Silymarin alleviates hepatic oxidative stress and protects against metabolic disorders in high-fat diet-fed mice

ABSTRACT

Silymarin is a potent antioxidant medicine and has been widely used for the treatment of liver diseases over 30 years. Recent studies suggest that silymarin may benefit patients with glucose intolerance. However, the mechanism underlying the action of silymarin is not clarified. The aim of this work was to assess the impact of silymarin on glucose intolerance in high-fat diet (HFD)-fed mice, and explore the potential therapeutic mechanisms. C57BL/6 mice were fed with HFD for 12 weeks, randomized, and treated orally with vehicle saline or silymarin (30 mg/kg) daily for 30 days. We found that silymarin significantly improved HFD-induced body weight gain, glucose intolerance, and insulin resistance in mice. Silymarin treatment reduced HFD-increased oxidative stress indicators (reactive oxygen species, lipid peroxidation, protein oxidation) and restored HFD-down-regulated activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) in the plasma and/or liver of the HFD-fed mice. Furthermore, silymarin decreased HFD-up-regulated hepatic NADPH oxidase expression and NF-κB activation in mice. Additionally, silymarin treatment mitigated HFD-increased plasma IL-1β, TNF-α levels, and HFD-enhanced hepatic NO, TLR4, and iNOS expression in mice. These novel data indicate that silymarin has potent anti-diabetic actions through alleviating oxidative stress and inflammatory response, partially by inhibiting hepatic NADPH oxidase expression and the NF-κB signaling.

KEYWORDS:

• Antioxidant status
• hepatic injury
• metabolic disorder
• NF-κB pathway
• obesity

Acknowledgements

We gratefully thank Professor Jide Tian (Department of Molecular & Medical Pharmacology, University of California Los Angeles, USA) for his helpful suggestions during the preparation of this manuscript. We also thank Pengzi Zhang for her technical help.

Declaration of interest

The authors have declared that no competing interests exist.

This study was supported by a Key Project of the Medical Science and Technology Development Foundation, Nanjing Department of Health (YKK12057), National Natural Science Foundation of China (81300651, 81200587), Science and Technology Planning Project of Jiangsu Province of China (BK20130088).