Polyphenol-rich extract from Wisteria floribunda (Willd.) DC. flowers promotes osteoblast differentiation and bone formation by modulating the mTOR pathway

Objective: To investigate the osteogenic effects of polyphenol-rich extracts from Wisteria floribunda (Willd.) DC. ( W. floribunda ) flowers and elucidate the underlying mechanisms. Methods: Polyphenolic compounds of W. floribunda extracts were analyzed, including flavonoids and glucoside derivatives. Osteogenic activity was assessed in MC3T3-E1 preosteoblast cells by measurement of alkaline phosphatase (ALP) activity, alizarin red S staining, and the expression of osteogenic markers (RUNX2, SP7, and ALPL). In vivo effects were evaluated in zebrafish larvae by assessing skeletal development and expression of osteogenic genes ( runx2a, sp7, and alpl). The role of mammalian target of rapamycin (mTOR) pathway was examined using rapamycin. Results: W. floribunda extracts significantly enhanced ALP activity, bone mineralization, and the expression of RUNX2, SP7, and ALPL in MC3T3-E1 cells. In zebrafish larvae, W. floribunda extracts improved vertebral mineralization and upregulated osteogenic genes. Mechanistically, the plant extract activated the mTOR pathway, and rapamycin treatment attenuated the extracts-induced ALP activity, mineralization, and vertebral formation in zebrafish, confirming mTOR involvement. Conclusions: W. floribunda extracts promote osteoblast differentiation and bone formation via mTOR pathway activation. These findings provide novel insights into the potential of W. floribunda extracts and support its further investigation as a natural therapeutic candidate for bone degenerative disorders such as osteoporosis.