 
         
         Abstract
         
         
            Silybum marianum Gaertn. (Milk thistle) has been used since ancient times for the relief of liver
            diseases characterized by intense oxidative stress such as inflammatory liver disease
            and cirrhosis. As oxidative stress by hyperglycemia is involved in micro- and macrovascular
            complications of type 2 diabetes, our aim was to assess the protective effect of milk
            thistle seed extract against oxidative stress induced by a high glucose concentration
            on endothelial cells (EA.hy926 cells). High-performance liquid chromatographic analysis
            shows flavonolignans silychristin and silibinin A and B as major components. No cell
            toxicity was observed for concentrations up to 100 µg/mL of milk thistle extract for
            24 h. Concentrations of 5–25 µg/mL of the extract were used to assess the protective
            effect on EA.hy926 cells treated with 30 mM glucose for 24 h. Oxidative damage by
            30 mM glucose was shown as a significant decrease in reduced glutathione and a significant
            increase in protein carbonyls and antioxidant enzyme activities. S. marianum extract recovered reduced glutathione and balanced the elevated carbonyls and enzyme
            activity. Silibinin alone also recovered reduced glutathione and antioxidant enzymes.
            S. marianum protects endothelial cell against oxidative damage by modulating antioxidant enzyme
            activity, reduced glutathione, and protein carbonyl levels.
         
         Key words
            Silybum marianum
            - Asteraceae - Flavonolignans - endothelial cells - oxidative damage - plant antioxidants