4.8. Measurement of Pro-Inflammatory Cytokines

The levels of TNF-α, IL-1β, IL-6 and PGE2 were measured with an ELISA kits as previously described [43]. In brief, cells were cultured at the density of 1 × 10⁶ cells/mL. After incubation for 12 h, RAW264.7 cells were treated with different concentrations of tested samples and then stimulated with LPS (1 μg/mL) for 18 h. In the experiment, we used dexamethasone as the positive control. The culture supernatants were detected using a specific ELISA kit for TNF-α, IL-1β, IL-6 and PGE2 according to the manufacturer’s instructions.