Inhibitory effect of andrographolide on MMP-2 activity and gene expression in equine chondrocyte culture induced by IL-1β. The primary equine chondrocytes were cultured in the conditioned media containing IL-1β (5 ng/mL), with or without andrographolide (10 to 90 µM), or left untreated as a control. After 24 hours of treatment, the culture medium samples were analyzed for MMP-2 activity by gelatin zymography (a). The numbers above the lanes indicate the fold changes of the enzyme activity compared to the control. The expression of MMP-2 messenger RNA (mRNA) of was performed in the collected cells by semiquantitative RT-PCR; (b) the representative images of agarose gel electrophoresis; (c) the bar graphs indicating relative expression of MMP-2 gene expression as fold change compared to the control. The bar graphs are expressed as mean ± SD of three independent experiments. The significant differences were tested by one-way ANOVA at (, #). Significant differences from the control () and IL-1β treated group (#), respectively.