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

Aim of the studyThe 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 methodsPhylligenin (lignan) was isolated from the fruits of Forsythia koreana and its anti-inflammatory activity was examined.Results and conclusionPhylligenin (1–100 μM) and the methanol extract of Forsythia koreana fruits inhibited cyclooxygenase-2 (COX-2)-mediated prostaglandin E2 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-κB (NF-κB) 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.