Antioxidants and cytoprotective effects of bergamot juice on ROS-induced SH-SY5Y cell death.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved in oxidative stress-associated pathologies. Over the past few years, following the growing interest about the antioxidant activity of compounds present in the diet, bergamot juice (BJ) has attracted attention as a result of its remarkable flavonoids content. Citrus bergamia Risso et Poiteau (bergamot) is a small tree growing almost exclusively in Calabria region (Italy). Bergamot fruit is used mostly for the extraction of its essential oil, while BJ is considered just a discarded product. Aim of the present study was to evaluate the cytoprotective effect of BJ against ROS-induced cell death. Treatment of SHSY-5Y human neuroblastoma cells with 6-hydroxydopamine (6-OHDA; 50 and 100 µM) resulted in significant cytotoxic effects, as assessed 24 hours later by MTT reduction assay (P<0.001 vs untreated cultures). Pre-incubation with BJ (0.5% and 1%) 1 hour prior to the exposure to 6-OHDA exhibited significant concentration-dependent prevention on 6-OHDA-induced cell death (P<0.05 and P<0.01 vs 6-OHDA-treated cells) and ROS production (P<0.001). Furthermore, Annexin-V test suggest that BJ can inhibit apoptosis induced by 6-OHDA. Evidence that BJ protects SHSY-5Y cells against hydrogen peroxide (H2O2 50-150 µM)-induced ROS generation and cell death highlights its antioxidant capability, as further assessed by both DPPH and reducing power tests. Collectively, our study indicate that the antioxidant properties of BJ may be responsible of its cytoprotective effect in vitro, while other mechanisms of action cannot be excluded.