Antioxidant capacities of endemic Sideritis sipylea and Origanum sipyleum from Turkey

Sideritis sipylea Boiss. and Origanum sipyleum L., an endemic species from Turkey, were extracted with different solvents such as water (WE), ethanol (EE), methanol (ME), acetone (AE). The highest total phenolic contents of S. sipylea and O. sipyleum were detected in ME and AE as 0.089 ± 0.007 and 0.156 ± 0.014 μg gallic acid/μg extract, respectively. The best IC50 values for hydroxyl radical scavenging were determined as 1.1 μg/ml in ME of S. sipylea and 3.6 μg/ml in AE of O. sipyleum. This value for butylated hydroxyanisole (BHA) was 2.2 μg/ml and 2-times higher than that for S. sipylea. Although IC50 value for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging was 4.5 μg/ml for ascorbic acid, the best values were determined as 0.05 mg/ml for ME of S. sipylea and 0.09 mg/ml for EE of O. sipyleum. Total antioxidant capacity of S. sipylea was similar with BHA and higher than O. sipyleum. According to this study, S. sipylea in comparison with O. sipyleum was generally more active plant as to antioxidant capacity.