[Note: Silymarin is extracted from milk thistle. Oxidized LDL (bad cholesterol) is considered a chief contributor to arterial plaque and heart disease.]
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. [Oxidation was inhibited by up to 86% at the highest dose.]
The flavonolignans that comprise silymarin include silichristin (SC), silidianin (SD), silibinin (SBN), and isosilibinin (IS). These flavonolignans (300 µM) 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 (CuSO4) 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 (Fc?R).
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 Fc?R expressed on monocytes/macrophages.
[For an explanation of this study including quotes from the authors, see “Study hints at milk thistle’s heart health benefits.”]
Source: Journal of Agricultural and Food Chemistry, June 11, 2008. 56 (11), 3966–3972, 2008. PMID: 18476698 by Wallace S, Vaughn K, Stewart BW, Viswanathan T, Clausen E, Nagarajan, S, Carrier D. Departments of Biological and Agricultural Engineering and Chemical Engineering, University of Arkansas, Fayetteville; Department of Microbiology and Immunology and Arkansas Children’s Nutrition Center, University of Arkansas for Medical Sciences, Little Rock; Department of Chemistry, University of Arkansas at Little Rock.