Effect of silymarin on oxidative damage in chicken liver cell membranes

In living beings, antioxidants are of vital importance for protection against oxidative damage caused by reactive oxygen species. Silymarin (SM), a plant-derived flavonoid present in the fruits and seeds of milk thistle Silybum marianum (L.) Gaertn., has a recognized hepatoprotective effect. In this work, the in vitro silymarin antioxidant effect on non-enzymatic peroxidation (NEP) in chicken liver mitochondria and microsomes was studied. Oxidative stress in the organelles was induced by subjecting the samples (1 mg of protein) to an ascorbate-Fe++-dependent prooxidant system at 37 °C. Oxidative damage was quantified by chemiluminescence (CL) using a Packard1900 TR liquid scintillation counter (Meriden CT, USA). CL expressed as cpm (counts per minute) was read every 10 minutes to establish the course of peroxidation as a function of time. Likewise, the total cpm value (sum of the readings) was used to compare the inhibitory effect of SM using different concentrations corresponding to 6.25; 12.5, and 25 μg of the active ingredient (silymarin phosphatide) per mg of mitochondrial and microsomal protein. Controls were run simultaneously without the addition of ascorbate. Peroxidation inhibition was dependent on the concentration of SM in the incubation mixture. The results show that a protective effect on induced oxidative damage was found for all concentrations tested.