Nasunin, a new player in the field of osteoblast protection against oxidative stress

This study investigated whether nasunin, the major component of anthocyanin pigment of eggplant (Solanum melongena L.), known for its antioxidant effects, counteracts tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in MC3T3-E1 osteoblastic cells. Pretreatment with purified nasunin (10-10-10-6 M) significantly increased viability and reduced apoptosis of MC3T3-E1 cells cultured with t-BHP (250 μM, 3 h). Furthermore, nasunin (10-9 M) prevented t-BHP-induced osteoblastic dysfunction and changes in the cytoskeleton organisation due to both an increase of intracellular glutathione and a decrease of intracellular reactive oxygen species. Moreover, t-BHP-induced reduction in osteoblast differentiation markers, such as alkaline phosphatase and collagen content, was recovered in nasunin-pretreated cells. Nasunin protects against t-BHP-induced osteoblastic dysfunction by activating the phosphoinositide 3-kinase/Akt signalling pathway (PI3K/Akt) since LY294002, a PI3K-specific inhibitor, worsened the cytotoxic effect of t-BHP and reversed the protective action of nasunin. Furthermore, nasunin prevented the decreased Akt phosphorylation observed in t-BHP-treated cells.