Inhibitory effect of Derris reticulata ethanol extract on LPS-induced macrophage activation

Background: Deiris reticulata Craib is a Thai medicinal plant in the Legiuninosae family. It has flavonoids as major active compounds similar to other plants in genus Denis. Several flavonoids have been identified to have anti-inflammatory activities. The anti-inflammatory mechanisms and potency of flavonoids from this medicinal plant is not known.

Objective: We investigated the effect of ethanolic extract fr om stem of D. reticulata on LPS-induced macrophage activation.

Methods: J774A.1 cells were treated with 6.25-100 g/ml the extract for 24 horns and then activated with 100 ng/ml lipopolysaccharide (LPS) for 24 horns. Tire extract inhibited nitric oxide production in LPS-activated J774A. 1 cells in concentration-dependent maimer with IC₅₀ 62.5 μg/ml. The effect of this extract on phagocytosis activity of LPS-activated J774A. 1 cells was also investigated.

Results: The extract at concentrations of 50 and 100 pg/ml significantly inhibited zymosan phagocytosis of LPS-activated cells in a concentration dependent maimer. It decreased the mRNA expression of the inducible nitric oxide synthase (iNOS) which plays a role in NO production and the cyclo-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-β and IL-6 in the LPS-activated J774A. 1 cells.

Conclusion: The results hi this study reveal for the first time that the ethanolic extract of D. reticulata stem has potential anti-inflammatory activity. It inhibited production of several known inflammatory mediators in LPS-activated macrophages. These findings may be useful to study this plant further as a source of anti­inflammatory activity.