Anti-Inflammatory effect of Dangyuja (Citrus grandis osbeck) Leaves in LPS-Stimulated RAW 264.7 Cells

Dangyuja (Citrus grandis Osbeck) is a native plant growing only on Jeju Island in Korea. In this study, antiinflammatory effect of dangyuja leaves on a murine macrophage cell line was investigated. RAW 264.7 murine macrophage cells were stimulated with lipopolysaccharide (LPS, 1 μg/mL) to induce expression of pro-inflammatory markers [interleukin (IL)-6 and inducible nitric oxide synthase (iNOS)]. The crude extract (80% MeOH Ex.) and solvent fractions (hexane, CHCl₃, EtOAc, BuOH, and H₂O Ex.) were obtained from dangyuja leaves. The CHCl3 fraction inhibited the nitric oxide (NO) and IL- 6 production in a dose-dependent manner. Also, the CHCl₃ fraction inhibited mRNA expression and protein levels of iNOS in a dose-dependent manner. Furthermore, the CHCl₃ fraction inhibited LPS-induced nuclear factor (NF)-κB activation and phosphorylation of mitogen-activated protein kinases (MAPKs: ERK, JNK, and p38). These results suggest that dangyuja leaves may inhibit LPS-induced production of inflammatory markers by blocking NF-κB and MAPKs signaling in RAW 264.7 cells.