The mobility of the Ty1 transposon in Saccharomyces cerevisiae was found to vary proportionally with the level of ROS generated in cells, which provides the possibility to determine antioxidant activity by changes in a cellular process instead of using chemical reactions. The study of propolis, royal jelly, and honey with the newly developed Ty1antiROS test reveals an inverse exponential dependence of antioxidant activity on increased concentrations. This dependence can be transformed to proportional by changing the source of ROS: instead of cell-produced to applied as hydrogen peroxide. The different test responses are not due to excess of added hydrogen peroxide, as evidenced by the exponential dependence found by usage of yap1Δ tester cells accumulating cell-generated ROS. Results indicate that the activity of antioxidants to oxidative radicals depends on the origin of ROS, and this activity is elevated for cell-generated ROS compared to ROS added as reagents in the assay.