Figure 3
Antioxidant effect of the O. labiatum extract (squares) and the isolated compound (triangles). The DPPH free radical scavenging, the FRAP, cupric ion reducing activity, and crocin bleaching effect are shown in A, B, C and D respectively (n = 5-6.). The DPPH data is shown as percentage inhibition. The IC50s for the extract were 13 ± 0.8 μg/mL, 53.62 ± 0.57, 47.32 ± 0.76 μg/mL and 54.86 ± 1.28 μg/mL respectively. Ascorbic acid was used as positive control. The extract exhibited strong antioxidant activity while the diterpenoid compound did not. *tested in two fold serial dilutions from 0.08-10 μg/mL.