Effects of phenolic compounds on bromobenzenemediated hepatotoxicity in mice

1. The hepatic protective effects of the phenolic compounds 7,8-dihydroxyflavone, morin, silymarin, caffeic acid and chlorogenic acid on bromobenzene-induced toxicity in mice were studied.

2. Morin, caffeic acid and chlorogenic acid at an oral dose of 200mg/kg failed to influence hepatotoxicity in vivo, while 7,8-dihydroxyflavone exhibited efficacy and potency higher than those of the reference compound silymarin.

3. 7,8-Dihydroxyflavone, an antioxidant and hepatoprotective agent in vitro, decreased serum glutamate-pyruvate transaminase levels (SGPT) in a dose-related manner, and at 200mg/kg inhibited bromobenzene-induced glutathione depletion in liver.     

Silymarin inhibits melanin synthesis in melanocyte cells

Objectives The aim was to search for inhibitors of melanogenesis from natural resources. Methods The inhibitory effect of silymarin on melanogenesis in a spontaneously immortalized mouse melanocyte cell line, Mel‐Ab, was studied. Key findings Silymarin significantly prevented melanin production in a dose‐dependent manner with an IC50 value (concentration producing 50% maximal inhibition) of 28.2 μg/ml, without effects on cell viability. Also, silymarin inhibited l ‐DOPA oxidation activity of tyrosinase, the rate‐limiting melanogenic enzyme, in cell based‐systems but it did not directly affect cell‐free tyrosinase activity. Furthermore, Western blot analysis indicated that silymarin decreased the expression of tyrosinase protein. Conclusions This study suggests that the depigmenting effect of silymarin might be attributable to inhibition of tyrosinase expression and that silymarin may be useful as a natural skin‐lightening agent.     

水飞蓟素在慢性疾病中的抗氧化作用研究概述

水飞蓟素(silymarin)作为护肝药物被广泛应用于各类肝病,其护肝作用与水飞蓟素强大的抗氧化、抗炎和抗脂质沉积等作用有关。越来越多研究表明水飞蓟素在氧化应激引发的如心血管疾病、代谢综合征、神经退行性疾病、癌症和并发症等慢性疾病都具有良好治疗效果。本篇列举了近五年水飞蓟素治疗慢性病的通路研究,重点阐述慢性疾病与氧化应激的损伤机制和水飞蓟素的抗氧化能力在其中发挥的关键作用,以期为水飞蓟素的临床使用提供用药思路。     

Silymarin prevents adriamycin-induced cardiotoxicity and nephrotoxicity in rats

Adriamycin is a potent anticancer agent, its clinical use is limited for its marked cardiotoxicity and nephrotoxicity. The present study aimed to investigate the possible protective role of the natural antioxidant silymarin on ADR-induced heart and kidney toxicity. Studies were performed on four groups of rats. 1--control group, 2--silymarin group (50 mg/kg), 3--adriamycin group (10 mg/kg), 4--adriamycin+silymarin group. On the third day after ADR injection, plasma was separated for determination of LDH, CPK, cholesterol and total lipids. 30 days after ADR injection, plasma was separated for determination of creatinine and urea levels. Frozen heart specimens (72 h) and frozen kidney specimens (30days) were used for estimation of lipid peroxides and GSH contents. Histopathological examinations of heart and kidney sections were also done. Pretreatment of ADR-treated rats with silymarin resulted in a significant decrease in the plasma CPK, LDH, creatinine and urea. On the other hand silymarin pretreatment did not change ADR-induced hyperlipidemia. Silymarin pretreatment significantly decreased the myocardial MDA contents. In addition, silymarin pretreatment normalized renal tissue contents of MDA and GSH. Histopathological examination of heart and kidney sections revealed that ADR caused only mild myocardial injury in silymarin pretreated rats. Also, silymarin pretreatment inhibited ADR-induced renal tubular damage in rats. These results have suggested that, silymarin ameliorated ADR-induced cardiotoxicity and protected against ADR-induced nephrotoxicity in male albino rats. The mechanisms of silymarin induced protection against ADR-induced toxicities were proved to be due to inhibition of lipid peroxidation and protection against GSH depletion.     

Improvement bioavailability of silymarin ameliorates severe dyslipidemia associated with metabolic syndrome

Abstract

1. To compare the effectiveness of different drug forms of silymarin: standardized extract of silymarin (SS), micronized silymarin (MS) and silymarin in the form of phytosome (PS) on dyslipidemia and liver fat accumulation in a model of metabolic syndrome, in non-obese hereditary hypertriglyceridemic rats. The second aim of this study was to slightly uncover the silymarin action on enzymes and proteins involved in cholesterol metabolism and excretion.

2. Silymarin administered to hereditary hypertriglyceridemic rats as dietary supplements (1%) for 4 weeks significantly lowered the plasma levels of triglycerides, total cholesterol and markedly increased HDL cholesterol level. Western blot analyses showed significant increase in the protein expression of CYP7A1 and CYP4A and increase in protein expression of selected ABC transporters. Silymarin in the form of phytosome and micronized silymarin were more effective forms of silymarin.

3. These findings suggest that silymarin may favorably affect the metabolism of cholesterol and triglycerides in rats with metabolic syndrome. Raising HDL levels suggests potentially important anti-atherogenic effect of silymarin. The changes in expression of cytochromes P450 and ABC transporters involved in cholesterol metabolism and excretion could be partially responsible for the hypolipidemic effect of silymarin.     

Flavonolignan Production in Cell Suspension Culture of Silybum marianum

The fruits of Silybum marianum (L.) Gaertn (Compositae) contain silymarin, an isomeric mixture of flavonolignans (silybin, silychristin, and silydianin). Silymarin acts as a strong anti-hepatotoxic. Silybum marianum cell cultures represent an alternate source of flavonolignans, but the yields of these compounds in such cultures are very low. In this study, in vitro cell culture systems of Silybum marianum were used to monitor the effect of elicitation (picloram, jasmonic acid, and light) on cell growth and production of silymarin. The presence of silymarin was established by high performance liquid chromatography and the greatest growth rates dry weight (32 mg) and silymarin content (0.413 mg g^{? 1} DW) were obtained with 3 mg l^{? 1} picloram and 2 mg l^{? 1} jasmonic acid in darkness after 28 days. The light grown cell suspension cultures showed reduced growth in term of dry weight (24 mg) and silymarin content. The data presented in this study demonstrate that media supplemented with 3 mg l^{? 1} picloram with JA in dark conditions can be useful for production of silymarin and growth in cell suspension cultures of Silybum marianum.     

Silymarin impacts on immune system as an immunomodulator: One key for many locks

Silymarin is a flavonoid complex extracted from the Silybum marianum plant. It acts as a strong antioxidant and free radical scavenger by different mechanisms. But in addition to antioxidant effects, silymarin/silybin reveals immunomodulatory affects with both immunostimulatory and immunosuppression activities. Different studies have shown that silymarin has the anti-inflammatory effect through the suppression of NF-κB signaling pathway and TNF-α activation. It also has different immunomodulatory activities in a dose and time-dependent manner. As an immunomodulator agent, silymarin inhibits T-lymphocyte function at low doses while stimulates inflammatory processes at high doses. Studies have shown that silymarin has attenuated autoimmune, allergic, preeclampsia, cancer, and immune-mediated liver diseases and also has suppressed oxidative and nitrosative immunotoxicity. Silymarin also has indicated dual effects on proliferation and apoptosis of different cells. In conclusion, based on the current review, silymarin has a broad spectrum of immunomodulatory functions under different conditions. Recognizing the exact mechanisms of silymarin on cellular and molecular pathways would be very valuable for treatment of immune-mediated diseases. Also further studies are needed to assess the utility of silymarin in protection against autoimmune, cancer, allergic and other diseases in human subjects.     

Gastric anti-ulcer activity of silymarin, a lipoxygenase inhibitor, in rats.

Oral treatment with silymarin was found to be effective in the prevention of gastric ulceration induced by cold-restraint stress, in rats. Statistically significant ulcer index values with respect to the control group, were observed. In 6 h pyloric-ligated animals silymarin showed a significant reduction in the number and severity of the ulcers; however, it did not alter the gastric secretion volume or acidity although histamine concentration was significantly decreased. In absolute ethanol-induced ulcers, treatment with silymarin 1 or 2 h before the anti-ulcerogenic agent, did not prevent the formation of gastric lesions. Furthermore, the hexosamine content was decreased significantly, but the total protein output was enhanced, showing similar values to those with the standard drug, carbenoxolone. These results suggest that the anti-ulcerogenic effect of silymarin could be related to its inhibitory mechanism of enzymatic peroxidation by the lipoxygenase pathway, avoiding leukotriene synthesis.     

Silymarin prevents palmitate-induced lipotoxicity in HepG2 cells: involvement of maintenance of Akt kinase activation

Whereas adipocytes have a unique capacity to store excess free fatty acids in the form of triglyceride in lipid droplets, non-adipose tissues, such as liver, have a limited capacity for storage of lipids. Saturated long-chain fatty acids, such as palmitate, are the major contributors to lipotoxicity. Silymarin is a mixture of flavonolignans, extracted from the milk thistle (Silibum marianum). Its hepatoprotective properties have been studied both in vitro and in vivo; however, its effect on palmitate-induced lipotoxicity has not been investigated. The objective of this study was to investigate (i) whether silymarin could protect HepG2 cells from palmitate-induced cell death in an in vitro model, and (ii) possible mechanisms involved in this hepatoprotective role of silymarin. HepG2 cells were treated with palmitate in the absence or presence of silymarin and supernatants or cell lysates were collected at varying time-points. Cell death was assayed by measuring DNA fragmentation, caspase-3 activity and lactate dehydrogenase release. Lipid peroxidation was assessed by measuring malondialdehyde and 4-hydroxyalkenals. Akt kinase activity was also measured. Incubation with palmitate caused significant death in HepG2 cells. Palmitate incubation did not cause significant changes in reactive oxygen species production or intracellular glutathione content, but markedly inhibited Akt kinase activity. Pre-treatment of HepG2 cells with silymarin prevented palmitate-induced inhibition of Akt kinase activity and attenuated cell death. Our results suggest that silymarin may be an effective agent in protecting hepatocytes from saturated fatty acids-induced cell death. These data also provide a further rationale for exploration of the use of silymarin in the treatment of non-alcoholic steatohepatitis.     

Silymarin liposomes improves oral bioavailability of silybin besides targeting hepatocytes,and immune cells

BackgroundSilymarin, a hepatoprotective agent, has poor oral bioavailability. However, the current dosage form of the drug does not target the liver and inflammatory cells selectively. The aim of the present study was to develop lecithin-based carrier system of silymarin by incorporating phytosomal–liposomal approach to increase its oral bioavailability and to make it target-specific to the liver for enhanced hepatoprotection.MethodsThe formulation was prepared by film hydration method. Release of drug was assessed at pH 1.2 and 7.4. Formulation was assessed for in vitro hepatoprotection on Chang liver cells, lipopolysaccharide-induced reactive oxygen species (ROS) production by RAW 267.4 (murine macrophages), in vivo efficacy against paracetamol-induced hepatotoxicity and pharmacokinetic study by oral route in Wistar rat.ResultsThe formulation showed maximum entrapment (55%) for a lecithin–cholesterol ratio of 6:1. Comparative release profile of formulation was better than silymarin at pH 1.2 and pH 7.4. In vitro studies showed a better hepatoprotection efficacy for formulation (one and half times) and better prevention of ROS production (ten times) compared to silymarin. In in vivo model, paracetamol showed significant hepatotoxicity in Wistar rats assessed through LFT, antioxidant markers and inflammatory markers. The formulation was found more efficacious than silymarin suspension in protecting the liver against paracetamol toxicity and the associated inflammatory conditions. The liposomal formulation yielded a three and half fold higher bioavailability of silymarin as compared with silymarin suspension.ConclusionsIncorporating the phytosomal form of silymarin in liposomal carrier system increased the oral bioavailability and showed better hepatoprotection and better anti-inflammatory effects compared with silymarin suspension.     

水飞蓟素胶囊化学成分的UPLC-Q-TOF-MS快速鉴定与分析

目的：通过超高效液相色谱-四级杆-飞行时间串联质谱法（UPLC-Q-TOF-MS）技术定性分析水飞蓟素胶囊中的化学成分。方法：采用Waters XBridge BEH C₁₈色谱柱（100 mm×2.1 mm,2.5 μm）,以0.1%甲酸水-甲醇梯度洗脱,体积流量0.3 mL·min^-1;进样量3 μL。质谱采用电喷雾离子源（ESI）,正负离子模式下同时采集,通过精确质量数、二级质谱碎片信息和保留时间,参照文献和对照品对化合物进行鉴定。结果：结合参考文献和对照品信息,共鉴定化合物15个,包括二氢黄酮化合物1个,黄酮醇化合物2个,二氢黄酮醇化合物3个,黄酮木脂素类9个。结论：建立了UPLC-Q-TOF-MS法对水飞蓟素胶囊的成分进行定性分析,为其质量控制及药效机制的阐明提供科学依据。     

Alterations in Regional Brain Neurotransmitters by Silymarin,a Natural Antioxidant Flavonoid Mixture,in BALB/c Mice

Silymarin, a natural antioxidant flavonoid mixture, exerts anti-inflammatory effects in the liver and hinders tumor formation. The effect of this flavonoid mixture on the central nervous system is unknown, although antioxidants are considered beneficial. Brain amines and metabolites were studied after a short-term silymarin treatment. BALB/c mice were intraperitoneally treated with 0, 10, 50, or 250 mg/kg of silymarin per day for 5 days. High-performance liquid chromatography coupled with electrochemical detection was performed to determine concentrations of norepinephrine (NE), dopamine (DA), dioxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxytryptamine (5-HT, serotonin) and 5-hydroxyindoleacetic acid (5-HIAA) in discrete brain regions. Analyses showed increased 5-HT levels in the cortex and increased DA and NE levels in the cerebellum in the highest dose group. Results indicated lack of general adverse effect on the brain amine metabolism and suggest that silymarin may have marginal serotonergic, dopaminergic, and noradrenergic effects.     

Effects of silymarin MZ-80 on hepatic oxidative stress in rats with biliary obstruction.

This study was designed to evaluate the effects of three pharmaceutical forms of silymarin (silymarin MZ-80, silybinin-beta-cyclodextrin, and silybinin) on the liver oxidative status in vitro and after oral administration to rats with extrahepatic biliary obstruction (EBO) and sham-operated animals. We evaluated thiobarbituric acid-reactive substances (TBARS), glutathione (GSH + GSSG) and their related enzyme activities (GSH peroxidase, GSSG reductase and GSH transferase). All three compounds inhibited the in vitro production of TBARS (IC(50) 56-533 micromol/l). These compounds, mainly silymarin MZ-80, also increased GSH peroxidase and GSH transferase activities. In EBO rats we found increases in TBARS production which was inhibited by 50-70% after treatment. Glutathione was reduced by 55% and elevated by silymarin MZ-80. GSH transferase increased in the group given silymarin MZ-80. We conclude that all three derivatives of silymarin show a clear ability to reduce lipid peroxidation in the liver. Silymarin MZ-80 was the only compound that enhanced the glutathione antioxidant system.     

Silymarin as a new hepatoprotective agent in experimental cholestasis: new possibilities for an ancient medication

Silymarin is a purified extract from milk thistle (Silybum marianun (L.) Gaertn), composed of a mixture of four isomeric flavonolignans: silibinin (its main, active component), isosilibinin, silydianin and silychristin. This extract has been empirically used as a remedy for almost 2000 years, and remains being used as a medicine for many types of acute and chronic liver diseases. Despite its routinely clinical use as hepatoprotectant, the mechanisms underlying its beneficial effects remain largely unknown. This review addresses in detail a number of recent studies showing a novel feature of silymarin as a hepatoprotective drug, namely: its anticholestatic properties in experimental models of hepatocellular cholestasis with clinical correlate. For this purpose, this review will cover the following aspects: 1. The chemistry of silymarin, including chemical composition and properties. 2. The current clinical applications of silymarin as a hepatoprotective agent, including the mechanisms by which silymarin is thought to exert its hepatoprotective properties, when known. 3. The physiological events involved in bile formation, and the mechanisms of hepatocellular cholestasis, focusing on cellular targets and mechanisms of action of drugs used to reproduce experimentally cholestatic diseases of clinical interest, in particular estrogens and monohydroxylated bile salts, where anticholestatic properties of silymarin have been tested so far. 4. The recent findings describing the impact of silymarin on normal bile secretion and its novel, anticholestatic properties in experimental models of cholestasis, with particular emphasis on the cellular/molecular mechanisms involved, including modulation of bile salt synthesis, biotransformation/depuration of cholestatic compounds, changes in transporter expression/activity, and evocation of signaling pathways.     

Choleretic effect of picroliv, the hepatoprotective principle of Picrorhiza kurroa

Picroliv, the hepatoprotective principle of the plant Picrorhiza kurroa, showed a dose-dependent (1.5-12 mg/kg x 7) choleretic effect in conscious rats and anaesthetised guinea pigs. It also possessed a marked anticholestatic effect against paracetamol- and ethynylestradiol-induced cholestasis. It antagonised the changes in bile volume as well as the contents (bile salts and bile acids). Silymarin, a known hepatoprotective agent, was tested simultaneously for comparison. Picroliv was found to be a more potent choleretic and anticholestatic agent than silymarin.     

熊去氧胆酸联合水飞蓟素治疗脂肪肝的疗效观察

目的观察熊去氧胆酸联合水飞蓟素(益肝灵)治疗脂肪肝的临床疗效。方法将60例脂肪肝患者随机分为观察组和对照组各30例。对照组均给予益肝灵治疗,观察组再加用熊去氧胆酸治疗。治疗后比较2组临床疗效和血液生化指标。结果观察组总有效率为90.0%高于对照组的63.3%,差异有统计学意义(P<0.05)。2组治疗后血清丙氨酸氨基转移酶(ALF)、天冬氨酸氨基转移酶(AST)、谷氨酰基转移酶(γ-GT)及三酰甘油(TG)、总胆固醇(TC)水平均低于治疗前,且观察组低于对照组,差异均有统计学意义(P<0.05)。结论熊去氧胆酸联合益肝灵治疗脂肪肝疗效显著,值得临床推广使用。     

Silymarin protection against major reactive oxygen species released by environmental toxins: exogenous H2O2 exposure in erythrocytes

Silymarin is a polyphenolic plant flavonoid (a mixture of flavonoid isomers such as silibinin, isosilibinin, silidianin and silichristin) derived from Silymarin marianum that has anti-inflammatory, hepatoprotective and anticarcinogenic effects. Our earlier studies have shown that silymarin plays a protective role against the oxidative damage induced by environmental contaminants like benzo(a)pyrene in erythrocyte haemolysates. During the detoxification of these environmental contaminants, the major reactive oxygen species generated is hydrogen peroxide (H(2)O(2)). Because H(2)O(2 )can easily penetrate into the cell and cause damage to biomolecules, the protective role of silymarin was further assessed against this cytotoxic agent in vitro in erythrocyte haemolysates. The protective effect was monitored by assessing the levels of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-s-transferase, glutathione peroxidase and malondialdehyde (LPO) in three groups: vehicle control, H(2)O(2)-exposed groups and drug co-incubation group (H(2)O(2) + silymarin). The protective effect of silymarin on the non-enzymic antioxidant glutathione and haemolysis, methaemoglobin content and protein carbonyl content were also assessed. It was observed that the activities of antioxidant enzymes and glutathione were reduced and the malondialdehyde levels were elevated after H(2)O(2 )exposure. There were also alterations in haemolysis, methaemoglobin content and protein carbonyl content, whereas after the administration of silymarin, the antioxidant enzyme activities reversed to near normal with reduced malondialdehyde content and normalized haemolysis, methaemoglobin content and protein carbonyl content. The results suggest that silymarin possesses substantial protective effect and free radical scavenging mechanism against exogenous H(2)O(2)-induced oxidative stress damages, hence, can be used as a protective drug against toxicity induced by environmental contaminants.     

Inhibition of cyclooxygenase-2 and inducible nitric oxide synthase by silymarin in proliferating mesenchymal stem cells: comparison with glutathione modifiers

Silymarin, a mixture of flavonolignans, is extracted from milk thistle (Silybum marianum) and has a strong antioxidant activity and exhibits anticarcinogenic, anti-inflammatory, and cytoprotective effects. In this study we attempted to determine whether silymarin and the glutathione modifiers, buthionine sulfoxamine (BSO) and N-acetylcysteine (NAC), are involved in regulation of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in proliferating mesenchymal stem cells (MSCs). Cellular glutathione was manipulated during a 14-day culture using BSO, NAC and silymarin. At intervals of 2, 7 and 14 days, cells were collected and COX-2 and iNOS levels were measured. In parallel, generation of cellular H₂O₂ and glutathione were measured. Supplementation of the culture media with BSO caused a dose-dependent decrease in MSC proliferation, whereas NAC or silymarin elevated the proliferation (p < 0.05). Treatment of MSC with NAC or silymarin caused a significant decrease in COX-2 levels. However, COX-2 levels in cells treated with high levels of NAC (1.0 mM) were significantly lower than those in MSCs treated with high levels of silymarin (100 μM). BSO (1.0 and 5.0 μM) caused a significant increase in COX-2 on days 2, 7 and 14. BSO caused a significant increase in iNOS, whereas NAC or silymarin decreased cellular iNOS. Overall result show that glutathione, iNOS and COX-2 in proliferating MSCs are affected by silymarin treatment. It appears that glutathione is the main target of silymarin, and in consequence iNOS and COX-2 are affected in response to silymarin treatment.