A Plant-Derived Flavonoid, Isobavachin, Promotes Osteogenesis and Alleviates Glucocorticoid-Induced Osteoporosis via Modulation of the ESR1-PI3K/Akt Signaling Pathway

Background: Glucocorticoid-induced osteoporosis (GIOP) is marked by impaired osteogenesis and reduced bone formation. Isobavachin (IBA), a flavonoid from Psoralea corylifolia, shows multiple potentials in anti-inflammatory and bone metabolism regulations, but its effects against GIOP remain unclear. This study investigated the osteoprotective effects and potential mechanism of IBA using zebrafish GIOP model. Methods: osteoprotective effects of IBA was assessed by fluorescence imaging in a prednisolone-induced zebrafish model, following with osteogenic gene expressions measured by RT-qPCR. Potential targets and pathways of IBA was filtered and predicted by network pharmacology, molecular docking, and molecular dynamics (MD) simulations, and finally validated with a pharmacological rescue experiment using a PI3K-specific inhibitor. Results: IBA improved bone mineralization and upregulated osteogenesis-related genes. Network pharmacology identified the PI3K-Akt pathway as a key pathway, with ESR1, GSK3B, MTOR, and CCND1 as core targets. PI3K inhibition attenuated the osteoprotective effects of IBA and suppressed downstream osteogenic gene expression. Conclusions: IBA alleviates GIOP by modulating the ESR1-associated PI3K-Akt signaling pathway and may serve as a multi-target therapeutic candidate for osteoporosis.