Milk thistle contains silymarin, which protects liver cell membrane and improves liver function. At present, milk thistle has become a hepatoprotective plant, which has been widely used for the treatment of acute and chronic hepatitis and cirrhosis. Many pharmacological experiments also showed that silymarin has the effects of lowering blood fat, protecting the heart muscle and preventing diabetes.
1 Chemical composition
1.1 Milk thistle oil: The content of oil in milk thistle fruit is about 26%, including 46.46% of linoleic acid and 2.46% of linolenic acid.
1.2 flavonoids: milk thistle fruit is rich in flavonoids, mainly silymarin, which contains silybin, dehydrosi-sflybin, silybinomer, silychrlstin and silydianin. milk thistle fruits also contains quercetin, silandrin, silymonin, flavanol, 5,7-dihydroxychromone, and polyhydmxyphenyl-chromanone.
1.3 Other compounds: milk thistle contains 12 polyacetylene compounds and one kind of polyolefin in the root, and also contains alkaloids such as betaine.
2 Pharmacological research
2.1 Hepatoprotective effects: Silymarin has strong anti-oxidant activity and is widely used as an anti-hepatotoxic agent in clinical. researches have shown that silymarin can significantly change the liver tissue hardening, diffuse necrosis, and lipidosis caused by the injection of CCl4 (carbon tetrachloride) in mineral oil solution to Wistar male rats; make the collagen band thinner and reduce the content of liver collagen; inhibit the levels of ALT, ALP, Gamma-GTP, and total bilirubin in the blood caused by CCl4; inhibit the elevated malondialdehyde levels in the liver homogenate; prevent hepatic glycogen from decreasing by CCl4; silymarin also inhibits absorption of ethanol by pregnant rats which affects fetal brain and liver tissue.
Silybin can significantly inhibit lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production in vivo; it can inhibit the cytotoxic effect of TNF on the hepatocyte cell line GSD-7701 and fibroblast cell line L929 in vitro; in vivo silybin has a protective effect on LPS-induced inflammation of the hepatic inflammatory lesions of P. acnes sensitized mice. It is suggested that the hepatoprotective mechanism of silybin is related to its inhibition of TNF production and activity. Studies have shown that the liver microsomal cytochrome P-450 content and activity caused by burns in Sprague-Dawley rats is significantly reduced, accompanied by increased liver lipid peroxidation activity, silybin can inhibit liver lipids, oxidative activity increasing, and protect liver drug metabolism enzyme activity.
2.2 Prevention and treatment of diabetes: The scientists used silymarin to treat diabetic rats induced by streptozotocin. The results showed that silymarin had no inhibitory effect on fructosamine, an early glycosylated product, but it inhibited lipid peroxidation (LPO), advanced glycationend products(AGEs) and pentosidine. Its mechanism of action is that silymarin can control chronic diabetic vascular complications by inhibiting the non-enzymatic glycosylation and oxidation of aortic tissue in diabetic rats. Silymarin inhibits non-enzymatic glycosylation and formation of oxidation products in kidney tissue, and significantly inhibits streptozotocin-induced diabetes. The increase in four kinds of fluorescent products, such as rat lipid peroxide (LPO), advanced glycosylation endproducts (AGEs), pentosidine, and HydroxynonenaX (FINE), resulted in reducing urinary protein excretion and renal lesions.
2.3 Reducing blood lipid: Milk thistle oil contains a large amount of linoleic acid, linolenic acid, which are polyunsaturated fatty acids, can promote the oxidation of cholesterol in the intestine, reducing blood fat, preventing atherosclerosis, significantly reducing the external source hypercholesterolemia, cholesterol and triglycerides. Milk thistle oil also has the role of lowering plasma cholesterol and treating hypertension.
2.4 Cardioprotective effects on cardiomyocytes: Silybin protects cardiomyocytes from infection with Coxsackile B5 virus, increases the rate of DNA synthesis, and reduces virus titer in the culture fluid of infected cells. Silybin can reduce the damage of hypoxic and hypoglycemic cultured cardiomyocytes, which can not only increase the tolerance of myocardial cells to hypoxia and hypoglycemia, but also partially counteract the damage effects of isoproterenol on hypoxia and hypoglycemic myocardial cells.
2.5 Anti-platelet aggregation: Study showed that intravenous injection of silymarin 80mg/kg and silybin 60mg/kg, the platelet adhesion rate was tested 1 hour before and after administration, the rates of maximum aggregation of rat platelets were reduced by 63% and 68%, respectively.
2.6 Antioxidation: Silymarin can reduce the content of malondialdehyde (MDA) and leukotrienes in damaged brain tissue by eliminating oxygen free radicals, inhibiting lipid peroxidation and 5-lipoxygenase activity, and increasing superoxide dismutase (SOD).
2.7 Side effects: the toxicity of milk thistle oil is very low, the rats fed gavage, the dose of 500mg/kg, for14 days without death. The LD50 for intravenous injection of silybin to mice was calculated to be 519 mg/kg using a chance unit method with a 95% confidence limit of 461 to 586 mg/kg.
2.8 Other effects: Exposure of mice to deep X-rays with minimal lethal doses and intragastric administration of silybin 100 mg/kg for 5 consecutive days. Rats in the medication group have improved survival and weight loss and recovered quickly. Radiation lesions are also lighter. The rats were given silybin 50 mg/kg in advance and triethyltin was intraperitoneally injected 30 minutes later. Electron microscopy observations indicate that silybin completely protects the delicate structure of the central nervous system from toxic effects. Silymarin can also improve the body’s immune function. Experiments have shown that silymarin can increase the phagocytosis rate and phagocytic index of mouse peritoneal macrophages, increase the number of peripheral blood leukocytes in mice, promote lymphocyte transformation and increase lymphocyte transformation percentage. Milk thistle oil has the effect of inhibiting mycobacterium tuberculosis in vitro, and its antibacterial potency is ≥100 (valency: ug/ml).
3 Applications
Treatment of 30 patients suffered from simple hyperlipidemia with silymarin tablets had similar cholesterol lowering effect and lipid-lowering level, while lowering triglyceride was better than lipid-lowering effect. Studies have shown that silymarin is an effective inhibitor of aldose reductase, which helps to improve the metabolism of polyols in NIDDM patients and prevent and treat some chronic complications of diabetes. Oral silybin can significantly reduce the erythrocyte sorbitol content in diabetic patients and improve nerve conduction velocity. Taking oral silybin 70 to 140 mg three times daily for more than 5 weeks can improve the symptoms of hepatitis patients. Silybum can be used to supplement the Zn and Se content in patients with hepatitis, correcting metabolic disorders.