The use of silymarin in the treatment of liver diseases

Silibinin prevents TPA-induced MMP-9 expression by down-regulation of COX-2 in human breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

The expression of matrix metalloproteinase-9 (MMP-9) and cyclooxygenase-2 (COX-2) are pivotal steps in breast cancer pathogenesis. In a previous study, we reported that silibinin suppresses TPA-induced MMP-9 expression through the Raf/MEK/ERK pathway.

AIMS OF THE STUDY

Herein we determined the co-relationship between MMP-9 and COX-2, as well as the effect of silibinin on 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced MMP-9 and COX-2 expression in the human breast cancer cells, MCF-7 and MDA-MB231.

METHODS

The toxicity of silibinin was evaluated by Quick Cell Proliferation Assay Kit II. MMP-9 and COX-2 expression were analyzed by Zymography and Western blotting, respectively. Adenoviral constitutively active (CA)-MEK was used to activate MEK/ERK pathway.

RESULTS

The expression of MMP-9 and COX-2 in response to TPA was increased, whereas TPA-induced MMP-9 and COX-2 expression was decreased by silibinin. Our results showed that TPA-induced MMP-9 expression was inhibited by celecoxib in a dose-dependent fashion, but not MMP-1-expression. Both MMP-9 and COX-2 expression were significantly increased by CA-MEK overexpression. In contrast, TPA-induced MMP-9 and COX-2 expression was decreased by UO126 (MEK 1/2 inhibitor).

CONCLUSION

Silibinin down-regulates TPA-induced MMP-9 expression through inhibition of COX-2 expression in breast cancer cells.

Solid state mechanochemical activation of Silybum marianum dry extract with betacyclodextrins: Characterization and bioavailability of the coground systems

Silybum marianum dry extract, whose therapeutic use is partially restricted by the insolubility in water of its main flavonolignans, was subjected to a mechanochemical activation process in planetary mill using betacyclodextrins as carriers. After optimization of the operating conditions according to an established theoretical model, the best active-to-carrier proportion was selected from the preliminary trials. When using the optimized conditions, the mechanochemical process permits an improvement of the physico-chemical properties of the active, which reaches an "activated" solid state, that is stable for at least 1 year. In fact, XRD, DRIFT and Raman spectroscopy analyses showed that the main extract component, Silybin, completely lost its crystalline structure after co-grinding with betacyclodextrins and formed weak interactions with the carrier. The powder characteristics remarkably changed after co-grinding, leading to a sample with a very small mean diameter and with a twofold increase of the specific surface area in comparison to the dry extract. The activated solid state of the coground systems remarkably enhanced the in vitro drug dissolution kinetics with consequent improved oral bioavailability. Furthermore, the in vivo studies on rats revealed a 6.6-fold bioavailability increase respect to the S. marianum Italian commercial product used as reference (Silirex 200 capsules).

Inhibitory effects of armepavine against hepatic fibrosis in rats

Activation of hepatic stellate cells (HSCs) plays a crucial role in liver fibrogenesis. armepavine (Arm, C₁₉H₂₃O₃N), an active compound from Nelumbo nucifera, has been shown to exert immunosuppressive effects on T lymphocytes and on lupus nephritic mice. The aim of this study was to investigate whether Arm could exert anti-hepatic fibrogenic effects in vitro and in vivo. A cell line of rat HSCs (HSC-T6) was stimulated with tumor necrosis factor-α (TNF-α) or lipopolysaccharide (LPS) to evaluate the inhibitory effects of Arm. An in vivo therapeutic study was conducted in bile duct-ligated (BDL) rats. BDL rats were given Arm (3 or 10 mg/kg) by gavage twice daily for 3 weeks starting from the onset of BDL. Liver sections were taken for fibrosis scoring, immuno-fluorescence staining and quantitative real-time mRNA measurements. In vitro, Arm (1-10 μM) concentration-dependently attenuated TNF-α- and LPS-stimulated α-SMA protein expression and AP-1 activation by HSC-T6 cells without adverse cytotoxicity. Arm also suppressed TNF-α-induced collagen collagen deposition, NFκB activation and MAPK (p38, ERK1/2, and JNK) phosphorylations. In vivo, Arm treatment significantly reduced plasma AST and ALT levels, hepatic α-SMA expression and collagen contents, and fibrosis scores of BDL rats as compared with vehicle treatment. Moreover, Arm attenuated the mRNA expression levels of col 1α2, TGF-β1, TIMP-1, ICAM-1, iNOS, and IL-6 genes, but up-regulated metallothionein genes. Our study results showed that Arm exerted both in vitro and in vivo antifibrotic effects in rats, possibly through anti-NF-κB activation pathways.

Improvement of inflammatory and toxic stress biomarkers by silymarin in a murine model of type one diabetes mellitus

Type 1 diabetes mellitus (T1DM) is characterized by an impairment of the insulin-secreting beta cells with an immunologic base. Inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and free radicals are believed to play key roles in destruction of pancreatic β cells. The present study was designed to investigate the effect of Silybum marianum seed extract (silymarin), a combination of several flavonolignans with immunomodulatory, anti-oxidant, and anti-inflammatory potential on streptozotocin (STZ)-induced T1DM in mouse. Experimental T1DM was induced in male albino mice by IV injection of multiplelow- doses of STZ for 5 days. Seventy-two male mice in separate groups received various doses of silymarin (20, 40, and 80 mg/kg) concomitant or after induction of diabetes for 21 days. Blood glucose and pancreatic biomarkers of inflammation and toxic stress (IL-1β, TNF-α, myeloperoxidase, lipid peroxidation, protein oxidation, thiol molecules, and total antioxidant capacity) were determined. Silymarin treatment reduced levels of inflammatory cytokines such as TNF-α and IL-1β and oxidative stress mediators like myeloperoxidase activity, lipid peroxidation, carbonyl and thiol content of pancreatic tissue in an almost dose dependent manner. No marked difference between the prevention of T1DM and the reversion of this disease by silymarin was found. Use of silymarin seems to be helpful in T1DM when used as pretreatment or treatment. Benefit of silymarin in human T1DM remains to be elucidated by clinical trials.

Influence of exogenous salicylic acid on flavonolignans and lipoxygenase activity in the hairy root cultures of Silybum marianum

Silymarin is one of the most potent antioxidant so far developed from plant sources used as hepatoprotectants. Influence of different concentrations (0, 1, 2, 4, 6 and 8mg/50ml culture) and exposure time (24, 48, 72, 96 and 120h) of salicylic acid on lipoxygenase activity, linoleic acid content, growth and production of silymarin in hairy root cultures of S. marianum were investigated. Detection and identification of flavonolignans was carried out by high performance liquid chromatograph method. Salicylic acid enhanced silymarin production (1.89mgg(-1) DW). The optimal feeding condition was the addition of salicylic acid (6 mg/50 ml culture) after 24h in which the silymarin content was 2.42 times higher than the control (0.78mgg(-1) DW). The content of silybin, isosilybin, silychristin, silydianin and taxifolin were 0.703, 0.017, 0.289, 0.02 and 0.863mgg(-1) DW respectively in these samples, while in non-treated hairy roots were 0.027, 0.046, 0.23, 0.022 and 0.453 respectively. Lipoxygenase activity also affected by elicitation. lipoxygenase activity increased 24h after treatment by approximately 1.57- fold (0.21 Delta OD(234)/mgproteinmin(-1)). Upon elicitation with salicylic acid, linoleic acid content of hairy roots (38.26mgg(-1) DW) were also elevated after 24h, in which the linoleic acid content was 2.37 times higher than the control (16.1mgg(-1) DW). It is feasible that elicitation with salicylic acid regulates the jasmonate pathway, which in turn mediates the elicitor-induced accumulation of silymarin.

Deleterious effects of silymarin on the expression of genes controlling endothelial nitric oxide synthase activity in carbon tetrachloride-treated rat livers

AIMS

Defects in intrahepatic nitric oxide (NO) are attributed to reduced blood flow due to portal hypertension caused by diminished endothelial NO synthase (eNOS) activity. The aim of this study is to identify the therapeutic effects of silymarin on eNOS/NO-related enzymes and hepatic enzymes in carbon tetrachloride (CCl4)-induced cirrhotic rats.

MAIN METHODS

CCl4 treated for 12 weeks was discontinued and then administrated with silymarin daily for 4 weeks. Collagen concentrations were determined by measuring hydroxyproline content. Serum was assayed for hepatic enzymes like alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities. NOS activities were measured by oxyhemoglobin oxidation assay, and levels of enzyme expression and phosphorylation were detected by Western-blot analyses.

KEY FINDINGS

Silymarin treatment restored the values for collagen content and ALT and ALP activities when compared to the values with spontaneous resolution following discontinuation of CCl4. CCl4 treatment highly increased eNOS expression and NOS activity in livers, but the phosphorylation was markedly decreased. Silymarin decreased significantly eNOS expression and activity. Expression and/or phosphorylation of enzymes activating eNOS were unchanged (Akt and AMPK) or decreased (PKA) by silymarin. Especially, the expression of caveolin-1, an inhibitor of eNOS was unchanged by CCl4, but its phosphorylation was significantly increased. However, silymarin markedly increased caveolin-1 expression but decreased its phosphorylation to expression.

SIGNIFICANCE

These results suggest that chronic silymarin treatment can improve cirrhosis-induced liver enzyme activities and fibrosis, but may aggravate the hemodynamic eNOS activity, particularly by decreasing eNOS expression and increasing caveolin-1 expression.

Silibinin inhibits translation initiation: implications for anticancer therapy

Silibinin is a nontoxic flavonoid reported to have anticancer properties. In this study, we show that silibinin exhibits antiproliferative activity on MCF-7 breast cancer cells. Exposure to silibinin leads to a concentration-dependent decrease in global protein synthesis associated with reduced levels of eukaryotic initiation factor 4F complex. Moreover, polysome profile analysis of silibinin-treated cells shows a decrease in polysome content and translation of cyclin D1 mRNA. Silibinin exerts its effects on translation initiation by inhibiting the mammalian target of rapamycin signaling pathway by acting upstream of TSC2. Our results show that silibinin blocks mammalian target of rapamycin signaling with a concomitant reduction in translation initiation, thus providing a possible molecular mechanism of how silibinin can inhibit growth of transformed cells.

Combined therapy of silymarin and desferrioxamine in patients with beta-thalassemia major: a randomized double-blind clinical trial

Silymarin, a flavonolignan complex isolated from Silybum marianum, has a strong antioxidant, hepatoprotective, and iron chelating activities. The present study was designed to investigate the therapeutic activity of orally administered silymarin in patients with thalassemia major under conventional iron chelation therapy. A 3-month randomized, double-blind, clinical trial was conducted in 59 beta-thalassemia major patients in two well-matched groups. Patients were randomized to receive a silymarin tablet (140 mg) three times a day plus conventional desferrioxamine therapy. The second group received the same therapy but a placebo tablet instead of silymarin. Clinical laboratory tests were assessed at the beginning and the end of the trial, except for serum ferritin level that was assessed at the middle of the trial as well. Results of this study revealed that the combined therapy was well tolerated and more effective than desferrioxamine in reducing serum ferritin level. Significant improvement in liver alkaline phosphatase and glutathione levels of red blood cells was also observed in silymarin-treated beta-thalassemia patients. However, no significant difference in serum ferritin levels was detected between silymarin and placebo groups after 1.5 and 3 months treatment, probably because of insufficient sample size to detect subtle changes in ferritin levels between groups. This is the first report showing the beneficial effects of silymarin in thalassemia patients and suggests that silymarin in combination with desferrioxamine can be safely and effectively used in the treatment of iron-loaded patients.

A randomized controlled trial to assess the safety and efficacy of silymarin on symptoms, signs and biomarkers of acute hepatitis

PURPOSE

Milk thistle or its purified extract, silymarin (Silybum marianum), is widely used in treating acute or chronic hepatitis. Although silymarin is hepatoprotective in animal experiments and some human hepatotoxic exposures, its efficacy in ameliorating the symptoms of acute clinical hepatitis remains inconclusive. In this study, our purpose was to determine whether silymarin improves symptoms, signs and laboratory test results in patients with acute clinical hepatitis, regardless of etiology.

METHODS

This is a randomized, placebo-controlled trial in which participants, treating physicians and data management staff were blinded to treatment group. The study was conducted at two fever hospitals in Tanta and Banha, Egypt where patients with symptoms compatible with acute clinical hepatitis and serum alanine aminotransferase (ALT) levels >2.5 times the upper limit of normal were enrolled. The intervention consisted of three times daily ingestion of either a standard recommended dose of 140 mg of silymarin (Legalon, MADAUS GmbH, Cologne, Germany), or a vitamin placebo for four weeks with an additional four-week follow-up. The primary outcomes were symptoms and signs of acute hepatitis and results of liver function tests on days 2, 4 and 7 and weeks 2, 4, and 8. Side-effects and adverse events were ascertained by self-report.

RESULTS

From July 2003 through October 2005, 105 eligible patients were enrolled after providing informed consent. No adverse events were noted and both silymarin and placebo were well tolerated. Patients randomized to the silymarin group had quicker resolution of symptoms related to biliary retention: dark urine (p=0.013), jaundice (p=0.02) and scleral icterus (p=0.043). There was a reduction in indirect bilirubin among those assigned to silymarin (p=0.012), but other variables including direct bilirubin, ALT and aspartate aminotransferase (AST) were not significantly reduced.

CONCLUSIONS

Patients receiving silymarin had earlier improvement in subjective and clinical markers of biliary excretion. Despite a modest sample size and multiple etiologies for acute clinical hepatitis, our results suggest that standard recommended doses of silymarin are safe and may be potentially effective in improving symptoms of acute clinical hepatitis despite lack of a detectable effect on biomarkers of the underlying hepatocellular inflammatory process.

Hepatoprotective effects of misoprostol and silymarin on carbon tetrachloride-induced hepatic damage in rats

The aim of this study was to investigate the effect of misoprostol, silymarin or the co-administration of misoprostol + silymarin on the carbon tetrachloride (CCl(4))-induced hepatic injury in rats. Misoprostol (10, 100, 1000 microg/kg), silymarin (25 mg/kg) or misoprostol (100 microg/kg) + silymarin (25 mg/kg) was given once daily orally simultaneously with CCl(4) and for 15 days thereafter. The results showed that misoprostol (10, 100 or 1000 microg/kg) conferred significant protection against the hepatotoxic actions of CCl(4) in rats, reducing serum alanine aminotransferase (ALT) levels by 24.7%, 42.6% and 49.4%, respectively compared with controls. Misoprostol, given at 100 or 1000 microg/kg, decreased aspartate aminotransferase (AST) by 28 and 43.6% and alkaline phosphatase (ALP) by 19.3% and 53.4% respectively. Meanwhile, silymarin reduced ALT, AST and ALP levels by 62.7%, 66.1% and 65.1% respectively. The co-administration of misoprostol (100 microg/kg) and silymarin (25 mg/kg) resulted in 61.4%, 66.1% and 57.5% reduction in ALT, AST and ALP levels respectively. Histopathological alterations and depletion of hepatocyte glycogen and DNA content by CCl(4) were markedly reduced after treatment with misoprostol, silymarin or misoprostol + silymarin. Image analysis of liver specimens revealed a marked reduction in liver necrosis; area of damage: 32.4%, 24% and 10.2% after misoprostol (10, 100 or 1000 microg/kg), 7.2% after silymarin and 10.9% after treatment with misoprostol 100 microg/kg + silymarin, compared with CCl(4) control group (46.7%). These results indicate that treatment with misoprostol protects against hepatocellular necrosis induced by CCl(4). This study suggests a potential therapeutic use for misoprostol in liver injury.

Silibinin protects OTA-mediated TNF-alpha release from perfused rat livers and isolated rat Kupffer cells

We studied the inhibitory effect of silibinin on ochratoxin A (OTA) and LPS-mediated tumor necrosis factor alpha (TNF-alpha) release and the leakage of cytotoxic markers glutamate dehydrogenase (GLDH) and lactate dehydrogenase (LDH), from isolated blood-free perfused rat livers, and from isolated pure rat Kupffer cells. In the recirculation perfusion model at the end point 90 min, 2.5 micromol/L OTA released 2600 pg/mL TNF-alpha without effects on liver vitality. LPS at 0.1 microg/mL induced 3000 pg TNF-alpha/mL with slight leakage of GLDH and LDH. Under similar experimental conditions, the addition of silibinin 10 min prior to OTA and LPS showed dose-dependent protection against OTA or LPS-induced hepatic TNF-alpha release. High-dose of silibinin (12.5 microg/mL) also completely restored GLDH and LDH levels in the perfusate. Pretreatment of isolated Kupffer cells with 0.02, 0.1, 0.5, 2.5, and 12.5 microg silibinin/mL 30 min prior to OTA reduced OTA-induced TNF-alpha levels to 90, 70, 25, 25, and 25% at 4 h, respectively, and abrogated any TNF-alpha release at 24 h. Similarly, in the presence of silibinin LPS-induced TNF-alpha levels decreased at 4 h to 71, 57, 18, 22, and 18%, respectively. However, after 24 h of LPS exposition the protection by silibinin vanished and TNF-alpha partially recurred into the incubation medium under LPS. In summary, silibinin had hepatoprotective effects against OTA- or LPS-mediated TNF-alpha release and also reduced the cytotoxicity of both toxins. Isolated Kupffer cells were even more sensitive to the protective effect than perfused livers and responded to very low concentrations of silibinin with a strong inhibition of toxins-mediated TNF-alpha release.

Molecular mechanisms of silybin and 2,3-dehydrosilybin antiradical activity--role of individual hydroxyl groups

The flavonolignans silybin (1) and 2,3-dehydrosilybin (2) are important natural compounds with multiple biological activities operating at various cell levels. Many of these effects are connected with their radical-scavenging activities. The molecular mechanisms of the antioxidant activity of these compounds and even the functional groups responsible for this activity are not yet well known. Their mechanism can be inferred from the structures of the dimeric products obtained from radical-mediated reactions of selectively methylated derivatives of 1 and 2. The radical oxidation of 1 methylated at 7-OH and 2 methylated at both 3-OH and 7-OH yields C-C and C-O dimers that enable the molecular mechanism of their E-ring interaction with radicals to be elucidated and shows the importance of the 20-OH group in this respect. The pivotal role of the 3-OH group in the radical-scavenging activity of 2 was confirmed through the formation of another type of dimer from its selectively methylated derivative.

[Effects of supplementation with the antioxidant flavonoid, silymarin, in chronic hepatitis C patients treated with peg-interferon + ribavirin. A placebo-controlled double blind study]

Since oxidative stress may play a pathogenetic role in chronic hepatitis C, and sustained virological response to antiviral therapy is limited in HCV1 genotype infection, a double blind study was performed in HCV1 patients treated with pegylated interferon + ribavirin, to assess the efficacy of supplementation with the antioxidant flavonoid silymarin.

PATIENTS AND METHODS

Thirty-two naive HCV1 positive patients with biopsy proven chronic hepatitis C, to be treated with pegylated interferon + ribavirin, have been randomized: group A): 16 patients have been given the antiviral therapy for 6-12 months plus placebo for the first 3 months; group B): 16 patients have been treated with pegylated interferon + ribavirin for 6-12 months plus silymarin, 2 x 166 mg/day, was given for 3 months. Serum alanine aminotransferase and HCV-RNA levels as well as parameters of oxidative stress such as plasma or red blood cell hemolysate, malondialdehyde, superoxide dismutase, glutathione peroxidase, catalase and myeloperoxidase were determined after 0, 1, 3, 6 and 12 months during the treatment. Sustained virological response as undetectable serum HCV RNA was evaluated 24 weeks after the end of therapy.

RESULTS

In the silymarin group, a more rapid decrease in the malondialdehyde level as well as a marked decrease in superoxide dismutase and an increase in myeloperoxidase activity after month 12 were found, alanine aminotransferase normalized in 6/16 (vs control 9/16) cases, and sustained virological response occurred in 3/16 (vs 7/16) patients.

DISCUSSION/CONCLUSION

Although silymarin supportation to antiviral therapy improved oxidative stress, it was able to affect favourably neither the alanine aminotransferase nor the sustained virological response. These contradictory findings may be related to randomization bias as patients in study group B had more negative predictors of response: they were older with higher fibrosis score and even with more severe pretreatment baseline oxidative stress. Regarding the recently published in vitro experiments with silybinin on HCV replication as well as the newest convincing clinical observations, we do suggest further studies with more than three times higher doses of silymarin in controlled trials to assess the value of this supplementation in antivirally treated HCV patients.

Silibinin inhibits hypoxia-inducible factor-1alpha and mTOR/p70S6K/4E-BP1 signalling pathway in human cervical and hepatoma cancer cells: implications for anticancer therapy

The hypoxia-inducible factor 1 (HIF-1) plays a critical role for tumour adaptation to microenvironmental hypoxia, and represents an appealing chemotherapeutic target. Silibinin is a nontoxic flavonoid reported to exhibit anticancer properties. However, the mechanisms by which silibinin inhibits tumour growth are not fully understood. In this study, silibinin was found to inhibit hypoxia-induced HIF-1alpha accumulation and HIF-1 transcriptional activity in human cervical (HeLa) and hepatoma (Hep3B) cells. Neither HIF-1alpha protein degradation rate nor HIF-1alpha steady-state mRNA level was affected by silibinin. Rather, we found that suppression of HIF-1alpha accumulation by silibinin correlated with strong dephosphorylation of mammalian target of rapamycin (mTOR) and its effectors ribosomal protein S6 kinase (p70S6K) and eukaryotic initiation factor 4E-binding protein-1 (4E-BP1), a pathway known to regulate HIF-1alpha expression at the translational level. Silibinin also activated Akt, a mechanistic feature exhibited by established mTOR inhibitors in many tumour cells. Moreover, silibinin reduced hypoxia-induced vascular endothelial growth factor (VEGF) release by HeLa and Hep3B cells, and this effect was potentiated by the PI3K/Akt inhibitor LY294002. Finally, silibinin was found to be a potent inhibitor of cell proliferation. These results show that silibinin is an effective inhibitor of HIF-1 and provide new perspectives into the mechanism of its anticancer activity.

Drug-drug interactions of silymarin on the perspective of pharmacokinetics

Silymarin, which is extracted from the milk thistle (Silybum marianum), has been used for centuries for treating hepatic disorders and its hepatoprotective effects have been known for hundreds of years. Silymarin is a mixture of polyphenoic flavonoids, which include silibinin (silybin A and silybin B), isosilyin A and B, silychristin A and B, silydianin and other phenol compounds. The pharmacokinetics of silibinin shows fast absorption and elimination. Silymarin undergoes phase I and phase II metabolism, especially phase II conjugation reactions, it undergoes multiple conjugation reactions, and is primarily excreted into bile and urine. Silymarin has a good safety profile, but little is known regarding its potential for drug interaction. Silymarin has limited effect on the pharmacokinetics of several drugs in vivo; despite silymarin decreasing the activity of cytochrome P-450 (CYPs) enzymes, UDP-glucuronosyltransferase (UGT) enzyme, and reducing P-glycoprotein (P-gp) transport. Health-care practitioners should caution patients against co-administration of silymarin and pharmaceutical drugs.

Positive effect of silymarin on cell growth and differentiation in bovine and murine mammary cells

Silymarin, a naturally acknowledged hepatoprotector used in humans to treat liver diseases has been tested in murine (HC11) and bovine (BME-UV) mammary epithelial cell lines to evaluate a possible direct effect on cell growth and differentiation in mammary gland. Silymarin enhanced cell proliferation (p < 0.05) from 10 to 1000 ng/ml in association with growth factors, (up to 20%) or alone (up to 15%) versus controls. Furthermore, silymarin (100 ng/ml) was able to increase (p < 0.05) beta-casein gene expression alone or in association with prolactin (5 microg/ml). These effects may be related with protein kinase B (AKT) activation induced by silymarin treatment (p < 0.05) and/or by a dose-related inhibitory effect (p < 0.05) on caspase-3 activity related to a protective role in cell apoptosis. These data suggest that silymarin should be considered a candidate to support mammary gland activity during a lactogenetic state.

Solid state mechanochemical simultaneous activation of the constituents of the Silybum marianum phytocomplex with crosslinked polymers

Simultaneous improvement of solubilization kinetics of main flavolignans of Silybum marianum extract was obtained cogrinding with two crosslinked polymers: micronized crospovidone, PVP-CL(R) and sodium carboxymethylcellulose, Ac-Di-Sol(R) in the 1:3 active-to-polymer weight ratio. By this process it was assessed that the main extract components lost its crystalline structure, and the powder surface area was increased by 2.1- and 1.7-fold in the coground products with Ac-Di-Sol(R) and PVP-CL(R), respectively. This activated status of the dry extract remained stable over a period of 2 years. Solubilization kinetics resulted ameliorated both in terms of entire dry extract and in terms of single components. When the 1/3 coground systems with PVP-CL(R) and Ac-Di-Sol(R) were dissolved in saturated conditions they gave a concentration improvement compared to the native product of 8 and 31 times of silybin A, 7 and 27 times of silybin B, whereas in the case of silychristin a double concentration was obtained only using Ac-Di-Sol(R). The in vivo studies on rats confirmed that this solubilization improvement corresponded to an effective oral bioavailability enhancement. The highest bioavailability improvement was obtained with Ac-Di-Sol(R), with a relative bioavailability of 88.6, 17.96, and 16.4 compared to the extract for silybin A, silybine B, and silychristine, respectively.

Isosilibinin inhibits advanced human prostate cancer growth in athymic nude mice: comparison with silymarin and silibinin

Earlier studies have shown the cancer chemopreventive efficacy of silymarin and its semi-purified constituent silibinin against prostate cancer (PCa), but the efficacy of other constituents of silymarin is largely unknown. In the present study, we assessed the in vivo growth inhibitory efficacy of one such constituent isosilibinin (a 50:50 mixture of isosilybin A and isosilybin B) in comparison with silymarin and silibinin in human PCa DU145 xenograft in athymic nude mice. Isosilibinin feeding (200 mg/kg body weight per day) significantly inhibited the growth of xenograft after 53 days of treatment (p < or = 0.005), which was equally or slightly better effective than silymarin and silibinin, respectively. Treatment with isosilibinin, silymarin and silibinin was stopped after 53 days and tumor volume was measured till 77 days. After 24 days of treatments withdrawal, tumor volume remain decreased, however, it was statistically significant only with isosilibinin (p < or = 0.05), suggesting its prolonged effect. Biomarker analysis showed that isosilibinin, silymarin and silibinin treatment for 53 days significantly inhibited the immunoreactivity for proliferating cell nuclear antigen (PCNA), microvessel density (CD31) and vascular endothelial growth factor along with significant increase in apoptotic cell population. The PCNA levels in tumors remained significantly low even after 24 days of treatments withdrawal. Western blot analysis of tumor tissue suggested that these flavonolignan formulations differentially alter the expression of cell cycle regulatory molecules, cyclins and Cdks. Overall, the results of present study suggest that isosilibinin has comparatively better efficacy against PCa and should be further analyzed for its clinical utility.

Liver fibrosis: consensus recommendations of the Asian Pacific Association for the Study of the Liver (APASL)

Liver fibrosis is a common pathway leading to cirrhosis, which is the final result of injury to the liver. Accurate assessment of the degree of fibrosis is important clinically, especially when treatments aimed at reversing fibrosis are being evolved. Liver biopsy has been considered to be the "gold standard" to assess fibrosis. However, liver biopsy being invasive and, in many instances, not favored by patients or physicians, alternative approaches to assess liver fibrosis have assumed great importance. Moreover, therapies aimed at reversing the liver fibrosis have also been tried lately with variable results. Till now, there has been no consensus on various clinical, pathological, and radiological aspects of liver fibrosis. The Asian Pacific Association for the Study of the Liver set up a working party on liver fibrosis in 2007, with a mandate to develop consensus guidelines on various aspects of liver fibrosis relevant to disease patterns and clinical practice in the Asia-Pacific region. The process for the development of these consensus guidelines involved the following: review of all available published literature by a core group of experts; proposal of consensus statements by the experts; discussion of the contentious issues; and unanimous approval of the consensus statements after discussion. The Oxford System of evidence-based approach was adopted for developing the consensus statements using the level of evidence from 1 (highest) to 5 (lowest) and grade of recommendation from A (strongest) to D (weakest). The consensus statements are presented in this review.

Treatment with silybin-vitamin E-phospholipid complex in patients with hepatitis C infection

The aim of this study was to evaluate the hepatoprotective and anti-inflammatory effects of silybin-phospholipids and vitamin E complex (SPV complex), by determining cytokine patterns and various markers of liver disease. Forty Caucasian patients with chronic HCV infection were recruited and divided into two groups: 30 were treated with SPV complex for 3 months, while the other 10 did not receive any treatment. Ten other subjects without HCV infection but with staeatosic diagnosis were recruited and treated with SPV complex. Biochemical and hepatic principal parameters were investigated at 0 (T0) and 3 months (T3). The group of HCV patients treated showed an improvement trend of hepatic indecises and viral load, and had a significant and persistent reduction of ALT (P = 0.02) and AST serum level (P = 0.01). In this group cytokines showed a statistically significant increase of IL-2 (P = 0.03) and IL-6 were significantly reduced (P = 0.02) at T0 and T3. After the treatment the group of hepatic steatosics showed a significant decrease in ALT (P = 0.02), AST (0.008), gammaGT (0.004) alkaline phosphatase (0.05), total cholesterol (P = 0.03), fasting glucose (P = 0.008), insulinemia (0.0006), HOMA value (0.002) and C-reactive protein (CRP; 0.04). There was a significant reduction of IFN-gamma, TNF-alpha, and IL-6 (P = 0.02, 0.05 and 0.04, respectively). The data suggest that the SPV complex exerts hepatoprotective, anti-inflammatory and antifibrotic effects. This new compound may therefore be useful in clinical practice in patients with chronic hepatitis C who cannot undergo conventional antiviral therapy.

Preparation and Characterization of Solid Lipid Nanoparticles Containing Silibinin

The study describes the development of stealth solid lipid nanoparticles (SLNs) as colloidal carriers for silibinin, a drug with very low solubility. Stealth SLNs were constituted mainly of bioacceptable and biodegradable lipids, such as stearic acid and surfactant Brij 78 (polyoxyethylene 20 stearyl ether) and can incorporate amounts of silibinin up to 7.55%. Stealth-loaded SLNs were in the nanometer size range. Thermal analysis (differential scanning calorimetry) showed that silibinin was dispersed in the stealth SLNs at an amorphous state. Release of silibinin from stealth SLNs was very slow. Stealth SLNs were stable without precipitation of silibinin on storage conditions and can be proposed for their parenteral administration.

Sugar coated liposomal flavonoid: A unique formulation in combating carbontetrachloride induced hepatic oxidative damage

Rats were administered a single dose of plant origin phenolic antioxidant Quercetin (QC) in free, liposome encapsulated and galactosylated liposome encapsulated forms 2 h prior to hepatotoxic dose of carbontetrachloride (CCl4, 40% v/v in olive oil, 1 ml/kg b.wt). Among those three different forms of QC tested, only galactosylated liposomal QC provided significant protection against CCl4 induced hepatic oxidative damage. After 24 h of injection (S.C.) hepatic cells of rats were found susceptible to CCl4 induced oxidative damage and it was monitored by the increased amount of conjugated diene in hepatic membrane. The two-fold increase in conjugated diene by the induction of CCl4 was decreased upto normal level by galactosylated liposomal QC pre-treatment. Carbontetrachloride induced membrane damage in hepatic cells and it was judged by the blood serum pathological and liver tissue histopathological examination. Membrane damage by the induction of CCl4 was further evaluated by the decreased level of plasma membrane (PM) bound enzyme Na+/K+ ATPase activity and it was increased only by the pre-treatment of galactosylated liposomal QC. Carbontetrachloride induced a substantial decrease both in enzymatic and molecular endogenous antioxidant levels in hepatic cells.The depression in antioxidant system in hepatic cells was completely prevented by a single dose of galactosylated lipsosomal QC prior to CCl4 treatment. Liver uptake of QC was estimated after 2 h of the flavonoid injection (8.9 micromol/kg body weight) (free or liposomal forms) and 85% of the injected QC was found in liver in the case of galactosylated liposomal QC. Whereas only 25% of the injected dose was detected in liver when an identical amount of free QC was injected. Carbontetrachloride also induced an alteration in membrane fluidity and it was evaluated by a decrease in membrane micro-viscosity. Free QC pre-treatment resulted in no protection against CCl4 induced increase in hepatic membrane fluidity, whereas galactosylated liposomal QC exerted a significant protection against the increase. Results of this study revealed that QC in galactosylated liposome could exert a significant protection against CCl4 induced hepatocellular injury.

Potential of pharmacokinetic profiling for detecting herbal interactions with drugs

The issue of herb-drug interactions has generated significant concern within the pharmaceutical industry and among regulatory authorities in recent years. Therefore, accurate models of predicting metabolic herb-drug interactions would be useful tools in efforts to avoid toxic adverse events. However, the majority of pharmacokinetic interactions listed for herbal medicinal products are based on theoretical predictions of the in vitro pharmacological effects of known constituents, which do not necessarily have to be the active ingredients. The prediction of herb-drug interactions is further complicated by the fact that pharmacokinetic data on active or (at least) known ingredients are often not available. The present article discusses the potential of pharmacokinetic profiling for detecting herb-drug interactions, using the most frequently cited interactions in the literature as examples. In particular, common mechanisms of herb-drug interactions are summarized, and the available experimental methods for detecting such interactions, as well as the limitations of these models, are critically evaluated. In addition, we discuss the question of whether the existing methods of detecting herb-drug interactions correlate with the clinical relevance. Effective screening tools that accurately predict metabolic herb-drug interactions would offer a tremendous advantage because it is not possible to study all potential herb-drug interactions in clinical trials.

Effects of silibinin on cell growth and invasive properties of a human hepatocellular carcinoma cell line, HepG-2, through inhibition of extracellular signal-regulated kinase 1/2 phosphorylation

The purpose of the current study is to evaluate the effect of silibinin on human hepatocellular carcinoma HepG-2 cells. Microculture tetrazolium test (MTT assay), Lactate dehydrogenase (LDH) release, Gelatin zymography, Griess reaction, Cell-based the extracelluar signal-regulated kinase (ERK) 1/2 phosphorylation assay and quantitative real-time RT-PCR were employed to appraise the effect of silibinin on cell proliferation, cytotoxicity, metastatic potential, nitric oxide (NO) production, ERK 1/2 phosphorylation and activation in HepG-2 cells. Silibinin inhibited cell proliferation, matrix metalloproteinase 2 enzymatic activity, NO production and ERK 1/2 phosphorylation in a dose-dependent manner without exerting any cytotoxicity effect. In addition, an expressive increase in mRNA levels of Raf kinase inhibitor protein (RKIP), sprouty-related protein 1 with EVH-1 domain (Spred-1), sprouty-related protein with EVH-1 domain 2 (Spred-2) coupled with a significant reduction in transcriptional levels of highly expressed in cancer (Hec1) and MMP-2 were observed. Altogether, these issues show for the first time that silibinin treatment could inhibit cell proliferation and invasive potential of HepG-2 cells through inhibition of ERK 1/2 cascade both directly (through suppression of ERK 1/2 phosphorylation) and indirectly (through up-regulation of RKIP, Spred-1 and Spred-2). In addition, cell growth and proliferation may be inhibited by silibinin through down-regulation of Hec1.

The pharmacokinetics of silymarin is altered in patients with hepatitis C virus and nonalcoholic Fatty liver disease and correlates with plasma caspase-3/7 activity

Silymarin, used by 30 to 40% of liver disease patients, is composed of six major flavonolignans, each of which may contribute to silymarin's hepatoprotective properties. Previous studies have only described the pharmacokinetics for two flavonolignans, silybin A and silybin B, in healthy volunteers. The aim of this study was to determine the pharmacokinetics of the major silymarin flavonolignans in liver disease patients. Healthy volunteers and three patient cohorts were administered a single, 600-mg p.o. dose of milk thistle extract, and 14 blood samples were obtained over 24 h. Silybin A and B accounted for 43% of the exposure to the sum of total silymarin flavonolignans in healthy volunteers and only 31 to 38% in liver disease cohorts as a result of accumulation of silychristin (20-36%). Area under the curve (AUC(0-24h)) for the sum of total silymarin flavonolignans was 2.4-, 3.3-, and 4.7-fold higher for hepatitis C virus (HCV) noncirrhosis, nonalcoholic fatty liver disease (p Collapse

Key Words Collapse

MESH Headings

• Adolescent
• Adult
• Aged
• Apoptosis
• Area Under Curve
• Caspase 3/blood
• Caspase 7/blood
• Cohort Studies
• Fatty Liver/metabolism
• Female
• Half-Life
• Hepatitis C/metabolism
• Humans
• Male
• Middle Aged
• Oxidative Stress
• Silymarin/blood
• Silymarin/pharmacokinetics

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Grants

• K24 DK066144 NIDDK NIH HHS
• RR00046 NCRR NIH HHS

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Affiliation(s)

Sarah J Schrieber Division of Pharmacotherapy and Experimental Therapeutics,School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7360, USA
Zhiming Wen
Manoli Vourvahis
Philip C Smith
Michael W Fried
Angela D M Kashuba
Roy L Hawke

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An updated systematic review with meta-analysis for the clinical evidence of silymarin

BACKGROUND

The potential benefit of silymarin (special extract from the fruits of Silybum marianum) in the treatment of liver diseases remains a controversial issue.

METHODS

For this systematic review electronic databases identified 65 papers for the search terms silymarin, silibinin, silicristin or milk thistle and clinical trial. Only 19 complied with the criteria'double-' or 'single-blind'. These publications were analysed from a clinical point of view and meta-analytic calculations were performed.

RESULTS

The clinical evidence ofa therapeutic effect of silymarin in toxic liver diseases is scarce. There is no evidence of a favourable influence on the evolution of viral hepatitis, particularly hepatitis C. In alcoholic liver disease, comparing with placebo, aspartate aminotransferase was reduced in the silymarin-treated groups (p = 0.01) while alkaline phosphatase was not. In liver cirrhosis, mostly alcoholic, total mortality was 16.1% with silymarin vs. 20.5% with placebo (n.s.); liver-related mortality was 10.0% with silymarin vs. 17.3% with placebo(p = 0.01).

CONCLUSIONS

Based on the available clinical evidence it can be concluded - concerning possible risks /probable benefits - that it is reasonable to employ silymarin as a supportive element in the therapy of Amanita phalloides poisoning but also (alcoholic and grade Child 'A') liver cirrhosis. A consistent research programme, consolidating existing evidence and exploring new potential uses,would be very welcome.

Protective effect of Tinospora cordifolia, Phyllanthus emblica and their combination against antitubercular drugs induced hepatic damage: an experimental study

This study investigated the hepatoprotective effect of two Indian medicinal plants Tinospora cordifolia (Tc), Phyllanthus emblica (Pe), and their combination, in a rat model of isoniazid, rifampicin and pyrazinamide induced hepatic damage. Hepatic damage was assessed using a composite score assigned to histopathological findings of degeneration, necrosis and fibrosis. The antituberculosis treatment (ATT), when given for 90 days, induced significant degeneration and necrosis (score: 7.5; p < 0.01 vs vehicle) associated with morphological changes. However, no change was found in the serum bilirubin and liver enzymes. Co-administration of silymarin (positive control, 50 mg/kg) with ATT protected against necrosis (score: 1.5; p < 0.001 vs ATT). Tc (100 mg/kg) showed a reduction in liver damage (score: 6.5), which was not statistically significant. On the other hand, Pe (300 mg/kg) prevented the necrotic changes to a significant extent (grade 1.0; p < 0.05; score [corrected] 5.5). Combination of Tc and Pe in their therapeutic doses (1:3) significantly prevented the necrosis (score: 3.5; p < 0.001 vs ATT). Similar effects were seen even when the doses were halved and were comparable to the silymarin group. Thus, this study proves the synergistic protective effects exerted by the combination of Tc and Pe when co-administered with ATT.

Antifibrotic effects of a herbal combination regimen on hepatic fibrotic rats

Liver fibrosis has been characterized as chronic inflammatory processes involving multiple molecular pathogenetic pathways. This therapeutic study investigated whether a combination regimen of Salvia miltiorrhiza (S), Ligusticum chuanxiong (L) and Glycyrrhiza glabra (G) exerted in vivo antifibrotic effects on rats with hepatic fibrosis. Fibrosis was induced in rats by dimethylnitrosamine (DMN) administration for 4 weeks. Fibrotic rats were randomly assigned to one of the three groups: control, SLG (50 mg/kg) or silymarin (50 mg/kg), each given by gavage twice daily for 3 weeks starting 1 week after DMN injection. The results showed that fibrosis scores of livers from DMN-treated rats with SLG (1.13 +/- 0.13) were significantly reduced in comparison with DMN-treated rats receiving vehicle (1.63 +/- 0.18). Moreover, the hepatic collagen content of DMN rats was significantly reduced by either SLG or silymarin treatment. The double immunohistochemical staining results also showed that alpha-SMA positive cells with NF kappa B nuclear translocation were decreased in the fibrotic livers by SLG and silymarin treatments. The mRNA expression levels of TGF-beta1, alpha-SMA, collagen1 alpha 2, iNOS and ICAM-1 genes were attenuated by SLG and silymarin treatment. The results showed that SLG exerted antifibrotic effects in rats with DMN-induced hepatic fibrosis.

Beneficial drugs for liver diseases

Liver diseases are a major problem of worldwide proportions. However, the number of drugs actually used successfully in humans is very small. In this review some of the most promising/studied drugs utilized for liver diseases were chosen and analysed critically from the basic to the clinical point of view. Antiviral agents are not discussed because excellent reviews have appeared on this topic. The compounds/preparations described herein are, alphabetically: colchicine, corticosteroids, curcumin, glycyrrhizin, interferons (for their antifibrotic properties), Liv 52, nitric oxide, resveratrol, silymarin, sulfoadenosylmethionine, and thalidomide. Colchicine and corticosteroids have been studied extensively in animals and humans; most clinical studies suggest that these compounds are not useful in the treatment of liver diseases. Glycyrrhizin is an herbal medicine with several components that has interesting hepatoprotective properties in patients with subacute liver failure but deserves more prospective controlled trials. Interferon has shown interesting antifibrotic properties in animals and humans; prospective studies on their antifibrotic/fibrolytic activity are required. Curcumin, resveratrol and thalidomide are very attractive newly discovered protective and curative compounds on experimental hepatic diseases. Their mechanism of action is associated with the ability to down-regulate NF-kappaB and to decrease pronecrotic and profibrotic cytokines. Unfortunately, clinical studies are lacking. Sulfoadenosylmethionine and silymarin are also promising drugs utilized mainly in cholestasis but the benefits can be expanded if more controlled trials are performed. The future is to carry out controlled prospective double-blind multicenter studies with the newly discovered drugs with proven beneficial effects on animals. Fundamental hepatobiology should also be encouraged.

Chemopreventive effect of silymarin on liver pathology in HBV X protein transgenic mice

There are currently limited therapeutic regimens available for effective treatment of hepatocellular carcinoma (HCC). Silymarin is a naturally derived polyphenolic antioxidant with hepatoprotective properties and is very widely used in clinical application; however, effect of silymarin on spontaneous HCC has not been studied. Silymarin was evaluated for its efficacy against spontaneous carcinogenesis using the HBV X protein (HBx) transgenic model. Silymarin was p.o. given to the HBx transgenic mice from 4 to 6 weeks of age. Our data indicated that silymarin has therapeutic effects on the early stages of liver damage, reversing fatty changes and recovering liver histopathology in a dose-dependent manner. To study the chemopreventive effects on the later stages of carcinogenesis, the mice at 13 months were split into a precancerous group and a group with significant liver carcinogenesis. After silymarin was given to the precancerous mice from 13 to 16 months of age, in contrast to an 80% incidence of HCC development in the untreated transgenic mice, no HCC was detected in any of these mice. Nonetheless, small hyperplastic nodules were detected in 86% of these precancerous mice. In the second group with notable HCC, silymarin was unable to block cancer progression. Although silymarin did not affect HBx expression, intracellular reactive oxygen species levels were decreased, cell proliferation was stimulated, and hepatocyte ultrastructure was found to significantly recover. In conclusion, silymarin exerts beneficial effects on the early stages of liver pathogenesis, preventing and delaying liver carcinogenesis. This drug should be considered as a potential chemopreventive agent for HBV-related hepatocarcinogenesis.

Silibinin inhibits colorectal cancer growth by inhibiting tumor cell proliferation and angiogenesis

Herein, for the first time, we investigated in vivo efficacy and associated molecular biomarkers and mechanisms of a chemopreventive agent, silibinin, against human colorectal carcinoma (CRC) HT29 xenograft growth. Nude mice were implanted with HT29 cells and fed with vehicle (carboxymethyl cellulose or phosphatidylcholine) or 200 mg/kg/d dose of silibinin or 100 and 200 mg/kg/d doses of silybin-phytosome (5 days per week) for 32 days. Silibinin inhibited tumor growth that accounted for 48% (P = 0.002) decrease in tumor volume and 42% (P = 0.012) decrease in tumor weight at the end of the experiment without any adverse health effect. A stronger antitumor efficacy was observed with silybin-phytosome preparation. Silibinin decreased proliferation index by 40% (P < 0.001), increased apoptotic index by approximately 2-fold (P = 0.001), and reduced microvessel density by 36% (P = 0.001) in tumors. Antiproliferative and proapoptotic effects of silibinin were associated with down-regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation as well as cyclin D1 expression. Antiangiogenic effect of silibinin was coupled with a strong decrease in inducible nitric oxide synthase (NOS) and NOS3, cyclooxygenase-1 (COX-1) and COX-2, and hypoxia-inducing factor-1 alpha (HIF-1 alpha) and vascular endothelial growth factor (VEGF). These findings suggest in vivo antitumor efficacy of silibinin against CRC involving its antiproliferative, proapoptotic, and antiangiogenic activities. The inhibition of ERK1/2 and Akt signaling may account for antiproliferative and proapoptotic effects, whereas down-regulation of NOS, COX, HIF-1 alpha, and VEGF expression could lead to antiangiogenic effect of silibinin against CRC. Overall, potential use of silibinin against human CRC could be suggested.

Interrelation between the inhibition of glycolytic flux by silibinin and the lowering of mitochondrial ROS production in perifused rat hepatocytes

Silibinin, the most biologically active component of the polyphenolic extract from milk thistle seeds, is widely used to prevent many types of hepatobiliary disorders. Recent evidence suggests new applications for this ancient medication, notably for the treatment of type 2 diabetes owing to its antihyperglycemic properties. As we have lately demonstrated that silibinin lowered glucose production from various gluconeogenic substrates in perifused rat hepatocytes, the aim of this study was to examine the effect of silibinin on both oxidative glucose utilization and reactive oxygen species (ROS) generation since the release of ROS secondary to an increased mitochondrial metabolism may contribute to diabetic damage. We found that silibinin dose-dependently reduced glycolysis from carbohydrates in a cell perifusion system via an inhibitory effect targeted on pyruvate kinase activity. Furthermore, a dramatic effect upon oxidative phosphorylation was shown, as evidenced by a fall in ATP-to-ADP ratio, together with an increase in lactate-to-pyruvate ratio. The most attractive finding was that silibinin, at a concentration as low as 10 microM, fully mitigated the rise in metabolic flow-driven ROS formation. In addition, studies on isolated liver mitochondria revealed that this low dose of silibinin depressed ROS production linked to the electron transfer chain activity. From these results, one may tentatively suggest that interesting activities for silibinin, beyond its general antioxidant status, could be expected from its potential clinical use, especially in pathological conditions when mitochondrial ROS formation is severely enhanced.

Herbal product use by persons enrolled in the hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) Trial

Herbal products, used for centuries in Far Eastern countries, are gaining popularity in western countries. Surveys indicate that persons with chronic hepatitis C (CHC) often use herbals, especially silymarin (milk thistle extract), hoping to improve the modest response to antiviral therapy and reduce side effects. The Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) Trial, involving persons with advanced CHC, nonresponders to prior antiviral therapy but still willing to participate in long-term pegylated interferon treatment, offered the opportunity to examine the use and potential effects of silymarin. Among 1145 study participants, 56% had never taken herbals, 21% admitted past use, and 23% were using them at enrollment. Silymarin constituted 72% of 60 herbals used at enrollment. Among all participants, 67% had never used silymarin, 16% used it in the past, and 17% used it at baseline. Silymarin use varied widely among the 10 participating study centers; men were more frequent users than women, as were non-Hispanic whites than African Americans and Hispanics. Silymarin use correlated strongly with higher education. No beneficial effect of silymarin was found on serum alanine aminotransferase or hepatitis C virus (HCV) RNA levels. Univariate analysis showed significantly fewer liver-related symptoms and better quality-of-life parameters in users than nonusers, but after reanalysis adjusted for covariates of age, race, education, alcohol consumption, exercise, body mass index, and smoking, only fatigue, nausea, liver pain, anorexia, muscle and joint pain, and general health remained significantly better in silymarin users. In conclusion, silymarin users had similar alanine aminotransferase and HCV levels to those of nonusers but fewer symptoms and somewhat better quality-of-life indices. Because its use among these HALT-C participants was self-motivated and uncontrolled, however, only a well-designed prospective study can determine whether silymarin provides benefit to persons with chronic hepatitis C.

Mechanism of the antioxidant action of silybin and 2,3-dehydrosilybin flavonolignans: a joint experimental and theoretical study

Flavonolignans from silymarin, the standardized plant extract obtained from thistle, exhibit various antioxidant activities, which correlate with the other biological and therapeutic properties of that extract. To highlight the mode of action of flavonolignans as free radical scavengers and antioxidants, 10 flavonolignans, selectively methylated at different positions, were tested in vitro for their capacity to scavenge radicals (DPPH and superoxide) and to inhibit the lipid peroxidation induced on microsome membranes. The results are rationalized on the basis of (i) the oxidation potentials experimentally obtained by cyclic voltammetry and (ii) the theoretical redox properties obtained by quantum-chemical calculations (using a polarizable continuum model (PCM)-density functional theory (DFT) approach) of the ionization potentials and the O-H bond dissociation enthalpies (BDEs) of each OH group of the 10 compounds. We clearly establish the importance of the 3-OH and 20-OH groups as H donors, in the presence of the 2,3 double bond and the catechol moiety in the E-ring, respectively. For silybin derivatives (i.e., in the absence of the 2,3 double bond), secondary mechanisms (i.e., electron transfer (ET) mechanism and adduct formation with radicals) could become more important (or predominant) as the active sites for H atom transfer (HAT) mechanism are much less effective (high BDEs).

The flavonoid silibinin decreases glucose-6-phosphate hydrolysis in perfused rat hepatocytes by an inhibitory effect on glucose-6-phosphatase

BACKGROUND/AIMS

The flavonoid silibinin has been reported to be beneficial in several hepatic disorders. Recent evidence also suggests that silibinin could be beneficial in the treatment of type 2 diabetes, owing to its anti-hyperglycemic properties. However, the mechanism(s) underlying these metabolic effects remains unknown.

METHODS

The effects of silibinin on liver gluconeogenesis were studied by titrating hepatocytes from starved rats with sub-saturating concentrations of various exogenous substrates in a perifusion system. Hepatocytes from fed rats were also used to investigate glycogenolysis from endogenous glycogen. The effect of silibinin on glucose-6-phosphatase kinetics was determined in intact and permeabilized rat liver microsomes.

RESULTS

Silibinin induced a dose-dependent inhibition of gluconeogenesis associated with a potent decrease in glucose-6-phosphate hydrolysis. This effect was demonstrated whatever the gluconeogenic substrates used, i.e. dihydroxyacetone, lactate/pyruvate, glycerol and fructose. In addition, silibinin decreased the glucagon-induced stimulation of both gluconeogenesis and glycogenolysis, this being associated with a reduction of glucose-6-phosphate hydrolysis. Silibinin inhibits glucose-6-phosphatase in rat liver microsomes in a concentration-dependent manner that could explain the decrease in glucose-6-phosphate hydrolysis seen in intact cells.

CONCLUSION

The inhibitory effect of silibinin on both hepatic glucose-6-phosphatase and gluconeogenesis suggests that its use may be interesting in treatment of type 2 diabetes.

Analysis of silibinin in rat plasma and bile for hepatobiliary excretion and oral bioavailability application

Silibinin is an herbal ingredient isolated from milk thistle. The aim of this study was to develop a simple liquid chromatographic system to assay silibinin in plasma and bile for pharmacokinetic study. Silibinin was given oral and intravenously. The plasma sample (25 microL) was vortex-mixed with 50 microL of internal standard solution (naringenin 10 microg/mL in acetonitrile) to achieve protein precipitation. Silibinin in the rat plasma and bile was separated using a reversed-phase C18 column (250 mm x 4.6 mm, 5 microm) with a mobile phase of acetonitrile -10 mM monosodium phosphate (pH 5.45 adjusted with orthophosphoric acid) (50:50, v/v) and the flow-rate of 1 mL/min. The UV detection wavelength was 288 nm. The concentration-response relationship from the present method indicated linearity over a concentration range of 0.5-100 microg/mL. Intra- and inter-assay precision and accuracy of silibinin fell well within the predefined limits of acceptability (<15%). An ultrafiltration method was used in this experiment and the protein binding of silibinin was 70.3+/-4.6%. After silibinin administration in rats, the disposition of silibinin in the plasma and bile fluid was due to rapid distribution and equilibration between the blood and hepatobiliary system, and the bile levels of unconjugated silibinin and total silibinin were greater than those in the plasma. The oral bioavailability of silibinin in rats was estimated to be 0.73%.

Milk thistle for alcoholic and/or hepatitis B or C virus liver diseases

BACKGROUND

Alcohol and hepatotoxic viruses cause the majority of liver diseases. Randomised clinical trials have assessed whether extracts of milk thistle, Silybum marianum (L) Gaertneri, have any effect in patients with alcoholic and/or hepatitis B or C virus liver diseases.

OBJECTIVES

To assess the beneficial and harmful effects of milk thistle or milk thistle constituents versus placebo or no intervention in patients with alcoholic liver disease and/or viral liver diseases (hepatitis B and hepatitis C).

SEARCH STRATEGY

The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and full text searches were combined (July 2007). Manufacturers and researchers in the field were contacted.

SELECTION CRITERIA

Only randomised clinical trials in patients with alcoholic and/or hepatitis B or C virus liver diseases (acute and chronic) were included. Interventions encompassed milk thistle at any dose or duration versus placebo or no intervention. The trials could be double blind, single blind, or unblinded. The trials could be unpublished or published and no language limitations were applied.

DATA COLLECTION AND ANALYSIS

The primary outcome measure was mortality. Binary outcomes are reported as relative risks (RR) with 95% confidence interval (CI). Subgroup analyses were performed with regard to methodological quality.

MAIN RESULTS

Eighteen randomised clinical trials assessed milk thistle in 1088 patients with alcoholic and/or hepatitis B or C virus liver diseases. The methodological quality was low: only 28.6% of the trials reported high methodological quality characteristics. Milk thistle versus placebo or no intervention had no significant effect on mortality (RR 0.78, 95% CI 0.53 to 1.15), complications of liver disease (RR 0.95, 95% CI 0.83 to 1.09), or liver histology. Liver-related mortality was significantly reduced by milk thistle in all trials (RR 0.50, 95% CI 0.29 to 0.88), but not in high-quality trials (RR 0.57, 95% CI 0.28 to 1.19). Milk thistle was not associated with a significantly increased risk of adverse events (RR 0.83, 95% CI 0.46 to 1.50).

AUTHORS' CONCLUSIONS

Our results question the beneficial effects of milk thistle for patients with alcoholic and/or hepatitis B or C virus liver diseases and highlight the lack of high-quality evidence to support this intervention. Adequately conducted and reported randomised clinical trials on milk thistle versus placebo are needed.

Effect of silymarin and vitamin E on gentamicin-induced nephrotoxicity in dogs

Drug-induced nephrotoxicity is an important cause of renal failure in dogs. Aminoglycoside antibiotics, such as gentamicin, can produce nephrotoxicity in dogs, due to in part to an imbalance of pro- and antioxidants (oxidative stress). Silymarin (the mixture of flavonolignans extracted from Silybum marianum) has potentially beneficial antioxidant properties. A control group (saline, group 1, n = 5) was compared with dogs that were administrated gentamicin by intramuscular injection, at dosage of 20 mg/kg, once daily for 9 days (groups 2-5, n = 5 per group). The effects of vitamin E (group 3) and silymarin (group 4) alone and in combination (group 5) were compared for induced nephrotoxicity. Renal function was assessed using serum biochemical markers (creatinine and urea). Malondialdehyde (MDA) concentration were measured as a marker of lipid peroxidation. The activity of total serum antioxidants (TSAO) was assessed as a marker of antioxidant defences. Serum creatinine and urea concentrations were increased significantly and TSAO was decreased significantly in group 2 compared with group 1. Serum creatinine concentrations but not urea concentrations were significantly lower in groups 3 and 4 than in group 2 (P = 0.001). Serum MDA concentrations was significantly different between groups 2 and 3 (P = 0.01), 2 and 4 (P < 0.001) and 4 and 5 (P = 0.01). TSAO activity was significantly in group 4 (silymarin) than in group 2 (P = 0.002). Silymarin and vitamin E decreased gentamicin-induced nephrotoxicity in dogs.

Therapeutic value of orally administered silibinin in renal cell carcinoma: manipulation of insulin-like growth factor binding protein-3 levels

OBJECTIVES

To investigate if the feeding of silibinin (an anticancer flavonoid) to mice inhibits in vivo renal cell carcinoma (RCC) growth via changes in insulin-like growth factor binding protein-3 (IGFBP-3) levels.

MATERIALS AND METHODS

Male severe combined immunodeficiency disease (SCID) mice (7 weeks old), with left kidneys injected with 1 million SN12K1 cells, were fed a silibinin-containing diet (0.1%, 0.2% and 0.4% w/w) or control AIN-93G diet for 39 days from 1 day after tumour engraftment.

RESULTS

There was a reduction in tumour deposits and tumour kidney weight in SCID mice fed with a 0.4% silibinin-containing diet compared to those fed the control diet. Mice with tumour injection (silibinin or control-diet group) had constant total body weight and food consumption. The mean plasma and tumourous kidney silibinin concentrations, as measured by high-pressure liquid chromatography-tandem mass spectrometry, increased with escalating doses of silibinin. Using real-time polymerase chain reaction and enzyme-linked immunosorbent assay, the mean tissue IGFBP-3 mRNA (in SN12K1-implanted kidney) and plasma IGFBP-3 levels increased in mice fed with 0.1% silibinin (tumour IGFBP-3 mRNA levels, 156% higher vs control-diet group, P = 0.007; and plasma IGFBP-3 levels, 61% higher vs control-diet group, P = 0.002) but not in mice fed with the higher silibinin pellet strengths.

CONCLUSION

Oral administration of silibinin suppressed local and metastatic tumour growth in vivo in an orthotopic xenograft model of RCC. This anti-neoplastic action of silibinin might involve IGFBP-3. The exact mechanism through which IGFBP-3 promotes silibinin's anticancer effects warrants further investigation.

Complementary and alternative medicine use by patients chronically infected with hepatitis C virus

Complementary and alternative medicine (CAM) is becoming increasingly popular in North America. The use of CAM is also popular in patients with chronic liver disease but is not well documented. The extent of use of CAM in chronic hepatitis C virus (HCV) infected patients was determined, and the demographic and clinical data between users and nonusers of CAM was compared. Seventy-six patients (30% female) with chronic HCV were interviewed. The mean age was 43+/-8 years. Current use of CAM for HCV was reported by 35 of 76 patients (46%). Eighteen of 76 patients within this group used herbal supplements (24%). The most commonly used herb was Silybum marianum (milk thistle), reported by 10 of 76 patients (13.2%). Commonly reported benefits of CAM use included reduction in fatigue, boost in the immune system and improved gastrointestinal function. No adverse effects of CAM use were reported. In the present study, four of 18 patients (22%) with chronic liver disease taking herbal therapies were on herbs that increased bleeding time. The use of CAM in chronic HCV patients is significant. Patients should be asked specifically about their use of CAM. CAM use may have implications affecting conventional treatment and management of HCV.

Advances in the use of milk thistle (Silybum marianum)

Milk thistle (Silybum marianum) is an herbal supplement used to treat liver and biliary disorders. Silymarin, a mixture of flavanoid complexes, is the active component that protects liver and kidney cells from toxic effects of drugs, including chemotherapy. Although milk thistle has not significantly altered the course of chronic liver disease, it has reduced liver enzyme levels and demonstrated anti-inflammatory and T cell-modulating effects. There is strong preclinical evidence for silymarin's hepatoprotective and anticarcinogenic effects, including inhibition of cancer cell growth in human prostate, skin, breast, and cervical cells. Milk thistle is considered safe and well-tolerated, with gastrointestinal upset, a mild laxative effect, and rare allergic reaction being the only adverse events reported when taken within the recommended dose range. More clinical trials of rigorous methodology, using standardized and well-defined products and dosages, are needed to evaluate the potential of silymarin against liver toxicity, chronic liver disease, and human cancers.

Review of clinical trials evaluating safety and efficacy of milk thistle (Silybum marianum [L.] Gaertn.)

Milk thistle extracts have been used as traditional herbal remedies for almost 2000 years. The extracts are still widely used to protect the liver against toxins and to control chronic liver diseases. Recent experimental and clinical studies suggest that milk thistle extracts also have anticancer, antidiabetic, and cardioprotective effects. This article reviews clinical trials of milk thistle conducted in the past 5 years including pharmacokinetic and toxicity studies, herb-drug interactions, and other safety issues. Several trials have studied the effects of milk thistle for patients with liver diseases, cancer, hepatitis C, HIV, diabetes, and hypercholesterolemia. Promising results have been reported in the protective effect of milk thistle in certain types of cancer, and ongoing trials will provide more evidence about this effect. In addition, new established doses and improvement on the quality and standardization of this herb will provide the much-awaited evidence about the efficacy of milk thistle in the treatment of liver diseases. Milk thistle extracts are known to be safe and well tolerated, and toxic or adverse effects observed in the reviewed clinical trials seem to be minimal. The future of milk thistle research is promising, and high-quality randomized clinical trials on milk thistle versus placebo may be needed to further demonstrate the safety and efficacy of this herb.