Suitability of TBA method for the evaluation of the oxidative effect of non-water-soluble and watersoluble rosemary extracts

The antioxidative effects of rosemary and grape-seed extracts spiked in human plasma were examined using the thiobarbituric acid (TBA) method. The TBA values of plasma spiked with reagents to generate reactive oxygen species, such as singlet oxygen (1O2), hydroxyl radicals (•OH), peroxynitrite (ONOO•), and superoxide anions (O2•-), were measured by a flow injection analysis method with fluorescence (FL) detection. TBA values obtained by the addition of 50 mg/mL of rosemary extracts for 1O2, •OH, ONOO-, and O2 •- increased to 964 ± 65%, 1063 ± 61%, 758 ± 78%, and 698 ± 41%, respectively (n = 3, P <0.01), whereas the values with 1 mg/mL of grape-seed extracts or tocopherol decreased (40.2 - 66.3%). Furthermore, the antioxidative effects of rosemary extract in rat plasma, spiked with reagents to generate •OH, were examined by high-performance liquid chromatography with FL detection. No peak, other than TBA-malondialdehyde, could be detected using wavelengths of 532 (λex) and 553 nm (λem). ©2011 by Japan Oil Chemists' Society.