BACKGROUND: Avicularin is a plant-derived flavonoid used in traditional Chinese medicine to treat conditions that include ankle fracture. Bradykinin stimulated MG-63 human osteoblastic osteosarcoma cells has previously been studied in an in vitro model. This study aimed to investigate the effects of avicularin on bradykinin-treated MG-63 human osteoblastic osteosarcoma cells in vitro.

MATERIAL AND METHODS: MG-63 cells were treated with increasing concentrations of avicularin for 48 hours, followed by 1 μM of bradykinin for 24 h. The MTT assay was used to measure cell viability. Quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to measure the expression of inflammatory mediators, interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) mRNA and protein, respectively. The expression of oxidative stress factors, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase were measured. Western blot and qRT-PCR were performed to determine p38, p65, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) protein levels and mRNA expression, respectively.

RESULTS: Avicularin had no cytotoxic effect on MG-63 cells. Avicularin significantly upregulated the expression levels IL-1β, IL-6, and TNF-α in the bradykinin treated group in a dose-dependent manner. Avicularin reduced the level of MDA and the activity of SOD and catalase in the bradykinin treated MG-63 cells, reduced p-p38, p-p65, iNOS, and COX-2 expression, and decreased the p-p38/p38 ratio and the p-p65/p65 ratio in bradykinin treated MG-63 cells in a dose-dependent manner.

CONCLUSIONS: Avicularin reduced the expression of inflammatory cytokines and the levels of markers of oxidative stress in MG-63 human osteoblastic osteosarcoma cells in vitro.

Keywords: ankle fractures, bradykinin, Cyclooxygenase 2, Cytokines, Inflammation Mediators, Interleukin-6, Nitric Oxide, Nitric Oxide Synthase Type II, Osteoblasts, Osteosarcoma