Anti-inflammatory activity of phylligenin, a lignan from the fruits of Forsythia koreana, and its cellular mechanism of action

Aim of the study: The fruits of Forsythia koreana have long been used in Chinese medicine to treat inflammatory disorders. However, the pharmacological data is not sufficient to clearly establish a scientific rationale for the anti-inflammatory medicinal use of this plant material, and the search for its active principles has been limited so far. Materials and methods: Phylligenin (lignan) was isolated from the fruits of Forsythia koreana and its anti-inflammatory activity was examined. Results and conclusion: Phylligenin (1-100 mu M) and the methanol extract of Forsythia koreana fruits inhibited cyclooxygenase-2 (COX-2)-mediated prostaglandin E-2 and inducible nitric oxide synthase (iNOS)-mediated nitric oxide (NO) synthesis from lipopolysaccharide-treated RAW 264.7 cells. In the mechanism study, phylligenin inhibited iNOS expression and nuclear factor-kB (NF-kB) activation but had no effect on COX-2 expression. Moreover, phylligenin significantly inhibited mouse carrageenan-induced paw edema by intraperitoneal administration (22.1-34.7% inhibition at 12.5-100 mg/kg). These pharmacological properties indicate that phylligenin possesses significant anti-inflammatory activity in vitro and in vivo, and may provide the scientific rationale for anti-inflammatory use of the fruits of Forsythia koreana. (C) 2008 Elsevier Ireland Ltd. All rights reserved.