Inhibitory effect on lipopolysaccharide-induced macrophage activation of an extract from derris reticulata

Abstract

Derris reticulata Craib is a Thai medicinal plant in the Leguminosae family. This plant has been used as expectorant and thirst relief. It has flavonoids as major active compounds similar to other plants in genus Derris. Several flavonoids have been identified to have anti-inflammatory activities. This study intended to investigate the effect of ethanolic extract from stem of D. reticulata on LPS-induced macrophage activation. Murine macrophage, J774A.1 cells, were treated with 6.25-100 µg/ml the extract for 24 h and then stimulated with 100 ng/ml lipopolysaccharide (LPS) for 24 h. The extract inhibited nitric oxide production in LPS-activated J774A.1 cells in concentration-dependent manner with IC₅₀ 62.5 µg/ml. The effect of this extract on phagocytosis activity of LPS-activated J774A.1 cells was also investigated. The extract at the concentrations of 50 and 100 µg/ml significantly inhibited zymosan phagocytosis of LPS-activated cells in a concentration dependent manner. It decreased the mRNA expression of the inducible nitric oxide synthase (iNOS) which plays role in NO production and the cy clo-oxygenase 2 (COX-2) which is responsible for prostaglandins (PGs) production in LPS-activated J774A.1 cells. This extract also inhibited the mRNA expression of pro-inflammatory cytokines, TNF- α, IL-1β and IL-6 in the LPS-activated J774A.1 cells. The results in this study reveal for the first time that the ethanolic extract of D. reticulate stem has potential anti-inflammatory activity. It inhibited production of several known inflammatory mediators in LPS-activated macrophages. These findings may be a useful information for developing this plant or it constituents to treat inflammation in the future.