Nano formulation of Sophora japonica extract stimulates osteogenic activity in osteoblasts

Sophora japonica (SJ) is used in traditional medicine in Asia, including Korea, for its medicinal properties. The extracts of SJ include several bioactive flavonoids, including Kaempferol (Kf). Kf exerts bone-forming activity in osteoblasts, but due to its high cost, low solubility, and limited bioavailability, its potential as a nutritional supplement remains unexplored and limited. Thus, we evaluated the effect of nanoformulation of acetone SJ extract (nSJE) enriched with 40% Kf for its bone-sparing properties. SEM image showed spherical morphology (~ 500 nm diameter) of nSJE. nSJE showed better aqueous solubility (0.011 mg/mL) than Kf (0.002 mg/mL) and demonstrated enhanced cellular uptake and a burst release of Kf for 8 h followed by slow release till 96 h than Kf. Treatment of nSJE augmented the osteogenic markers like ALP activity and expressions of osterix, osteocalcin, and collagen 1α. nSJE treatment also enhanced osteoblast differentiation and terminal markers like collagen synthesis and mineralization in osteoblasts. To induce osteogenesis in osteoblasts, nSJE stimulated WNT and BMP signaling pathways involved in bone formation. nSJE has increased osteogenic ability even at lower Kf doses, making it an economically viable alternative to pure Kf for harnessing bone-forming capacities in bone diseases such as osteoporosis and fracture repair.