Anti-Inflammatory Effects of Scopoletin and Underlying Mechanisms

The present study determined the anti-inflammatory activity and related mechanisms of scopoletin. It was found that scopoletin significantly inhibited croton oil-induced mouse ear edema. Scopoletin could also decrease the vascular dye leakage induced by topical application of croton oil, consistent with the reduced myeloperoxidase (MPO) activity and polymorphonuclear (PMN) infiltration. The inhibitor of nitric oxide (NO) synthase l-N^ω -nitro-arginine (l-NN, 10 mg/kg) attenuated croton oil-induced ear edema by 56.5%. However, pretreatment of l-NN did not affect the inhibitory effects of scopoletin (100 mg/kg) on mouse ear edema, which suggested that scopoletin exerted anti-inflammatory activities in an endothelial NO-independent manner. Further research revealed that scopoletin reduced the overproduction of PGE₂ and TNF-α in croton oil-treated mouse ears. Scopoletin was also shown to attenuate the hind paw edema induced by carrageenan in mice, and lower the MPO activity and malondialdehyde (MDA) level in paw tissues. These findings imply that the anti-inflammatory activities of scopoletin involve inhibition of eicosanoid biosynthesis, cell influx, and peroxidation.