Pterostilbene's protective effects against photodamage caused by UVA/UVB irradiation

Aim: The aim of this study was to further elucidate the mechanism of pterostilbene against UVA/UVB irradiation and the Nuclear factor E2-related factor 2 (Nrf2) signal pathway. Methods: A photo-damage model with UVA/UVB irradiation in HaCat cells was established and used in this study. The dose of pterostilbene was selected through MTS assay. Cell proliferation and apoptosis in Nrf2 and knockdown Nrf2 cells was detected by MTS assay. Expression of CAT, HO-1, and SOD in Nrf2 and knockdown Nrf2 cells was explored by qPCR. Western blot was used to analysis of Nrf2 nuclear translocation changes in Nrf2 and knockdown Nrf2 cells. Protein carbonyl content and MDA content was tested. Results: Our photo-damage model was successfully established and 20J/cm² UVA and 57mJ/cm² UVB irradiation was the suitable dose for HaCaT cell damage study. UVA/UVB irradiation would affect Nrf2 protein location, especial for 9.75 μM pterostilbene dose. In addition, cell proliferation could be significantly inhibited by UVA/UVB treatments (P<0.05), whereas, 9.75 μM pterostilbene treatment can alleviate the photo-damage. UVA/UVB irradiation would lead to decreased expressions of CAT, HO-1, and SOD. Carbonyl content and MDA was significantly changed by UVA/UVB treatments (P<0.05). The adverse events could be reversed by adding 9.75 μM pterostilbene. Western blot analysis showed that Nrf2 cytoplasm content in UVA/UVB treated cells was reduced and Nrf2 nuclear content was increased, which are different with the normal HaCaT cells without knockdown Nrf2 treatment (P<0.05). The results of cell proliferation, apoptosis, and cell antioxidant capacity in knockdown Nrf2 treated HaCaT cells were also significantly different with the normal HaCaT cells without knockdown Nrf2 treatment (P<0.05). Conclusion: We hypothesize that pterostilbene could play an anti-oxidation role via the Nrf2 signal pathway.