Ursolic Acid from Perilla frutescens (L.) Britt. Regulates Zymosan-Induced Inflammatory Signaling in Raw 264.7

Background: Inflammation is considered one of the hallmarks of inflammatory diseases. Ursolic acid (UA) may exert therapeutic effects; however, the anti-inflammatory effects of UA require further study. Objectives: This study evaluated the effects of UA from Perilla frutescens (L.) Britt. leaves on pro-inflammatory activity induced by zymosan. Methods: Ursolic acid was extracted from P.frutescens (L.) Britt. leaves using ethanol, and thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) were used for UA analysis. The effect of UA on zymosan-induced cytokine production was evaluated by enzyme-linked immunosorbent assay (ELISA). Western blotting detected phosphorylation of extracellular signal-regulated kinases (ERK) 1/2, p38, and p47phox in Raw 264.7 cells. Reactive oxygen species (ROS) were measured using a specific immunofluorescent dye. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activities were assayed using a luminometer. Results: Zymosan-induced tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-12 p40 in macrophages were significantly inhibited by UA (30 μg/mL, P < 0.001). In addition, UA (30 μg/mL, P < 0.001) significantly inhibited zymosan-induced phosphorylation of ERK1/2, p38, p47phox, ROS, and NADPH oxidase in the cells. Importantly, blockade of Dectin-1 using laminarin, a pure β-glucan, markedly abrogated the UA-mediated inhibition of zymosan-induced production of inflammatory cytokines, ERK1/2, p38, ROS, and p47phox phosphorylation in macrophages. Conclusions: Collectively, these data indicate that UA regulates zymosan-induced inflammatory responses and suggest novel approaches for managing excessive inflammatory responses.