Fig. 1. Cytotoxicity tests of Sal B. The primary chondrocytes were cultured and the cells were treated with different concentrations of Sal B (0, 20, 40, 60, 80, 100, 200 μM) for 24 h. Sal B (0 μM) groups as the control group. (A) The chemical structural formula of Sal B; (B) the MTT assay to examine the effect of Sal B on chondrocyte activity. Six replicates were made for each group, all assays were performed in triplicate. *P < 0.01 versus Sal B (0 μM) group.