Abstract
Essential oil extracted from the aerial parts of Rosmarinus officinalis by hydrodistillation was analyzed by gas chromatography/mass spectrometry and the components identified were 15. The major constituents of the essential oil were 1,8-cineole (35.32%), trans-caryophyllene (14.47%), borneol (9.37%), camphor (8.97%), alpha-pinene (7.9%) and alpha-thujone (6.42%). R. officinalis essential oil was screened for its in vitro antioxidant activities using three different and complementary assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH), beta-carotene bleaching test and reducing power. The results of the DPPH assay showed an IC50 inhibitory concentration of 110.20 mu g/ml. In the beta-carotene bleaching test, the IC50 value was 20.00 mu g/ml. At a higher concentration (70 mu g/ml), this essential oil exhibited a lower reducing power with an absorbance value of 0.72 +/- 0.02. The corresponding value EC50 was evaluated as 38.68 mu g/ml. Comparison of the antioxidant properties of the investigated essential oil with those expressed by BHT (used as a positive control), showed that this oil exhibited a slightly weak antioxidant potential than BHT and therefore acts as a natural antioxidant agent.