Anti-inflammatory activity of the ethanol extract of Dictamnus dasycarpus leaf in lipopolysaccharide-activated macrophages

Dictamnus dasycarpus is widely used as a traditional remedy for the treatment of eczema, rheumatism, and other inflammatory diseases in Asia. The current study investigates the molecular mechanism of anti-inflammatory action of the ethanol extract of Dictamnus dasycarpus leaf (DE) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Nitric oxide (NO) production was assessed by Griess reaction and the mRNA and protein expressions of pro inflammatory cytokines, transcription factor, and enzymes were determined by real-time RT-PCR and immunoblotting analysis. DE (0.5 and 1 mg/mL) suppressed the NO production by 10 and 33%, respectively, compared to the untreated group in LPS-stimulated RAW 264.7 cells. DE (0.5 and 1 mg/mL) reduced the mRNA expression of key transcription factor nuclear factor-κB by 7 and 24%, respectively compared to the untreated group in LPS activated macrophage. The pro inflammatory cytokines such as tumor necrosis factor α and interleukin 1β were also decreased by DE treatment. Moreover, the protein expression of pro inflammatory enzymes, inducible nitric oxide synthase and cyclooxygenase 2 were also dramatically attenuated by DE in a dose dependent manner. These results suggest that Dictamnus dasycarpus leaf has a potent anti-inflammatory activity and can be used for the development of new anti-inflammatory agents.