Inhibiting NF-κB activation and ROS production are involved in the mechanism of silibinin's protection against D-galactose-induced senescence

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

The food plant Silybum marianum (L.) Gaertn.: Phytochemistry, Ethnopharmacology and clinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

Silybum marianum (L.) Gaertn. or Milk thistle is a medicinal plant native to Northern Africa, Southern Europe, Southern Russia and Anatolia. It also grows in South Australia, North and South America. In traditional knowledge, people have used S. marianum for liver disorders such as hepatitis, liver cirrhosis and gallbladder diseases. The main active compound of the plant seeds is silymarin, which is the most commonly used herbal supplement in the United States for liver problems. Nowadays, S. marianum products are available as capsules, powders, and extracts.

AIM OF STUDY

The aim of our study is to draw a more comprehensive overview of the traditional heritage, pharmacological benefits and chemical fingerprint of S. marianum extracts and metabolites; as well as their metabolism and bioavailability.

MATERIALS AND METHODS

An extensive literature search has been conducted using relavant keywords and papers with rationale methodology and robust data were selected and discussed. Studies involving S. marianum or its main active ingredients with regards to hepatoprotective, antidiabetic, cardiovascular protection, anticancer and antimicrobial activities as well as the clinical trials performed on the plant, were discussed here.

RESULTS

S. marianum was subjected to thousands of ethnopharmacological, experimental and clinical investigations. Although, the plant is available for use as a dietary supplement, the FDA did not yet approve its use for cancer therapy. Nowadays, clinical investigations are in progress where a global evidence of its real efficiency is needed.

CONCLUSION

S. marianum is a worldwide used herb with unlimited number of investigations focusing on its benefits and properties, however, little is known about its clinical efficiency. Moreover, few studies have discussed its metabolism, pharmacokinetics and bioavailability, so that all future studies on S. marianum should focus on such areas.

Cardioprotective Efficacy of Silymarin Liquisolid in Isoproterenol Prompted Myocardial Infarction in Rats

Myocardial infarction (MI) is the principal cause of death in many countries. Silymarin (SM) is a herbal antioxidant and can be efficiently used in preventing cardiovascular diseases (CVDs). The study is aimed to enhance the absorption rate and biological activity of SM by using liquisolids besides investigating the cardioprotective activity of SM and its selected liquisolid formula against isoproterenol prompted cardiotoxicity in rats. Eight formulae were prepared according to (2³) full-factorial design. The effect of viscosity increasing agent type and concentration, as well as the carrier/coat ratio on the dissolution rate and angle of repose were studied. All formulae were tested for content uniformity, micromeritic properties, dissolution performance besides the evaluation of its physicochemical properties, and scanning electron microscopy (SEM). Based on the factorial design outcomes, the highest desirability was obtained from F3 with excipient ratio value (R) of 20%, dissolution rate at Q_5 min of 26.9%, and angle of repose of 19. Oral administration of F3 liquisolid and SM revealed a significant protective efficacy against the modification of cardiac plasma markers, brain natriuretic peptide (BNP), interleukin-10 (IL-10), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)-β1 besides cardiac superoxide dismutase (SOD), malondialdehyde (MDA), and total protein kinase-1 (Akt-1) levels. Additionally, they minimized cardiac inducible nitric oxide synthase (iNOS), microRNA-34a (miR-34a), and p38 mitogen-activated protein kinase (p38-MAPK) levels. In conclusion, F3 liquisolid compact possessed an overall pronounced results over pure SM reckoned to its enhanced solubility and efficacy.

Silibinin attenuates adipose tissue inflammation and reverses obesity and its complications in diet-induced obesity model in mice

Background

Obesity is a multifactorial chronic disease that comprises several pathological events, such as adipose hypertrophy, fatty liver and insulin resistance. Inflammation is a key contributer to development of these events, and therefore, targeting inflammation is increasingly considered for management of obesity and its complications. The aim of the current study was to investigate therapeutic outcomes of anti-inflammatory activities of the natural compound Silibinin in reversing obesity and its complication in mice.

Methods

C57BL/6 male mice were fed high-fat diet for 8 weeks until development of obesity, and then injected with 50 mg/kg silibinin intraperitoneally twice per week, or vehicle for 8 weeks. Throughout the experiment, mice were continuously checked for body weight and food intake, and glucose tolerance test was performed toward the end of the experiment. Animals were sacrificed and serum and tissues were collected for biochemical, histological, and gene expression analysis to assess silibinin effects on adipose inflammation, fat accumulation, liver adipogenesis and glucose homeostasis.

Results

Silibinin treatment reversed adipose tissue inflammation and adipocyte hypertrophy, and blocked progression in weight gain and obesity development with no significant effects on rates of food intake. Silibinin also reversed fatty liver disease and restored glucose homeostasis in treated animals, and reversed hyperglycemia, hyperinsulinemia and hypertriglyceridemia.

Conclusion

In this study, we demonstrated that silibinin as an anti-inflammatory therapy is a potential alternative to manage obesity, as well as its related complications. Moreover, silibinin-based therapies could further evolve as a novel treatment to manage various inflammation-driven disorders.

Natural Compounds as Beneficial Antioxidant Agents in Neurodegenerative Disorders: A Focus on Alzheimer's Disease

The positive role of nutrition in chronic neurodegenerative diseases (NDs) suggests that dietary interventions represent helpful tools for preventing NDs. In particular, diets enriched with natural compounds have become an increasingly attractive, non-invasive, and inexpensive option to support a healthy brain and to potentially treat NDs. Bioactive compounds found in vegetables or microalgae possess special properties able to counteract oxidative stress, which is involved as a triggering factor in neurodegeneration. Here, we briefly review the relevant experimental data on curcuminoids, silymarin, chlorogenic acid, and compounds derived from the microalga Aphanizomenon flos aquae (AFA) which have been demonstrated to possess encouraging beneficial effects on neurodegeneration, in particular on Alzheimer's disease models.

Age‑associated variation in the expression and function of TMEM16A calcium‑activated chloride channels in the cochlear stria vascularis of guinea pigs

The present study was designed to investigate the expression and function of transmembrane protein 16 (TMEM16A), a calcium‑activated chloride channel (CaCC), in the stria vascularis (SV) of the cochlea of guinea pigs at different ages, and to understand the role of CaCCs in the pathogenesis of presbycusis (age‑related hearing loss), the most common type of sensorineural hearing loss that occurs with natural aging. Guinea pigs were divided into the following groups: 2 weeks (young group), 3 months (youth group), 1 year (adult group), D‑galactose intervention (D‑gal group; aging model induced by subcutaneous injection of D‑galactose) and T16Ainh‑A01 (intraperitoneal injection of 50 µg/kg/day TMEM16A inhibitor T16Ainh‑A01 for 2 weeks). Differences in the hearing of guinea pigs between the various age groups were analyzed using auditory brainstem response (ABR), and immunofluorescence staining was performed to detect TMEM16A expression in the SV and determine the distribution. Reverse transcription‑quantitative PCR and western blot analyses were conducted to detect the mRNA and protein levels of TMEM16A in SV in the different age groups. Morris water maze behavior analysis demonstrated that spatial learning ability and memory were damaged in the D‑gal group. Superoxide dismutase activity and malondialdehyde content assays indicated that there was oxidative stress damage in the D‑gal group. The ABR thresholds gradually increased with age, and the increase in the T16Ainh‑A01 group was pronounced. Immunofluorescence analysis in the cochlear SV of guinea pigs in different groups revealed that expression of TMEM16A increased with increasing age (2 weeks to 1 year); fluorescence intensity was reduced in the D‑gal model of aging. As the guinea pigs continued to mature, the protein and mRNA contents of TMEM16A in the cochlea SV increased gradually, but were decreased in the D‑gal group. The findings indicated that CaCCs in the cochlear SV of guinea pigs were associated with the development of hearing in guinea pigs, and that downregulation of TMEM16A may be associated with age‑associated hearing loss.

Natural silibinin modulates amyloid precursor protein processing and amyloid-β protein clearance in APP/PS1 mice

Silibinin has been shown to attenuate cognitive dysfunction and inhibit amyloid-beta (Aβ) aggregation in Alzheimer's disease (AD) models. However, the underlying mechanism by which silibinin improves cognition remains poorly understood. In this study, we investigated the effect of silibinin on β-secretase levels, Aβ enzymatic degradation, and oxidative stress in the brains of APP/PS1 mice with cognitive impairments. Oral administration of silibinin for 2 months significantly attenuated the cognitive deficits of APP/PS1 mice in the Y-maze test, novel object recognition test, and Morris water maze test. Biochemical analyses revealed that silibinin decreased Aβ deposition and the levels of soluble Aβ1-40/1-42 in the hippocampus by downregulating APP and BACE1 and upregulating NEP in APP/PS1 mice. In addition, silibinin decreased the MDA content and increased the activities of the antioxidant enzymes CAT, SOD, and NO. Based on our findings, silibinin is a potentially promising agent for preventing AD-associated Aβ pathology.

Silibinin Alleviates the Learning and Memory Defects in Overtrained Rats Accompanying Reduced Neuronal Apoptosis and Senescence

Excessive physical exercise (overtraining; OT) increases oxidative stress and induces damage in multiple organs including the brain, especially the hippocampus that plays an important role in learning and memory. Silibinin, a natural flavonoid derived from milk thistle of Silybum marianum, has been reported to exert neuroprotective effect. In this study, rats were subjected to overtraining exercise, and the protective effects of silibinin were investigated in these models. Morris water maze and novel object recognition tests showed that silibinin significantly attenuated memory defects in overtrained rats. At the same time, the results of Nissl, TUNEL and SA-β-gal staining showed that silibinin reversed neuronal loss caused by apoptosis, and delayed cell senescence of the hippocampus in the overtrained rats, respectively. In addition, silibinin decreased malondialdehyde (MDA) levels which is associated with reactive oxygen species (ROS) generation. Silibinin prevented impairment of learning and memory caused by excessive physical exercise in rats, accompanied by reduced apoptosis and senescence in hippocampus cells.

Molecular and biochemical evidence on the protective role of ellagic acid and silybin against oxidative stress-induced cellular aging

Aging is a natural process in living organisms that is defined by some molecular and cellular changes with time. Various causes such as mitochondrial DNA aberrations, aggregation of proteins, telomere shortening, and oxidative stress have an influential role in aging of the cells. Natural antioxidants are compounds that are potent to protect the body from detrimental effects of molecules such as free radicals. The aim of this study was to evaluate the anti-aging properties of ellagic acid (EA) and silybin (SIL), as natural antioxidant compounds on rat embryonic fibroblast (REF) cells. These cells were pre-incubated with EA and SIL, thereafter were exposed to hydrogen peroxide (H2O2). Then, the cell viability, SA-β-GAL activity, distribution of cell cycle, NF-κB, and mitochondrial complex I, II/IV enzyme activity were measured. The results of this study revealed the protective effects of EA and SIL in H2O2-treated REF cells, which confirm the previous achieved data on antioxidant and anti-inflammatory characteristics of EA and SIL against H2O2 in the treated REF cells. However, more new in vivo experiments are required to discover the anti-aging effects and mechanism of action of such compounds.

Effects of Resveratrol and other Polyphenols on Sirt1: Relevance to Brain Function During Aging

BACKGROUND

Classically the oxidative stress and more recently inflammatory processes have been identified as the major causes of brain aging. Oxidative stress and inflammation affect each other, but there is more information about the effects of oxidative stress on aging than regarding the contribution of inflammation on it.

METHODS

In the intense research for methods to delay or mitigate the effects of aging, are interesting polyphenols, natural molecules synthesized by plants (e.g. resveratrol). Their antioxidant and anti-inflammatory properties make them useful molecules in the prevention of aging.

RESULTS

The antiaging effects of polyphenols could be due to several related mechanisms, among which are the prevention of oxidative stress, SIRT1 activation and inflammaging modulation, via regulation of some signaling pathways, such as NF-κB.

CONCLUSION

In this review, we describe the positive effects of polyphenols on the prevention of the changes that occur during aging in the brain and their consequences on cognition, emphasizing the possible modulation of inflammaging by polyphenols through a SIRT1-mediated mechanism.

Onjisaponin B prevents cognitive impairment in a rat model of D-galactose-induced aging

In this study, we investigated the potential effect of onjisaponin B (OB) on aging rats induced by D-gal (D-galactose). Sub-acute aging model was established in rats by the subcutaneous injection of D-gal (120 mg/kg) for 42 days, accompanied with OB (10, 20 mg/kg, p.o.) or normal saline intervention for 28 days since the 14th day after the beginning of D-gal stimulation. Morris water maze test and step-down passive avoidance test were conducted to evaluate the cognitive function of the rats. The superoxidase dismutase (SOD), malondialdehyde (MDA), glutathione (GSH) and glutathione peroxidase (GSH-px) contents in hippocampus were measured by according kits, respectively. And the hippocampus levels of inflammatory mediators including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were assayed by enzyme-linked immunosorbent assay (ELISA). Furthermore, the expressions of SOD1, MDA5, GSH, GSH-px, NF-кB pathway were present by western blot. It revealed that administration of OB was able to significantly attenuate the D-gal-induced changes in the hippocampus, ranging from cognitive capacity, oxidative stress to inflammation response. In a nutshell, our data provided evidence that OB could contribute to the restoration of cognitive ability by improving the antioxidant and anti-inflammatory capacity in D-gal induced aging rats.

Enhanced migration of murine fibroblast-like 3T3-L1 preadipocytes on type I collagen-coated dish is reversed by silibinin treatment

Migration of fibroblast-like preadipocytes is important for the development of adipose tissue, whereas excessive migration is often responsible for impaired adipose tissue related with obesity and fibrotic diseases. Type I collagen (collagen I) is the most abundant component of extracellular matrix and has been shown to regulate fibroblast migration in vitro, but its role in adipose tissue is not known. Silibinin is a bioactive natural flavonoid with antioxidant and antimetastasis activities. In this study, we found that type I collagen coating promoted the proliferation and migration of murine 3T3-L1 preadipocytes in a dose-dependent manner, implying that collagen I could be an extracellular signal. Regarding the mechanisms of collagen I-stimulated 3T3-L1 migration, we found that NF-κB p65 is activated, including the increased nuclear translocation of NF-κB p65 as well as the upregulation of NF-κB p65 phosphorylation and acetylation, accompanied by the increased expressions of proinflammatory factors and the generation of reactive oxygen species (ROS). Reduction of collagen I-enhanced migration of cells by treatment with silibinin was associated with suppression of NF-κB p65 activity and ROS generation, and negatively correlated with the increasing sirt1 expression. Taken together, the enhanced migration of 3T3-L1 cells induced on collagen I-coated dish is mediated by the activation of NF-κB p65 function and ROS generation that can be alleviated with silibinin by upregulation of sirt1, leading to the repression of NF-κB p65 function and ROS generation.

Melatonin-mediated upregulation of GLUT1 blocks exit from pluripotency by increasing the uptake of oxidized vitamin C in mouse embryonic stem cells

Melatonin and vitamin C are powerful antioxidants that improve the reprogramming efficiency of induced pluripotent stem cells (iPSCs). However, the effects of the combined treatment of vitamin C and melatonin on the differentiation of embryonic stem cells (ESCs) have not yet been examined. In this study, we showed that melatonin synergizes with vitamin C to derail exit from pluripotency of mouse ESCs. This effect is related to the increased uptake of dehydroascorbate, the oxidized form of vitamin C, through glucose transporter 1 (Glut1) transporter, which in turn, is upregulated by melatonin treatment. Analysis of the cell signaling pathway profiling systems and specific pathway inhibition indicated that melatonin enhances Glut1 expression by activating the PI3K/AKT and MAPK/ERK signaling pathways. Our findings provide a theoretical basis for application of melatonin in research on ESCs and iPSCs and for further investigation of the effect of combinatorial compounds on cell reprogramming.-Wu, H., Song, C., Zhang, J., Zhao, J., Fu, B., Mao, T., Zhang, Y. Melatonin-mediated upregulation of GLUT1 blocks exit from pluripotency by increasing the uptake of oxidized vitamin C in mouse embryonic stem cells.

Silibinin ameliorates Aβ25-35-induced memory deficits in rats by modulating autophagy and attenuating neuroinflammation as well as oxidative stress

Alzheimer's disease (AD) is a progressive, neurodegenerative disease. Accumulating evidence suggests that inflammatory response, oxidative stress and autophagy are involved in amyloid β (Aβ)-induced memory deficits. Silibinin (silybin), a flavonoid derived from the herb milk thistle, is well known for its hepatoprotective activities. In this study, we investigated the neuroprotective effect of silibinin on Aβ_25-35-injected rats. Results demonstrated that silibinin significantly attenuated Aβ_25-35-induced memory deficits in Morris water maze and novel object-recognition tests. Silibinin exerted anxiolytic effect in Aβ_25-35-injected rats as determined in elevated plus maze test. Silibinin attenuated the inflammatory responses, increased glutathione (GSH) levels and decreased malondialdehyde (MDA) levels, and upregulated autophagy levels in the Aβ_25-35-injected rats. In conclusion, silibinin is a potential candidate for AD treatment because of its anti-inflammatory, antioxidant and autophagy regulating activities.

Wound Healing Activity of Silibinin in Mice

BACKGROUND

Silibinin is a semi-purified fraction of silymarin contained in milk thistle (Silybum marianum Asteraceae). Primarily known for its hepatoprotective actions, silymarin may also stimulate epithelialization and reduce inflammation in excision wound. Previous studies show antioxidant, anti-inflammatory, and antimicrobial actions of silibinin. However, wound healing property of silibinin is not well studied.

OBJECTIVE

This study investigates wound healing activity of silibinin topical formulation.

MATERIALS AND METHODS

Wound healing activity of 0.2% silibinin gel was assessed by incision and excision wound models in mice. Animals were divided into gel base, silibinin gel, and Mega Heal gel® treated groups with six animals in each group. Wound contraction, wound tissue tensile strength, and hydroxyproline content were measured, and histopathological evaluation of wound tissue of all the above treatment groups was carried out.

RESULTS

Application of 0.2% silibinin hydrogel for 8 days led to 56.3% wound contraction compared to 64.6% using standard Mega Heal gel with a subsequent increase in hydroxyproline content, which was significantly higher (P < 0.001) over control animals showing 33.2% contraction. After 14 days, percentage of contraction reached 96.1%, 97.6%, and 86.7%, respectively. Wound tissue tensile strength with silibinin (223.55 ± 3.82 g) and standard (241.38 ± 2.49 g) was significantly higher (P < 0.001) than control (174.06 ± 5.75 g). Histopathology of silibinin and standard gel treated wound tissue showed more fibroblasts, fewer macrophage infiltration, and well-formed collagen fibers.

CONCLUSION

Here, we show potent wound healing activity of silibinin hydrogel formulation.

SUMMARY

0.2% silibinin hydrogel showed potent wound healing activity in incision and excision wound models in mice. Abbreviations Used: ROS: Reactive oxygen species.

Effect of silibinin and vitamin E on the ASK1-p38 MAPK pathway in D-galactosamine/lipopolysaccharide induced hepatotoxicity

Apoptosis signal-regulating kinase 1 (ASK1), a redox-sensor mitogen-activated protein kinase kinase kinase (MAPKKK) that activates p38 MAPK pathways in oxidative stress-induced hepatotoxicity in D-galactosamine/lipopolysaccharide (D-GalN/LPS) model, is a key central pathway in which specific targeting of ASK1 deactivation is of a great therapeutic potential. We tested the effect of silibinin and vitamin E in curative and prophylactic manner of treatment on the negative modulators of ASK1, thioredoxin1 (Trx1), thioredoxin reductase1 (TrxR1), and the protein phosphatase (PP5), whereas they have previously proven to have hepatoprotective effect. Either curative or prophylactic silibinin and vitamin E groups significantly decreased ASK1 and p38 MAPK levels through increasing the gene expression of Trx1, TrxR1, and PP5 to reduce the oxidative stress as demonstrated by decreasing the levels of NADPH oxidase 4 (NOX4), TBARS and conjugated diene with a concomitant increase in the levels of GSH, CAT, and SOD. These results were confirmed by histopathology examination which illustrated progressive degenerative changes of hepatocytes such as hydropic degeneration, vacuolation, pyknosis, karyolysis, and loss of architecture of some cells in D-GalN/LPS treatment, and these features were alleviated with silibinin and vitamin E administration. In conclusion, silibinin and vitamin E decreased ASK1-p38 MAPK pathway through deactivating the upstream signalling ASK1 molecule via increasing the levels of Trx1 and TrxR1 as well as the PP5 to alleviate in D-GalN/LPS induced hepatotoxicity.

Protective effect of centella triterpene saponins against cyclophosphamide-induced immune and hepatic system dysfunction in rats: its possible mechanisms of action

This study was designed to investigate the protective effects of the centella triterpene saponins (EXT) on cyclophosphamide (CYP)-induced hepatotoxicity and immunosuppression in rats. The phytochemical profile of EXT was analyzed for centella saponins by using high-performance liquid chromatographic (HPLC). Therapeutic efficacy of EXT (250 mg/kg/day p.o) on hematological profile of blood, liver function markers, and cytokine profiles in CYP (10 mg/kg/day p.o)-treated rats. In addition, weights of immune organs (spleen and thymus) and histopathological changes in the liver, intestine, and spleen were also evaluated. The active principles in EXT were identified as madecassoside, asiaticoside, and asiatic acid by HPLC analysis. Upon administration of EXT, enhanced levels of glutamate pyruvate transaminase, alkaline phosphatase, and lipid peroxidation were found reduced while the levels of reduced glutathione and hematological parameters and relative weights of immune organs were restored to normal in CYP-treated rats. The hepatic mRNA level of TNF-α, which was increased during CYP administration, was significantly decreased by the EXT treatment. The decreased levels of mRNA expression of other cytokines like IFN-γ, IL-2, GM-CSF, after CYP treatment, were also found elevated upon administration of the EXT. Histopathological examination of the intestine, liver, and spleen indicated that the extract could attenuate the CYP-induced hepatic and immune organ damage. These results indicated that EXT modulated the immune and hepatic system function of rats against CYP-induced immunosuppression and hepatotoxicity by restoring the cytokine production, antioxidant system, and multiorgan injury. Thus, triterpene saponins may provide protective and/or therapeutic alternative against the immune-mediated liver diseases.

Silymarin as a Natural Antioxidant: An Overview of the Current Evidence and Perspectives

Silymarin (SM), an extract from the Silybum marianum (milk thistle) plant containing various flavonolignans (with silybin being the major one), has received a tremendous amount of attention over the last decade as a herbal remedy for liver treatment. In many cases, the antioxidant properties of SM are considered to be responsible for its protective actions. Possible antioxidant mechanisms of SM are evaluated in this review. (1) Direct scavenging free radicals and chelating free Fe and Cu are mainly effective in the gut. (2) Preventing free radical formation by inhibiting specific ROS-producing enzymes, or improving an integrity of mitochondria in stress conditions, are of great importance. (3) Maintaining an optimal redox balance in the cell by activating a range of antioxidant enzymes and non-enzymatic antioxidants, mainly via Nrf2 activation is probably the main driving force of antioxidant (AO)  action of SM. (4) Decreasing inflammatory responses by inhibiting NF-κB pathways is an emerging mechanism of SM protective effects in liver toxicity and various liver diseases. (5) Activating vitagenes, responsible for synthesis of protective molecules, including heat shock proteins (HSPs), thioredoxin and sirtuins and providing additional protection in stress conditions deserves more attention. (6) Affecting the microenvironment of the gut, including SM-bacteria interactions, awaits future investigations. (7) In animal nutrition and disease prevention strategy, SM alone, or in combination with other hepatho-active compounds (carnitine, betaine, vitamin B₁₂, etc.), might have similar hepatoprotective effects as described in human nutrition.

Silibinin ameliorates LPS-induced memory deficits in experimental animals

Neuroinflammation is considered as one of the predisposing factor in the etiology of several neurodegenerative disorders. Therefore, the objective of the present study was to evaluate the protective effect of silibinin (SIL) in the lipopolysaccharide (LPS)-induced neuroinflammatory model. The effect of SIL on memory function was also evaluated on normal rats without LPS administration. In the first experiment, male rats were divided into five groups. Except control group animals, all rats received bilateral intracerebroventricular injection of LPS (5 μg/5 μl) into lateral ventricles on the first day of the experimental schedule. Control rats received bilateral intracerebroventricular injection of artificial cerebrospinal fluid into lateral ventricles. SIL in doses of 50, 100 and 200 mg/kg, p.o. was administered 1h before LPS injection and continued for 7 days. On Day-7, SIL attenuated the LPS-induced long-term and working memory loss in elevated plus and Y-maze test respectively. Further, SIL dose-dependently attenuated LPS-induced decrease in acetylcholine level and increase in the acetylcholinestrase activity in hippocampus and pre-frontal cortex. SIL ameliorated LPS-induced decrease in the mitochondrial complex activity (I, IV and V) and integrity, increase in lipid peroxidation and decrease in the activity of superoxide dismutase in both the brain regions. SIL attenuated amyloidogenesis in the hippocampus, while it decreased the LPS-induced increase in the level of NFκB in the pre-frontal cortex. In another study, SIL dose-dependently, enhanced memory functions in the normal rats, indicating its nootropic activity. Hence, SIL could be a potential candidate in the management of neuroinflammation-related memory disorders.

Melatonin regulates mesenchymal stem cell differentiation: a review

Among the numerous functions of melatonin, the control of survival and differentiation of mesenchymal stem cells (MSCs) has been recently proposed. MSCs are a heterogeneous population of multipotent elements resident in tissues such as bone marrow, muscle, and adipose tissue, which are primarily involved in developmental and regeneration processes, gaining thus increasing interest for tissue repair and restoration therapeutic protocols. Receptor-dependent and receptor-independent responses to melatonin are suggested to occur in these cells. These involve antioxidant or redox-dependent functions of this indolamine as well as secondary effects resulting from autocrine and paracrine responses. Inflammatory cytokines and adipokines, proangiogenic/mitogenic stimuli, and other mediators that influence the differentiation processes may affect the survival and functional integrity of these mesenchymal precursor cells. In this scenario, melatonin seems to regulate signaling pathways that drive commitment and differentiation of MSC into osteogenic, chondrogenic, adipogenic, or myogenic lineages. Common pathways suggested to be involved as master regulators of these processes are the Wnt/β-catenin pathway, the MAPKs and the, TGF-β signaling. In this respect melatonin emerges a novel and potential modulator of MSC lineage commitment and adipogenic differentiation. These and other aspects of the physiological and pharmacological effects of melatonin as regulator of MSC are discussed in this review.

Effect of silibinin in reducing inflammatory pathways in in vitro and in vivo models of infection-induced preterm birth

Infection-induced preterm birth is the largest cause of infant death and of neurological disabilities in survivors. Silibinin, from milk thistle, exerts potent anti-inflammatory activities in non-gestational tissues. The aims of this study were to determine the effect of silibinin on pro-inflammatory mediators in (i) human fetal membranes and myometrium treated with bacterial endotoxin lipopolysaccharide (LPS) or the pro-inflammatory cytokine IL-1β, and (ii) in preterm fetal membranes with active infection. The effect of silibinin on infection induced inflammation and brain injury in pregnant mice was also assessed. Fetal membranes and myometrium (tissue explants and primary cells) were treated with 200 μM silibinin in the presence or absence of 10 μg/ml LPS or 1 ng/ml IL-1β. C57BL/6 mice were injected with 70 mg/kg silibinin with or without 50 μg LPS on embryonic day 16. Fetal brains were collected after 6 h. In human fetal membranes, silibinin significantly decreased LPS-stimulated expression of IL-6 and IL-8, COX-2, and prostaglandins PGE2 and PGF2α. In primary amnion and myometrial cells, silibinin also decreased IL-1β-induced MMP-9 expression. Preterm fetal membranes with active infection treated with silibinin showed a decrease in IL-6, IL-8 and MMP-9 expression. Fetal brains from mice treated with silibinin showed a significant decrease in LPS-induced IL-8 and ninjurin, a marker of brain injury. Our study demonstrates that silibinin can reduce infection and inflammation-induced pro-labour mediators in human fetal membranes and myometrium. Excitingly, the in vivo results indicate a protective effect of silibinin on infection-induced brain injury in a mouse model of preterm birth.

Saponins from Aralia taibaiensis attenuate D-galactose-induced aging in rats by activating FOXO3a and Nrf2 pathways

Reactive oxygen species (ROS) are closely related to the aging process. In our previous studies, we found that the saponins from Aralia taibaiensis have potent antioxidant activity, suggesting the potential protective activity on the aging. However, the protective effect of the saponins and the possible underlying molecular mechanism remain unknown. In the present study, we employed a D-galactose-induced aging rat model to investigate the protective effect of the saponins. We found that D-galactose treatment induced obvious aging-related changes such as the decreased thymus and spleen coefficients, the increased advanced glycation end products (AGEs) level, senescence-associated β-galactosidase (SAβ-gal) activity, and malondialdehyde (MDA) level. Further results showed that Forkhead box O3a (FOXO3a), nuclear factor-erythroid 2-related factor 2 (Nrf2), and their targeted antioxidants such as superoxide dismutase 2 (SOD2), catalase (CAT), glutathione reductase (GR), glutathione (GSH), glutamate-cysteine ligase (GCL), and heme oxygenase 1 (HO-1) were all inhibited in the aging rats induced by D-galactose treatment. Saponins supplementation showed effective protection on these changes. These results demonstrate that saponins from Aralia taibaiensis attenuate the D-galactose-induced rat aging. By activating FOXO3a and Nrf2 pathways, saponins increase their downstream multiple antioxidants expression and function, at least in part contributing to the protection on the D-galactose-induced aging in rats.

Xanthoceraside attenuates tau hyperphosphorylation and cognitive deficits in intracerebroventricular-streptozotocin injected rats

RATIONALE

Xanthoceraside, a novel triterpenoid saponin extracted from the fruit husks of Xanthoceras sorbifolia Bunge, reverses cognitive deficits in intracerebroventricular injection of Aβ25-35 or Aβ1-42 mice. However, whether xanthoceraside has a positive effect on hyperphosphorylated tau protein remains unclear.

OBJECTIVES

We investigated the effects of xanthoceraside on behavioural impairments induced by intracerebroventricular injection of streptozotocin (STZ) in rats and its potential mechanisms.

MATERIALS AND METHODS

The rats were administered with xanthoceraside (0.06, 0.12 or 0.24 mg/kg) or vehicle once daily after STZ intracerebroventricular injections. The Y-maze test and novel object recognition test were performed 21 and 22 days after the second STZ injection, respectively. The levels of hyperphosphorylated tau, phosphatidylinositol-3-kinase (PI3K)/serine/threonine protein kinase B (Akt), glycogen synthase kinase-3β (GSK-3β), protein phosphatase 1 (PP-1) and protein phosphatase 2A (PP-2A) were also tested by Western blot.

RESULTS

Xanthoceraside treatment significantly attenuated learning and memory impairments and reduced the level of STZ-induced hyperphosphorylated tau protein. Xanthoceraside also enhanced PP-2A and PP-1 expressions, increased PI3K (p85) and Akt (Ser473) phosphorylation and decreased GSK-3β (tyr216) phosphorylation.

CONCLUSIONS

Xanthoceraside has protective effect against learning and memory impairments and inhibits tau hyperphosphorylation in the hippocampus, possibly through the inhibition of the PI3K/Akt-dependent GSK-3β signalling pathway and an enhancement of phosphatases activity.

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.

Sparstolonin B inhibits pro-angiogenic functions and blocks cell cycle progression in endothelial cells

Sparstolonin B (SsnB) is a novel bioactive compound isolated from Sparganium stoloniferum, an herb historically used in Traditional Chinese Medicine as an anti-tumor agent. Angiogenesis, the process of new capillary formation from existing blood vessels, is dysregulated in many pathological disorders, including diabetic retinopathy, tumor growth, and atherosclerosis. In functional assays, SsnB inhibited endothelial cell tube formation (Matrigel method) and cell migration (Transwell method) in a dose-dependent manner. Microarray experiments with human umbilical vein endothelial cells (HUVECs) and human coronary artery endothelial cells (HCAECs) demonstrated differential expression of several hundred genes in response to SsnB exposure (916 and 356 genes, respectively, with fold change ≥2, p<0.05, unpaired t-test). Microarray data from both cell types showed significant overlap, including genes associated with cell proliferation and cell cycle. Flow cytometric cell cycle analysis of HUVECs treated with SsnB showed an increase of cells in the G1 phase and a decrease of cells in the S phase. Cyclin E2 (CCNE2) and Cell division cycle 6 (CDC6) are regulatory proteins that control cell cycle progression through the G1/S checkpoint. Both CCNE2 and CDC6 were downregulated in the microarray data. Real Time quantitative PCR confirmed that gene expression of CCNE2 and CDC6 in HUVECs was downregulated after SsnB exposure, to 64% and 35% of controls, respectively. The data suggest that SsnB may exert its anti-angiogenic properties in part by downregulating CCNE2 and CDC6, halting progression through the G1/S checkpoint. In the chick chorioallantoic membrane (CAM) assay, SsnB caused significant reduction in capillary length and branching number relative to the vehicle control group. Overall, SsnB caused a significant reduction in angiogenesis (ANOVA, p<0.05), demonstrating its ex vivo efficacy.

Wnt/β-catenin signaling induces the aging of mesenchymal stem cells through promoting the ROS production

Recent studies have demonstrated that the Wnt/β-catenin signaling plays an important role in stem cell aging. However, the mechanisms of cell senescence induced by Wnt/β-catenin signaling are still poorly understood. Our preliminary study has indicated that activated Wnt/β-catenin signaling can induce MSC aging. In this study, we reported that the Wnt/β-catenin signaling was a potent activator of reactive oxygen species (ROS) generation in MSCs. After scavenging ROS with N-acetylcysteine, Wnt/β-catenin signaling-induced MSC aging was significantly attenuated and the DNA damage and the expression of p16(INK4A), p53, and p21 were reduced in MSCs. These results indicated that the Wnt/β-catenin signaling could induce MSC aging through promoting the intracellular production of ROS, and ROS may be the main mediators of MSC aging induced by excessive activation of Wnt/β-catenin signaling.

Molecular mechanisms for anti-aging by natural dietary compounds

Aging is defined as a normal decline in survival with advancing age; however, the recent researches have showed that physiological functions of the body change during the aging process. Majority of the changes are often subject to a higher risk of developing diseases, such as cardiovascular disease, type II diabetes, Alzheimer's disease, Parkinson's disease, as well as the dysregulated immune and inflammatory disorders. Aging process is controlled by a complicated and precise signaling network that involved in energy homeostasis, cellular metabolism and stress resistance. Over the past few decades, research in natural dietary compounds by various organism and animal models provides a new strategy for anti-aging. Natural dietary compounds act through a variety mechanisms to extend lifespan and prevent age-related diseases. This review summarizes the current understanding on signaling pathways of aging and knowledge and underlying mechanism of natural dietary compounds that provide potential application on anti-aging and improve heath in human.

Role of ROS in the protective effect of silibinin on sodium nitroprusside-induced apoptosis in rat pheochromocytoma PC12 cells

Silibinin mostly has been used as hepatoprotectants, but it has other interesting activities, e.g. anti-cancer, cardial protective and brain-protective activities. A previous study demonstrated that silibinin protected amyloid β (Aβ)-induced mouse cognitive disorder by behavioural pharmacological observation. This study assessed the effect of silibinin on sodium nitroprusside (SNP)-treated rat pheochromocytoma PC12 cells. Subsequent morphologic observation, flow cytometric analysis and Western blot analysis indicated that treatment with SNP significantly induced apoptosis in PC12 cells. However, silibinin eliminated the apoptotic effect by reactive oxygen species (ROS) generation, especially hydroxyl free radical. Silibinin-induced autophagy through ROS generation when exerting a protective effect and silibinin-induced autophagy also enhanced the ROS generation since 3-methyladenine (3-MA), a specific autophagy inhibitor, decreased the ROS generation and rapamycin, an autophagy inducer, enhanced the ROS generation. Therefore, there exists a positive feedback loop between autophagy and ROS generation. Autophagy prevented SNP-induced apoptosis, since the addition of 3-MA significantly eliminated the protective effect of silibinin. This protective effect was attributed to the generation of ROS and its two downstream Ras/PI3K/NF-κB and Ras/Raf/MEK/ERK pathways. Both prevented PC12 cells from apoptosis. The PI3K/NF-κB pathway induced autophagy to protect PC12 cells, but the Raf/MEK/ERK pathway directly protected PC12 cells bypassing the autophagic effect.