Figure 4.

The protective effects of pre-treatment with 10 µM PUN for 24 h on UV-A-induced downregulation of Nrf2 target antioxidant genes. HO-1 (A) and NQO1 (B) mRNA expressions were assessed by RT-PCR (details in “Materials and Methods” section) at 1, 3, and 5 h after UV-A irradiation in ARPE-19 cells pre-treated and not with 10 µM PUN (24 h). Values were expressed as the mean percentage relative to unirradiated and not pre-treated cells (control 100%) ± SEM of three independent experiment performed in single. Differences between mean values were assessed by one-way ANOVA analysis followed by post hoc Newman–Keuls. ** = p < 0.01 and *** = p < 0.001 vs. control; ° = p < 0.05 vs. PUN alone; ^§§ = p < 0.01 and ^§§§ = p < 0.001 vs. UV-A alone at the same experimental time.