SIRT1 and cancer: Since previous studies have demonstrated that PD [36,37] as well as other polyphenolic pro-oxidant compounds [38,39] can regulate the level of Sirtuin 1 (SIRT1) and Nuclear factor erythroid 2-related factor 2 (Nrf2), which are key transcriptional masters governing oxidative stress response in both cancer and normal cells [40,41], we investigated the potential involvement of these proteins in PD-induced effects, by examining their protein and gene expression levels via Western blot and real-time PCR, following PD exposure.