9-Hydroxy-isoegomaketone inhibits LPS-induced NO and inflammatory cytokine production in RAW264.7 cells

Isoegomaketone (IK) is a known component of Perilla frutescens that reportedly exhibits anti-inflammatory, anti-cancer and anti-allergic properties. A novel compound known as 9-HIK has been isolated from the extract of a radiation mutant P. frutescens var. crispa using supercritical carbon dioxide. In the present study, 9-HIK induced heme oxygenase-1 (HO-1) mRNA expression in RAW264.7 cells, with maximal levels observed 4 h after 9-HIK treatment. In addition, 9-HIK inhibited the mRNA and protein expression of pro-inflammatory mediators, such as IL-6 and interferon-β, as well as the production of nitric oxide (NO) in lipopolysaccharide-stimulated RAW264.7 cells. Furthermore, N-acetyl-L-cysteine, a reactive oxygen species scavenger, inhibited NO production and HO-1 mRNA expression levels through the nuclear factor erythroid 2-related factor 2 pathway. Overall, 9-HIK displayed anti-inflammatory properties in LPS-induced RAW264.7 cells via direct suppression of inflammatory mediators and HO-1 induction.