Protective Effects of Ursolic Acid on Osteoblastic Differentiation via Activation of IER3/Nrf2 / 치위생과학회지

ABSTRACT

BACKGROUND: Oxidative stress is a known to be associated with in the pathogenesis of many inflammatory diseases, including periodontitis. Ursolic acid is a pentacyclic triterpenoid with has antimicrobial, antioxidative, and anticancer properties. However, the role of ursolic acid in the regulating of osteogenesis remains undetermined. This study was aimed to elucidate the crucial osteogenic effects of ursolic acid and its ability to inhibit oxidative stress by targeting the immediate early response 3 (IER3)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. METHODS: Cell proliferation was determined using water-soluble tetrazolium salt assay, cell differentiation was evaluated by alkaline phosphatase (ALP) activity, and formation of calcium nodules was detected using alizarin red S stain. Generation of reactive oxygen species (ROS) was determined using by DCFH-DA fluorescence dye in hydrogen peroxide (H₂O₂2)-treated MG-63 cells. Expression levels of IER3, Nrf2, and heme oxygenase-1 (HO-1) were analyzed using western blot analysis. RESULTS: Our results showed that ursolic acid up-regulated the proliferation of osteoblasts without any cytotoxic effects, and promoted ALP activity and mineralization. H₂O₂-induced ROS generation was found to be significantly inhibited on treatment with ursolic acid. Furthermore, in H₂O₂-treated cells, the expression of the early response genes: IER3, Nrf2, and Nrf2-related phase II enzyme (HO-1) was enhanced in the presence of ursolic acid. CONCLUSION: The key findings of the present study elucidate the protective effects of ursolic acid against oxidative stress conditions in osteoblasts via the IER3/Nrf2 pathway. Thus, ursolic acid may be developed as a preventative and therapeutic agent for mineral homeostasis and inflammatory diseases caused due to oxidative injury.