Figure 3: PCA inhibits H2O2-induced oxidative stress levels in RA-FLSs. (a and b) The ROS level in H2O2-induced MH7A cells treated by PCA was detected by DCFDA staining. (c and d) The levels of MDA and SOD in H2O2-induced MH7A cells treated by PCA were determined by respective ELISA assay kits. ***P < 0.001 versus control group. #P < 0.05 and ###P < 0.001 versus H2O2 (5 μM) group. PCA: Protocatechuic acid, RA-FLSs: Rheumatoid arthritis fibroblast-like synoviocytes, MDA: Malonaldehyde, SOD: Superoxide dismutase, ELISA: Enzyme-linked immunosorbent assay.