Plumbagin exerts protective effects in nucleus pulposus cells by attenuating hydrogen peroxide-induced oxidative stress, inflammation and apoptosis through NF-κB and Nrf-2.

Plumbagin, one of the constituents responsible for the various biological activities of Plumbago zeylanica has been demonstrated to possess antioxidant activity, which may inhibit lipid peroxidation in a dose- and time-dependent manner. In the present study, we aimed to examine the protective effects of plumbagin as well as the underlying mechansim through which plumbagin attenuates hydrogen peroxide (H2O2)-induced oxidative stress in nucleus pulposus cells (NPCs). For this purpose, the NPCs were incubated with fresh medium containing H2O2 (200 µM) at 37˚C in a humidified 5% CO2 atmosphere for 6 h, and cultured with various concentrations of plumbagin (0, 0.5, 1, 2, 5, 10 and 20 µM). Treatment with plumbagin significantly increased the viability of the H2O2-exposed NPCs in a dose‑dependent manner. Moreover, plumbagin significantly reduced the generation of reactive oxygen species, lipid peroxidation, as well as the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 in the H2O2‑exposed NPCs. Glutathione (GSH) content, as well as the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxdiase (GSH-Px) were increased. We found that the administration of plumbagin significantly inhibited the activity of caspase-9 and -3, and downregulated NF-κB expression and upregulated Nrf-2 expression in the H2O2-exposed NPCs. Taken together, these findings suggest that plumbagin exerts neuroprotective effects in NPCs by attenuating H2O2‑induced oxidative stress, inflammation and apoptosis through mediating the expression of NF-κB and Nrf-2.