Fig. 6.
The protective effects of test compounds on UVA-mediated downregulation of Nrf2 target protein and antioxidant enzyme activities. (A) Time-dependent effects of UVA (8 J/cm2) on Nrf2 target proteins (GCLC, GST and NQO1) in B16F10 cells were determined by Western blot analysis at 3, 6 and 12 h post-irradiation. ***P<0.001 versus unirradiated control cells. (B) At 6 h after UVA irradiation, Nrf2 target proteins were examined in B16F10 cells pretreated with test compounds (CA, QU and AV) at 7.5–30 µM. GCLC, GST, NQO1 and the loading control (α-Tubulin) were detected at 73, 25, 31 and 50 kDa, respectively. Enzyme activities of (C) GST and (D) NQO1 in B16F10 cells pretreated with test compounds (CA, QU and AV) at 6 h after UVA irradiation. The statistical significance of differences between the control and irradiated cells was evaluated by Student’s t test and between UVA-irradiated and compounds-treated cells by one-way analysis of variance (ANOVA) with Dunnett’s multiple comparison test. ###P<0.001 versus unirradiated control cells. *P<0.05; **P<0.01; ***P<0.001 versus untreated cells exposed to UVA.