Milk Thistle Extracts Inhibit the Oxidation of Low-Density Lipoprotein (LDL) and Subsequent Scavenger Receptor-Dependent Monocyte Adhesion

Abstract

Silymarin encompasses a group of flavonolignans that are extracted from Silybum marianum (Asteraceae) fruits. The silymarins have previously been reported to lower low-density lipoprotein (LDL) levels associated with high-fat diets. The present study reports the efficacy of the silymarins in inhibiting oxidized low-density lipoprotein (oxLDL) generation and subsequent scavenger receptor (SR) mediated monocyte adherence to oxLDL. The flavonolignans that comprise silymarin include silichristin (SC), silidianin (SD), silibinin (SBN), and isosilibinin (IS). These flavonolignans (300 microM) lowered oxLDL generation, measured by the thiobarbituric acid-reacting substances (TBARS) assay, by 60.0, 28.1, 60.0, and 30.1%, respectively. SBN treatment of LDL in the presence of copper sulfate (CuSO 4) resulted in a significant dose-dependent inhibition of monocyte adhesion. Inhibition was paralleled by a decrease in binding of anti-oxLDL antibodies recognized by U937 monocyte Fc gamma receptors (FcgammaR). These results showed that silymarin and SBN, likely through antioxidant and free radical scavenging mechanisms of action, inhibit the generation of oxLDL and oxidation-specific neoepitopes recognized by SR and FcgammaR expressed on monocytes/macrophages.

Shoot regeneration and free-radical scavenging activity in Silybum marianum L.

“…However, this is first report on the antioxidant activity of regenerated tissues of S. marianum. Our results are consistent with numerous previous findings in which positive correlation between total phenolic content and antioxidant activity for Silybum and other related plant species was reported (Koksal et al 2009;Vaknin et al 2008;Wallace et al 2008;Zheng and Wang 2001). Iqbal and Srivastava (2000) concluded that yield of silybin content in cultured tissues of S. marianum varied with age and composition of the medium.…”

“…In a recent study, it has been demonstrated that the protective effect of silymarin is most likely due to its freeradical scavenging activity (FRSA) (Wallace et al 2008).…”

<i>Taraxacum officinale</i> and <i>Silybum marianum</i> alone or combined orchestrate experimentally induced hepatic steatosis through lipogenecity, glucose tolerance and oxidant/antioxidant status

“…In this study, the ox-LDL levels were significantly increased in group I when compared to treated groups, however, dandelion and milk thistle supplementation improved this which is more obvious in combination group as reported previously by Wallace et al (2008) and Colle et al (2012) who reported the protective effects of both herbs most likely through antioxidant and free radical scavenging mechanisms.…”

Silybum marianum (milk thistle) and its main constituent, silymarin, as a potential therapeutic plant in metabolic syndrome: A review

“…Silymarin and silybin, likely through antioxidant and free radical scavenging, inhibited the generation of oxLDL and oxidation‐specific neoepitopes recognized by scavenger receptor and FcgammaR expressed on monocytes/macrophages. Also, it is suggested that silybin probably blocks the interaction between endothelial cells and circulating monocytes by inhibiting TNF‐α‐induced expression of endothelial cell adhesion molecules intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 (Wallace et al, ). Moreover, silymarin can increase HDL level, which has a protective effect on atherosclerosis and an important role in the reverse transport of cholesterol (Poruba et al, ).…”