Bone Fracture-healing Properties and UPLC-MS Analysis of an Enriched Flavonoid Fraction from Oxystelma esculentum

Abstract

Oxystelma esculentum has been used as a folk medicine to treat jaundice, throat infections, and skin problems. In the current study, the bone fracture-healing properties of a flavonoid enriched fraction (Oxy50-60F) of O. esculentum were investigated in Swiss mice using a drill-hole injury model. Oxy50-60F (1 mg/kg/day, 5 mg/kg/day, and 10 mg/kg/day) was administered orally (from the next day) after a 0.6 mm drill-hole injury in mice femur mid diaphysis for 7 days and 14 days. Parathyroid hormone (40 μg/kg; 5 times/week) was given subcutaneously as the positive control. Confocal imaging for bone regeneration, micro-architecture of femur bones, ex-vivo mineralisation, haematoxyline & eosin staining, measurement of reactive oxygen species, gene expression of osteogenic and anti-inflammatory genes were studied. Quercetin, kaempferol, and isorhamnetin glycosides were identified in the active fraction using mass spectrometry techniques. Our results confirm that Oxy50-60F treatment promotes fracture healing, callus formation at drill-hole sites and stimulates osteogenic and anti-inflammatory genes. Oxy50-60F administration to fractured mice exhibited significantly better micro-CT parameters in a dose-dependent manner and promoted nodule mineralisation at days 7 and 14 post-injury. Oxy50-60F also prevents ROS generation by increasing expression of the SOD2 enzyme. Overall, this study reveals that Oxy50-60F has bone regeneration potential in a cortical bone defect model, which supports its use in delayed-union and non-union fracture cases.