Metabolic and vascular effects of silybin in hypertensive patients with high 1-h post-load plasma glucose

Silybin induces endothelium-dependent vasodilation via TRPV4 channels in mouse mesenteric arteries

Silybin is a flavonolignan extracted from the seeds of Silybum marianum that has been used as a dietary supplement for treating hepatic diseases and components of metabolic syndrome such as diabetes, obesity and hypertension. Transient receptor potential vanilloid 4 (TRPV4) channels are Ca²⁺-permeable, nonselective cation channels that regulate vascular endothelial function and blood flow. However, the relationship between silybin and TRPV4 channels in small mesenteric arteries remains unknown. In our study, we carried out a molecular docking experiment by using Discovery Studio v3.5 to predict the binding of silybin to TRPV4. Activation of TRPV4 with silybin was detected via intracellular Ca²⁺ concentration ([Ca²⁺]_i) measurement and patch clamp experiments. The molecular docking results showed that silybin was likely to bind to the ankyrin repeat domain of TPRV4. [Ca²⁺]_i measurements in mesenteric arterial endothelial cells (MAECs) and TRPV4-overexpressing HEK293 (TRPV4-HEK293) cells demonstrated that silybin induced Ca²⁺ influx by activating TRPV4 channels. The patch clamp experiments indicated that in TRPV4-HEK293 cells, silybin induced TRPV4-mediated cation currents. In addition, in high-salt-induced hypertensive mice, oral administration of silybin decreased systolic blood pressure (SBP) and significantly improved the arterial dilatory response to acetylcholine. Our findings provide the first evidence that silybin could induce mesenteric endothelium-dependent vasodilation and reduce blood pressure in high-salt-induced hypertensive mice via TRPV4 channels, thereby revealing the potential effect of silybin on preventing endothelial dysfunction-related cardiovascular diseases.

A Comprehensive Review of the Cardiovascular Protective Properties of Silibinin/Silymarin: A New Kid on the Block

Silibinin/silymarin has been used in herbal medicine for thousands of years and it is well-known for its hepato-protective properties. The present comprehensive literature review aimed to critically summarize the pharmacological properties of silymarin extract and its main ingredient silibinin in relation to classical cardiovascular risk factors (e.g., diabetes mellitus, etc.). We also assessed their potential protective and/or therapeutic application in cardiovascular diseases (CVDs), based on experimental and clinical studies. Pre-clinical studies including in vitro tests or animal models have predominantly implicated the following effects of silymarin and its constituents: (1) antioxidant, (2) hypolipidemic, (3) hypoglycemic, (4) anti-hypertensive and (5) cardioprotective. On the other hand, a direct amelioration of atherosclerosis and endothelial dysfunction after silymarin administration seems weak based on scarce data. In clinical trials, the most important findings are improved (1) glycemic and (2) lipid profiles in patients with type 2 diabetes mellitus and/or hyperlipidemia, while (3) the anti-hypertensive effects of silibinin/silymarin seem very modest. Finally, the changes in clinical endpoints are not robust enough to draw a firm conclusion. There are significant limitations in clinical trial design, including the great variety in doses and cohorts, the underlying conditions, the small sample sizes, the short duration and the absence of pharmacokinetic/pharmacodynamic tests prior to study commitment. More data from well-designed and high-quality pre-clinical and clinical studies are required to firmly establish the clinical efficacy of silibinin/silymarin and its possible therapeutic application in cardiovascular diseases.

THE EFFECTS OF REALSIL (SILYBIN-PHOSPHOLIPID-VITAMIN E COMPLEX) ON LIVER ENZYMES IN PATIENTS WITH NON-ALCOHOLIC FATTY LIVER DISEASE (NAFLD) OR NON-ALCOHOLIC STEATO-HEPATITIS (NASH): A SYSTEMATIC REVIEW AND META-ANALYSIS OF RCTS

Background

The aim of the present study was to systematically review the effects of Realsil (silybin-phospholipid-vitamin E complex) on liver enzymes in patients with NAFLD or NASH.

Methods

We searched Web of Science, MEDLINE, Google Scholar, Cochrane Library, Science Direct, ProQuest, Scopus, and 1868 articles were found up to December 2018. Four studies that examined the effect of Realsil intake on liver enzymes among NAFLD or NASH patients were included. Exclusion criteria include: animal studies, studies with the design other than clinical trials, studies on non-adult individuals, studies that assess the effect of vitamin E, silybin, or phospholipid solely, studies that examined the effect of Realsil on other outcomes, or studies with insufficient data.

Results

The analysis demonstrated that Realsil intake led to a significant decrease in Gamma-Glutamyl Transpeptidase (GGT) levels (standardized mean difference (SMD) =-0.37; 95% confidence interval (CI]): -0.68 to -0.06). Realsil intake non-significantly decrease alanine transaminase (ALT) levels (SMD=-1.02 U/L; 95% CI: -2.23 to 0.20) and non-significantly increase aspartate aminotransferase (AST) levels (SMD = 0.17 U/L; 95% CI: -0.26-0.61).

Conclusion

Realsil intake was associated with a significantly decreased circulating GGT level without any significant effect on AST and ALT levels.