2.3. Active Compounds Dose-Dependently Increase the Viability of PC12 Cells Exposed to H2O2All the aforementioned active compounds were tested for their ability to enhance cell viability in various concentrations ranging from 0.5 to 10 μM. Concentration gradients of all the active compounds differed. Cells were pretreated with different derivatives for 24 h, and incubated with 600 μM H2O2 for another 24 h. The results are shown in Figure 1B. Compounds 1, 1a, 1b, 1d, 2b, and 2f exhibited dose-dependent activation, and 1 and 1d showed better action gradients. Furthermore, compound 1appears to be active even at 0.5 μM.