Inhibitory Effect of Aqueous Extract from Lonicera japonica Flower on LPS-induced Inflammatory Mediators in RAW 264.7 Macrophages.

금은화 수용성 추출물의 LPS 유도 염증매개물 억제 효과

Objective : Lonicera japonica (Caprifoliaceae) has long been used for treatment of infectious diseases in oriental countries. The aim of this study was to investigative the effect by which the aqueous extract from flower of L. japonica (LJFAE) inhibited the lipopolysaccharide (LPS)-induced inflammatory mediators in murine macrophages, RAW 264.7 cells Methods : The dried flowers of L. japonica were extracted with distilled water at $100^{\circ}C$ for 7 h. The extract was filtered through 0.45 ${\mu}m$ filter, freeze-dried. The dried extract was dissolved in Hank's balanced salt solution (HBSS) and filtered through 0.22 ${\mu}m$ filter before use. Accumulated nitrite, an oxidative product of nitric oxide (NO), was measured in the culture medium by the Griess reaction. The levels of prostaglandin E2 (PGE2), tumor necrosis factor-$\alpha$ (TNF-$\alpha$), interleukin-1$\beta$ (IL-1$\beta$), and IL-6 production, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression were measured by enzyme-linked immunosorbent assay and Western blot analysis. Results: LJFAE (10-400 ${\mu}g$/ml) per se had no cytotoxic effect in unstimulated macrophages, but LJFAE concentration-dependently reduced NO, PGE2, TNF-, IL-l, and IL-6 production and COX-2 activity caused by stimulation of LPS. The levels of iNOS and COX-2 protein expressions were markedly suppressed by the treatment with LJFAE in a concentration dependent manner. Conclusions : These results suggest that LJFAE suppress the NO and PGE2production in macrophages by inhibiting iNOS and COX-2 expression and these properties may contribute to the anti-inflammatory activity of Lonicera japonica.