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

• Oxidative stress is involved in the age-related decrease in osteoblast activity.
• Antioxidants are known to protect against oxidative damage during ageing.
• Nasunin is a natural antioxidant from the eggplant peel.
• Nasunin prevents MC3T3-E1 osteoblast cells from oxidative damage.
• The protective effect of nasunin involves PI3K/Akt pathway.

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.