Abstract: Objective To explore the protective effect of alpinetin on lipopolysaccharide (LPS)-induced rat chondrocytes damage and its mechanism. Methods The chondrocytes from the knee joints of suckling rats were isolated and cultured. They were divided into control group, LPS induction group (model group) and LPS induction plus alpinetin treatment group (alpinetin group). LPS were used to induce inflammation in the model group and the alpinetin group. The alpinetin group was treated with different concentrations of alpinetin after LPS induction. The CCK-8 method was used to detect chondrocyte activity, and the inflammation protection was observed by fluorescein diacetate/propidium iodide (FDA/PI) staining, real-time PCR (qPCR) and immunofluorescence staining effect. Results CCK-8 suggested that when the concentration of alpinetin was 5 mg/L, the absorbance of chondrocytes was the highest. FDA/PI staining results showed that the number of live cells was reduced in the model group compared with that the control group, while the number of dead cells were increased. Compared with the model group, the number of live cells were increased in the alpinetin group, while the number of dead cells decreased. qPCR results showed that the expression levels of interleukin-1β (IL-1β), IL-6, inducible nitric oxide synthase (iNOS) , tumor necrosis factor (TNF-α) and human matrix metalloproteinase-13 (MMP-13) gene were decreased in the alpinetin group compared with those of the model group, while the expression level of type Ⅱ collagenase (Col2a1) was increased (P＜0.05). Immunofluorescence staining indicated that the expression level of IL-6 was significantly reduced in the alpinetin group compared with that of the model group. Conclusion Alpinetin can effectively protect the inflammatory damage of chondrocytes induced by LPS and promote the proliferation of chondrocytes, which provides a theoretical basis for the treatment of osteoarthritis.

Key words: chondrocytes, osteoarthritis, interleukin-6, lipopolysaccharides, alpinetin