Abstract
Silybum marianum is a medicinal plant that has long been used as hepatoprotective remedy. It has been used for the treatment of numerous liver disorders characterized by functional impairment or degenerative necrosis. Its hepatoprotective activity is unique and acts in different ways, including antioxidant and anti-inflammatory activities, cell permeability regulator and membrane stabilizer, stimulation of liver regeneration and inhibition of deposition in collagen fibers, which may lead to cirrhosis. Most of documented data with Silybum marianum are about liver disorders; however, recently several beneficial properties on a wide variety of other disorders such as renal protection, hypolipidemic and anti-atherosclerosis activities, cardiovascular protection, prevention of insulin resistance, especially in cirrhotic patients, cancer, and Alzheimer prevention. It is also used as a food remedy. This review article aims to present different aspects of Silybum marianum, especially the data in recently published articles about its effects on different diseases, apart from presenting the aspects of its hepatoprotection.
Silybum marianum is a medicinal plant whose therapeutic history dates back to 2000 years ago and was used as a hepatoprotective medication to treat jaundice and enlarged liver and spleen. Originally, Silybum marianum was a native of Asia and Southern Europe, but now it is found throughout the world. 1 The Food & Drug Administration in Germany has proposed this medicinal plant to treat digestive disorders, intoxication, and alcoholic liver and as a complement drug to treat enlarged liver. 2
Numerous experimental and clinical studies have documented that Silybum marianum with its antioxidant activity and other liver protective properties is a unique hepatoprotective agent. Silymarin is the main component of Silybum marianum that has been documented to be highly hepatoprotective. It has been used for the treatment of numerous liver disorders characterized by functional impairment or degenerative necrosis. Although its mechanisms of action is not fully understood, it seems that it acts in different ways, including antioxidant and anti-inflammatory activities, cell permeability regulator and membrane stabilizer, stimulating liver regeneration and inhibiting deposition of collagen fibers, which may lead to cirrhosis. Silybum marianum and its major flavonoid, silymarin, are effective and well-tolerated antidotes for use against hepatotoxics, especially psychotropic drugs and the toxic agents produced by Amanita phalloide. 3
Most of documented data about Silybum marianum are about liver disorders; however, it has beneficial property on a wide variety of other disorders such as hypoglycemic activity and reducing insulin resistance in patients with type 2 diabetes mellitus and its complications. 4,5 Silymarin is also able to protect kidneys against nephrotoxic agents. 6 The hepatoprotective effects of Silybum marianum have been well documented. However, recent researches have considered it as a key for all diseases. It is also used as a food remedy. This review article aims to present different aspects of Silybum marianum, especially the data in recently published articles about its effects on different diseases, apart from presenting the aspects of its hepatoprotection. 6
Botany and Morphology
Silybum marianum is of Asteriaceae family and has various other names including milk thistle, Marian thistle, Mary thistle, Mary’s thistle, Saint Mary’s thistle, Blessed milk thistle, Mediterranean milk thistle, variegated thistle, Cardus marianus, and Scotch thistle. Silybum marianum has shiny pale green leaves and red to purple flowers with white veins. In Persian and Arabic countries, it is called Mary thiqhal. 7
Silybum marianum is a biennale, glabrous, pale green, spinescent plant with straight stems. Leaves of this plant are big and have white spots around the veins. It has several pinnate parts as triangular-ovary parts. Silybum marianum has simple or a little branched or relatively thick branches that terminate to a green mass and with longitudinal rakes. It grows up to 200 cm in height, with the stem of cottony, having an overall conical shape. Its leaves are oblong to lanceolate, and the stem is usually hollow. Silybum marianum is either lobate or pinnate, with spiny edges and hairless, shiny green, with milk-white veins. The flower heads of this plant are up to 12 cm long and wide, with red-purple color (Figure 1). 7

Silybum marianum.
Growth Regions
This plant grows in European, Asian, and American countries. In Iran, it is distributed widely in Noode, Kelardasht, Poshtkooh, Hezar Valley, Moghan, Poshtkooh, Gonbad-e Kāvus, Gorgan, and Mollathani in Ahvaz, as well as Shoush, Hamidiyeh, Ramhormoz, Izeh and Kazeroun in other regions of Iran. 7
Chemical Compounds
The seeds of this plant contain many compounds such as silybin, silibinin A and B, silicristin, silidianin, apigenin, dehydrosilybin, deoxysilyn cristin, deoxysilyn dianin, among other. Extract of dried seed of this plant contains up to 4% silymarin. Silymarin is a combination of flavonoids such as silibinin A and B, silidianin, silicristin, and dihydroxysilibin. 8,9 Other flavonolignans present in extract of this plant include sylandrin, silybinom, silyhermin, and myristic, palmitic, and stearic acids, which may have hepatoprotective properties. 4 In addition, dried seeds of the plant contain up to 20% oil without medicinal properties. 7
Silymarin is readily absorbed from the gastrointestinal tract and then reaches its maximum blood concentration after 2 to 4 hours. Its half-life excretion is 6 hours. Eighty percent of this drug is excreted from the bile. Bioavailability of this drug depends on the type of formulation. Sylibin is the most effective antioxidant and hepatoprotective substance present in silymarin, and its concentration in bile is 60 times more than the other components. 2
Pharmacology and Therapeutic Effects
Various beneficial effects of Silybum marianum or its derivatives have been reported including hepatoprotection, renal protection, hypolipidemic and anti-atherosclerosis activities, cardiovascular protection, prevention of insulin resistance, especially in cirrhotic patients, cancer, and Alzheimer prevention. Silymarin in the traditional medicine is consumed in European countries to treat different types of diseases and liver disorders. 10,11
Liver Diseases
The uses of Silybum marianum as hepatoprotective dates back to 2000 years ago. Different clinical and laboratory studies have also documented that silymarin protects the liver against toxicities resulting from various toxins such as carbon tetrachloride, acetaminophen, and tetrachloromethane. 7
It has been reported that silymarin provides the hepatoprotective effect by different mechanisms including antioxidant activity and scavenging free radicals, increase of cellular glutathione concentration, stimulation of DNA polymerase, and stabilization of hepatocellular membrane. 7
Numerous studies have strongly suggested that the hepatoprotective effects of silymarin are mainly due to its antioxidant activity and free radical scavenging property. This effect is reflected by glutathione modulation and the membrane stabilization that it produces. 12
Stimulation of DNA polymerase by silymarin results in increase in the synthesis of ribosomal RNA and reconstruction of liver cells. Increase of cellular glutamine concentration stabilizes superoxide dismutase and glutathione peroxidase. Silymarin decreases the enlarged liver by inhibiting 5-lipoxygenase cycle and inhibiting production of leukotrienes and free radicals in Kupffer cells of liver. Moreover, silybin in the mouse’s hepatocyte cells inhibits production of peroxidation lipid and cellular damage. 13
Actually the effect of silymarin on cellular permeability is associated with alterations of membrane lipids including cholesterol and phospholipids. Silymarin also act on other lipid compartments in the liver that may influence the uptake and secretion of lipoproteins. 14
Data on the influence of silymarin on triglyceride metabolism in the liver are scanty. It is known that in rats silibinin is able to partly antagonize the increase in total lipids and triglycerides produced in the liver by carbon tetrachloride and, probably, to activate fatty acid β-oxidation. It has also been suggested that silymarin may diminish triglyceride synthesis in the liver. 15
Lettéron et al studied the mechanisms of action of silymarin that provide protection against lipid peroxidation and the hepatotoxicity of carbon tetrachloride in mice, and they came to the conclusion that silymarin works by reducing metabolic activation by carbon tetrachloride and by acting as an antioxidant that prevents chain rupture. 16
Other authors have shown that silymarin affords hepatoprotection against specific injury induced by microcystin (a hepatotoxin), paracetamol, halothane, and alloxan in several experimental models. 17
Different researchers on live animals suggest that silymarin protects liver cells against different types of diseases including viruses, chemical substances, and natural toxic substances. Pretreatment of laboratory animals with silymarin protects them against intoxication from Amanita muscaria. Administration of silybin (50 mg/kg) in dogs has protected them against the intoxication resulting from a lethal dose of Amanita muscaria even after 40 hours after administration of silybin. 18 Moreover, pretreatment of laboratory animals with silymarin inhibits occurrence of liver intoxication and production of peroxidation lipid resulting from administration of halothane, thallium tetrachloride, carbon tetrachloride, and acetaminophen in these animals significantly. 19 Administration of silymarin or silybin to rats inhibited the activity of the liver enzymes including γ-glutamyl transpeptidase, alanine transaminase, and aspartate transaminase, indicating inhibition of hepatotoxicity resulting by the alcohol effect. 20 Silymarin inhibits alcoholic liver resulting from biliary atresia in rat. 21
Clinical researches indicate that consumption of 120 mg silybin twice a week for 2 months decreased aspartate transaminase and alanine transaminase levels in blood serum of patients with liver diseases. 20 In a study that was conducted on 2637 patients with chronic liver disorders, administration of silymarin extract for 8 weeks caused significant decrease in the amount of liver enzyme in 88% of patients. Minor side effects of the drug were observed only in less than 1% of patients. 22
Silymarin is also used in the treatment of intoxication resulting from Amanita muscaria. This treatment decreased morality up to 80% in patients. 18
Administration of intravenous silybin (20-50 mg/kg/day for 3-4 days) inhibited liver damage completely up to 48 hours after intoxication with Amanita muscaria. In a study conducted on 250 people intoxicated by Amanita muscaria, 46 deaths were reported in the nontreated group. However, no mortality was observed in the group comprising 16 individuals who received silybin. 23 In another study, 18 people who had been poisoned with Amanita muscaria were treated with silybin. The results revealed that only one person who took Amanita mushroom to commit suicide and was not treated for 60 hours had died. 24
Other authors have shown that silymarin affords hepatoprotection against specific injury induced by microcystin (a hepatotoxin), paracetamol, halothane, and alloxan in several experimental models. 25
Administration of silymarin in the treatment of alcohol-induced liver disease indicates contradictory results. A multiple controlled double-blind study conducted on 300 patients with alcohol-induced liver disease showed that silymarin (420 mg/day) led to significant reduction in enzyme levels and liver histology evaluation following 4 weeks. 26 An additional study was conducted on 170 patients with alcohol-induced cirrhosis who were administered silymarin for a period of 4 years. The result showed reduction in mortality when compared with the control group. 27 Inversely, in a double-blind study of administration of silymarin at 280 and 150 mg doses (3 times daily) on patients with cirrhosis of the liver did not reduce mortality compared with the control group. 28 In another investigation performed on 116 people with alcohol-induced hepatitis, the use of 420 mg/day silymarin for 3 months appeared to show no significant improvement compared with control group; however, 46% of the patients were able to stop drinking alcohol. 29
It is known that silibinin is capable of neutralizing 2 effects of ethanol in rats: the reduction in labeled glycerol incorporation into isolated hepatocytes lipids and the inhibition of phospholipid synthesis. 30 In addition, silibinin stimulates synthesis of phosphatidylcholine and increases cholinephosphate cytidylyltransferase activity in rat liver. 31 It is well established that silymarin acts as an antioxidant, preventing chain rupture and reducing metabolic activation by carbon tetrachloride. 15,32
Administration of silymarin demonstrates contradictory results in patients with hepatitis. A double-blind investigation was done on 20 patients with active chronic hepatitis who were treated by 240 mg silipide twice a day for a week, and the γ-glutamyl transpeptidase level reduced significantly when compared with the control group. 6 Another examination assessed 157 patients with viral hepatitis. Twenty-nine patients were treated with silymarin (140 mg, 3 times a day) while 28 received placebo. The results showed significant reduction in bilirubin content and aspartate transaminase and alanine transaminase levels in the group under treatment with silymarin when compared with that of the control group. 33 In contrast, silymarin did not improve diseases in an examination on 151 patients with viral hepatitis. 34
Another mechanism by which silymarin acts against liver injury is by stimulation of liver tissue regeneration, which is done by increase in protein synthesis. Silibinin, apart from increasing protein synthesis, causes an increase in the formation of ribosomes and in DNA synthesis. However, the increase in protein synthesis is induced only in injured livers and not in healthy livers. Silibinin stimulates protein synthesis in the liver probably by physiological regulation of RNA polymerase I and stimulates the formation of ribosomes. 35
Silymarin has been shown to inhibit the hepatic cytochrome P450 (CYP) detoxification system. Silibinin is able to inhibit numerous hepatic CYP enzyme activities. This effect might explain the hepatoprotective properties of silymarin against the intoxication due to Amanita phalloides. The toxin of Amanita phalloides that becomes lethal for hepatocytes is activated by the CYP system. Therefore, inhibition of toxin bioactivation contributes to the limitation of its toxic effects. Furthermore, silymarin can contribute toward protection against free radicals generated by enzymes of the CYP system. 36
One of the most effective property of silymarin is its ability to inhibit cellular permeability, which is associated with quantitative and qualitative alterations in membrane lipids. 37 This suggests that silymarin may influence lipoprotein secretion and uptake. In this regard, silymarin and silibinin have been shown to reduce the turnover and synthesis of phospholipids in the rat liver. Moreover, silibinin has been shown to reduce labeled glycerol incorporation into lipids of isolated hepatocytes and also neutralize the inhibition of phospholipid synthesis. 38
Furthermore, silibinin is able to stimulate phosphatidylcholine synthesis and increase the activity of cholinephosphate cytidylyltransferase in rat liver. 31
It should be noted that data on the effect of silymarin on triglyceride metabolism in the liver are scanty. Silibinin partly antagonizes the increase in triglyceride and total lipids produced in the liver by carbon tetrachloride. It may also diminish triglyceride synthesis in the liver. 25
Silymarin is able to provide protection against hepatotoxicity of carbon tetrachloride and lipid peroxidation. Silymarin has also been shown in several experimental models to have hepatoprotection against injury induced by paracetamol, halothane, alloxan, and microcystin (a hepatotoxin). 25,39
Hypoglycemic Activity
Silymarin has been shown to reduce the plasma levels of cholesterol and low-density lipoprotein in hyperlipidemic animals. It also reduces phospholipid levels, especially those transported in low-density lipoprotein. 25
Laboratory studies show that silymarin led to improved low-density lipoprotein excretion and reduced cholesterol synthesis in liver cells and also in prevention of complications of high cholesterol and reduction in formation of atherosclerosis plaque in hypercholesterolemia rat and rabbit. 40
Data obtained from animal models of hepatic injury showed that silymarin was capable of normalizing the increase in plasma lipids following administration of carbon tetrachloride and antagonizing the serum-free fatty acids reduction induced by thioacetamide. In hepatic injury produced by paracetamol, silymarin improved low-density lipoprotein binding to hepatocytes, which is a reliable factor for the reduction of low-density lipoprotein in plasma. However, in an animal model of hepatic injury induced by thioacetamide, silymarin was not able to normalize the reduction in triglycerides in serum. 25
The results of clinical research have also shown that silymarin can be introduced as a blood cholesterol reducer in hypercholesterolemia patients. The daily use of silymarin in 420 mg dosage on 15 people with hypercholesterolemia led to reduced cholesterol concentration in the gallbladder compared with the control group, implying cholesterol synthesis in the liver. 41 Fourteen patients with type II hyperlipidemia were clinically examined, as silymarin in 420 mg doses led to reduced total blood cholesterol and increased high-density lipoprotein cholesterol in patients. 42
Renal Diseases
It has been reported that silybin present in the silymarin inhibits renal toxicity resulting from administration of cisplatin in laboratory mice. Moreover, silybin has inhibited renal disorders resulting from the effect of cyclosporine in laboratory mouse. 43
Recent studies have suggested that silymarin for kidney health might be as important as for liver. Silymarin concentrates in kidney cells and aids in regeneration of the cells by increasing protein and nucleic acid synthesis. It has been suggested that silymarin increases cell replication by 30%, which is related to 2 important components of silymarin: silybin and silychristin. Silymarin has beneficial effects on diabetic nephropathy. 44 –46
It has been shown that silymarin might be effective for the prevention of nephropathy-induced premature death in diabetic patients. A study conducted on 60 diabetic patients with urinary albumin excretion >300 mg/day showed that the silymarin-treated group had 50% decrease in urine albumin–creatinine ratio after 3 months of silymarin consumption. In most cases renal impairments have been attributed to oxidative stress, inflammation, and fibrosis, and silymarin seems to act in these ways.
The potential effects of silymarin in diabetic nephropathy have been shown in a few studies. It is also effective in preventing proteinuria in type 2 diabetes mellitus with overt nephropathy. The effect of silymarin has mostly been related to its antioxidant and anti-inflammatory effects. 6,47 In this regard, adding silymarin to renin–angiotensin system inhibitors in type 2 diabetic patients having proteinuria with overt nephropathy could reduce malondialdehyde, urinary excretion of albumin, and tumor necrosis factor-α. 46,48
Nervous System
It has been reported that alcohol consumption may lead to reduced learning ability in rats’ offspring. However, this effect was prevented when it was co-administered with silymarin. Inflammation of the nerves is the main cause of extensive nerve cell damage. Moreover, silymarin can inhibit brain damage caused by blockages in brain vessels. 49 The influence of silymarin has been proved in the improvement of nerve conduction of nerve fibers in patients with diabetes. 50
Diabetes mellitus has been shown to reduce learning, memory, and cognitive skills, and administration of silymarin at 100 mg/kg dose enhanced the ability to store data in memory and to recall it in diabetic rats. However, it does not improve short-term spatial memory in diabetic rats. This beneficial effects of silymarin has been attributed to attenuation of lipid peroxidation in hippocampus tissue. 51
Endocrine Gland
Results gained through study on animals suggest that silymarin protects pancreas from chemical compounds including alloxan and cyclosporine. Sixty patients affected by alcoholic liver cirrhosis with insulin resistance diabetes were treated with silymarin. The outcome showed significant reduction in fasting blood glucose, daily mean blood glucose level, glycosuria, and insulin demand during 6 months. 52
Hematologic Effects
One of the main properties of silymarin is antioxidant effects on blood compounds. Oxidation of blood compounds was found to be important in intensifying cardiovascular and other chronic diseases. Based on laboratory reports, silymarin helps prevent hemolysis of red blood cells induced by copper and administration of hydrogen peroxide and other oxygen-derived free radical producing materials. 53
Immune System
Laboratory data indicate that silymarin has no effect on nonstimulated neutrophils and chemotactic and phagocytic activities. However, silymarin inhibits myeloperoxidase release when neutrophils are evoked. Incubation of neutrophils with silymarin results in retardation of the function of leukocyte mobility inhibitors.
Treatment with silymarin led to increase in lectin as the stimulator of lymphoblast deformation in a double-blind, placebo-controlled trial on 40 patients with alcoholic liver cirrhosis. Besides, the number of T8+ cells dropped and lymphocytotoxicity suppressed significantly compared with that of the control group. 54
Anticancer Effects
Laboratory data show that silymarin and especially silybin produce chemopreventive effects on epidermal cancer cells, prostate, as well as animal breast cancer. 55 Silymarin showed cytoprotective effects on cancer cells of prostate and human breasts encountered with carcinogenic agents. Pre-inoculation of cancer cells with silybin before exposure to silybin led to increased Adriamycin effect in the prevention of cell growth. 56
It should be noted that because of the strong antioxidant effects of Silybum marianum, there is a concern that this plant may produce interactions in fixing lymphocytotoxicity function of chemotherapy medicines acting through biochemical peroxidative paths. However, silybin can strength cytotoxic cisplatin and doxorubicin synergestic interactions, and there is no evidence about its interaction with their cytotoxicity effect. 57
Data from animal studies emphasize that silymarin can prevent carcinogenesis in epithelial tumors of different rat models. For example, feeding rats with silymarin could protect them against chemicals and UVB effects causing cancer. 58
Stimulating effects of silymarin on liver DNA is exerted on noncancerous cells. Silymarin in a study on hepatoma-bearing rats did not stimulate tumor growth. 59 Among studies in human subjects, there is a report of a man with hepatocellular carcinoma through biopsy proved to be unable to have surgery and then his disease improved by taking daily 450 mg silymarin.
Osteoporosis
Taxifolin found in Silybum marianum has considerable estrogenic properties. Additionally, flavonoid compounds in silymarin can affect metaphysis of femur without any connection with B estrogenic receptors through exerting any estrogenic agonist effect on the uterus. 60
Psoriasis
Silymarin has been used traditionally to treat psoriasis. It may act to improve psoriasis by removing unwanted metabolites from body cells especially liver and also inhibiting cAMP cycle and the synthesis of leukotrienes. There is a potential of enhanced cAMP cycle and increased synthesis of leukotrienes in patients with psoriasis that its inhibition by silymarin possibly leads to improvements. 61
Side Effects and Toxicities
Toxicity and Contraindications
Types of allergic reactions can occur in people who are sensitive to natural products. An allergic reaction to Silybum marianum has also been reported. There is a report of an adverse reaction to Silybum marianum in an English woman who seemingly had a capsule containing several plant extracts. However, it is not obvious that to which plant in the capsule the reaction was produced. Also a case of anaphylaxis in a patient with a known allergy to the kiwi fruit has been reported. 62
Acute Toxicity
In animals, silymarin was found to have no significant side effect even when administered at high doses. Because of the stimulatory effects of the plant on the liver and gallbladder, some experts believe that a mild laxative effect may occur during earlier days of consumption. However, in a randomized, controlled trial the side effects of this herb hardly dominated the placebo. In a study of several thousand patients, very low incidences of adverse effects were found, which mainly were limited to mild gastrointestinal disorders. 63
Chronic Toxicity
Long-term use of this herb is safe with no incidence of abnormality. There is no report alluding to adverse herb reactions during the course of a disease or in patients with organ-specific disorder. 64
Drug Interactions With Other Herbal or Chemical Medicines
Silybum marianum can lower demand for insulin in diabetic patients with alcohol-related liver cirrhosis. However, there is no study about the effect of the herb on glucose metabolism change in patients without liver disease. 65
In a double-blind trial on 6 women patients who were chronically using psychoactive drugs, the amount of liver enzymes including alanine transaminase and aspartate transaminase were increased. Taking 400 mg silymarin twice daily for 90 days led to decreased lipoperoxidase and liver damage when compared with the control group. 66
Silymarin can reduce adverse effect of chemical medicines such as anticancer drugs including paclitaxel, cisplatin, methothexate, fluorouracil, and blood lipid reducing drugs including clofibrate, lovastatin, pravastatin, and psychoactive drugs like haloperidol, tacrine, and some other medicines including nitrous oxide, acetaminophen, metronidazole, and cyclosporine. 67
Consumption During Breastfeeding and Pregnancy
Silybum marianum consumption during pregnancy, breastfeeding, and also for children is permitted. Although the side effects caused by plants in long term have not been proven during pregnancy, during breastfeeding, and also for children, this belief is considered based on long-term historical use as a food.
Consumption of this drug is suggested for the treatment of pruritus associated with bile duct obstruction in pregnant women. In addition, use of this herb in pregnant women leads to inhibited liver damage. Administration is essential to pregnant women poisoned with Amanita mushroom. 68
Dose
The doses of plant recommended here is the amount of commonly administered doses of the herb rather than an applicable document. However, doses are only determined for silymarin alone and should be adjusted when combined with others. Furthermore, they vary based on the type and severity of the condition of treatment and even the patient’s individual characteristics.
In adults, reports of herb specialists suggest a range of doses. The doses used in the literature ranged from 280 to 800 mg daily silymarin. Most studies have applied concentrated standard product containing 70% to 80% silymarin. Standardized plant extract dose is defined as 100 to 200 mg substance taken orally twice a day with meals. 64
In several studies, taking a 100 mg dose of Silybin co-administered with phosphatidylcholine, 3 times daily, has been introduced due to its higher reabsorption. In Europe, silybin was injected intravenously at 20 to 50 mg/kg of body weight dosage 3 or 4 times daily for the treatment of acute hepatotoxic induced by Amanita poison. 64
Tea is not a desirable method of administration because silymarin cannot dissolve in water well. But they can be used as herbal tea if seeds are crushed and fried. The usual dose is described as 12 to 15 g fried and crushed grains, 3 times a day with meals. The dose of tincture is 3 to 6 mL, 3 times daily with meal. 9,69,70
Available standardized products should contain at least 70% silymarin. 3
Discussion
As already mentioned, silymarin or Silybum marianum has been considered as a key for all diseases. It acts with various mechanism; however, it is a very potent antioxidant and it seems that the main mechanism of action of this plant is activity as a free radical scavenger and prevention of lipid peroxidation. Silybum marianum has been shown to have some additional mechanism by which it is able to protect liver, specifically. It increases the cellular glutathione in the liver, regulates membrane permeability of liver cells, and increases their membrane stability in the presence of xenobiotic damages, regulates nuclear expression by means of a steroid-like effect, and inhibits the transformation of stellate hepatocytes into myofibroblasts, the one that is responsible for the deposition of collagen fibers leading to cirrhosis. 71 How it acts in other organs, other than acting as an antioxidant, is not clear. Silymarin (and especially silybin) is a powerful antioxidant and free radical scavenger that restores a lot of internal antioxidants and prevents oxidative stress. 72
Oxidative stress has been shown to be implicated in a wide range of pathological conditions such as chronic inflammation and the generation of damage, particularly during ischemia/reperfusion, 73,74 neurological disorders, 75,76 diabetes, 77,78 atherosclerosis, 79,80 cardiovascular diseases, 81,82 cancer, 83,84 gastrointestinal, 85,86 and infectious, 86 –88 diseases or wound complication. 89,90 These conditions involve many changes such as alterations in redox stat. 91 –94 Antioxidants possess the ability to counteract these conditions. 64,66,92
Various experimental and clinical investigations have demonstrated promising results for the treatment and prevention of life-threatening diseases with plants antioxidants. 95 –104 These agents are also effective in inhibition of toxic agents–induced complications. 105 –110 Therefore, Silybum marianum or silymarin, which is a powerful antioxidant and free radical scavenger, 4 should mainly act in this way in the prevention of diseases and pathologic conditions.
Laboratory data associated with rats have shown that 2-week remedy with silybin would protect them from cyclosporine-induced lipid peroxidation. 18 Silybin prevents low-density lipoprotein from peroxidation in vitro and protects human leukocytes against hydrogen peroxide, preventing DNA damage. 66 Silymarin also has antioxidant effects in human platelets and acts as antioxidant in human liver and pulmonary microsomes and consequently provide protective action against induced lipid peroxidation with chemicals. 66
Animal studies have shown that increased chronic iron overload leads to oxidation stress and liver damage and that silymarin can inhibit this toxicity by its antioxidant activity. 111
Human studies have demonstrated that silymarin may enhance superoxide dismutase in red blood cells and lymphocytes level in patients with alcoholic cirrhosis, thus increasing antioxidant effects. 26
Footnotes
Author Contributions
All the authors wrote the first draft of the article. MRK revised and edited the last version.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was done with support of Research Deputy of Shahrekord University of Medical Sciences, Shahrekord, Iran.
Ethical Approval
This study is exempt from oversight by human subjects research protection as there were no human subjects involved.
