The antioxidant activity of eugenol [1] was equal to
or better than the activities of TBHQ and BHT. Surprisingly,
cirsimaritin [2] displayed poor antioxidant
activity in our assays. Isothymusin [3] was the most active
anti-oxidant compound among those isolated from
O. sanctum. Compound 3 was about 50% more active
than the synthetic anti-oxidants TBHQ and BHT at 10-
pM concentrations. Also, the activity of isothymonin
[4] was similar to that of eugenol [1] and showed
slightly more activity than BHT and TBHQ at 10 pM
concentration. Although compound 6 was not as active
as compounds 1-4, it demonstrated better antioxidant
activity than vitamin E or compounds 2 and 5.