Figure 1. P. frutescens extract (PFE) inhibited O₂˙^– production, elastase release, and formation of reactive oxygen species (ROS) in N-formyl-Met-Leu-Phe (fMLF)-activated human neutrophils.

Human neutrophils (6 × 10⁵ cells/ml)were pre-incubated with dimethylsulfoxide (DMSO) or PFE (1, 3, and 10 μg/ml) and then activated with fMLF (0.1 μM). (A,B) O₂˙^– and elastase release were detected spectrophotometrically using cytochrome c reduction and elastase substrate, respectively. (C) The fluorescence intensity of dihydrorhodamine 123 (DHR123) was used to detect the intracellular ROS. The ROS formation in fMLF-activated neutrophils pretreated with PFE (red line) was decreased, as compared with those without PFE (black line). The dashed line indicated neutrophils that were not treated with fMLF (basal group). (D) The mean values of fluorescence intensity from panel C. Data are expressed as the mean ± standard error of the mean, n = 7, *p < 0.05, ***p < 0.001, as compared to the fMLF group.