Self-emulsifying formulation of Spinacia oleracea reduces the dose and escalates bioavailability of bioactive compounds to accelerate fracture repair in rats

Background Spinach ( Spinacia oleracea) is a rich source of flavonoids and therefore widely used therapeutically as an antioxidant agent in traditional medicine. The present study was undertaken to study the bone regenerating property of dried Spinacia oleracea extract (DSE) and self-emulsifying formulation of the extract (FDSE) on drill-hole model of fracture repair in rats. Methods 0.8 mm hole was drilled in the diaphyseal region of femur in adult SD rats. DSE and formulated extract (FDSE) was administered orally and fractured femur was collected after treatment regimen. Micro-CT, transcriptional analysis and measurement of calcein intensity of callus formed at the injured site was performed to study the efficacy of the extract and formulation on bone regeneration. Further, compounds from extract were assessed for in-vitro osteoblast activity. Results Micro-architecture of the regenerated bone at injured site exhibited 26% ( p < 0.001) and 35% ( p < 0.01) increased BV/TV (bone volume /tissue volume) and Tb.N. (trabecular number) for DSE (500 mg.kg − 1 ). Further, FDSE exhibited similar augmentation in BV/TV ( p < 0.01) and Tb. N ( p < 0.01) parameters at dose of 250 mg.kg − 1 . Analogous results were obtained from transcriptional analysis and calcein intensity at the fractured site. 3-O-Methylpatuletin, one of the compound isolated from the extract stimulated the differentiation and mineralization of primary osteoblast and depicted concentration dependent antagonizing effect of H 2 O 2 in osteoblast apparently, minimizing ROS generation thus affectivity in fracture repair. Conclusions The present study showed that bone regenerating property of spinach was augmented by formulating extract to deliverable form and can be further studied to develop as therapeutic agent for fracture repair. Graphical abstract