Fig. 4

Natural active compounds reduce the cytokines-induced mRNA levels MMP3 (a) and MMP13 (b) in ELACs. The chondrocytes were pre-treated with a combination of IL-1β (2.5 ng/mL) and OSM (2 ng/mL) for 2 h, after which they were treated with various concentrations of SE (sesamin; 0.25–1 μM), AD (andrographolide; 1.25–5 μM), and VA (vanillylacetone; 20–80 μM), for 24 h. The mRNA levels were assessed by real-time RT-PCR. Results are presented as mean ± SEM. * signifies statistical significance compared with control (*p < 0.05), whereas # signifies statistical significance in relation to the cytokines treatment group (#p < 0.05)