The effect of silymarin on mesenteric ischemia-reperfusion injury

Role of Silymarin in Cancer Treatment: Facts, Hypotheses, and Questions

The flavonoid silymarin extracted from the seeds of Sylibum marianum is a mixture of 6 flavolignan isomers. The 3 more important isomers are silybin (or silibinin), silydianin, and silychristin. Silybin is functionally the most active of these compounds. This group of flavonoids has been extensively studied and they have been used as hepato-protective substances for the mushroom Amanita phalloides intoxication and mainly chronic liver diseases such as alcoholic cirrhosis and nonalcoholic fatty liver. Hepatitis C progression is not, or slightly, modified by silymarin. Recently, it has also been proposed for SARS COVID-19 infection therapy. The biochemical and molecular mechanisms of action of these substances in cancer are subjects of ongoing research. Paradoxically, many of its identified actions such as antioxidant, promoter of ribosomal synthesis, and mitochondrial membrane stabilization, may seem protumoral at first sight, however, silymarin compounds have clear anticancer effects. Some of them are: decreasing migration through multiple targeting, decreasing hypoxia inducible factor-1α expression, inducing apoptosis in some malignant cells, and inhibiting promitotic signaling among others. Interestingly, the antitumoral activity of silymarin compounds is limited to malignant cells while the nonmalignant cells seem not to be affected. Furthermore, there is a long history of silymarin use in human diseases without toxicity after prolonged administration. The ample distribution and easy accessibility to milk thistle-the source of silymarin compounds, its over the counter availability, the fact that it is a weed, some controversial issues regarding bioavailability, and being a nutraceutical rather than a drug, has somehow led medical professionals to view its anticancer effects with skepticism. This is a fundamental reason why it never achieved bedside status in cancer treatment. However, in spite of all the antitumoral effects, silymarin actually has dual effects and in some cases such as pancreatic cancer it can promote stemness. This review deals with recent investigations to elucidate the molecular actions of this flavonoid in cancer, and to consider the possibility of repurposing it. Particular attention is dedicated to silymarin's dual role in cancer and to some controversies of its real effectiveness.

Ameliorative effects of silymarin on HCl-induced acute lung injury in rats; role of the Nrf-2/HO-1 pathway

OBJECTIVES

Aspiration is a common cause of acute lung injury (ALI), which lacks an effective treatment. Inflammation and oxidative stress play key roles in ALI development. Silymarin is an active extract of Silybum marianum plant seeds (milk thistle). Silymarin has potent anti-inflammatory and antioxidant effects; however its role in aspiration induced ALI has not been investigated. The aim of this study is to investigate the role of silymarin in the treatment of hydrochloric acid (HCl) aspiration induced ALI and explores its mechanisms of action.

MATERIALS AND METHODS

The study included three groups of rats: Control non-treated group, ALI group (intra-tracheal HCl injected), and silymarin treated ALI group. White blood cells (WBCs) with differential count, oxidative stress parameters, B-cell lymphoma 2 (Bcl-2), transforming growth factor-beta (TGF-β), cyclooxygenase 2 (COX-2), nuclear factor erythroid 2-related factor-2 (Nrf-2), and heme oxygenase-1 (HO-1) were investigated. Lung tissue histopathology and immunohistochemical expression of survivin and proliferating cell nuclear antigen (PCNA) were also examined.

RESULTS

The results of the study showed that HCL caused histopathological changes in ALI with leukocytopenia and increased oxidative stress biomarkers. It increased TGF-β, up-regulated mRNA expression of COX-2, Nrf-2, and HO-1 and increased survivin and PCNA but decreased Bcl-2. Silymarin ameliorated the histopathological lung injury with further up-regulation of Nrf-2 and HO-1 mRNA and decreased the inflammatory and fibrotic parameters together with up-regulation of the anti-apoptotic and the proliferation parameters.

CONCLUSION

The protective effect of silymarin against ALI is mediated by Nrf-2/HO-1 pathway with subsequent antioxidant, anti-inflammatory, antiapoptotic, and proliferating activities.

ANTIOXIDANT ENZYMES ACTIVITY IN EXPERIMENTAL ISCHEMIA-REPERFUSION INJURY

Background. Blood loss during civil and military limb trauma is the most common cause of preventable death. Complications due to the use of a hemostatic tourniquet are widely investigated nowadays. Therefore, the standards of the past have to be improved. Objective. The aim of the research is to study the reaction of the enzyme chain of the liver antioxidant system in the presence of modifications of ischemia-reperfusion injury (IRI). Methods. 210 white male-rats, aged 5-5.5 months, were used in the research. The dynamics of antioxidant enzymes activity catalase (Cat) and superoxide dismutase (SOD) in liver tissue in cases of modifications of ischemia-reperfusion injury (IRI) were studied. The period of investigation was in 24 hours, 3, 7, 14 days after the injury. Results. In cases of simulated IRI the catalase level mainly decreased at each period of the experiment. The peak of SOD activity was evidenced on the 1st, 3rd or 7th days after the experimental IRI according to the degree of trauma severity. Thus, IRI combined with severe blood loss and mechanical trauma caused the severest affection of the antioxidant system. Even a single application of hemostatic tourniquet caused similar wavelike reactions at different times. Conclusions. The development of IRI is accompanied by a significant depression of the liver antioxidant system. The most significant changes were evidenced in cases of IRI combined with blood loss and mechanical trauma, but even a single application of a tourniquet caused active response of the antioxidant enzymes.

Ischemic Colitis after Cardiac Surgery: Can We Foresee the Threat?

Introduction

Ischemic colitis (IC) remains a great threat after cardiac surgery with use of extracorporeal circulation. We aimed to identify predictive risk factors and influence of early catecholamine therapy for this disease.

Methods

We prospectively collected and analyzed data of 224 patients, who underwent laparotomy due to IC after initial cardiac surgery with use of extracorporeal circulation during 2002 and 2014. For further comparability 58 patients were identified, who underwent bypass surgery, aortic valve replacement or combination of both. Age ±5 years, sex, BMI ± 5, left ventricular function, peripheral arterial disease, diabetes and urgency status were used for match-pair analysis (1:1) to compare outcome and detect predictive risk factors. Highest catecholamine doses during 1 POD were compared for possible predictive potential.

Results

Patients’ baseline characteristics showed no significant differences. In-hospital mortality of the IC group with a mean age of 71 years (14% female) was significantly higher than the control group with a mean age of 70 (14% female) (67% vs. 16%, p<0.001). Despite significantly longer bypass time in the IC group (133 ± 68 vs. 101 ± 42, p = 0.003), cross-clamp time remained comparable (64 ± 33 vs. 56 ± 25 p = 0.150). The majority of the IC group suffered low-output syndrome (71% vs. 14%, p<0.001) leading to significant higher lactate values within first 24h after operation (55 ± 46 mg/dl vs. 31 ± 30 mg/dl, p = 0.002). Logistic regression revealed elevated lactate values to be significant predictor for colectomy during the postoperative course (HR 1.008, CI 95% 1.003–1.014, p = 0.003). However, Receiver Operating Characteristic Curve calculates a cut-off value for lactate of 22.5 mg/dl (sensitivity 73% and specificity 57%). Furthermore, multivariate analysis showed low-output syndrome (HR 4.301, CI 95% 2.108–8.776, p<0.001) and vasopressin therapy (HR 1.108, CI 95% 1.012–1.213, p = 0.027) significantly influencing necessity of laparotomy.

Conclusion

Patients who undergo laparotomy for IC after initial cardiac surgery have a substantial in-hospital mortality risk. Early postoperative catecholamine levels do not influence the development of an IC except vasopressin. Elevated lactate remains merely a vague predictive risk factor.

Modulatory effect of silymarin on pulmonary vascular dysfunction through HIF-1α-iNOS following rat lung ischemia-reperfusion injury

Silymarin is a traditional therapeutic used to protect the liver, acting to oppose lipid peroxidation, to enhance liver regeneration and functioning as an antioxidant. However, the effects of silymarin on pulmonary vascular dysfunction have not been investigated. In the present study, the modulatory effects of silymarin on pulmonary vascular dysfunction and the underlying mechanisms behind this were investigated in a lung ischemia-reperfusion (I/R) injury rat model. Male Sprague Dawley rats were randomly divided into 3 groups, including: i) A control group (n=10); ii) an I/R group (n=10); and iii) a silymarin-treated group (n=10). All experimental rats received 250 mg/kg/day of silymarin for 8 days. Silymarin was demonstrated to markedly improve lung I/R-induced pulmonary vascular dysfunction and lung moisture. Following silymarin treatment, inflammation and oxidative stress in the lung I/R-injury rats were demonstrably suppressed. Treatment with silymarin also inhibited the activation of caspase-3 and -9, and hypoxia inducible factor-1α (HIF-1α) and inducible nitric oxide synthase (iNOS) protein expression in the lung I/R-injury rats. Silymarin was concluded to impact upon pulmonary vascular dysfunction through the HIF-1α-iNOS pathway in the lung I/R injury rat model.

Pretreatment With Erythropoietin Attenuates Intestinal Ischemia Reperfusion Injury by Further Promoting PI3K/Akt Signaling Activation

BACKGROUND

Erythropoietin (EPO) has been shown to be beneficial in resolution of acute inflammation and intestinal ischemia/reperfusion (IR) injury is featured by the excessive immune response. The current research is designed to evaluate the effect and potential mechanisms of EPO on the intestinal IR injury. Therefore, the effect of EPO on intestinal IR injury was examined by the change of intestinal histology; the expression of pro-inflammatory cytokines tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interferon γ (IFN-γ); and the protein levels of EPOR, p-EPOR, p85, p-p85, Akt, p-Akt, IκΒ-α, p-p65, and p65.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomly divided into three groups: sham group (sham), IR-saline group (IRI), and the IR-EPO group (EPO). Rats were treated with EPO (5000 U/kg) 1 hour before IR induction. A rat model of IR injury was established by ligating the superior mesenteric artery for 30 minutes, followed by reperfusion for 1 hour. Intestinal histology, pro-inflammatory cytokines, and mediators were assessed. The effect of EPO on PI3K/Akt/NF-κB signaling and EPOR were also measured.

RESULTS

EPO significantly decreased the pathologic changes of intestinal and reduced the elevation of pro-inflammatory cytokines TNF-α, IL-1β, and IFN-γ in intestinal and serum caused by IR which was associated with suppressing NF-κB activation by further promoting activation of PI3K/Akt signaling.

CONCLUSIONS

EPO ameliorated the acute intestinal injury caused by IR, which was associated with further activating PI3K/Akt signaling to suppress NF-κΒ-mediating inflammation. Our findings suggest that EPO could be useful for preventing IR-induced intestinal injury.

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.