfusion injury induced pulmonary vascular dysfunction through the hypoxia-inducible factor-1α (HIF-1α) and inducible nitric oxide synthase (iNOS) mechanism in pulmonary vascular dysfunction rat model [110]. Likewise, silymarin efficiently retrieved the normal function of endothelium and vascular elasticity as compared to estrogen replacement in rat aortas tissues when incubated with 50 mg/L silymarin and 10 μM ß-estradiol. Silymarin improved the endothelial function by increasing the smooth muscle relaxation to sodium nitroprusside drug and reducing phenylephrine hydrochloride (PE), and potassium chloride (PCl) contractility of ovariectomized (OVX) rats [111]. Silibinin is a significant component of silymarin. The daily dose of 20 mg/kg Silibinin administered to diabetic mice has shown to improve the endothelial dysfunction by lowering the plasma and aorta asymmetric dimethylarginine (ADMA) levels and reducing nitric oxide synthase (NOS) inhibition [112]. Silymarin also improved in reinstating the endothelial dysfunction and vascular elastically in aged rats [113]. Oxidative stress leads to decreased bioavailability of nitric oxide (NO) and produces harmful peroxynitrite, causing endothelial dysfunction [8]. Silymarin maintains the level of nitric oxide that regulates the vascular tone human umbilical vein endothelial cells (HUVECs) and reduces the vascular stiffness, therefore reducing endothelial dysfunction, that is considered a leading cause of atherosclerosis [114].

Antioxidants are molecules that inhibit the chain reaction of oxidative stress and protect cellular components from injury [90,91]. They are classified into enzymatic and non-enzymatic antioxidants. Enzymatic antioxidants include Superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GRX) and catalase (CAT). Non-enzymatic antioxidants, based on their source of origin, are divided into exogenous and endogenous antioxidants. The endogenous antioxidant is glutathione (GSH) also called master antioxidant, uric acid, and albumin, while the exogenous antioxidants include carotenoids, ascorbic acid (Vit-C), α- tocopherol (Vit-E) and flavonoids [92,93]. These antioxidants prevent the lipids, proteins, and DNA of cells from damaging effects of ROS [90]. Antioxidant enzymes, e.g., Mn-SOD in mitochondria or Cu/Zn-SOD in cytosol catalyze the dismutation of superoxide anion O2−% to O2, and finally to H2O2 [94]. CAT or GPX finally converts H2O2 to water and oxygen [95]. Some studies demonstrated an increased incidence of coronary heart disease due to the reduction in antioxidants [96]. Decreased level of antioxidants have also been observed in heart diseases, e.g., SOD level was found decreased in a patient suffering from myocardial infarction and angina pectoris [97] while, consumption of antioxidants chiefly vitamin C and vitamin E reduce the incidence of CVDs in some patients [98]. It should be noted that antioxidants, in case of CVD patients, cannot reverse the damage but only minimize the CVDs complications [99]. Numerous drugs possess antioxidant properties, e.g., Nebivolol; a β1 receptor antagonist activates eNOS to stimulate NO formation. This drug has positive effects on endothelial function and heart in case of hypertensive heart disease [100]. Other antioxidants drugs such as statins, ascorbic acid, and α- tocopherol have also been used in preventing CVDs [93]. Biomarkers of oxidative stress are relevant in the assessment of the disease status and health-enhancing effects of antioxidants [101]. The role of oxidative stress in cardiovascular pathophysiology has encouraged quantification of ROS as a promising biomarker that reflects the disease initiation and progress. Biomarkers of oxidative stress and antioxidants could be useful in diagnosing CVDs. However, this has proven to be a difficult task given the transitory nature of ROS [102]. Elevated serum markers of lipid peroxidation with end product reactive aldehydes, such as malondialdehyde biomarkers are predictors of oxidative stress [35]. Nitrotyrosine and Myeloperoxidase are also considered as promising biomarkers for CVDs risk prediction [101]. Antioxidant defense enzymes, e.g., GPx, and CAT may serve as a potential biomarker. The oxidative modifications enhance their validity as a proposed biological marker of cardiovascular diseases [103]. Silymarin has antioxidative effects in both animals and humans. Increased level of antioxidants and decreased level of oxidative stress have been observed after treatment with silymarin. Silymarin as the herbal antioxidant is used in preventing CVDs with fewer side effects and can scavenge ROS and enhances antioxidant enzymes. For that, silymarin is more effective than others antioxidants [104]. It is at least ten times more powerful as compared to vitamin E [105]. Silymarin increases the membrane stability and helps in tissue regeneration [106]. It has therapeutic effects in the treatment of nonalcoholic fatty liver disease (NAFLD), and Meta-analysis of randomized control trials indicated that silymarin caused significant reduction of AST and ALT levels [107]. Meanwhile, if incipient NAFLD progresses, the ensuing CVDs remain the primary cause for the high mortality of NAFLD patients [108]. Protective role of silymarin in CVDs including Vascular Dysfunction, Hypertension, Ischemia, Cardiac Hypertrophy, Cardiotoxicity Ischemia and Cardiac Hypertrophy have been discussed below in detail and summarized in Table 1.

4.2. Hypertension Hypertension is a multifactorial disorder of different internal mechanisms which contribute to the pathology of blood pressure. It is considered as the primary risk factor for CVDs [115–117]. Oxidative stress has a pivotal role in inducing hypertension by increasing levels of Ang II /Aldosterone, H2O2, O2–· and decreasing the production of NO [118,119]. The levels of free radical scavengers such as Vit-E, GSH and SOD have been reported to be decreased in hypertensive patients [120]. Hypertension is also associated with elevated ROS formation in various organs including vasculature, kidney, and brain [121]. Silymarin has protective effects against hypertension by reducing oxidative stress [122–124]. The oral dose of silymarin (300 mg/kg) for 8–12 days caused reduction of death rates in hypertensive rats. Silybin decreased hypertension and incidence of post-occlusion arrhythmias in hypertensive rats to the same extent as that of positive control drug, tetrandrine. The author concluded that silybin might be useful in hypertensive patients, experiencing acute myocardial infarction [125]. Silymarin also regulated hypertension induced by Deoxycorticosterone acetate (DOCA) salt in rats [126]. Multiple daily doses of oral silymarin (300, 500 mg/kg/) resulted in the reduction of pulse and blood pressure (systolic) in hypertensive rats. Antihypertensive effects of silymarin are due to its antioxidant activity which increases the enzymatic level (GSH, SOD, CAT), and decreases oxidative stress markers, e.g., Thiobarbituric acid (TBARS) level and urinary K + excretion [104]. Silymarin is an antagonist for the human angiotensin AT1 receptor. It blocks the interaction of angiotensin II [127], thereby increasing smooth muscle relaxation and promoting water and salt excretion, thus reducing the blood pressure. Silymarin exerts its effect through direct antioxidant action [41], similar to the classic antihypertensive agents (e.g., Ang II candesartan) [128]. Furthermore, administration of silymarin in normotensive rabbits helped in lowering the intraocular pressure (IOP) by interfering with aqueous humor formation [129]. Instilled Silibinin solution (0.75%) was found to reduce IOP more than pilocarpine 2% drops in normotensive rabbits, whereas their combination extended the duration of the IOP-reducing effect. Further extensive clinical studies in humans are needed to strengthen the fact of

4.1. Vascular dysfunction Endothelium layer has a significant positive effect on the vascular 692

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

Table 1 summarizes experimental results of doses and effects of silymarin in humans and animal models. Silymarin improves cardiovascular diseases by normalizing biological parameters and restoring cardiovascular function. Model

Dose of Silymarin

Findings (effects)

References

Rats Rats Mice HUVECs Rats Rats Rabbits Rats Rats Human Mice Rats HUVECs Rabbits Human Rats Human

250 mg/kg/day 50 mg/L 20 mg/Kg/day 6.25 – 25 ug/ml 300 mg/kg daily 300,500 mg/kg/day 0.75% drops 100 - 200 mg/kg 1–10 g/kg, i.v 140 mg/Td 30 mg/kg 50 mg/kg 6.25 – 50 ug/ml 200 mg/kg 150 mg/Td/6months 100 mg/kg 600 mg/ Bd oral cap

Improves pulmonary vascular dysfunction Restore endothelial function and vascular tone Improves endothelial dysfunction Protects ECs, ↑ nitric oxide content Reduces blood pressure lowers BP and heart rate Lowers intraocular pressure (IOP) Protects abdominal aorta I/R injury Reduces cerebral ischemic/reperfusion Cardioprotection for coronary artery bypass Attenuates cardiac hypertrophy, ↓NF-kB Normalize parameters, reduce cardiotoxicity Anti-atherosclerotic activity, ↓TNF- α Decreases cholesterol, ↓triglyceride, ↑HDL Reduces plasma lipids, ↑HDL Anticholesterolemic ↓ plasma lipids, ↑HDL Reduces cholesterol, triglyceride, ↑HDL

[110] [111] [112] [114] [125] [126] [129] [131,132] [133] [136] [141] [146] [159] [160–163] [164] [165] [168]

4.4. Cardiotoxicity

silymarin as a normotensive adjuvant drug.

Cardiotoxicity is the occurrence of heart electrophysiology dysfunction or muscle damage. The heart becomes weaker and is not capable of pumping and circulating blood. Cardiotoxicity may be caused by chemicals including metals, environmental pollutants, oxidative agents, chemotherapy drugs or other medications [143]. Studies suggest the plausible role of oxidative stress in inducing cardiac toxicity [144,145]. Antioxidants are useful in the treatment of cardiotoxicity and studies revealed the possible preventive effects of silymarin against cardiotoxicity induced by chemicals [146]. Administration of dose-dependent silymarin (50 mg/kg) in male rats with cardiotoxicity induced by Adriamycin resulted in normalizing the biological parameters, e.g., GSH, lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and lipid peroxides levels and protecting the heart through inhibition of lipid peroxidation [147]. Silymarin protects the heart muscles of mice against environmental pollutants such as acrolein-induced cardiotoxicity at the dose of 100 mg/kg by reducing lipid peroxidation, elevating antioxidant enzymes level, and preventing apoptosis [148]. Recent studies indicated that silymarin reduced the concentration of LDH, CPK, aspartate transaminase (AST) and increased the level of GSH enzyme in doxorubicin-induced cardiotoxicity in rats. Thus, silymarin has robust cardio-protective efficacy against doxorubicin toxicity and could be used in combination with doxorubicin. The protective effects of the silymarin against cardiotoxicity induced by doxorubicin include radical scavenging, iron chelating and cell membrane stabilization [149,150]. For that reason, silymarin may be used as a novel therapeutic agent in combination with anti-cancer medications to prevent cardiotoxicity induced by anti-tumor drugs.

4.3. Ischemia and cardiac hypertrophy Ischemic heart disease refers to the reduction in the blood supply to the heart due to thrombosis, atherosclerosis or coronary artery spasm [37,130]. In the experimental study, rats were administered with intraperitoneal silymarin in the dose of 200 mg/kg. Results showed that rats incurred significantly minor damage to the kidneys, lungs, and liver than the control group, while no significant change on myocardium was observed. Silymarin reduced ROS level in the rat model and protected the lungs, liver, and kidneys from acute supraceliac abdominal aorta ischemia/reperfusion injury [131]. Silymarin in the dose of 100 mg/kg for 7 days was found effective in protecting kidney of rats from ischemia/reperfusion (I/R) injury by increasing the antioxidant enzymes levels, e.g., superoxide dismutase and glutathione peroxidase and reducing urea, creatinine, and cystatin in the serum [132]. Dose-dependent i.v administration of silymarin (1–10 g/kg) also reduced cerebral ischemic/reperfusion (CI/R) in rats. This study revealed that rats were protected from CI/R-induced stroke injury by silymarin via quenching free radicals and reducing the inflammatorymediated tissue injury by blocking the activation of proinflammatory transcription factors, e.g., signal transducer and activator of transcription (STAT)-1) and Nuclear Factor(NF)-kappa B [133,134]. Silymarin scavenged free radicals and reduced the inflammation and oxidant stress markers in mesenteric ischemia/reperfusion injury in rats through increased serum levels of circulating heat shock protein (Hsp)70, tumor necrosis factor-α (TNF-α), SOD, and thiobarbituric acid reactive substance (TBARS) [135]. Pre-operative administration of silymarin might reduce the preoperative morbidity and myocardial injury during coronary artery bypass grafting surgery during maintenance of cardiac enzymes, e.g., creatine kinase (CK)-MB [136]. Cardiac hypertrophy is a determinant of congestive heart failure [137]. Previous studies indicated that silymarin inhibited the NF-kB pathway [138] and helped in improving and attenuating cardiac hypertrophy [139,140]. Administration of varying doses of Silibinin blocked the cardiac hypertrophy by inhibiting the NF-kB activation and reduced the generation of the epidermal growth factor receptor (EGFR) [141]. Silymarin attenuated the phenylephrine-stimulated phosphorylation of extracellular regulated kinase 1 and 2 (ERK1/2) and phenylephrine phosphorylation of protein kinase B (Akt). It also diminished the phenylephrine stimulated a hypertrophic response in heart-derived H9c2 cells [142].

4.5. Hypercholesterolemia and atherosclerosis Hypercholesterolemia is characterized by elevated level of blood cholesterol [151]. Cholesterol is a waxy, fat-like substance that accumulates in the blood vessels [152] and helps in the production of essential substances required for normal biological processes in the cell membrane [153,154]. However, high amount of cholesterol in the body tends to increase the risk of developing heart diseases (particularly coronary artery disease) [155]. Hypercholesterolemia in combination with arterial hypertension accelerates the process of atherosclerosis [156]. Increased ROS formation may facilitate the oxidation of LDH in atherosclerosis, so antioxidants are effective against hypercholesterolemia-induced atherosclerosis through reduction of low-density lipoprotein (LDL) cholesterol level [157]. Silymarin antioxidant has an anti693

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

5.2. Prevents ROS formation enzymes e.g. NAPDH oxidases and xanthine oxidase

hyperlipidemic and anti-atherosclerotic activity and inhibits the expression of adhesion molecules [158]. Silymarin in different concentrations (6.25 - 50 ug/ml) suppressed the TNF-α induced DNA binding of NF-κB/Rel in HUVECs [159]. The effects of daily dose of 200 mg/kg of silymarin and 10 mg/kg of levostatin on serum lipoprotein and atherosclerosis development were demonstrated in hypercholesterolemic rabbits. The results showed significantly lower cholesterol and triglyceride level, enhanced highdensity lipoprotein (HDL) cholesterol levels and reduced atherosclerotic plaque in the arteries [160–163]. Treatment of dyslipidemia with the daily dose of 150 mg of flavonoids in humans for six months improved the lipoprotein profile HDL- cholesterol and caused an overall reduction in plasma lipids (total cholesterol, triglycerides) [164]. Silymarin in the dose of 100 mg/kg was administered to rats previously fed with high cholesterol diet to evaluate its anti-cholesterolemic effects. An increase in HDL-cholesterol and drop in the liver cholesterol contents were observed. Moreover, inhibition of high cholesterol diet-induced reduction in the level of liver glutathione antioxidant was also observed [165]. However, serum cholesterol level was not reduced after parenteral administration of silymarin in rats [166], suggesting that silymarin exerted its effect via fat-mediated improved bioavailability or by blocking cholesterol resorption [166,167]. Clinical trials to demonstrate the effectiveness of silymarin were conducted on hyperlipidemic patients. Results revealed that 600 mg capsules of silymarin twice daily reduced the serum cholesterol, triglyceride and LDH and increased the level of HDL [168]. Therefore, it is demonstrated that silymarin recovered atherosclerosis by reducing triglyceride and LDL and enhancing the HDL level. Pre-clinical and clinical research should be designed to further investigate the beneficial effects of silymarin in animals and humans respectively.

Silymarin prevents the free radical formation by inhibiting specific enzyme of ROS production in mitochondria, the main site of ROS generation. Silymarin reduces electron leakage and ROS formation through the reduction in activity of enzymes e.g. α-ketoglutarate dehydrogenase [104]. Silymarin also inhibits the up-regulation of myocardial NADPH oxidase activity and also decreases the NADPH oxidase over-expression caused by arsenic and increases the activity of Nrf2 expression in the tissue [176]. Xanthine oxidase is considered another source of free radical generation that damages the myocardial tissue. Silymarin reduces superoxide production by suppressing Xanthine oxidase activity [177].Thus, it helps in down-regulation of both NADPH oxidase and Xanthine oxidase and plays a grave role in reducing ROS and oxidative stress. 5.3. Activation of antioxidant enzymes and inhibiting lipid peroxidation Silymarin has the ability to activate the group of enzymatic and non-enzymatic antioxidants [104]. Silymarin preserves cellular functions and structures by restoring the enzymatic antioxidant activity (SOD, CAT, and GSH) and signal transduction located in the membrane [132]. It results in minimizing free radicals damage and curing cardiac toxicity which is associated with decreased antioxidant enzymes such as (CAT, SOD, and GSH) [176,178]. Silymarin in the dose of 100 mg/kg/ BW showed a significant activation in the antioxidants level (SOD, CAT and GPx)and inhibited lipid peroxidation in rats [179]. Lipid Peroxidation in the cell membrane is the result of interaction between free radicals and unsaturated fatty acid in the lipid. Silymarin shows antioxidant activity against Lipid Peroxidation and protects the tissues through inhibition of linoleic acid peroxidation catalyze by lipoxygenase [23]. Oxidative stress is also involved in the development of atherosclerotic lesions [180]. Silymarin appears to be effective in reducing the inflammatory-related lipid oxidation and progression of atherosclerosis through modulating the enzymatic degradation of arachidonic acid by cyclo-oxygenase and lipoxygenase and reduces LDL oxidation [181].

5. Antioxidant mechanism of silymarin Silymarin prevents CVDs via several mechanisms that include (1) Scavenging free radicals and chelating metals-promoters such as Fe and Cu (2) Prevents ROS formation enzymes e.g. NAPDH Oxidases (3) activates antioxidant enzymes and inhibiting of lipid peroxidation (4) Regulating the cell membrane permeability and increasing the stability (5) Increases ribosomal protein synthesis by Stimulation RNA polymerase and (6) Regulation of signaling through activation of Nrf2 and inhibition of NF-κB.

5.4. Regulating the permeability and increasing the stability of cell membrane Silymarin has been reported to be cytoprotective and helps in regulating the permeability and stability of the cell membrane. It binds to different membrane proteins and modifies several functions of transporters and receptors located in the cell membranes [182]. Silymarin decreases the cellular absorption of xenobiotics and causes reduction of lipoxygenase especially leukotriene through regulation of transporter of intracellular and/or extracellular ions with driving force for ATPbinding [183,184]. In transmembrane molecules, Silymarin inhibits the expression of adhesion molecules (e.g. E-selectin) on the surface of leukocytes endothelial cells which play an important role in the regulation of cell-cell adhesion [159]. Silymarin also interacts with ABC transporters and shares their effects on the p-glycoprotein (P-gp) ATPase activity [185].

5.1. Scavenging free radicals and chelating metals-promoters such as Fe and Cu Silymarin is a good chelating agent of metals, e.g., Fe, Cu and also scavenges free radicals in a direct way. Deposition of iron in heart induces cardiac dysfunction. The chelating of metal ions occurs by Hatom transport and may decrease harmful effects of oxidative stress [169]. Administration of silymarin (100 mg/kg) reduces the level of iron and oxidative stress in the blood plasma of rats [170–172]. Silymarin is also a strong scavenger of HOCI and inhibits the hydroxyl radical formation in the direct way. This effect has been shown due to the presence of the phenolic hydroxyl group at the carbon atom, which is essential for the inhibition of xanthine oxidase activity[173]. Silymarin minimizes the overproduction of (O2·ˉ) in xanthine oxidase activity and prevents haem-mediated oxidative modification of LDL [173]. Treatment with silymarin (50 μM) resulted in significant inhibition of free radicals (O2·ˉ) and H2O2 release by monocytes from preeclamptic women [174]. Silymarin has been shown to be more scavenger for OH· radical than O2•−. The free radical scavenging activity of silymarin components vary from each other, however, the studies reported that silydianin and silychristin are more active than the silibinin [104,175].

5.5. Increases ribosomal protein synthesis by stimulating RNA polymerase enzyme Silymarin stimulates protein synthesis in the injured cells and catalyzes the synthesis of nuclear DNA in the cell [23]. Silibinin causes the marked increase in the synthesis of ribosomal RNA (polymerase I), in the rats [186]. The mechanism whereby silymarin stimulates protein synthesis has not been defined clearly, however, it is suggested that this effect may be due to the physiological regulation of RNA polymerase I at the specific binding site that stimulates the formation of the 694

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

ribosome.

disease, Lancet 360 (9343) (2002) 1347–1360. [3] P. Björntorp, " Portal" adipose tissue as a generator of risk factors for cardiovascular disease and diabetes, Arterioscler. Thromb. Vasc. Biol. 10 (4) (1990) 493–496. [4] H.B. Hubert, et al., Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham heart study, Circulation 67 (5) (1983) 968–977. [5] J.A. Ambrose, R.S. Barua, The pathophysiology of cigarette smoking and cardiovascular disease: an update, J. Am. Coll. Cardiol. 43 (10) (2004) 1731–1737. [6] R.B. D’Agostino, et al., General cardiovascular risk profile for use in primary care, Circulation 117 (6) (2008) 743–753. [7] K.K. Ray, et al., The ACC/AHA 2013 guideline on The treatment of blood cholesterol to reduce atherosclerotic cardiovascular disease risk in adults: the good the bad and the uncertain: a comparison with ESC/EAS guidelines for the management of dyslipidaemias 2011, Eur. Heart J. 35 (15) (2014) 960–968. [8] T. Heitzer, et al., Endothelial dysfunction, oxidative stress, and risk of cardiovascular events in patients with coronary artery disease, Circulation 104 (22) (2001) 2673–2678. [9] I.M. Fearon, S.P. Faux, Oxidative stress and cardiovascular disease: novel tools give (free) radical insight, J. Mol. Cell. Cardiol. 47 (3) (2009) 372–381. [10] J.F. Keaney, Atherosclerosis: from lesion formation to plaque activation and endothelial dysfunction, Mol. Aspects Med. 21 (4) (2000) 99–166. [11] W. Dröge, Free radicals in the physiological control of cell function, Physiol. Rev. 82 (1) (2002) 47–95. [12] D.G. Harrison, M.C. Gongora, Oxidative stress and hypertension, Med. Clin. North Am. 93 (3) (2009) 621–635. [13] O.I. Aruoma, Free radicals, oxidative stress, and antioxidants in human health and disease, J. Am. Oil Chem. Soc. 75 (2) (1998) 199–212. [14] K.A. Ahmad, et al., Antioxidant therapy for management of oxidative stress induced hypertension, Free Radic. Res. (2017) 1–18 just-accepted. [15] F. Kvasnička, et al., Analysis of the active components of silymarin, J. Chromatogr. A 990 (1) (2003) 239–245. [16] S. Foster, Milk thistle: Silybum marianum. Botanical series no. 305, En Compositae, Nomenclature, Milk_Thistle, Food, Active_Principles, Medicines, History, Plant_Parts, Review, Silybum_marianum, Hepatoprotective, Liver, Seeds, Clinical_Trials (EBBD, 190001873), American Botanical Council, Austin, Texas, 1991, p. 8. [17] A. Karkanis, D. Bilalis, A. Efthimiadou, Cultivation of milk thistle (Silybum marianum L. Gaertn.), a medicinal weed, Ind. Crops Prod. 34 (1) (2011) 825–830. [18] M. Blumenthal, The ABC Clinical Guide to Herbs, American Botanical Council, 2003. [19] R. Vasanthi, H.N. ShriShriMal, D.K. Das, Phytochemicals from plants to combat cardiovascular disease, Curr. Med. Chem. 19 (14) (2012) 2242–2251. [20] T.-m. Ding, et al., Determination of active component in silymarin By RP-LC and LC/MS, J. Pharm. Biomed. Anal. 26 (1) (2001) 155–161. [21] Y. Haddad, et al., Antioxidant and hepatoprotective effects of silibinin in a rat model of nonalcoholic steatohepatitis, Evid. Based Compl. Altern. Med. (2011) nep164. [22] B. Janiak, et al., Die wirkung von silymarin auf gehalt und function einiger durch einwirkung von tetrachlorkohlenstoff bzw. Halothan beeinflussten mikrosomalen Leberenzyme, Arzneimittelforschung 23 (1973) 1322–1326. [23] F. Fraschini, G. Demartini, D. Esposti, Pharmacology of silymarin, Clin. Drug Invest. 22 (1) (2002) 51–65. [24] M. El-Samaligy, N. Afifi, E. Mahmoud, Increasing bioavailability of silymarin using a buccal liposomal delivery system: preparation and experimental design investigation, Int. J. Pharm. 308 (1-2) (2006) 140–148. [25] X. Li, et al., Development of silymarin self-microemulsifying drug delivery system with enhanced oral bioavailability, Aaps Pharmscitech. 11 (2) (2010) 672–678. [26] J.I. Lee, et al., Separation and characterization of silybin, isosilybin, silydianin and silychristin in milk thistle extract by liquid chromatography–electrospray tandem mass spectrometry, J. Chromatogr. A 1116 (1-2) (2006) 57–68. [27] C. Tamayo, S. Diamond, Review of clinical trials evaluating safety and efficacy of milk thistle (Silybum marianum [L.] Gaertn.), Integr. Cancer Ther. 6 (2) (2007) 146–157. [28] G. Karimi, et al., “Silymarin”, a promising pharmacological agent for treatment of diseases, Iran. J. Basic Med. Sci. 14 (4) (2011) 308. [29] J.M. McCord, The evolution of free radicals and oxidative stress, Am. J. Med. 108 (8) (2000) 652–659. [30] V. Lobo, et al., Free radicals, antioxidants and functional foods: impact on human health, Pharmacognosy Reviews 4 (8) (2010) 118. [31] K. Brieger, et al., Reactive oxygen species: from health to disease, Swiss Med. Wkly. 142 (2012) w13659. [32] B. D’Autréaux, M.B. Toledano, ROS as signalling molecules: mechanisms that generate specificity in ROS homeostasis, Nat. Rev. Mol. Cell Biol. 8 (10) (2007) 813. [33] P.C. Dedon, S.R. Tannenbaum, Reactive nitrogen species in the chemical biology of inflammation, Arch. Biochem. Biophys. 423 (1) (2004) 12–22. [34] V.I. Lushchak, Free radicals, reactive oxygen species, oxidative stress and its classification, Chem. Biol. Interact. 224 (2014) 164–175. [35] E. Niki, Biomarkers of lipid peroxidation in clinical material, Biochim. Et Biophys. Acta (BBA)-Gen. Subj. 1840 (2) (2014) 809–817. [36] O.S. Ademowo, et al., Lipid (per) oxidation in mitochondria: an emerging target in the ageing process? Biogerontology 18 (6) (2017) 859–879. [37] F.J. Giordano, Oxygen, oxidative stress, hypoxia, and heart failure, J. Clin. Invest. 115 (3) (2005) 500. [38] R.E. Clempus, K.K. Griendling, Reactive oxygen species signaling in vascular

5.6. Regulation of signaling through activation of Nrf2 and inhibition of NFκB Nrf2 is the transcription factor that is considered to be the redoxsensitive master regulator of oxidative stress signaling. It is activated by several mechanisms such as phosphorylation of Nrf2 by upstream kinase and stabilization of Nrf2 via Keap1 cysteine modification [187]. Silymarin polyphenol interacts with signaling pathways, e.g., the Nrf2/ Keap1 and NF-κB pathways, resulting in increased expression of genes encoding for cytoprotective molecules and antioxidants enzymes. Also, reduced expression of NF-κB-regulated genes decreases the production of pro-inflammatory cytokines [188]. Thus, inhibition of NF-kB pathway by treating with silymarin could attenuate inflammatory reaction that stimulates atherosclerosis. Transcription factor NF-κB is responsible for regulation of many cellular processes. NF-κB is found in the cytoplasm and comprises protein groups that can bind to DNA. It is activated by stimuli such as oxidative stress and regulates the transcription of a range of genes [189]. Silymarin, in the dose-dependent concentration, inhibits NF-κB pathway and blocks TNF-α-induced activation of NF-kB via inhibition of phosphorylation and degradation process, thereby reducing the NFκB gene expression [190]. Higher concentration of silymarin inhibits the production of NO and iNOS gene expression by blocking the activation NF-κB/Rel activation [191,192]. Silymarin in low concentration restores the activity of nuclear factor 2(Nrf2) signaling by inducing phosphorylation of Nrf2 via activation of upstream protein kinases. Silymarin also interacts with Keap1 cysteine thiols and restores Nrf2 signaling [188]. Moreover, silymarin significantly suppresses the activity of ERK/p38 mitogen-activated protein kinase (MAPK) pathway in Beas-2B cells. It also inhibits ERK1/2 activation at the lower dose and induces c-Jun N-terminal kinases (JNKs) activation at higher doses [104]. 6. Conclusion Studies support the involvement of oxidative stress in the pathogenesis and development of CVDs like hypertension, atherosclerosis, ischemia, vascular dysfunction, Cardiotoxicity, cardiomyopathies and heart failure. Substantial clinical trials have been conducted to examine the protective effects of silymarin antioxidant in cardiovascular diseases. Silymarin shows a wide range of mechanisms in preventing the CVDs by increasing enzymatic antioxidants, mitochondrial enzymes and expression of Nrf2 and decreases lipid peroxidation, expressions of NOX4, LDL, total cholesterol, and triglyceride level in the blood, thus preventing cardiac dysfunction and dyslipidemia. Clinical trials to examine the effects of silymarin on protein expression MAKPs, NOX2 and NF-κB pathways in endothelial cells of the blood vessels await further investigation. Conflict of interest None Submission declaration and verification This manuscript has not been published previously, and it is not under consideration elsewhere. All authors approved to submit this manuscript to this journal. References [1] E.J. Benjamin, et al., heart disease and stroke statistics—2017 update: a report from the American Heart Association, Circulation 135 (10) (2017) e146–e603. [2] M. Ezzati, et al., Selected major risk factors and global and regional burden of

695

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

[76] L.A. Sena, N.S. Chandel, Physiological roles of mitochondrial reactive oxygen species, Mol. Cell 48 (2) (2012) 158–167. [77] J.F. Turrens, Mitochondrial formation of reactive oxygen species, J. Physiol. 552 (2) (2003) 335–344. [78] Q. Chen, et al., Production of reactive oxygen species by mitochondria central role of complex III, J. Biol. Chem. 278 (38) (2003) 36027–36031. [79] M.P. Murphy, How mitochondria produce reactive oxygen species, Biochem. J. 417 (1) (2009) 1–13. [80] L.B. Becker, New concepts in reactive oxygen species and cardiovascular reperfusion physiology, Cardiovasc. Res. 61 (3) (2004) 461–470. [81] E.C. Viel, et al., Xanthine oxidase and mitochondria contribute to vascular superoxide anion generation in DOCA-salt hypertensive rats, Am. J. Physiol.-Heart Circ. Physiol. 295 (1) (2008) H281–H288. [82] R. Harrison, Physiological roles of xanthine oxidoreductase, Drug Metab. Rev. 36 (2) (2004) 363–375. [83] J. George, A.D. Struthers, Role of urate, xanthine oxidase and the effects of allopurinol in vascular oxidative stress, Vasc. Health Risk Manage. 5 (2009) 265. [84] J. Dawson, M. Walters, Uric acid and xanthine oxidase: future therapeutic targets in the prevention of cardiovascular disease? Br. J. Clin. Pharmacol. 62 (6) (2006) 633–644. [85] S. Moncada, R. Palmer, E. Higgs, Nitric oxide: physiology, pathophysiology, and pharmacology, Pharmacol. Rev. 43 (2) (1991) 109–142. [86] U. Förstermann, T. Münzel, Endothelial nitric oxide synthase in vascular disease, Circulation 113 (13) (2006) 1708–1714. [87] A. Gorren, B. Mayer, Tetrahydrobiopterin in nitric oxide synthesis: A novel biological role for pteridines, Curr. Drug Metab. 3 (2) (2002) 133–157. [88] U. Landmesser, et al., Oxidation of tetrahydrobiopterin leads to uncoupling of endothelial cell nitric oxide synthase in hypertension, J. Clin. Invest. 111 (8) (2003) 1201. [89] C. Szabó, et al., Endothelial dysfunction in a rat model of endotoxic shock. importance of the activation of poly (ADP-ribose) synthetase By peroxynitrite, J. Clin. Invest. 100 (3) (1997) 723. [90] I. Young, J. Woodside, Antioxidants in health and disease, J. Clin. Pathol. 54 (3) (2001) 176–186. [91] H. Sies, Oxidative stress: oxidants and antioxidants, Exp. Physiol. 82 (2) (1997) 291–295. [92] S. Sen, et al., Free radicals, antioxidants, diseases and phytomedicines: current status and future prospect, Int. J. Pharm. Sci. Rev. Res. 3 (1) (2010) 91–100. [93] E. Birben, et al., Oxidative stress and antioxidant defense, World Allergy Org. J. 5 (1) (2012) 9. [94] J.M. MatÉs, C. Pérez-Gómez, I.N. De Castro, Antioxidant enzymes and human diseases, Clin. Biochem. 32 (8) (1999) 595–603. [95] P. Morrissey, N. O’brien, Dietary antioxidants in health and disease, Int. Dairy 8 (5-6) (1998) 463–472. [96] A. Gawron-Skarbek, et al., Cardiovascular risk factors and total serum antioxidant capacity in healthy men and in men with coronary heart disease, BioMed. Res. Int. (2014). [97] S.A. Ahmad, R.S. Al-Sayed, Effect of Antioxidant and Lipid Profile on the Coronary Heart Disease, (2013). [98] M.N. Diaz, et al., Antioxidants and atherosclerotic heart disease, New Engl. J. Med. 337 (6) (1997) 408–416. [99] Y.-J. Xu, et al., Prevention of diabetes-induced cardiovascular complications upon treatment with antioxidants, Heart Failure Rev. 19 (1) (2014) 113–121. [100] M.U. Khan, et al., Nebivolol: a multifaceted antioxidant and cardioprotectant in hypertensive heart disease, J. Cardiovasc. Pharmacol. 62 (5) (2013) 445–451. [101] E. Ho, et al., Biological markers of oxidative stress: applications to cardiovascular research and practice, Redox. Biol. 1 (1) (2013) 483–491. [102] I. Marrocco, F. Altieri, I. Peluso, Measurement and clinical significance of biomarkers of oxidative stress in humans, Oxid. Med. Cell. Longev. (2017). [103] Y. Wang, O.K. Chun, W.O. Song, Plasma and dietary antioxidant status as cardiovascular disease risk factors: a review of human studies, Nutrients 5 (8) (2013) 2969–3004. [104] P.F. Surai, Silymarin as a natural antioxidant: an overview of the current evidence and perspectives, Antioxidants 4 (1) (2015) 204–247. [105] M. Herrero, A. Cifuentes, E. Ibañez, Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: a review, Food Chem. 98 (1) (2006) 136–148. [106] N. Farhana Mohd Fozi, et al., Milk thistle: a future potential anti-osteoporotic and fracture healing agent, Curr. Drug Targets 14 (14) (2013) 1659–1666. [107] S. Zhong, et al., The therapeutic effect of silymarin in the treatment of nonalcoholic fatty disease: a meta-analysis (PRISMA) of randomized control trials, Medicine (Baltimore) 96 (49) (2017) e9061. [108] V.G. Athyros, et al., The use of statins alone, or in combination with pioglitazone and other drugs, for the treatment of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis and related cardiovascular risk. an expert panel statement, Metabolism 71 (2017) 17–32. [109] M.K. Reriani, L.O. Lerman, A. Lerman, Endothelial function as a functional expression of cardiovascular risk factors, Biomarkers 4 (3) (2010) 351–360. [110] Y. Jin, et al., Modulatory effect of silymarin on pulmonary vascular dysfunction through HIF-1α-iNOS following rat lung ischemia-reperfusion injury, Exp. Ther. Med. 12 (2) (2016) 1135–1140. [111] B. Demirci, et al., Silymarin improves vascular function of aged ovariectomized rats, Phytother. Res. 28 (6) (2014) 868–872. [112] G.L. Volti, et al., Effect of silibinin on endothelial dysfunction and ADMA levels in obese diabetic mice, Cardiovasc. Diabetol. 10 (1) (2011) 62. [113] B. Demirci, et al., Treated effect of silymarin on vascular function of aged rats:

smooth muscle cells, Cardiovasc. Res. 71 (2) (2006) 216–225. [39] D.D. Heistad, Oxidative stress and vascular disease, Arterioscl. Thromb.Vasc. Biol. 26 (4) (2006) 689–695. [40] N.S. Dhalla, R.M. Temsah, T. Netticadan, Role of oxidative stress in cardiovascular diseases, J. Hypertens. 18 (6) (2000) 655–673. [41] A.C. Montezano, R.M. Touyz, Molecular mechanisms of hypertension—reactive oxygen species and antioxidants: a basic science update for the clinician, Can. J. Cardiol. 28 (3) (2012) 288–295. [42] K.A. Ahmad, et al., Antioxidant therapy for management of oxidative stress induced hypertension, Free Radic. Res. 51 (4) (2017) 428–438. [43] L.L. Ji, Antioxidants and oxidative stress in exercise, Exp. Biol. Med. 222 (3) (1999) 283–292. [44] A.A. Sovari, Cellular and molecular mechanisms of arrhythmia by oxidative stress, Cardiol. Res. Pract. (2016). [45] R. Stocker, J.F. Keaney Jr, Role of oxidative modifications in atherosclerosis, Physiol. Rev. 84 (4) (2004) 1381–1478. [46] F. Violi, et al., Atherothrombosis and oxidative stress: mechanisms and management in elderly, Antioxid. Redox. Signal. 27 (14) (2017) 1083–1124. [47] T.C. Squier, Oxidative stress and protein aggregation during biological aging, Exp. Gerontol. 36 (9) (2001) 1539–1550. [48] R. Radi, Peroxynitrite, a stealthy biological oxidant, J. Biol. Chem. 288 (37) (2013) 26464–26472. [49] T. Münzel, et al., Pathophysiological role of oxidative stress in systolic and diastolic heart failure and its therapeutic implications, Eur. Heart J. 36 (38) (2015) 2555–2564. [50] A.K. Srivastava, N.R. Pandey, A. Blanc, Activation of mitogen-activated protein kinases and protein kinase B/Akt signaling by oxidative stress in vascular smooth muscle cells: Involvement in vascular pathophysiology, Pathophysiology of Cardiovascular Disease, Springer, 2004, pp. 405–416. [51] K. Sugamura, J.F. Keaney, Reactive oxygen species in cardiovascular disease, Free Radic. Biol. Med. 51 (5) (2011) 978–992. [52] M.M. Elahi, Y.X. Kong, B.M. Matata, Oxidative stress as a mediator of cardiovascular disease, Oxid. Med. Cell. Longev. 2 (5) (2009) 259–269. [53] D.X. Zhang, D.D. Gutterman, Mitochondrial reactive oxygen species-mediated signaling in endothelial cells, Am. J. Physiol.-Heart Circ. Physiol. 292 (5) (2007) H2023–H2031. [54] B. Lassègue, K.K. Griendling, NADPH oxidases: functions and pathologies in the vasculature, Arterioscler. Thromb. Vasc. Biol. 30 (4) (2010) 653–661. [55] J. Kuroda, et al., NADPH oxidase 4 (Nox4) is a major source of oxidative stress in the failing heart, Proceedings of the National Academy of Sciences 107 (35) (2010) 15565–15570. [56] N. Anilkumar, et al., A 28-kDa splice variant of NADPH oxidase-4 is nuclear-localized and involved in redox signaling in vascular cells significance, Arterioscler. Thromb. Vasc. Biol. 33 (4) (2013) e104–e112. [57] K. Bedard, K.-H. Krause, The NOX family of ROS-generating NADPH oxidases: physiology and pathophysiology, Physiol. Rev. 87 (1) (2007) 245–313. [58] S. Altenhöfer, et al., The NOX toolbox: validating the role of NADPH oxidases in physiology and disease, Cell. Mol. Life Sci. 69 (14) (2012) 2327–2343. [59] E. Panieri, M.M. Santoro, ROS signaling and redox biology in endothelial cells, Cell. Mol. Life Sci. 72 (17) (2015) 3281–3303. [60] D. Sorescu, et al., Superoxide production and expression of nox family proteins in human atherosclerosis, Circulation 105 (12) (2002) 1429–1435. [61] T.J. Guzik, et al., Systemic regulation of vascular NAD(P)H oxidase activity and nox isoform expression in human arteries and veins, Arterioscler. Thromb. Vasc. Biol. 24 (9) (2004) 1614–1620. [62] J.D. Van Buul, et al., Expression and localization of NOX2 and NOX4 in primary human endothelial cells, Antioxid. Redox. Signal. 7 (3-4) (2005) 308–317. [63] P.A. Krijnen, et al., Increased Nox2 expression in human cardiomyocytes after acute myocardial infarction, J. Clin. Pathol. 56 (3) (2003) 194–199. [64] I.M. Quesada, et al., Selective inactivation of NADPH oxidase 2 causes regression of vascularization and the size and stability of atherosclerotic plaques, Atherosclerosis 242 (2) (2015) 469–475. [65] G. Giardino, et al., NADPH oxidase deficiency: a multisystem approach, Oxid. Med. Cell. Longev. (2017) 4590127. [66] L. Loffredo, et al., Does NADPH oxidase deficiency cause artery dilatation in humans? Antioxid. Redox. Signal. 18 (12) (2013) 1491–1496. [67] F. Violi, et al., Nox2 is determinant for ischemia-induced oxidative stress and arterial vasodilatation: a pilot study in patients with hereditary Nox2 deficiency, Arterioscler. Thromb. Vasc. Biol. 26 (8) (2006) e131–2. [68] K. Matsuno, et al., Nox1 is involved in angiotensin II-mediated hypertension: a study in Nox1-deficient mice, Circulation 112 (17) (2005) 2677–2685. [69] M.K. Cathcart, Regulation of superoxide anion production by NADPH oxidase in monocytes/macrophages: contributions to atherosclerosis, Arterioscler. Thromb. Vasc. Biol. 24 (1) (2004) 23–28. [70] I. Takac, et al., The E-loop is involved in hydrogen peroxide formation by the NADPH oxidase Nox4, J. Biol. Chem. 286 (15) (2011) 13304–13313. [71] C. Schürmann, et al., The NADPH oxidase Nox4 has anti-atherosclerotic functions, Eur. Heart J. 36 (48) (2015) 3447–3456. [72] S. Kovac, et al., Nrf2 regulates ROS production by mitochondria and NADPH oxidase, Biochim. Et Biophys. Acta (BBA)-Gen. Subj. 1850 (4) (2015) 794–801. [73] A.M. Garrido, K.K. Griendling, NADPH oxidases and angiotensin II receptor signaling, Mol. Cell. Endocrinol. 302 (2) (2009) 148–158. [74] A. Nguyen Dinh Cat, et al., Angiotensin II, NADPH oxidase, and redox signaling in the vasculature, Antioxid. Redox. Signal. 19 (10) (2013) 1110–1120. [75] S. Mennickent, Pleiotropic Effects of Statins, in Hypercholesterolemia, InTech, 2015.

696

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

[148] E. Taghiabadi, et al., Protective effect of silymarin against acrolein-induced cardiotoxicity in mice, EVid.-Based Complement. Altern. Med. (2012). [149] Š Chlopčíková, et al., Chemoprotective effect of plant phenolics against anthracycline‐induced toxicity on rat cardiomyocytes. Part I. Silymarin and its flavonolignans, Phytother. Res. 18 (2) (2004) 107–110. [150] G.M. Attia, R.A. Elmansy, S.A. Algaidi, Silymarin decreases the expression of VEGF-A, iNOS and caspase-3 and preserves the ultrastructure of cardiac cells in doxorubicin induced cardiotoxicity in rats: a possible protective role, Int. J. Clin. Exp. Med. 10 (2) (2017) 4158–4173. [151] D.J. Rader, J. Cohen, H.H. Hobbs, Monogenic hypercholesterolemia: new insights in pathogenesis and treatment, J. Clin. Invest. 111 (12) (2003) 1795. [152] H. Tunstall-Pedoel, R. Chen, P. Kramarz, Prevalence of individuals with both raised blood pressure and raised cholesterol in WHO MONICA project population surveys 1989-1997, Eur. Heart J. (2004) Wb Saunders co ltd 32 Jamestown Rd, London NW1 7by, England. [153] E.N. Marieb, K. Hoehn, Human Anatomy & Physiology, Pearson Education, 2007. [154] L. Sherwood, Human physiology: from cells to systems, Cengage Learn. (2015). [155] B. Ivanovic, M. Tadic, Hypercholesterolemia and hypertension: two sides of the same coin, Am. J. Cardiovasc. Drugs 15 (6) (2015) 403–414. [156] A.P. Hoeks, et al., Different effects of hypertension, atherosclerosis and hyperlipidaemia on arterial distensibility, J. Hypertens. 13 (12) (1995) 1712–1717. [157] T.J. Anderson, et al., The effect of cholesterol-lowering and antioxidant therapy on endothelium-dependent coronary vasomotion, New Engl. J. Med. 332 (8) (1995) 488–493. [158] T. Radjabian, H.F. Huseini, Anti-hyperlipidemic and anti-atherosclerotic activities of silymarins from cultivated and wild plants of Silybum marianum L. with different content of flavonolignans, Iran. J. Pharmacol. Ther. 9 (2) (2010) 63–67. [159] J.S. Kang, et al., Silymarin inhibits TNF‐α‐induced expression of adhesion molecules in human umbilical vein endothelial cells, FEBS Lett. 550 (1-3) (2003) 89–93. [160] T. Radjabian, et al., Effect of silymarin, the seed extract of cultivated and endemic Silybum marianum (L.) Gaertn., on serum lipid levels and atherosclerosis development in hypercholesterolemic rabbits, J. Med. Plants 1 (13) (2005) 33–41. [161] M. Metwally, A. El-Gellal, S. El-Sawaisi, Effects of silymarin on lipid metabolism in rats, World Appl. Sci. J. 6 (12) (2009) 1634–1637. [162] E. Heidarian, M. Rafieian-Kopaei, Effect of silymarin on liver phoshpatidate phosphohydrolase in hyperlipidemic rats, Biosci. Res. 9 (2) (2012) 59–67. [163] N. Skottova, V. Krecman, Dietary silymarin improves removal of low density lipoproteins by the perfused rat liver, Acta Univ. Palacki Olomuc Fac. Med. 141 (1998) 39–40. [164] P.P. Toth, et al., Bergamot reduces plasma lipids, atherogenic small dense LDL, and subclinical atherosclerosis in subjects with moderate hypercholesterolemia: a 6 months prospective study, Front. Pharmacol. (6) (2016) 299. [165] V. Krečman, et al., Silymarin inhibits the development of diet-induced hypercholesterolemia in rats, Planta Medica 64 (02) (1998) 138–142. [166] N. Łkottová, et al., Effect of silymarin on serum cholesterol levels in rats, Biomed. Papers (1998). [167] L. Sobolová, et al., Effect of silymarin and its polyphenolic fraction on cholesterol absorption in rats, Pharmacol. Res. 53 (2) (2006) 104–112. [168] H.M. Alkuraishy, S. Alwindy, Beneficial Effects of Silymarin on Lipid Profile in Hyperlipidemic Patients: Placebo Controlled Clinical Trail, (2012). [169] F. Di Meo, et al., Free radical scavenging by natural polyphenols: atom versus electron transfer, J. Phys. Chem. A 117 (10) (2013) 2082–2092. [170] S. Chouhan, S. Flora, Arsenic and Fluoride: Two Major Ground Water Pollutants, (2010). [171] Y. Chtourou, T. Boudawara, N. Zeghal, Protective role of silymarin against manganese‐induced nephrotoxicity and oxidative stress in rat, Environ. Toxicol. 29 (10) (2014) 1147–1154. [172] M. Muthumani, P.S. Milton, Silibinin Attenuates Arsenic Induced Alterations in serum and Hepatic Lipid Profiles in Rats. (2013). [173] Z. Varga, et al., Structure prerequisite for antioxidant activity of silybin in different biochemical systems in vitro, Phytomedicine 13 (1-2) (2006) 85–93. [174] R. Cristofalo, et al., Silibinin attenuates oxidative metabolism and cytokine production by monocytes from preeclamptic women, Free Radic. Res. 47 (4) (2013) 268–275. [175] K.P. Anthony, M.A. Saleh, Free radical scavenging and antioxidant activities of silymarin components, Antimicrobial. Agents Chemother. 2 (4) (2013) 398–407. [176] M. Muthumani, S.M. Prabu, Silibinin potentially attenuates arsenic-induced oxidative stress mediated cardiotoxicity and dyslipidemia in rats, Cardiovasc. Toxicol. 14 (1) (2014) 83–97. [177] J.M. Pauff, R. Hille, Inhibition studies of bovine xanthine oxidase by luteolin, silibinin, quercetin, and curcumin, J. Nat. Prod. 72 (4) (2009) 725–731. [178] C. Soto, et al., Silymarin increases antioxidant enzymes in alloxan-induced diabetes in rat pancreas, Compar. Biochem. Physiol. Part C: Toxicol. Pharmacol. 136 (3) (2003) 205–212. [179] F.A. Kadir, et al., PASS-predicted hepatoprotective activity of Caesalpinia sappan in thioacetamide-induced liver fibrosis in rats, Sci. World J. (2014). [180] R. Singh, S. Devi, R. Gollen, Role of free radical in atherosclerosis, diabetes and dyslipidaemia: larger‐than‐life, Diabetes Metab. Res. Rev. 31 (2) (2015) 113–126. [181] G. Leonarduzzi, et al., Inflammation-related gene expression by lipid oxidationderived products in the progression of atherosclerosis, Free Radical Biol. Med. 52 (1) (2012) 19–34. [182] T.M. Sissung, et al., Pharmacogenetics of membrane transporters: an update on current approaches, Mol. Biotechnol. 44 (2) (2010) 152–167. [183] P. Vitaglione, et al., Dietary antioxidant compounds and liver health, Crit. Rev. Food Sci. Nutr. 44 (7-8) (2005) 575–586.

Dependant on nitric oxide pathway, Pharm. Biol. 52 (4) (2014) 453–457. [114] Y.-K. Wang, Y.-j. Hong, Z.-Q. Huang, Protective effects of silybin on human umbilical vein endothelial cell injury induced by H 2 O 2 in vitro, Vasc. Pharm. 43 (4) (2005) 198–206. [115] K.V. Narayan, M.K. Ali, J.P. Koplan, Global noncommunicable diseases—where worlds meet, New Engl. J. Med. 363 (13) (2010) 1196–1198. [116] G.W. Booz, Novel drugs targeting hypertension revisited, J. Cardiovasc. Pharmacol. 56 (3) (2010) 213. [117] T. Barhoumi, et al., T Regulatory lymphocytes prevent angiotensin ii–induced hypertension and vascular injury, Hypertension 57 (3) (2011) 469–476. [118] V. Mayorov, et al., 130-Scavenging of reactive isolevuglandins in mitochondria reduces vascular oxidative stress and attenuates hypertension, Free Radic. Biol. Med. 100 (2016) S66. [119] S. Tsiropoulou, et al., Biomarkers of Oxidative Stress in Human Hypertension, Hypertension and Cardiovascular Disease, Springer, 2016, pp. 151–170. [120] K.V. Kumar, U. Das, Are free radicals involved in the pathobiology of human essential hypertension? Free Radic. Res. Commun. 19 (1) (1993) 59–66. [121] R.M. Touyz, Reactive oxygen species, vascular oxidative stress, and redox signaling in hypertension: what is the clinical significance? Hypertension 44 (3) (2004) 248–252. [122] S. Kimura, et al., Mitochondria-derived reactive oxygen species and vascular MAP Xkinases, Hyperfine Int. 45 (3) (2005) 438–444. [123] B. Lassègue, K.K. Griendling, Reactive Oxygen Species in Hypertension** An Update, Oxford University Press, 2004. [124] R. Rodrigo, et al., Implications of oxidative stress and homocysteine in the pathophysiology of essential hypertension, J. Cardiovasc. Pharmacol. 42 (4) (2003) 453–461. [125] H. Chen, et al., Protective effects of silybin and tetrandrine on the outcome of spontaneously hypertensive rats subjected to acute coronary artery occlusion, Int. J. Cardiol. 41 (2) (1993) 103–108. [126] G. Jadhav, C. Upasani, Antihypertensive effect of Silymarin on DOCA salt induced hypertension in unilateral nephrectomized rats, Orient. Pharm. Exp. Med. 11 (2) (2011) 101–106. [127] R. Bahem, et al., Modulation of calcium signaling of angiotensin AT1, endothelin ETA, and ETB receptors by silibinin, quercetin, crocin, diallyl sulfides, and ginsenoside Rb1, Planta Medica 81 (08) (2015) 670–678. [128] K. Tokuda, et al., Pressure-independent effects of angiotensin II on hypertensive myocardial fibrosis, Hyperfine Interact. 43 (2) (2004) 499–503. [129] S.A. Hussain, et al., Effect of Silibinin in lowering the intraocular pressure in normotensive rabbits: Interaction with Pilocarpine and Cyclopentolate, Iraq. J. Pharm. Sci. (ISSN: 1683–3597) 16 (2) (2017) 34–38. [130] Z. Vlodaver, R.W. Asinger, J.R. Lesser, Pathology of ischemic heart disease, Congestive Heart Failure and Cardiac Transplantation, Springer, 2017, pp. 59–79. [131] A. Koçarslan, et al., Intraperitoneal administration of Silymarin Protects end organs from Multivisceral Ischemia/Reperfusion injury in a rat model, Braz. J. Cardiovasc. Surg. 31 (6) (2016) 434–439. [132] F. Turgut, et al., Antioxidant and protective effects of silymarin on ischemia and reperfusion injury in the kidney tissues of rats, Int. Urol. Nephrol. 40 (2) (2008) 453–460. [133] Y.-C. Hou, et al., Preventive effect of silymarin in cerebral ischemia–reperfusioninduced brain injury in rats possibly through impairing NF-κB and STAT-1 activation, Phytomedicine 17 (12) (2010) 963–973. [134] A. Zholobenko, M. Modriansky, Silymarin and its constituents in cardiac preconditioning, Fitoterapia 97 (2014) 122–132. [135] M. Demir, et al., The effect of silymarin on mesenteric ischemia-reperfusion injury, Med. Principles Pract. 23 (2) (2014) 140–144. [136] D.T. Altaei, D.I.A. Jamal, D.D. Dilshad, The Cardioprotection of Silymarin in Coronary Artery Bypass Grafting Surgery, in Artery Bypass, InTech, 2013. [137] S. Hein, et al., Progression from compensated hypertrophy to failure in the pressure-overloaded human heart, Circulation 107 (7) (2003) 984–991. [138] R.T. Atawia, et al., Modulatory effect of silymarin on inflammatory mediators in experimentally induced benign prostatic hyperplasia: emphasis on PTEN, HIF-1α, and NF-κB, Naunyn-Schmiedeberg’s Arch. Pharmacology 387 (12) (2014) 1131–1140. [139] X.-J. Yu, et al., Inhibition of NF-κB activity in the hypothalamic paraventricular nucleus attenuates hypertension and cardiac hypertrophy by modulating cytokines and attenuating oxidative stress, Toxicol. Appl. Pharmacol. 284 (3) (2015) 315–322. [140] L. Zelarayan, et al., NF-kappaB activation is required for adaptive cardiac hypertrophy, Cardiovasc. Res. 84 (3) (2009) 416–424. [141] W. Ai, et al., Silibinin attenuates cardiac hypertrophy and fibrosis through blocking EGFR‐dependent signaling, J. Cell. Biochem. 110 (5) (2010) 1111–1122. [142] I. Anestopoulos, et al., Silibinin protects H9c2 cardiac cells from oxidative stress and inhibits phenylephrine-induced hypertrophy: potential mechanisms, J. Nutr. Biochem. 24 (3) (2013) 586–594. [143] V.B. Pai, M.C. Nahata, Cardiotoxicity of chemotherapeutic agents, Drug Saf. 22 (4) (2000) 263–302. [144] F. Foufelle, B. Fromenty, Role of endoplasmic reticulum stress in drug‐induced toxicity, Pharmacol. Res. Perspect. 4 (1) (2016). [145] Z.V. Varga, et al., Drug-induced mitochondrial dysfunction and cardiotoxicity, Am. J. Physiol.-Heart Circ. Physiol. 309 (9) (2015) H1453–H1467. [146] B.M. Razavi, G. Karimi, Protective effect of silymarin against chemical-induced cardiotoxicity, Iranian J. Basic Med. Sci. 19 (9) (2016) 916. [147] N.A. El-Shitany, S. El-Haggar, K. El-Desoky, Silymarin prevents adriamycin-induced cardiotoxicity and nephrotoxicity in rats, Food Chem. Toxicol. 46 (7) (2008) 2422–2428.

697

Biomedicine & Pharmacotherapy 102 (2018) 689–698

A. Taleb et al.

[184] R. Gazak, D. Walterova, V. Kren, Silybin and silymarin-new and emerging applications in medicine, Curr. Med. Chem. 14 (3) (2007) 315–338. [185] S. Zhang, M.E. Morris, Effects of the flavonoids biochanin A, morin, phloretin, and silymarin on P-glycoprotein-mediated transport, J. Pharmacol. Exp. Ther. 304 (3) (2003) 1258–1267. [186] J. Sonnenbichler, Biochemical effects of the flavonolignane silibinin on mRNA, protein, and RNA synthesis in rat livers, Plant Flavonoids in Biology and Medicine: Biochemical, Pharmacological and Structure-activity Relationship, (1986), pp. 319–331. [187] T. Ishii, et al., Transcription factor Nrf2 coordinately regulates a group of oxidative stress-inducible genes in macrophages, J. Biol. Chem. 275 (21) (2000) 16023–16029. [188] Y.-J. Surh, NF-κB and Nrf2 as potential chemopreventive targets of some anti-

[189] [190] [191]

[192] [193]

698

inflammatory and antioxidative phytonutrients with anti-inflammatory and antioxidative activities, Asia Pac. J. Clin. Nutr. 17 (S1) (2008) 269–272. M. Buelna-Chontal, C. Zazueta, Redox activation of Nrf2 & NF-κB: a double end sword? Cellular signalling 25 (12) (2013) 2548–2557. S.K. Manna, et al., Silymarin suppresses TNF-induced activation of NF-κB, c-Jun Nterminal kinase, and apoptosis, J. Immunol. 163 (12) (1999) 6800–6809. M. Gharagozloo, Z. Amirghofran, Effects of silymarin on the spontaneous proliferation and cell cycle of human peripheral blood leukemia T cells, J. Cancer Res. Clin. Oncol. 133 (8) (2007) 525–532. L. Abenavoli, et al., Milk thistle in liver diseases: past, present, future, Phytother. Res. 24 (10) (2010) 1423–1432. R. Saller, et al., An updated systematic review of the pharmacology of silymarin, Complement. Med. Res. 14 (2) (2007) 70–80.