Chinese propolis and its major bioactive compounds suppressed mastitis pathogen-induced NF-κB activation and induces ARE transcriptional activity. (a) Effects of CP on mastitis pathogen-induced NF-κB promoter activation in HEK-293T cells. Cells were pretreated with 20 μg/mL CP and identified isolated active compounds from propolis (caffeic acid, 50 μM; CAPE, 5 μM; chrysin, 50 μM; ferulic acid, 50 μM; galangin, 25 μM; kaempferol, 50 μM; pinocembrin, 50 μM; and quercetin, 50 μM) for 1 h and then stimulated with TNF-α (25 ng/mL) for another 12 h. ###P < 0.001 compared to the vehicle control; ∗P < 0.05 and ∗∗∗P < 0.001 compared to TNF-α control. (b) Effects of propolis on mastitis pathogens-induced ARE promoter activation in HEK-293T cells. Cells were treated with CP or identified isolated active compounds. tBHQ (15 μM) treatment for 7 h was used as ARE positive control. ∗P < 0.05 and ∗∗∗P < 0.001 compared to the vehicle control. The data represent the mean ± SD of four independent experiments.