The use of silymarin in the treatment of liver diseases

Silymarin in liposomes and ethosomes: pharmacokinetics and tissue distribution in free-moving rats by high-performance liquid chromatography-tandem mass spectrometry

The aim of this study was to prepare silymarin formulations (silymarin entrapped in liposomes and ethosomes, formulations referred to as LSM and ESM, respectively) to improve oral bioavailability of silymarin and evaluate its tissue distribution by liquid chromatography with tandem mass spectrometry (LC-MS/MS) in free-moving rats. Silibinin is the major active constituent of silymarin, which is the main component to be analyzed. A rapid, sensitive, and repeatable LC-MS/MS method was developed and validated in terms of precision, accuracy, and extraction recovery. Furthermore, the established method was applied to study the pharmacokinetics and tissue distribution of silymarin in rats. The size, ζ potential, and drug release of the formulations were characterized. These results showed that the LSM and ESM encapsulated formulations of silymarin may provide more efficient tissue distribution and increased oral bioavailability, thus improving its therapeutic bioactive properties in the body.

In vivo efficacy study of milk thistle extract (ETHIS-094™) in STAM™ model of nonalcoholic steatohepatitis

INTRODUCTION

A subcategory of nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) is characterized by accumulation of fat accompanied by inflammatory infiltration and hepatocellular damage. The active complex of milk thistle is a lipophilic extract from its seeds, comprising three isomers, collectively known as silymarin. Silymarin has demonstrated antioxidant, anti-inflammatory, and antifibrotic properties, and has been extensively studied in the treatment of liver diseases. The majority of published clinical research on silymarin has used Legalon(®) (Rottapharm/Madaus), containing the patented extract of milk thistle ETHIS-094™ (Euromed). The current study was undertaken to examine the effects of ETHIS-094™ in the Stelic Animal Model (STAM™), a validated and widely used animal model for NASH.

METHODS

After 4 h fasting from 4 to 8 weeks of age, 15 male mice in whom NASH had been induced were orally administered, once daily, either (1) vehicle (saline) at a volume of 10 mL/kg, (2) vehicle supplemented with milk thistle at a dose of 500 mg/kg, or (3) vehicle supplemented with milk thistle at a dose of 1,000 mg/kg.

RESULTS

Mean liver weight and the liver-to-body weight ratio were significantly (P < 0.01) decreased in the milk thistle high-dose group compared with the vehicle group. NAFLD activity score (NAS) tended to decrease in the milk thistle treatment groups compared with vehicle group, as did steatosis scores.

CONCLUSION

Milk thistle extract administration induced a decreasing trend in NAS compared with the vehicle group. Milk thistle induced a numerical decrease of the steatosis score compared with vehicle, and this was accompanied by a statistically significant decrease in liver weight and the liver-to-body weight ratio, implying a potential anti-steatosis effect of milk thistle.

Silibinin potentially attenuates arsenic-induced oxidative stress mediated cardiotoxicity and dyslipidemia in rats

Cardiac dysfunction is one of the major causes of mortality and morbidity throughout the world. Chronic exposure of arsenic (As) mainly leads to cardiotoxic effect. Cardiotoxicity was induced by the sodium arsenite as the source of As (5 mg/kg BW, PO) for 4 weeks. As intoxication significantly (p < 0.05) increased the serum cardiac markers, viz. creatine kinase-MB, lactate dehydrogenase, aspartate transaminase, alanine transaminase and alkaline phosphatase, oxidative stress markers in heart, plasma total cholesterol (TC), triglycerides (TG), phospholipids (PL), free fatty acids (FFA), low density lipoprotein cholesterol, very low density lipoprotein cholesterol as well as cardiac lipid profile (TC, TG and FFA) and significantly (p < 0.05) decreased the level of serum high density lipoprotein cholesterol, cardiac PL, mitochondrial enzymes such as ICDH, SDH, MDH, α-KDH and NADH dehydrogenase, levels of enzymatic antioxidant, nonenzymatic antioxidants and membrane-bound ATPases in heart. In addition, As-intoxicated rats showed a significant (p < 0.05) up-regulation of myocardial NADPH (NOX) oxidase sub units such as NOX2 and NOX4 as well as Keap-1 and down-regulation of Nrf2 and HO-1 protein expressions. Pre-administration of silibinin (SB) (75 mg/kg BW) remarkably recovered all these altered parameters to near normalcy in As-induced cardiotoxic rat. Moreover, the light microscopic and transmission electron microscopic study further supports the protective efficacy of SB on the heart mitochondria. In conclusion, our data demonstrate that SB has a potential to extenuate the arsenic-induced cardiotoxicity and dyslipidemia in rat.

Milk thistle extract and silymarin inhibit lipopolysaccharide induced lamellar separation of hoof explants in vitro

The pathogenesis of laminitis is not completely identified and the role of endotoxins (lipopolysaccharides, LPS) in this process remains unclear. Phytogenic substances, like milk thistle (MT) and silymarin, are known for their anti-inflammatory and antioxidant properties and might therefore have the potential to counteract endotoxin induced effects on the hoof lamellar tissue. The aim of our study was to investigate the influence of endotoxins on lamellar tissue integrity and to test if MT and silymarin are capable of inhibiting LPS-induced effects in an in vitro/ex vivo model. In preliminary tests, LPS neutralization efficiency of these phytogenics was determined in an in vitro neutralization assay. Furthermore, tissue explants gained from hooves of slaughter horses were tested for lamellar separation after incubation with different concentrations of LPS. By combined incubation of explants with LPS and either Polymyxin B (PMB; positive control), MT or silymarin, the influence of these substances on LPS-induced effects was assessed. In the in vitro neutralization assay, MT and silymarin reduced LPS concentrations by 64% and 75%, respectively, in comparison PMB reduced 98% of the LPS concentration. In hoof explants, LPS led to a concentration dependent separation. Accordantly, separation force was significantly decreased by 10 µg/mL LPS. PMB, MT and silymarin could significantly improve tissue integrity of explants incubated with 10 µg/mL LPS. This study showed that LPS had a negative influence on the structure of hoof explants in vitro. MT and silymarin reduced endotoxin activity and inhibited LPS-induced effects on the lamellar tissue. Hence, MT and silymarin might be used to support the prevention of laminitis and should be further evaluated for this application.

Effects and tolerance of silymarin (milk thistle) in chronic hepatitis C virus infection patients: a meta-analysis of randomized controlled trials

OBJECTIVE

This study aimed to evaluate the efficacy and safety of silymarin on chronic hepatitis C virus- (HCV-) infected patients.

METHODS

Randomized controlled trials (RCTs) of silymarin in chronic HCV-infected patients up to April 1, 2014 were systematically identified in PubMed, Ovid, Web of Science, and Cochrane Library databases.

RESULTS

A total of 222 and 167 patients in five RCTs were randomly treated with silymarin (or intravenous silibinin) and placebo, respectively. Serum HCV RNA relatively decreased in patients treated with silymarin compared with those administered with placebo, but no significance was found (P = 0.09). Meta-analysis of patients orally treated with silymarin indicated that the changes of HCV RNA are similar in the two groups (P = 0.19). The effect on alanine aminotransferase (ALT) of oral silymarin is not different from that of placebo (P = 0.45). Improvements in quality-of-life (Short Form-36) in both silymarin and placebo recipients were impressive but relatively identical (P = 0.09).

CONCLUSION

Silymarin is well tolerated in chronic HCV-infected patients. However, no evidence of salutary effects of oral silymarin has yet been reported based on intermediate endpoints (ALT and HCV RNA) in this population. Moreover, intravenous administration of silymarin should be further studied.

Silybin reduces obliterated retinal capillaries in experimental diabetic retinopathy in rats

Silybin has been previously reported to possess anti-inflammatory properties, raising the possibility that it may reduce vascular damage in diabetic retinopathy. Present study was designed to investigate this potential effect of silybin and its underlying mechanisms in experimental diabetic retinopathy. Diabetes was induced with streptozotocin (STZ) plus high-fat diet in Sprague-Dawley rats, and silybin was administrated for 22 weeks after the induction of diabetes. Histochemical and immunofluorescence techniques were used to assess the obliterated retinal capillaries, leukostasis, and level of retinal intercellular adhesion molecule-1 (ICAM-1). Western blot was performed to quantitate the expression of retinal ICAM-1. Results showed that silybin treatment significantly prevented the development of obliterated retinal capillaries in diabetes, compared with vehicle treatment. In addition, leukostasis and level of the retinal ICAM-1 were found to decrease considerably in silybin-treated diabetic groups. In conclusion, these results indicate that silybin reduces obliterated retinal capillaries in experimental diabetes, and the recovered retinal vascular leukostasis and level of ICAM-1 at least partly contributes to the preventive effect of silybin.

A new pro-prodrug aminoacid-based for trans-ferulic Acid and silybin intestinal release

The aim of this work was the preparation and characterization of a pro-prodrug able to simultaneously transport silybin, a drug possessing various pharmacological effects, and trans-ferulic acid, a known antioxidant. More specifically, l-phenylalanine-N-(4-hydroxy-3-methoxy-phenyl) prop-2-en-O-(2R,3R)-3,5,7-trihydroxy-2-((2R,3R)-3-(4-hydroxy-3-methoxyphenyl)-2-(hydroxymethyl)-2,3-dihydro-benzo-(1,4)-dioxin-6-yl)croman-4-one was synthesized by using the aminoacid l-phenylalanine (l-Phe) as carrier. Indeed, l-Phe is characterized by an intrinsic chemical reactivity due to the presence of an amino group, placed on the chiral center, and of a carboxylic group. The synthesis has been characterized first by adding silybin by means of carboxylic group and then, with the aim to confer antioxidant properties to this new carrier, by linking trans-ferulic acid to l-Phe via amino group. The so obtained derivative was then characterized by FT-IR, and ¹H-NMR spectroscopies. Furthermore, its ability to inhibit lipid peroxidation induced by tert-butyl hydroperoxide in rat liver microsomes, was evaluated. The 1,1-diphenyl-2-picrylhydrazyl radical-scavenging effect, was also assessed. The release of silybin and trans-ferulic acid was determined in simulated gastric and intestinal fluids over the time. The results showed that the covalent bond between both (i) silybin; or (ii) trans-ferulic acid and the amino acid was degraded by enzymatic reactions. In addition, the pro-prodrug, showed strong antioxidant and scavenger activities. Due to these properties, this new pro-prodrug could be applied for the treatment of intestinal pathologies and it might improve the therapeutic potential of silybin which is strongly limited by its low solubility.

Engineered silybin nanoparticles educe efficient control in experimental diabetes

Silybin, is one imminent therapeutic for drug induced hepatotoxicity, human prostate adenocarcinoma and other degenerative organ diseases. Recent evidences suggest that silybin influences gluconeogenesis pathways favorably and is beneficial in the treatment of type 1 and type 2 diabetes. The compound however is constrained due to solubility (0.4 mg/mL) and bioavailabilty limitations. Appropriate nanoparticle design for silybin in biocompatible polymers was thus proposed as a probable solution for therapeutic inadequacy. New surface engineered biopolymeric nanoparticles with high silybin encapsulation efficiency of 92.11% and zeta potential of +21 mV were designed. Both the pure compound and the nanoparticles were evaluated in vivo for the first time in experimental diabetic conditions. Animal health recovered substantially and the blood glucose levels came down to near normal values after 28 days treatment schedule with the engineered nanoparticles. Restoration from hyperglycemic damage condition was traced to serum insulin regeneration. Serum insulin recovered from the streptozotocin induced pancreatic damage levels of 0.17 ± 0.01 µg/lit to 0.57 ± 0.11 µg/lit after nanoparticle treatment. Significant reduction in glycated hemoglobin level, and restoration of liver glycogen content were some of the other interesting observations. Engineered silybin nanoparticle assisted recovery in diabetic conditions was reasoned due to improved silybin dissolution, passive transport in nanoscale, and restoration of antioxidant status.

Hepatoprotective effect of silymarin on di(2-ethylhexyl)phthalate (DEHP) induced injury in liver FL83B cells

Di(2-ethylhexyl)phthalate (DEHP), is a toxic environmental pollutant in our life which can contaminate air, water, and soil. The hepatoprotective effect of silymarin on DEHP-induced injury in FL83B mouse liver cells was investigated by analyzing the cell viability, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), cell cycle arrest, and cell morphology. The results revealed that cell viability decreased while released LDH and ALT increased with the increase of DEHP concentrations. Moreover, cell population of sub-G1 and S phase increased as the concentrations of DEHP increased. Silymarin at 25 μM achieved the highest hepatoprotective effect and exhibited 79% cell viability while only 46% cell viability was found in DEHP injured control. It was also found to reduce LDH release and cell populations of sub-G1 and S phase. Therefore, silymarin could ameliorate DEHP-induced injury and have potential to be further developed as a natural ingredient of health food against phthalate plasticizers induced liver injury.

Pathogenesis of liver cirrhosis

Liver cirrhosis is the final pathological result of various chronic liver diseases, and fibrosis is the precursor of cirrhosis. Many types of cells, cytokines and miRNAs are involved in the initiation and progression of liver fibrosis and cirrhosis. Activation of hepatic stellate cells (HSCs) is a pivotal event in fibrosis. Defenestration and capillarization of liver sinusoidal endothelial cells are major contributing factors to hepatic dysfunction in liver cirrhosis. Activated Kupffer cells destroy hepatocytes and stimulate the activation of HSCs. Repeated cycles of apoptosis and regeneration of hepatocytes contribute to pathogenesis of cirrhosis. At the molecular level, many cytokines are involved in mediation of signaling pathways that regulate activation of HSCs and fibrogenesis. Recently, miRNAs as a post-transcriptional regulator have been found to play a key role in fibrosis and cirrhosis. Robust animal models of liver fibrosis and cirrhosis, as well as the recently identified critical cellular and molecular factors involved in the development of liver fibrosis and cirrhosis will facilitate the development of more effective therapeutic approaches for these conditions.

Colostrum yield and piglet growth during lactation are related to gilt metabolic and hepatic status prepartum

It was hypothesized that colostrum production could be influenced by sow peripartum endocrine, metabolic, and hepatic status. The plant extract silymarin was shown to influence endocrine and hepatic status in several species. The aims of the present study were to investigate the effects of silymarin intake during late pregnancy on sow hormonal and hepatic status and to determine whether relations exist between sow hepatic and metabolic status during the peripartum period and colostrum yield and piglet performances during lactation. From d 107 of pregnancy until farrowing, nulliparous sows were either fed 12 g/d of silymarin (SIL; n = 15) or no treatment (Control; n = 12). Piglet BW was recorded directly after birth, 24 h after birth of the first piglet, and at 7, 14, and 21 d of lactation. Blood samples were collected from sows on d 107 and 109 of pregnancy, daily from d 111 of pregnancy until d 2 of lactation, and on d 7 and 21 of lactation. They were assayed for endocrine, metabolic, and hepatic variables. Colostrum yield was estimated during 24 h starting at the onset of farrowing. Silymarin did not influence colostrum yield (3.7 ± 0.3 kg) or gross composition (P > 0.10), nor did it affect serum prolactin concentrations or plasma concentrations of progesterone, estradiol-17β, or cortisol (P > 0.10). Mean litter BW gain was lower (P < 0.05) during the first week and tended (P < 0.10) to be lower during the second week of lactation in litters from SIL sows. Silymarin had no effect on plasma concentrations of aspartate transaminase, alanine transaminase, γ-glutamyl transferase (γ-GT), alkaline phosphatase, or total cholesterol (P > 0.10). Colostrum yield was positively correlated with urea (r = 0.50; P = 0.01) and creatinine (r = 0.43; P = 0.03) concentrations in sows on the day before farrowing. Mean litter BW gain over 2 wk was negatively correlated with concentrations of β-hydroxybutyric acid (r = -0.50; P = 0.01) and γ-GT (r = -0.42; P = 0.03) on the day before farrowing and was positively correlated with urea concentrations on the day before farrowing (r = 0.54; P = 0.01). In conclusion, at the dose of 12 g/d, silymarin did not influence prolactin concentrations or the hepatic status of sows, had no impact on colostrum production, and decreased litter BW gain in early lactation. Colostrum yield and litter performance during lactation were correlated with some markers of sow metabolic and hepatic status measured during the prepartum period.

Identification of isosilybin a from milk thistle seeds as an agonist of peroxisome proliferator-activated receptor gamma

Peroxisome proliferator-activated receptor gamma (PPARγ) is a key regulator of glucose and lipid metabolism. Agonists of this nuclear receptor are used in the treatment of type 2 diabetes and are also studied as a potential treatment of other metabolic diseases, including nonalcoholic fatty liver disease. Silymarin, a concentrated phenolic mixture from milk thistle (Silybum marianum) seeds, is used widely as a supportive agent in the treatment of a variety of liver diseases. In this study, the PPARγ activation potential of silymarin and its main constituents was investigated. Isosilybin A (3) caused transactivation of a PPARγ-dependent luciferase reporter in a concentration-dependent manner. This effect could be reversed upon co-treatment with the PPARγ antagonist T0070907. In silico docking studies suggested a binding mode for 3 distinct from that of the inactive silymarin constituents, with one additional hydrogen bond to Ser342 in the entrance region of the ligand-binding domain of the receptor. Hence, isosilybin A (3) has been identified as the first flavonolignan PPARγ agonist, suggesting its further investigation as a modulator of this nuclear receptor.

Hepatoprotective Effects of Silybum marianum (Silymarin) and Glycyrrhiza glabra (Glycyrrhizin) in Combination: A Possible Synergy

Oxidative stress, lipid peroxidation, and transaminase reactions are some of the mechanisms that can lead to liver dysfunction. A time-dependent study was designed to evaluate the ability of silymarin (SLN) and glycyrrhizin (GLN) in different dosage regimens to lessen oxidative stress in the rats with hepatic injury caused by the hepatotoxin carbon tetrachloride. Wistar male albino rats (n = 60) were randomly assigned to six groups. Group A served as a positive control while groups B, C, D, E, and F received a dose of CCl4 (50% solution of CCl4 in liquid paraffin, 2 mL/kg, intraperitoneally) twice a week to induce hepatic injury. Additionally, the animals received SLN and GLN in different doses for a period of six weeks. CCl4 was found to induce hepatic injury by significantly increasing serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and thiobarbituric acid reactive substances while decreasing total protein and the activities of reduced glutathione, superoxide dismutase, and catalase. Treatment with various doses of SLN and GLN significantly reduced ALT, AST, ALP, and TBARS levels and increased GSH, SOD, and CAT levels. Our findings indicated that SLN and GLN have hepatoprotective effects against oxidative stress of the liver.

Protective effect of silymarin against cisplatin-induced ototoxicity

OBJECTIVES

Silymarin is a plant extract with strong antioxidant properties in addition to anti-inflammatory and anticarcinogenic actions. The aim of this study was to investigate the potential preventive effect of silymarin on cisplatin ototoxicity in an auditory cell line, HEI-OC1 cells.

METHODS

Cultured HEI-OC1 cells were exposed to cisplatin (30 μM) with or without pre-treatment with silymarin (50 μM). Cell viability was evaluated using MTT assay. Hoechst 33258 staining was used to identify cells undergoing apoptosis. Western blot analysis was done to evaluate whether silymarin inhibits cisplatin-induced caspase and PARP activation. Cell-cycle analysis was done by flow cytometry to investigate whether silymarin is capable of protecting cisplatin-induced cell cycle arrest.

RESULTS

Cell viability significantly increased in cells pretreated with silymarin compared with cells exposed to cisplatin alone. Pre-treatment of silymarin appeared to protect against cisplatin-induced apoptotic features on Hoechst 33258 staining. Cisplatin increased cleaved caspase-3 and PARP on Western blot analysis. However, pre-treatment with silymarin inhibited the expression of cleaved caspase-3 and PARP. Silymarin did attenuate cell cycle arrest and apoptosis in HEI-OC1 cells.

CONCLUSIONS

Our results demonstrate that silymarin treatment inhibited cisplatin-induced cytotoxicity in the auditory cell line, HEI-OC1. Silymarin may be a potential candidate drug to eliminate cisplatin induced ototoxicity.

Beneficial effects of silibinin against the progression of metabolic syndrome, increased oxidative stress, and liver steatosis in Psammomys obesus, a relevant animal model of human obesity and diabetes

BACKGROUND

Insulin resistance and oxidative stress are major pathogenic mechanisms leading to chronic liver diseases in diabetic subjects. The gerbil Psammomys obesus is a unique model of nutritional diabetes resembling the disease in humans. This study investigated whether the natural ingredient silibinin, known as hepatoprotective, could decrease oxidative stress and reduce liver damage in obese gerbils.

METHODS

Control animals were fed their vegetable-based low caloric diet while two other rat groups ingested a high calorie diet for 14 weeks. Silibinin, or its vehicle, was administrated by gastric intubation (100 mg/kg per day) from the 7th week of treatment, which corresponds to an established insulin resistance state. At the end of the experiments, the hepatic biochemical profile, markers of oxidative stress in either plasma or liver tissue, and histological alterations were examined.

RESULTS

Diabetic P. obesus displayed many metabolic disturbances (hyperinsulinemia, hyperglycemia, dyslipidemia), which were aggravated for the last 8 weeks. These events were coupled with greater oxidative stress (decline in glutathione, rise in lipoperoxidation). In addition, glutathione peroxidase activity was reduced while the level of superoxide dismutase was elevated. Interestingly, treatment with silibinin alleviated most of the metabolic defects, especially high triglyceride levels, reduced insulin resistance and largely restored antioxidant status. Also, Masson's trichrome staining revealed distinct steatosis, yet silibinin partially reversed this manifestation.

CONCLUSION

Silibinin affords substantial protection against the progression of insulin resistance in Type 2 diabetes mellitus for P. obesus by hampering the oxidative process and improving hepatic metabolism.

Therapeutic potential of morin against liver fibrosis in rats: modulation of oxidative stress, cytokine production and nuclear factor kappa B

Therapeutic potential of morin, a member of flavonoid family, against carbon tetrachloride (CCl4)-induced liver fibrosis in rats was investigated and compared with that of silymarin. Results show that treatment with morin (30 mg/kg/day) revealed attenuation in liver index and serum biomarkers of liver function that were enhanced by chronic CCl4 intoxication. Further, morin inhibited the elevated levels of malondialdehyde and nitric oxide and restored hepatic reduced glutathione to its normal level. The increased production of hepatic hydroxyproline content by CCl4 was markedly decreased by administration of morin. In addition, treatment with morin significantly attenuated the inflammatory responses caused by CCl4 as evident by the decreased hepatic tumor necrosis factor-alpha (TNF-α) level, immunohistochemical expressions of inducible nitric oxide synthase and nuclear factor kappa B. Collectively, this study indicates that morin possesses antifibrotic effect in the CCl4 model of fibrosis via reducing oxidative stress, inflammatory responses and fibrogenic markers.

Quantum-chemical study on relationship between structure and antioxidant properties of hepatoprotective compounds occurring in Cynara scolymus and Silybum marianum

Accurate quantum computations based on the density functional theory have been performed to study the relationship between the electronic geometry and antioxidant capacity of chlorogenic acid, silybin and all geometric stereoisomers of cynarine, isolated from plant extract of Cynara scolymus and Silybum marianum. To elucidate their antioxidant activity, the HOMO orbital distribution, adiabatic ionization potential (AIP), spin density in free radicals, homolytic dissociation enthalpies (BDE), and proton dissociation enthalpies (PDE) of the O – H bonds have been calculated. For minimum energy conformations, the antioxidative parameters were quantitatively analyzed at the B3LYP/6-311G(d,p) level of theory. The results have shown that the hydrogen transfer mechanism is more preferable in nonpolar medium than in water. From the results obtained we can conclude that SET-PT (single electron transfer followed by proton transfer) is the most preferred mechanism in water medium. The catechol moiety and planar geometry of trans-stilbene and cis-stilbene moieties in cynarine stereoisomers, chlorogenic acid and their phenoxy radicals strongly contribute to enhancement of the antioxidant activity of these compounds. Trans,trans-cynarine appears to be the best candidate for proton and hydrogen atom donor. It has been predicted that cis,cis, trans,cis and cis,trans stereoisomers of cynarine show antioxidant capacity. Our study shows that all of the investigated compounds reveal strong antioxidant activity.

Effects of the plant extract silymarin on prolactin concentrations, mammary gland development, and oxidative stress in gestating gilts

The impacts of supplementing the diet of gestating gilts twice daily with 4 g of the plant extract silymarin on circulating hormonal concentrations, oxidative status, mammary development, and mammary gene expression at the end of gestation were determined. Gilts were fed conventional diets during gestation and on d 90 they were assigned as controls (CTL; n = 16) or treated (TRT; n = 17) animals. Treatment consisted of providing 4 g of silymarin twice daily until d 110, at which time all gilts were slaughtered to collect mammary tissue for compositional analyses and measures of gene expression and oxidative status, and liver and corpora lutea for measures of oxidative stress variables. Blood samples for hormonal assays and evaluation of oxidative stress biomarkers were obtained on d 89, 94, and 109 of gestation. Silymarin increased (P = 0.05) circulating concentrations of prolactin over all samples in the repeated in time analysis. In separate analyses for each sampling time, prolactin concentrations in TRT gilts tended (P < 0.10) to be greater than in CTL gilts on d 94 of gestation. Repeated in time analysis also revealed that silymarin reduced (P ≤ 0.05) plasmatic accumulation of biomarkers of oxidative damage to protein (protein carbonyls) between d 89 and 109. There was no effect (P > 0.10) of treatment on progesterone, estradiol, leptin, or 8-hydroxy-2'-deoxyguanosine concentrations. Percent fat in mammary parenchyma was greater (P ≤ 0.05), percent protein was lesser (P ≤ 0.05), and concentrations of both RNA (P ≤ 0.01) and DNA (P < 0.05) were lesser in TRT than CTL gilts. Mammary parenchyma from TRT gilts had lower (P ≤ 0.05) mRNA abundance for STAT5A and leptin and tended to have lower (P ≤ 0.10) abundance for STAT5B than CTL gilts. Silymarin reduced (P ≤ 0.001) protein carbonyls concentrations in liver of TRT gilts. No effect of treatment was observed on antioxidant gene expression and enzymatic activities in liver samples while total superoxide dismutase activity tended to be higher (P ≤ 0.10) in the corpora lutea of TRT animals when compared with CTL. This is the first demonstration that, in female pigs, silymarin can increase prolactin concentrations and protect against oxidative stress, yet the increase in prolactin was not enough to have beneficial effects on mammary gland development in late gestation.

Targeting events in melanoma carcinogenesis for the prevention of melanoma

Melanoma is one of the few tumors that have increased in incidence over the last few decades. Strategies devoted solely to protecting against ultraviolet radiation have, at best, had a modest impact on the development of melanoma. Chemoprevention is an under-explored approach that could significantly decrease the morbidity and mortality from this deadly cancer. However, the scientific and logistical challenges of performing clinical studies in chemoprevention require innovative approaches to prove the effectiveness of putative preventive agents. There are several pharmacological and nutriceutical agents that are mechanistically linked to events in melanoma carcinogenesis that are candidates for advanced human studies. We will review the data for several promising agents, including statins, curcumin, resveratrol, silymarin and green tea, and discuss some importance issues and concepts that should be considered in any melanoma chemoprevention strategy.

Chemistry and biological activities of flavonoids: an overview

There has been increasing interest in the research on flavonoids from plant sources because of their versatile health benefits reported in various epidemiological studies. Since flavonoids are directly associated with human dietary ingredients and health, there is need to evaluate structure and function relationship. The bioavailability, metabolism, and biological activity of flavonoids depend upon the configuration, total number of hydroxyl groups, and substitution of functional groups about their nuclear structure. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. Most recent researches have focused on the health aspects of flavonoids for humans. Many flavonoids are shown to have antioxidative activity, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, anti-inflammatory, and anticancer activities, while some flavonoids exhibit potential antiviral activities. In plant systems, flavonoids help in combating oxidative stress and act as growth regulators. For pharmaceutical purposes cost-effective bulk production of different types of flavonoids has been made possible with the help of microbial biotechnology. This review highlights the structural features of flavonoids, their beneficial roles in human health, and significance in plants as well as their microbial production.

Multitargeting and antimetastatic potentials of silibinin in human HepG-2 and PLC/PRF/5 hepatoma cells

Hepatocellular carcinoma (HCC) is the most common sort of primary liver malignancy with poor prognosis. This study aimed at examining the effects of silibinin (a putative antimetastatic agent) on some transcriptional markers mechanistically related to HCC recurrence and metastasis in HepG-2 [hepatitis B virus (HBV)-negative and P53 intact) and PLC/PRF/5 (HBV-positive and P53 mutated) cells. The expression of 27 genes in response to silibinin was evaluated by real-time RT-PCR. The MMP gelatinolytic assay and microculture tetrazolium test (MTT) were tested. Silibinin was capable of suppressing the transcriptional levels of ANGPT2, ATP6L, CAP2, CCR6, CCR7, CLDN-10, cortactin, CXCR4, GLI2, HK2, ID1, KIAA0101, mortalin, PAK1, RHOA, SPINK1, and STMN1 as well as the enzymatic activity of MMP-2 but promoted the transcripts of CREB3L3, DDX3X, and PROX1 in both cells. Some significant differences between the cells in response to silibinin were detected that might be related to the differences of the cells in terms of HBV infection and/or P53 mutation, suggesting the possible influence of silibinin on HCC through biological functions of these 2 prognostic factors. In conclusion, our findings suggest that silibinin could potentially function as a multitargeting antimetastatic agent and might provide new insights for HCC therapy particularly for HBV-related and/or P53-mutated HCCs.

Free Radical Scavenging and Antioxidant Activities of Silymarin Components

Silymarin is an over the counter food supplement that is sold as a liver enhancement and liver protection preparation. It is a major constituent of the seeds of Silybum marianum which is composed of a mixture of seven major components and several minor compounds. The seven major components: taxifolin, silychristin, silydianin, silybin A, silybin B, iso-silybin A and iso-silybin B were isolated and purified from the crude mixture of silymarin using preparative high performance liquid chromatography to determine which were the most effective for liver protection. Free radical scavenging, hydroxyl radical antioxidant capacity, oxygen radical antioxidant capacity, trolox-equivalent antioxidant capacity and total antioxidant capacity antioxidant activities were determined for each of the individual purified components as well as the crude silymarin mixture. Taxifolin was the most effective component for scavenging free radicals in the DPPH assay with an EC₅₀ of 32 µM far more effective than all other components which showed EC₅₀ ranging from 115 to 855 µM. Taxifolin was also found to be the most effective antioxidant in the oxygen radical antioxidant capacity (ORAC) assay with a trolox equivalent of 2.43 and the second most effective in the hydroxyl radical antioxidant capacity (HORAC) assay with a gallic acid equivalent of 0.57. Other antioxidants assays did not show significant differences between samples.

Silymarin's Protective Effects and Possible Mechanisms on Alcoholic Fatty Liver for Rats

Silymarin has been introduced fairly recently as a hepatoprotective agent. But its mechanisms of action still have not been well established. The aim of this study was to make alcoholic fatty liver model of rats in a short time and investigate silymarin’s protective effects and possible mechanisms on alcoholic fatty liver for rats. The model of rat’s alcoholic fatty liver was induced by intragastric infusion of ethanol and high-fat diet for six weeks. Histopathological changes were assessed by hematoxylin and eosin staining (HE). The activities of alanine transarninase (ALT) and aspartate aminotransferase (AST), the levels of total bilirubin (TBIL), total cholesterol (TC) and triglyceride (TG) in serum were detected with routine laboratory methods using an autoanalyzer. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) and the level of malondialdehyde (MDA) in liver homogenates were measured by spectrophotometry. The TG content in liver tissue was determined by spectrophotometry. The expression of nuclear factor-κB (NF-κB), intercellular adhesion molecule-1 (ICAM-1) and interleukin-6 (IL-6) in the liver were analyzed by immunohistochemistry. Silymarin effectively protected liver from alcohol-induced injury as evidenced by improving histological damage situation, reducing ALT and AST activities and TBIL level in serum, increasing SOD and GPx activities and decreasing MDA content in liver homogenates and reducing TG content in liver tissue. Additionally, silymarin markedly downregulated the expression of NF-κB p65, ICAM-1 and IL-6 in liver tissue. In conclusion, Silymarin could protect against the liver injury caused by ethanol administration. The effect may be related to alleviating lipid peroxidation and inhibiting the expression of NF-κB.

Protective effects of silymarin against acetaminophen-induced hepatotoxicity and nephrotoxicity in mice

This study was designed to estimate protective effects of silymarin on acetaminophen ( N-acetyl- p-aminophenol, paracetamol; APAP)-induced hepatotoxicity and nephrotoxicity in mice. Treatment of mice with overdose of APAP resulted in the elevation of aspartate aminotransferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), and serum creatinine (SCr) levels in serum, liver, and kidney nitric oxide (NO) levels and significant histological changes including decreased body weight, swelling of hepatocytes, cell infiltration, dilatation and congestion, necrosis and apoptosis in liver, and dilatation of Bowman’s capsular space and glomerular capillaries, pale-stained tubules epithelium, cell infiltration, and apoptosis in kidney. Posttreatment with silymarin 1 h after APAP injectionfor 7 days, however, significantly normalized the body weight, histological damage, serum ALT, AST, BUN, SCr, and tissue NO levels. Our observation suggested that silymarin ameliorated the toxic effects of APAP-induced hepatotoxicity and nephrotoxicity in mice. The protective role of silymarin against APAP-induced damages might result from its antioxidative and anti-inflammatory effects.

Neuroprotective potential of silymarin against CNS disorders: insight into the pathways and molecular mechanisms of action

Silymarin, a C25 containing flavonoid from the plant Silybum marianum, has been the gold standard drug to treat liver disorders associated with alcohol consumption, acute and chronic viral hepatitis, and toxin-induced hepatic failures since its discovery in 1960. Apart from the hepatoprotective nature, which is mainly due to its antioxidant and tissue regenerative properties, Silymarin has recently been reported to be a putative neuroprotective agent against many neurologic diseases including Alzheimer's and Parkinson's diseases, and cerebral ischemia. Although the underlying neuroprotective mechanism of Silymarin is believed to be due to its capacity to inhibit oxidative stress in the brain, it also confers additional advantages by influencing pathways such as β-amyloid aggregation, inflammatory mechanisms, cellular apoptotic machinery, and estrogenic receptor mediation. In this review, we have elucidated the possible neuroprotective effects of Silymarin and the underlying molecular events, and suggested future courses of action for its acceptance as a CNS drug for the treatment of neurodegenerative diseases.

Relevance of in vitro and clinical data for predicting CYP3A4-mediated herb-drug interactions in cancer patients

The use of complementary and alternative medicines (CAM) by cancer patients is increasing. Concomitant use of CAM and anticancer drugs could lead to serious safety issues in patients. CAM have the potential to cause pharmacokinetic interactions with anticancer drugs, leading to either increased or decreased plasma levels of anticancer drugs. This could result in unexpected toxicities or a reduced efficacy. Significant pharmacokinetic interactions have already been shown between St. John's Wort (SJW) and the anticancer drugs imatinib and irinotecan. Most pharmacokinetic CAM-drug interactions, involve drug metabolizing cytochrome P450 (CYP) enzymes, in particular CYP3A4. The effect of CAM on CYP3A4 activity and expression can be assessed in vitro. However, no data have been reported yet regarding the relevance of these in vitro data for the prediction of CAM-anticancer drug interactions in clinical practice. To address this issue, a literature research was performed to evaluate the relevance of in vitro data to predict clinical effects of CAM frequently used by cancer patients: SJW, milk thistle, garlic and Panax ginseng (P. ginseng). Furthermore, in clinical studies the sensitive CYP3A4 substrate probe midazolam is often used to determine pharmacokinetic interactions. Results of these clinical studies with midazolam are used to predict pharmacokinetic interactions with other drugs metabolized by CYP3A4. Therefore, this review also explored whether clinical trials with midazolam are useful to predict clinical pharmacokinetic CAM-anticancer drug interactions. In vitro data of SJW have shown CYP3A4 inhibition after short-term exposure and induction after long-term exposure. In clinical studies using midazolam or anticancer drugs (irinotecan and imatinib) as known CYP3A4 substrates in combination with SJW, decreased plasma levels of these drugs were observed, which was expected as a consequence of CYP3A4 induction. For garlic, no effect on CYP3A4 has been shown in vitro and also in clinical studies garlic did not affect the pharmacokinetics of both midazolam and docetaxel. Milk thistle and P. ginseng predominantly showed CYP3A4 inhibition in vitro. However, in clinical studies these CAM did not cause significant pharmacokinetic interactions with midazolam, irinotecan, docetaxel and imatinib. Most likely, factors as poor pharmaceutical availability, solubility and bioavailability contribute to the lack of significant clinical interactions. In conclusion, in vitro data are useful as a first indication for potential pharmacokinetic drug interactions with CAM. However, the discrepancies between in vitro and clinical results for milk thistle and P. ginseng show that clinical studies are required for confirmation of potential interactions. At last, midazolam as a model substrate for CYP3A4, has convincingly shown to correctly predict clinical interactions between CAM and anticancer drugs.

Puerarin, isolated from Pueraria lobata (Willd.), protects against hepatotoxicity via specific inhibition of the TGF-β1/Smad signaling pathway, thereby leading to anti-fibrotic effect

Recently, the TGF-β1/Smad signaling pathway has been investigated in the pathogenesis of hepatofibrosis, and pharmacological treatment of liver fibrosis targeted this pathway to determine its contribution to the inhibition of fibrotic development. Importantly, ethnopharmacology-derived Pueraria lobata has been reported to effectively reverse the fibrotic process in the liver. In the present study, we performed dimethylnitrosamine (DMN)-induced liver fibrosis in rats to assess the benefits of puerarin (PR), which was isolated from Pueraria lobata (Willd.), on ECM-derived hepatocytes associated with the TGF-β1/Smad pathway. Our results showed that the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), hyaluronic acid (HA), laminin (LN), type III precollagen (PCIII) and type IV collagen (CIV) were significantly reduced by PR treatment, while hepatic homogenates showed decreased levels of hydroxyproline (Hyp) and collagen I (Col I). Masson's trichrome staining indicated that the DMN-induced liver fibrosis was alleviated. In addition, the protein expression levels of transforming growth factor-β l (TGF-β l), smad2, smad3, α-SMA and TIMP-1 were downregulated specifically by PR treatment, whereas the protein expression levels of smad7 and MMP-1 were upregulated. Furthermore, we evaluated the PR-mediated inhibitory effect on TGF-β1-treated proliferation and activation in a rat liver stellate cell line (HSC-T6). These data resulted in inhibition of the cell growth of HSC-T6 in a dose-dependent manner and a reduction in TβRI, smad2 and smad3 expressed proteins in the presence of PR on TGF-β1-treated HSC-T6 cells, while smad7 levels were downregulated. Taken together, these findings identify a unique effect for PR-regulation of the TGF-β1/Smad pathway in blocking fibrotic development and provide a promising strategy for hepatofibrosis treatment.

Chinese herbal medicine-derived compounds for cancer therapy: a focus on hepatocellular carcinoma

ETHNOPHARMACOLOGICAL RELEVANCE

Hepatocellular carcinoma (HCC) as the major histological subtype of primary liver cancer remains one of the most common malignancies worldwide. Due to the complicated molecular pathogenesis of HCC, the option for effective systemic treatment is quite limited. There exists a critical need to explore and evaluate possible alternative strategies for effective control of HCC. With a long history of clinical use, Chinese herbal medicine (CHM) is emerging as a noticeable choice for its multi-level, multi-target and coordinated intervention effects against HCC. With the aids of phytochemistry and molecular biological approaches, in the past decades many CHM-derived compounds have been carefully studied through both preclinical and clinical researches and have shown great potential in novel anti-HCC natural product development. The present review aimed at providing the most recent developments on anti-HCC compounds derived from CHM, especially their underlying pharmacological mechanisms.

MATERIALS AND METHODS

A systematic search of anti-HCC compounds from CHM was carried out focusing on literatures published both in English (PubMed, Scopus, Web of Science and Medline) and in Chinese academic databases (Wanfang and CNKI database).

RESULTS

In this review, we tried to give a timely and comprehensive update about the anti-HCC effects and targets of several representative CHM-derived compounds, namely curcumin, resveratrol, silibinin, berberine, quercetin, tanshinone II-A and celastrol. Their mechanisms of anti-HCC behaviors, potential side effects or toxicity and future research directions were discussed.

CONCLUSION

Herbal compounds derived from CHM are of much significance in devising new drugs and providing unique ideas for the war against HCC. We propose that these breakthrough findings may have important implications for targeted-HCC therapy and modernization of CHM.

Hepatoprotective action of Orthosiphon diffusus (Benth.) methanol active fraction through antioxidant mechanisms: an in vivo and in vitro evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Preparations of Orthosiphon diffusus (Benth.) have been used by folk medicinal practitioners in the Western Ghats of India for treating inflammation, hepatitis and jaundice for many years and their effectiveness is widely acclaimed among the tribal communities.

AIM OF THE STUDY

To evaluate the mechanisms behind the antioxidant and hepatoprotective potential of Orthosiphon diffusus methanol active fraction (MAF) using in vivo (rat) and in vitro (cell culture) models.

MATERIALS AND METHODS

Neutralization of CCl4-induced hepatotoxicity by MAF was evaluated in rats. Towards this, serum levels of hepatic injury markers (lactate dehydrogenase and alkaline phosphatase), antioxidant enzymes in the liver homogenates, and histological examination were performed. In in vitro studies, mechanisms of neutralization of H2O2-induced toxicity by MAF using MTT, Comet assay and up-regulation of antioxidant enzymes at genetic level (RT-PCR) was performed in HepG2 cells.

RESULTS

Rats pre-treated with Orthosiphon diffusus MAF demonstrated significantly reduced levels of serum LDH (1.3-fold, p<0.05) and ALP (1.6-fold, p<0.05). Similarly, multiple dose MAF administration demonstrated significantly enhanced levels (p<0.05) of antioxidant enzymes in the liver homogenates. Histological analysis revealed complete neutralization of CCl4-induced liver injury by the extract. The in vitro studies demonstrated that, pre-treatment of MAF effectively prevented H2O2-induced oxidative stress, genotoxicity and significantly enhanced (~6-fold, p<0.01) expression of genes for antioxidant enzymes.

CONCLUSIONS

Orthosiphon diffusus MAF demonstrated significant hepatoprotection against CCl4-induced hepatotoxicity by antioxidant mechanisms comparable to silymarin. H2O2-induced oxidative stress was completely neutralized by MAF through enhanced expression of genes for antioxidant enzymes. Therefore, this study validates the use of Orthosiphon diffusus by folk medicinal practitioners in India. Further, MAF of Orthosiphon diffusus can serve as a strong candidate for the development of herbal hepatoprotective agents.

Increase of phosphatase and tensin homolog by silymarin to inhibit human pharynx squamous cancer

Silymarin is an active principle from the seeds of the milk thistle plant and is widely used as a hepatoprotective gent due to its antioxidant-like activity. In the present study, we evaluated the potential efficacy of silymarin against oral cancer and investigated its possible mechanism of action. Cell viability assay and western blotting analyses were used to identify silymarin-induced apoptotic cell death in human pharynx squamous cell carcinoma (FaDu) cells. The short interfering RNA (siRNA) is used to confirm the role of phosphatase and tensin homolog (PTEN) in silymarin-induced apoptosis. Treatment of FaDu cells with silymarin resulted in a significant decrease in cell viability (up to 70%). Silymarin inhibited the phosphorylation of Akt (over 10-fold) with an increase in expression of PTEN (five to sixfold). Consequently, the level of Bcl-2 expression was decreased five to sixfold and caspase 3 activated to induce apoptosis. Treatment with siRNA specific to PTEN gene diminished the action of silymarin. The results suggest that silymarin inhibits the Akt signaling pathway by increasing PTEN expression in FaDu cells and directly affects Bcl-2 family members. Also, we demonstrated the inhibitory activity of silymarin for oral cancer is related to cell survival. These mechanisms may in part explain the actions of silymarin and provide a rationale for the development of silymarin as an anticancer agent.

Dual effects of silymarin on nasopharyngeal carcinoma cells (NPC-TW01)

BACKGROUND

Silymarin is an active component from the seeds of Silybum marianum and is widely used as a hepatic protection agent. Apoptosis induced by silymarin has been mentioned in cervical cancer cells. However, silymarin shows dual effects on tumor cells: cytostatic action at a low dose and cytotoxic action at higher dose. Thus, in the present study, we focused on low-dosing of silymarin in nasopharyngeal carcinoma cells, NPC-TW01 (TW01).

METHODS

Cell viability assay was used to screen the effect of silymarin in TW01 cells. Western blot analysis was used to identify the expressions of antioxidant enzymes and anti-/proapoptotic proteins. Fluorescent dyes are employed to detect the content of reactive oxygen species (ROS) and cell apoptosis.

RESULTS

Treatment of TW01 cells with silymarin at a low dose (80 µmol/l) resulted in a significant increase of antioxidant enzymes. Silymarin increased the expressions of superoxide dismutase 1, catalase, and glutathione peroxidase. Consequently, the cell apoptosis was reduced markedly. An increase of Bcl-2 expression and a decrease of activated caspase-3 or apoptosis-inducing factor (AIF) were observed in TW01 cells at a low dose (80 µmol/l) treatment.

CONCLUSION

Silymarin at a low dose can induce cytostatic effect on TW01 cells mainly through an increase of antioxidant-like action. Thus, silymarin should be applied carefully to patients with nasopharyngeal carcinoma.

Fungal profiles in various milk thistle botanicals from US retail

Milk thistle (MT) dietary supplements are widely consumed due to their possible beneficial effect on liver health. As botanicals, they can be contaminated with a variety of fungi and their secondary metabolites, mycotoxins. This study was conducted in an effort to determine the mycological quality of various MT botanical supplements from the US market. Conventional plating methods were used for the isolation and enumeration of fungi, while conventional microscopy as well as molecular methods were employed for the speciation of the isolated strains. Results showed that a high percentage of the MT samples tested were contaminated with fungi. Total counts ranged between <2.00 and 5.60 log10 colony forming units per gram (cfu/g). MT whole seeds carried the highest fungal levels followed by MT cut herb. No live fungi were recovered from MT seed tea bags, liquid extracts, capsules or soft gels. Potentially toxigenic molds from the Aspergillus sections Flavi and Nigri as well as Eurotium, Penicillium, Fusarium and Alternaria species were isolated from MT supplements. The predominant molds were Eurotia (E. repens, E. amstelodami and E. rubrum), A. flavus, A. tubingensis, A. niger and A. candidus. To our knowledge, this is the first study reporting on fungal contamination profiles of MT botanicals.

Hepatoprotection of 1β-hydroxyeuscaphic acid - the major constituent from Rubus aleaefolius against CCl4-induced injury in hepatocytes cells

CONTEXT

Rubus aleaefolius Poir. (Rosaceae) is used as a folk medicine to treat various types of hepatitis with significant effects in Fujian Province of China. The ethyl acetate fraction of R. aleaefolius root ethanol extract proved effective after our testing in vivo animal experiments.

OBJECTIVE

The protective effects of a major constituent, 1β-hydroxyeuscaphic acid isolated from R. aleaefolius was first investigated against carbon tetrachloride (CCl4)-induced injury in liver cells from hepatocytes cell line (BRL-3A).

MATERIALS AND METHODS

Treatment of BRL-3A with CCl4 led to generation of free radicals detected after a 2 h incubation and produced cell injury demonstrated by increased leakage of alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) in the media. Exposure to CCl4 caused apoptosis to cells but did not induce lipid peroxidation. Following treatment with 1β-hydroxyeuscaphic acid at doses ranging from 1 to 100 µg/mL for 24 h, cellular morphology, cell growth function (MTT assay), ALT, AST, malondialdehyde (MDA) and superoxide dismutase (SOD) were assessed and evaluated under control and exposed conditions.

RESULTS

The IC50 of 1β-hydroxyeuscaphic acid was 15 μg/mL. Exposure of injured BRL-3A at 20 μg/mL changed abnormal size, cellular shrinkage, and enhanced regulation. ALT, AST, MDA enzyme levels were reduced and SOD activity was increased.

DISCUSSION AND CONCLUSION

Treatment with 1β-hydroxyeuscaphic acid has significant hepatoprotective activity by lowering the leakage of intracellular enzymes, reducing the oxidation of proteins and decreasing the incidence of apoptosis. These results provide a basis for confirming the traditional uses of R. aleaefolius in treating hepatic diseases.

Free radical scavenging by natural polyphenols: atom versus electron transfer

Polyphenols (synthetically modified or directly provided by human diet) scavenge free radicals by H-atom transfer and may thus decrease noxious effects due to oxidative stress. Free radical scavenging by polyphenols has been widely theoretically studied from the thermodynamic point of view whereas the kinetic point of view has been much less addressed. The present study describes kinetic-based structure-activity relationship for quercetin. This compound is very characteristic of the wide flavonoid subclass of polyphenols. H-atom transfer is a mechanism based on either atom or electron transfer. This is analyzed here by quantum chemical calculations, which support the knowledge acquired from experimental studies. The competition between the different processes is discussed in terms of the nature of the prereaction complexes, the pH, the formation of activated-deprotonated forms, and the atom- and electron-transfer efficiency. The role of the catechol moiety and the 3-OH group of quercetin as scavengers of different types of free radicals (CH3OO(•), CH3O(•), (•)OH, and (•)CH2OH) is rationalized. Identifying the exact mechanism and accurately evaluating kinetics is of fundamental importance to understand antioxidant behavior in physiological environments.

A randomized double-blind, placebo-controlled study of therapeutic effects of silymarin in β-thalassemia major patients receiving desferrioxamine

OBJECTIVE

Thalassemia is one of the most common genetic disorders worldwide. Chronic blood transfusions treat the underlying anemia but may lead to iron toxicity. Effective iron chelation remains one of the main targets of clinical management of thalassemia major. In this study, iron-chelating activity of silymarin, a flavonolignan isolated from silybum marianum, was examined in β-thalassemia major.

METHODS

Patients were treated with the combination of desferrioxamine and silymarin (Legalon(®) ; n = 49) or desferrioxamine plus placebo (n = 48) for 9 months. The serum levels of ferritin, iron, total iron-binding capacity (TIBC), soluble transferrin receptor, and hepcidin were determined at the baseline and after 9-month therapy. Liver function test was performed before and after treatment in both groups.

RESULTS

Serum ferritin levels decreased significantly from the beginning to the end of silymarin treatment (3028.8 ± 2002.6 vs. 1972.2 ± 1250.6 ng/mL); however, no significant change in serum ferritin was observed in the patients receiving placebo (2249.0 ± 1304.2 vs. 2015.6 ± 1146.8). Moreover, serum iron and TIBC levels were significantly reduced in silymarin group compared with placebo. Patients on silymarin therapy also exhibited a significant decrease in serum levels of hepcidin and soluble transferrin receptor after 9-month treatment period. A significant improvement in liver function test was observed in silymarin group in comparison with placebo.

CONCLUSION

This study shows that silymarin is effective at reducing iron overload in patients when used in conjunction with desferrioxamine. Therapeutic effects of silymarin on a background of desferrioxamine suggest the potential effectiveness of silymarin alone in reducing body iron burden.

Antioxidant and Anti-Hepatitis C Viral Activities of Commercial Milk Thistle Food Supplements

Milk thistle dietary supplements that contain silymarin are widely marketed and used in the USA and other countries for liver enhancement and recovery. More recently, silymarin has also been identified as a possible antiviral for the treatment of hepatitis C virus (HCV) infection. To assess different brands of commercially sold silymarin, 45 products were collected from local stores and analyzed for their silymarin content, antioxidant activities, and antiviral activity against HCV. Antioxidant activity was measured as radical scavenging activity using DPPH and by estimating their antioxidant capacity as trolox equivalent. Anti-HCV activity was measured in an HCV genotype 1b replication inhibition assay. Samples were found to vary widely in their silymarin content, with some samples having none or very low concentrations while silymarin represented higher than 80% of other samples. Both antioxidant and anti-HCV activity correlated with the overall level of silymarin.

Milk thistle and its derivative compounds: a review of opportunities for treatment of liver disease

Milk thistle extracts have been used as a "liver tonic" for centuries. In recent years, silibinin, the active ingredient in milk thistle extracts, has been studied both in vitro and in vivo to evaluate the beneficial effects in hepatic disease. Silibinin increases antioxidant concentrations and improves outcomes in hepatic diseases resulting from oxidant injury. Silibinin treatment has been associated with protection against hepatic toxins, and also has resulted in decreased hepatic inflammation and fibrosis. Limited information currently is available regarding silibinin use in veterinary medicine. Future study is justified to evaluate dose, kinetics, and treatment effects in domestic animals.

Effects of single or repeated silymarin administration on pharmacokinetics of risperidone and its major metabolite, 9-hydroxyrisperidone in rats

1. The interactions between herbal dietary supplements and therapeutic drugs have emerged as an important issue and P-glycoprotein (P-gp) has been reported as one of the significant factors of these interactions. 2. The objective of this article is to examine the effects of single and repeated administrations of silymarin on pharmacokinetics of a P-gp substrate, risperidone, and its major metabolite, 9-hydroxyrisperidone, in rats. 3. To determine the plasma levels of risperidone and 9-hydroxyrisperidone in rats, a HPLC method was developed using a liquid-liquid acid back extraction. When risperidone (6 mg/kg) was co-administered with silymarin (40 mg/kg) to rats orally, the C(max) of 9-hydroxyrisperidone was significantly increased to1.3-fold (p < 0.05), while the other pharmacokinetic parameters did not show any significant differences. Expanding the experiment where rats were repeatedly administered with silymarin for 5 days prior to giving risperidone, the C(max) of risperidone and 9-hydroxyrisperidone were significantly increased to 2.4-fold (p < 0.001) and 1.7-fold (p < 0.001), respectively, and the AUC(0-t), as well to 1.7-fold (p < 0.05) and 2.1-fold (p < 0.01), respectively. 4. The repeated exposures of silymarin, compared to single administration of silymarin, increased oral bioavailability and affected the pharmacokinetics of risperidone and 9-hydroxyrisperidone, by inhibiting P-gp.

Apoptosis induction by OTA and TNF-α in cultured primary rat hepatocytes and prevention by silibinin

In cultures of primary rat hepatocytes, apoptosis occurred after application of 20 ng/mL tumor necrosis factor alpha (TNF-α). However, this was only in the presence of 200 ng/mL of the transcriptional inhibitor actinomycin D (ActD). This toxic effect was completely prevented in the presence of 25 µg/mL soluble TNF-α receptor I (sTNFR I) in the supernatant of hepatocyte cell cultures. Apoptosis also occurred after application of 12.5 µmol/L ochratoxin A (OTA). However, that was not prevented by up to 500 µg/mL sTNFR I, indicating that TNF-α/TNFR I is not involved in OTA mediated apoptosis in hepatocytes. The antioxidative flavanolignan silibinin in doses from 130 to 260 µmol/L prevented chromatin condensation, caspase-3 activation, and apoptotic DNA fragmentation that were induced by OTA, by 10 mmol/L hydrogen peroxide (H₂O₂) and by ultraviolet (UV-C) light (50 mJ/cm²), respectively. To achieve protection by silibinin, the drug was applied to the cell cultures for 2 h in advance. OTA stimulated lipid peroxidation on cultured immortalized rat liver HPCT cells, as was revealed by malondialdehyde (MDA) production. Lipid peroxidation occurred further by H₂O₂ and ActD/TNF-α incubation. These reactions were also suppressed by silibinin pretreatment. We conclude that the anti-apoptotic activity of silibinin against OTA, H₂O₂ and ActD/ TNF-α is caused in vitro by the antioxidative effects of the flavanolignan. Furthermore, cytotoxicity of the pro-apoptotic toxins was revealed by MTT-test. When applied separately, ActD and TNF-α showed no cytotoxic effects after 24 h, but were cytotoxic if applied in combination. The used concentrations of OTA, H₂O₂ and the dose of UV-C caused a substantial decrease in viability within 36 h that was prevented mostly by silibinin. We conclude that silibinin is a potent protective compound against apoptosis and cytotoxicity caused by OTA and the investigated compounds.

Evaluation of the Chinese Medicinal Herb, Graptopetalum paraguayense, as a Therapeutic Treatment for Liver Damage in Rat Models

The incidence of cirrhosis is rising due to the widespread occurrence of chronic hepatitis, as well as the evident lack of an established therapy for hepatic fibrosis. In the search for hepatoprotective therapeutic agents, Graptopetalum paraguayense (GP) showed greater cytotoxicity toward hepatic stellate cells than other tested herbal medicines. Histopathological and biochemical analyses suggest that GP treatment significantly prevented DMN-induced hepatic inflammation and fibrosis in rats. Microarray profiling indicated that expression of most of metabolism- and cell growth and/or maintenance-related genes recovered to near normal levels following GP treatment as classified by gene ontology and LSM analysis, was observed. ANOVA showed that expression of 64% of 256 liver damage-related genes recovered significantly after GP treatment. By examining rat liver samples with Q-RT-PCR, five liver damage-related genes were identified. Among them, Egr1 and Nrg1 may serve as necroinflammatory markers, and Btg2 may serve as a fibrosis marker. Oldr1 and Hmgcs1 were up- and down-regulated markers, respectively. A publicly accessible website has been established to provide access to these data Identification of 44 necroinflammation-related and 62 fibrosis-related genes provides useful insight into the molecular mechanisms underlying liver damage and provides potential targets for the rational development of therapeutic drugs such as GP.

Highlights on Anthocyanin Pigmentation and Copigmentation: A Matter of Flavonoid π-Stacking Complexation To Be Described by DFT-D

Anthocyanidins are a class of π-conjugated systems responsible for red, blue, and purple colors of plants. They exhibit the capacity of aggregation in the presence of other natural compounds including flavonols. Such complexations induce color modulation in plants, which is known as copigmentation. It is largely driven by π-interactions existing between pigments and copigments. In this work, the energies of copigmentation-complexation and self-association are systematically evaluated for an anthocyanidin/flavonol couple prototype (3-O-methylcyanidin/quercetin). To describe noncovalent interactions, DFT-D appears mandatory to reach a large accuracy. Due to the chemical complexity of this phenomenon, we also aim at assessing the relevance of both B3P86-D2 and ωB97X-D functionals. The benchmarking has shown that B3P86-D2 possesses enough accuracy when dealing with π-π interactions with respect to both spin component scaled Møller-Plesset second-order perturbation theory post Hartree-Fock method and experimental data. UV-vis absorption properties are then evaluated with time-dependent DFT for the different complexes. The use of range-separated hybrid functionals, such as ωB97X-D, helped to correctly disentangle and interpret the origin of the UV-vis experimental shifts attributed to the subtle copigmentation phenomenon.