Milk thistle extracts inhibit the oxidation of low-density lipoprotein (LDL) and subsequent scavenger receptor-dependent monocyte adhesion.
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.
Wallace
Sunny
S
Department of Biological and Agricultural Engineering, 203 Engineering Hall, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Vaughn
Katherine
K
Stewart
Bradford W
BW
Viswanathan
Tito
T
Clausen
Edgar
E
Nagarajan
Shanmugam
S
Carrier
Danielle Julie
DJ
D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D020944:Silybum marianum / Q000737:chemistry*; D009000:Monocytes / Q000502:physiology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D051116:Receptors, Scavenger / Q000037:antagonists & inhibitors* / Q000502:physiology; D012838:Silymarin / Q000494:pharmacology
D008077:Lipoproteins, LDL; D010936:Plant Extracts; D051116:Receptors, Scavenger; D012838:Silymarin; C099252:oxidized low density lipoprotein