RESUMO
OBJECTIVE To screen the active site of Jiegu ointment in promoting fracture healing in New Zealand rabbits. METHODS The ethanol extract of Jiegu ointment， as well as the ethyl acetate and n-butanol parts， were prepared and mixed with honey to form a plaster with appropriate viscosity. The radial fracture model of left forelimb in New Zealand rabbit was established and divided into model control group， ethanol extract group， ethyl acetate fraction group and n-butanol fraction group， with 6 rabbits in each group. Except for model control group， rabbits of all other groups were treated with corresponding polar part of Jiegu ointment for external application， for 4 weeks. The radial fracture healing of rabbits was studied by X-ray examination. Enzyme-linked immunosorbent assay was used to detect the serum levels of interleukin-6 （IL-6）， tumor necrosis factor α （TNF-α）， osteocalcin （OC）， vascular endothelial growth factor A （VEGFA）， basic fibroblast growth factor 2 （bFGF2） and alkaline phosphatase （ALP）. HE staining was adopted to observe the changes of pathological morphology of rabbit fracture site， and immunohistochemical method was used to detect the protein expression of bFGF2 in fracture site of rabbits. RESULTS The healing speed of the fracture site in the n-butanol fraction group was the fastest， followed by ethanol extract group， and the ethyl acetate fraction group was the slowest； the serum levels of TNF-α and IL-6 in n-butanol fraction group decreased the fastest， while the levels of ALP， bFGF2， OC and VEGFA increased the fastest [significant increase compared with ethanol extract group （P＜0.01）]； the chondrocytes at the fracture fraction completely disappeared， forming a large number of bone marrow cavities， and the bone trabeculae in the bone marrow cavity were officially formed. The expression level of bFGF2 was also higher than ethanol extract group. CONCLUSIONS The effect of n-butanol fraction on promoting fracture healing is more significant than ethyl acetate fraction and ethanol extract， and n-butanol fraction is the active fraction of Jiegu ointment to promote fracture healing.