Figure 2.

Inhibitory effects of 4,5−diCQA on IL-1β-induced nitrite, PGE₂, iNOS, COX-2, and TNF-α in rat primary chondrocytes. Cells were pre-treated with 4,5-diCQA (10, 20, and 40 μM) for 1 h, followed by IL-1β (5 ng/mL) stimulation for 24 h. (A) Nitrite production was determined in the cultured medium using a Griess reagent. (B) PGE₂ production was determined in the cultured medium using an ELISA kit after 24 h. (C) Expression of the iNOS, COX-2, and TNF-α was determined using Western blot analysis. α-Tubulin served as an internal control. (D–F) Quantitative data of (C) were analyzed using the ImageJ bundled with Java 1.8.0_172 software. n = 5 per group. Data are represented as mean ± SD of three independent experiments. ### p < 0.005 vs. control group; ** p < 0.05, and *** p < 0.005 compared with the IL-1β-treated group.