Down-regulation of TNFα secretion from activated microglial cells by Af extract. Microglial cells were treated with the indicated concentrations of Af extract, followed by stimulation with LPS (100 ng/mL). After 5 h, conditioned media were collected and tested for cytokine levels by ELISA. TNFα levels in the activated cells (designated as 100%) were 900 pg/mL. Data represent the means ± SEM of two independent experiments (n = 4). * p < 0.01; ** p < 0.001.