Secondary metabolites isolated from Castilleja rubra exert anti-inflammatory effects through NF-κB inactivation on lipopolysaccharide-induced RAW264.7 macrophages.

8-Epiloganin (1), mussaenoside (2), and 5-O-caffeoylshikimic acid (3) have been isolated from Castilleja rubra, and the anti-inflammatory properties of these metabolites in a cell culture system were investigated. Compounds 1-3 suppressed not only the production of nitric oxide (NO) and prostaglandin E2, but also the expression of inducible NO synthase and cyclooxygenase-2 induced by lipopolysaccharide (LPS) in the RAW264.7 murine macrophage cell line. Compounds 1-3 also inhibited the release of pro-inflammatory cytokines induced by LPS, namely, tumor necrosis factor-α and interleukin-1β. The underlying mechanism of the anti-inflammatory action of compounds 1-3 was associated with downregulation of nuclear factor-κB.