Evaluation of antioxidant activity of extracts from the roots and shoots of Scutellaria alpina L. and S. altissima L. in selected blood cells.

BACKGROUND: It is widely known that reactive oxygen species (ROS) can cause oxidative damage in cells and have been linked to the pathogenesis of oxidative diseases, such as atherosclerosis, ischemia, neurodegenerative disease, diabetes, or cancer. Recently, much attention has been focused on preventive strategies for oxidative stress and related diseases. Plants represent a source of bioactive compounds whose antioxidant activity may be useful in protecting against pro-oxidative reactions.

OBJECTIVES: The study determines the in vitro biological activity of the ethanolic extracts from the shoots and roots of Scutellaria species (S. altissima and S. alpina) in selected blood cells (blood platelets and lymphocytes).

MATERIAL AND METHODS: Platelet activity, both resting and after thrombin stimulation, was used to indicate the ability of the plant extracts to inhibit the production of superoxide anion radicals (O2 •-) and platelet lipid peroxidation. The generation of superoxide anion radicals was measured by cytochrome c reduction. Lipid peroxidation in blood platelets was measured by the level of thiobarbituric acid reactive substances (TBARS). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay was used to determine the protective effect of Scutellaria extracts on lymphocyte cells against oxidative damage induced by hydroxyl radicals.

RESULTS: Extracts (5-50 μg/mL) containing phenolic compounds from both Scutellaria species distinctly reduced nonenzymatic lipid peroxidation and arachidonic acid metabolism by blood platelets in vitro. When given at the tested concentration, the extracts reduced the generation of O2 •- in resting blood platelets and platelets activated by thrombin in vitro. All Scutellaria extracts (10 μg/mL) containing phenolic compounds also protected human lymphocytes against oxidative stress induced by hydrogen peroxide (H2O2).

CONCLUSIONS: The present study suggests that the natural extracts from S. altissima and S. alpina have antioxidant properties and, therefore, may be beneficial in the prevention of diseases in which blood platelets and lymphocytes are involved, i.e., cancer or inflammatory and infective diseases.