Influence of silybin on biophysical properties of phospholipid bilayers

Abstract

Aim: Silybin (silibinin) is major biologically active flavonolignan extracted from milk thistle (Sylibum marianum). Its biological activities include hepato‐protection, anticancer properties, and antioxidant‐ and membrane‐stabilizing functions. Although membranes are postulated to be one of the cellular targets for silybin, little is known about its interaction with phospholipid bilayers. Methods: In the present work, the interactions of silybin with phosphatidylcholine bilayers were studied in detail using fluorescence spectroscopy, microcalorimetry and electron spin resonance techniques. Results: The results showed that silybin interacted with the surface of lipid bilayers. It affected the generalized polarization of the fluorescent probe Prodan, while not influencing the more deeply located Laurdan. Silybin lowered the main phospholipid phase transition temperature as judged by microcalorimetry, and caused the immobilization of spin probe Tempo‐palmitate located on the surface of membranes. The mobility of spin probes 5‐ and 16‐doxyl stearic acid was not affected by silybin. Silybin‐induced quenching of 1,6‐diphe‐nyl‐1,3,5‐hexatriene fluorescence indicated that some flavonoid molecules partitioned into the hydrophobic region of membranes, which did not change significantly the biophysical properties of the deeper membrane regions. Conclusion: Such a behavior of silybin in membranes is in accordance with its postulated biological functions and neglectable side effects of therapies using silybin.

The Protective Effect of Silybin against Lasalocid Cytotoxic Exposure on Chicken and Rat Cell Lines

“…This feature enables silybin penetration mainly to lipid bilayer component of the membrane leading to strengthen its biophysical structure. These effects on membrane stabilization may correspond to the cell protection and lack of serious side effects after the drug administration [38]. …”

Free radical scavenging activity of silibinin in nitrite-induced hemoglobin oxidation and membrane fragility models

“…Various studies indicated that silibinin significantly increases glutathione levels, which serve as a free radical scavenger (Das and Vasudevan, 2006). Silibinin is relatively hydrophobic and its penetration into the cell is limited (Sainz-Pardo et al, 1994) and membrane structures are postulated to be one of the cellular targets for silibinin as it interacts with the surface of lipid bilayer (Wesolowska et al, 2007), its effect on erythrocytes may be explained by their incorporation into these lipid bilayers of the cell membrane leading to reducing hemolysis. Silibinin on the other hand, is able to increase the activity of both superoxide dismutase and glutathione peroxidase, which may explain the protective effect of the drug against free radicals and also stabilizing the effect on the red cell membrane (Altorjay et al, 1992).…”

Cytoprotective effect of silybin against lasalocid-induced toxicity in HepG2 cells

“…Such behavior of silybin in membranes is in line with its postulated biological functions. Membrane stabilization and cell protection may correspond to the observed lack of serious side effects of this drug (Wesołowska et al 2007). Silybin at concentrations higher than 50 μM decreased LDH activity and total cellular protein content.…”