Effect of polyphenol-rich plant extracts on ROS, IL-6 and MCP-1 production from preadipocytes exposed to TNFα. (a) Cells were exposed to 10 μM of DCFH-DA for 45 min at 37°C and then were treated with TNFα (5 ng/mL) in the presence or not of each plant extract (25 μM GAE) or caffeic acid (25 μM) for 1 h. (b) Cells were treated with TNFα (5 ng/mL) in the presence or not of each plant extract (25 μM GAE) for 24 h. Then, levels of IL-6 were measured by ELISA kit. (c) According to the experimental condition used for IL-6 detection, levels of MCP-1 were measured by ELISA kit. Data are means ± SEM of three independent experiments. *: p < 0.05, **: p < 0.01, ***: p < 0.001, ****: p < 0.0001 as compared to TNFα.