Evaluation of the Neuroprotective Effect of Silymarin on Acrylamide-Induced Neurotoxicity

Protective effect of aspirin and gentisic acid, a plant-derived phenolic acid, on acrylamide-induced neurotoxicity by inhibiting apoptosis and autophagy

Acrylamide (ACR) is a toxic agent for humans and animals. Gentisic acid, an aspirin metabolite, has antioxidant activity. Therefore, the present study investigated the probable protective effects of aspirin and gentisic acid on ACR-induced neurotoxicity in PC12 cells and rats. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to assess the effects of aspirin and gentisic acid (1.25, 2.5, 5 µM) on ACR (5 mM) toxicity. Male Wistar rats were randomly divided into 13 groups: (1) Control group, (2) ACR (50 mg/kg, 11 days, i.p.), (3-5) ACR + aspirin (25, 50, 75 mg/kg, 11 days, p.o.), (6-8) ACR + gentisic acid (25, 50, 75 mg/kg, 11 days, p.o.), (9) ACR + vitamin E (200 mg/kg, every other day, i.p.), (10, 11) Aspirin (75, 100 mg/kg, 11 days, p.o.), (12, 13) Gentisic acid (75, 100 mg/kg, 11 days, p.o.). Behavioral tests were assessed on the final day of the study. In the cerebral cortex, malondialdehyde (MDA), glutathione (GSH), cleaved-caspase-3, and microtubule-associated protein 1A/1B-light chain 3 (LC3) protein levels were evaluated. When compared with the ACR group, aspirin (2.5, 5 µM) and gentisic acid (2.5 µM) significantly enhanced cell viability. In comparison to the control group, ACR induced severe motor impairment, elevated MDA, cleaved-caspase-3, LC3 II/I ratio, and decreased GSH levels in the cerebral cortex of rats. ACR-induced changes were significantly reversed by aspirin and gentisic acid (25 mg/kg). Oxidative stress, apoptosis, and autophagy play important roles in the neurotoxicity of ACR. Aspirin and gentisic acid significantly reduced ACR-induced toxicity by inhibiting the mentioned mechanisms.

Silymarin ameliorates motor function and averts neuroinflammation-induced cell death in the rat model of Huntington's disease

Huntington's disease (HD) is a scarce neurodegenerative disorder defined by chorea (unusual involuntary movements), behavioral presentations, psychiatric features, and cognitive deterioration. Although the precise pathogenic mechanism behind HD has not yet been identified, the most widely acknowledged pathways include excitotoxicity, mitochondrial malfunction, neuroinflammation, neurochemical imbalance, oxidative stress, and apoptosis HD has no efficient therapy. Current medications have drawbacks. Silymarin, a compound made up of standardized extracts obtained from the seeds of the Silybum marianum and polyphenolic flavonolignan, is utilized in therapeutic settings to treat a variety of experimental disorders in animals. Silymarin's key pharmacological activities include anti-cancer, hepatoprotection, antioxidant, cardioprotection, and anti-inflammatory. It also has no adverse side effects on people or animals. The current study aims to provide Silymarin's neuro-pharmacological activities or therapeutic qualities in HD. In this study, Thirty-six male Sprague-Dawley rats (200-220 g, 8 weeks) at the initial of the study were used. Silymarin solution (100 mg/Kg) was administered by oral gavage for 21 days to ameliorate neural damage in rats injected with 3-nitropropionicacid (3-NP) in a preliminary rat model of HD. The results showed that administration of silymarin to HD rats reduced gliosis, improved motor coordination and muscle activity, and increased striatal volume and the number of neurons and glial cells. Our results suggest that silymarin provides a protective environment for nerve cells and can have beneficial effects against the harmful effects of HD.

Silymarin pretreatment protects against ethanol-induced memory impairment: Biochemical and histopathological evidence

BACKGROUND

Ethanol (Eth.) abuse induces memory impairment. Oxidative damage and apoptosis are considered the likely causes of memory impairment. Silymarin (Sil.) is a flavonoid isolated from the plant Silymarin marianum (milk thistle). While studies have reported the neuroprotective effect of Sil. against neurodegenerative processes, the precise mechanism of action of Sil. in Eth.-induced memory impairment remains unclear.

METHODS

Twenty-eight rats were equally divided into four groups: Control (saline 1 ml/rat); Sil. (200 mg/kg for 30 days); Eth. (2 g/kg/day for 30 days); and Sil. + Eth. Behavioral tests including inhibitory avoidance and open field were used to investigate memory and locomotion. Brain antioxidant parameters, including catalase, superoxide dismutase, total antioxidant capacity and total thiol group, plus oxidative parameters, including malondialdehyde and total oxidant status, followed by hippocampal apoptosis (Bax/Bcl2, cleaved caspase) and histopathological changes were evaluated in the groups.

RESULTS

While the administration of Eth. impaired memory, Sil. significantly reversed Eth-induced memory deficits. Eth. administration also augmented brain oxidative and hippocampal apoptosis parameters. In contrast, a marked reduction in brain antioxidant and anti-apoptotic parameters was observed in the Eth. group. At the tissue level, hippocampal sections from Eth.-treated animals revealed severe neuronal damage. The administration of Sil. to Eth.-treated rats remarkably alleviated all the said Eth.-induced biochemical and histopathological effects. On the contrary, Sil. alone did not change the behavior and biochemical/molecular parameters.

CONCLUSION

The memory-enhancing effect of Sil. in Eth.-induced demented rats may be partly mediated by the augmented antioxidant effects and amelioration of apoptotic and histopathological changes.

Silymarin constrains diacetyl-prompted oxidative stress and neuroinflammation in rats: involvements of Dyn/GDNF and MAPK signaling pathway

Neuroinflammation, a major component of many CNS disorders, has been suggested to be associated with diacetyl (DA) exposure. DA is commonly used as a food flavoring additive and condiment. Lately, silymarin (Sily) has shown protective and therapeutic effects on neuronal inflammation. The study aimed to explore the role of Sily in protecting and/or treating DA-induced neuroinflammation. Neuroinflammation was induced in rats by administering DA (25 mg/kg) orally. Results revealed that Sily (50 mg/kg) obviously maintained cognitive and behavioral functions, alleviated brain antioxidant status, and inhibited microglial activation. Sily enhanced IL-10, GDNF and Dyn levels, reduced IFN-γ, TNFα, and IL-1β levels, and down-regulated the MAPK pathway. Immunohistochemical investigation of EGFR and GFAP declared that Sily could conserve neurons from inflammatory damage. However, with continuing DA exposure during Sily treatment, oxidative stress and neuroinflammation were less mitigated. These findings point to a novel mechanism involving the Dyn/GDNF and MAPK pathway through which Sily might prevent and treat DA-induced neuroinflammation.

Silibinin and Naringenin against Bisphenol A-Induced Neurotoxicity in Zebrafish Model-Potential Flavonoid Molecules for New Drug Design, Development, and Therapy for Neurological Disorders

Bisphenol A (BPA), a well-known xenoestrogen, is commonly utilised in the production of polycarbonate plastics. Based on the existing evidence, BPA is known to induce neurotoxicity and behavioural issues. Flavonoids such as silibinin and naringenin have been shown to have biological activity against a variety of illnesses. The current research evaluates the neuropharmacological effects of silibinin and naringenin in a zebrafish model against neurotoxicity and oxidative stress caused by Bisphenol A. In this study, a novel tank diving test (NTDT) and light−dark preference test (LDPT) were used in neurobehavioural investigations. The experimental protocol was planned to last 21 days. The neuroprotective effects of silibinin (10 μM) and naringenin (10 μM) in zebrafish (Danio rerio) induced by BPA (17.52 μM) were investigated. In the brine shrimp lethality assay, the 50% fatal concentrations (LC50) were 34.10 μg/mL (silibinin) and 91.33 μg/mL (naringenin) compared to the standard potassium dichromate (13.15 μg/mL). The acute toxicity investigation found no mortality or visible abnormalities in the silibinin- and naringenin-treated groups (LC50 > 100 mg/L). The altered scototaxis behaviour in LDPT caused by BPA was reversed by co-supplementation with silibinin and naringenin, as shown by decreases in the number of transitions to the light zone and the duration spent in the light zone. Our findings point to BPA’s neurotoxic potential in causing altered scototaxis and bottom-dwelling behaviour in zebrafish, as well as the usage of silibinin and naringenin as potential neuroprotectants.

Analysis of silymarin-modulating effects against acrylamide-induced cerebellar damage in male rats: Biochemical and pathological markers

BACKGROUND

Acrylamide (ACR) is a well-proven neurotoxin and potential food carcinogen in humans and rodent models. Silymarin (SIL) is a flavonoid mixture isolated from seeds, leaves, and fruits of Silymarin marianum (milk thistle) that possesses a free-radical scavenging effect.

OBJECTIVE

In this work, the primary focus was to investigate the efficacy of SIL to mitigate ACR-induced subacute neurotoxic effects and oxidative changes in rat cerebellum.

METHODS

Adult male rats were treated intraperitoneally with ACR (50 mg/kg) with or without SIL (160 mg/kg). The neuropathology and biochemical parameters viz. lipid peroxidation (measured as levels of malondialdehyde or MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), serotonin (5-hydroxytryptamine; 5-HT), dopamine (DA), and cathepsin D (CTSD) in the cerebellum have been evaluated.

RESULTS

The data showed that ACR induced redox disruptions as measured by increased MDA levels and inhibition of CAT, SOD, and GPx antioxidant enzyme activities. Besides, cerebellar monoamine neurotransmitters, 5-HT and DA, were depleted in ACR-treated rats. Furthermore, ACR administration caused a significant elevation of CTSD activity, indicating that ACR could trigger apoptosis or apoptosis-like death. At the tissue level, cerebellar cortex sections from ACR-treated animals were characterized by severe neuronal damage. The administration of SIL to ACR-treated rats remarkably alleviated all the aforementioned ACR-induced effects.

CONCLUSION

SIL has a potent therapeutic effect against ACR-induced cerebellar neurotoxicity in experimental rats via the attenuation of oxidative/antioxidative responses and the inhibition of CTSD-activity.

The Possible Neuroprotective Effect of Silymarin against Aluminum Chloride-Prompted Alzheimer's-Like Disease in Rats

Alzheimer's disease (AD) is a worldwide rapidly growing neurodegenerative disease. Here, we elucidated the neuroprotective effects of silymarin (SM) on the hippocampal tissues of aluminum chloride (AlCl3)-induced Alzheimer-like disease in rats using biochemical, histological, and ultrastructural approaches. Forty rats were divided into control, SM, AlCl3, and AlCl3 + SM groups. Biochemically, AlCl3 administration resulted in marked elevation in levels of lipid peroxidation (LPO) and nitric oxide (NO) and decrease in levels of reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). Moreover, AlCl3 significantly increased tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), and acetylcholinesterase (AChE) activities. Furthermore, myriad histological and ultrastructural alterations were recorded in the hippocampal tissues of AlCl3-treated rats represented as marked degenerative changes of pyramidal neurons, astrocytes, and oligodendrocytes. Additionally, some myelinated nerve fibers exhibited irregular arrangement of their myelin coats, while the others revealed focal degranulation of their myelin sheaths. Severe defects in the blood-brain barrier (BBB) were also recorded. However, co-administration of SM with AlCl3 reversed most of the biochemical, histological, and ultrastructural changes triggered by AlCl3 in rats. The results of the current study indicate that SM can potentially mend most of the previously evoked neuronal damage in the hippocampal tissues of AlCl3-kindled rats.

Milk thistle (Silybum Marianum) as an antidote or a protective agent against natural or chemical toxicities: a review

Biological and chemical agents cause dangerous effects on human health via different exposing ways. Recently, herbal medicine is considered as a biological and safe treatment for toxicities. Silybum marianum (milk thistle), belongs to the Asteraceae family, possesses different effects such as hepatoprotective, cardioprotective, neuroprotective, anti-inflammatory and anti-carcinogenic activities. Several studies have demonstrated that this plant has protective properties against toxic agents. Herein, the protective effects of S. marianum and its main component, silymarin, which is the mixture of flavonolignans including silibinin, silydianin and silychristin acts against different biological (mycotoxins, snake venoms, and bacterial toxins) and chemical (metals, fluoride, pesticides, cardiotoxic, neurotoxic, hepatotoxic, and nephrotoxic agents) poisons have been summarized. This review reveals that main protective effects of milk thistle and its components are attributed to radical scavenging, anti-oxidative, chelating, anti-apoptotic properties, and regulating the inflammatory responses.

Silymarin Ameliorates Acrylamide-Induced Hyperlipidemic Cardiomyopathy in Male Rats

Acrylamide (AA) is a well-known potent carcinogen and neurotoxin that has been recently linked to atherosclerotic pathogenesis. The present study is aimed at investigating the protective effect of silymarin (SIL) as an antioxidant against AA-induced hyperlipidemic cardiomyopathy in male rats. The obtained results showed that animals exposed to AA exhibited a significant increase in the levels of cardiac serum markers, serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol with a significant decrease in high-density lipoprotein cholesterol. Furthermore, AA intoxication significantly increased the malondialdehyde level (a hallmark of lipid peroxidation) and reduced antioxidant enzyme activities (i.e., superoxide dismutase, catalase, and glutathione peroxidase). SIL administration significantly attenuated all these biochemical perturbations in AA-treated rats, except for the decreased high-density lipoprotein cholesterol. Our results were confirmed by histopathological assessment of the myocardium. In conclusion, this study demonstrated a beneficial effect of SIL therapy in the prevention of AA-induced cardiotoxicity by reversing the redox stress and dyslipidemia in experimental animals.

Effects of silymarin on metabolic syndrome: a review

Metabolic syndrome is one of the rising global health problems and medical challenges due to several clinical complications it may cause, for example increasing the risk of myocardial infarction and hypertension. However, great attention has been directed toward determining the worthiness of herbal medicines. There are emerging studies on preventive and therapeutic effects of silymarin on different components of metabolic syndrome. Extracted from the dried seeds of milk thistle plant (Silybum marianum L.), silymarin has been used in the treatment of different diseases for many years. Several protective effects have been identified for this herb such as decreasing insulin resistance, regulating blood pressure and lipid profile, as well as antioxidant and cytoprotective effects. This review aims to discuss available human and experimental researches into the promising effects of silymarin on different elements of metabolic syndrome. All related human and experimental papers published from 2012 to date were included in this review. Reviewing different human and experimental studies into the effects of silymarin on metabolic syndrome, we deduced that silymarin possesses promising effects on different components of this syndrome. Although the complete mechanism of action and target organs for silymarin require further verification and investigation, high-risk individuals may benefit from supplementation with this herbal medicine. © 2018 Society of Chemical Industry.