Figure 4. Influence of pretreatment time on the protective effect of pinosylvin against oxidative stress in the ARPE-19 cell line. Cells were pretreated with 5 µM pinosylvin for times ranging from 2 h to 48 h before oxidative stress was evoked by exposure to 500 µM hydroquinone (HQ) for another 24 h before the viability test. Data are mean value±standard deviation (SD), n = 5. *p<0.05, significantly different from cells exposed to HQ, ANOVA, and the t test.