Phenolics-rich extracts from Silybum marianum and Prunella vulgaris reduce a high-sucrose diet induced oxidative stress in hereditary hypertriglyceridemic rats

The study tested the effects of phenolics-rich extracts from the plants Silybum marianum (silymarin) and Prunella vulgaris (PVE) on blood and liver antioxidant status and lipoprotein metabolism. Hereditary hypertriglyceridemic rats fed on standard diet (STD) or high-sucrose diet (HSD, 70 cal% of sucrose) for two weeks were used. HSD doubled plasma and liver triacylglycerol (TAG) and increased plasma VLDL-TAG and VLDL-cholesterol compared to STD. Administration of silymarin or PVE as 1% dietary supplements in HSD did not influence lipid levels in plasma or liver, but both extracts caused decrease in plasma VLDL-cholesterol levels. HSD-induced oxidative stress was manifested in increased TBARS and conjugated dienes (CD) content, decreased GSH levels and glutathione peroxidase (GPX) activity in blood and liver. In blood the activity of superoxide dismutase (SOD) decreased, whereas in liver the activity of catalase increased after HSD. Feeding on HSD containing phenolics-rich extracts resulted in reduction of TBARS and CD content and in increase of blood GPX activity and elevated GSH content in liver. Besides, silymarin increased the activity of SOD and level of GSH in blood. Catalase activity in blood or liver was not influenced by the presence of plant extracts in the diet. These results indicate that silymarin and PVE improve antioxidant status in blood and liver and positively affect plasma lipoprotein profile in an experimental model of dietary induced hypertriglyceridemia. (C) 2004 Elsevier Ltd. All rights reserved.