Anti-inflammatory potential of an ethyl acetate fraction isolated from Justicia gendarussa roots through inhibition of iNOS and COX-2 expression via NF-κB pathway

► Ethyl acetate (EJG) extract is more potent than other extracts in carrageenan induced paw edema. ► EJG was investigated for its anti-inflammatory mechanisms in vitro in LPS-stimulated peripheral mononuclear cells (hPBMCs). ► EJG inhibited the activation of cyclooxygenase, 5-lipoxygenase, interleukin-6 and nuclear factor kappa B in hPBMCs. ► EJG reduced the LPS induced expression of iNOS and COX-2 genes in hPBMCs. Justicia gendarussa Burm.f. ( J. gendarussa) is a plant used as traditional medicine in different parts of India and China to treat inflammatory disorders like rheumatoid arthritis. But its mechanism of anti-inflammatory action is still unclear. Hence in this context, the objective of our study is to reveal the mechanism of anti-inflammatory activity of J. gendarussa which would form an additional proof to the traditional knowledge of this plant. The anti-inflammatory function and mechanism(s) of action was studied in an ethyl acetate fraction isolated from methanolic extract of J. gendarussa roots (EJG). Anti-inflammatory studies were conducted on rats using partitioned fractions isolated from methanolic extract of J. gendarussa roots. In carrageenan-induced rat paw edema, ethyl acetate fraction brought about 80% and 93% edema inhibition at 3rd and 5th hour at a dose of 50 mg/kg, when compared to other extracts and Voveran. We investigated whether EJG inhibits the release of cycloxygenase (COX), 5-lipoxygenase (5-LOX), interleukin-6 (IL-6) and nuclear factor kappa B (NF-κB) in LPS stimulated human peripheral blood mononuclear cells (hPBMCs). Results shows that EJG dose dependently inhibited LPS-activated COX, 5-LOX, IL-6, and NF-κB in hPBMCs. EJG also reduced LPS induced levels of iNOS and COX-2 mRNA expression in hPBMCs. This study provides an insight into the probable mechanism(s) underlying the anti-inflammatory activity of EJG and therefore, we report the first confirmation of the anti-inflammatory potential of this traditionally employed herbal medicine in vitro.