Roots of Erigeron annuus Attenuate Acute Inflammation as Mediated with the Inhibition of NF- κ B-Associated Nitric Oxide and Prostaglandin E2 production.

Erigeron annuus is a naturalized plant belonging to Compositae (asteraceae) family, which is called the annual fleabane, and commonly found at meadows and roadside. This study investigated the anti-inflammatory effects of the extract of E. annuus roots (EER), as assessed by the paw edema formation and histological analysis in rat, and the productions of nitric oxide (NO), prostaglandin E2 (PGE2), and pro-inflammatory cytokines in Raw264.7 murine macrophages. Carrageenan treatment promoted infiltration of inflammatory cells and caused swelling in the hind paw. Oral administrations of EER (0.3 g/kg and 1 g/kg) attenuated acute inflammation similar to the result using dexamethasone (1 mg/kg). Treatment of macrophages with lipopolysaccharide (LPS) simulated inflammatory condition: LPS significantly increased the productions of NO, PGE2, and proinflammatory cytokines. EER suppressed activation of macrophages, preventing the induction of iNOS and COX-2 protein expressions. LPS treatment induced phosphorylation of I- κ B α and increased the level of nuclear NF- κ B protein, both of which were suppressed by concomitant treatment of EER. In conclusion, EER ameliorated acute inflammation in rats, and the induction of NO, PGE2, and proinflammatory cytokines in Raw264.7 cells. EER's effects may be associated with its inhibition of NF- κ B activation, suggesting its effect on inflammatory diseases.