Rotula aquatica Lour attenuates secretion of proinflammatory mediators and cytokines in lipopolysaccharide-induced inflammatory responses in murine RAW 264.7 macrophages

Rotula aquatica belongs to the family Boraginaceae, and is reported to contain baunerol, steroids and alkaloids. In Ayurveda, R. aquatica has been used for the treatment of various diseases such as diabetes, treatment of piles, venereal disease, and cancer. The current study aims to investigate the anti-inflammatory effect of methanolic extract of R. aquatica (MERA) in RAW 264.7 cells. The cytotoxicity of MERA was analyzed by MTT assay. The total cyclooxygenase (COX) activity, 5-lipoxygenase (5-LOX) activity, myeloperoxidase activity, inducible nitric oxide synthase activity, nitrate level and reactive oxygen species production were studied in LPS-stimulated RAW 264.7 cells. The gene level expression of cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) were also evaluated in this study. The MERA did not show any cytotoxicity at different concentrations (6.25–100 µg/ml). MERA (100 μg/ml) inhibited total COX and 5-LOX activity at 50.53 and 62.03%, respectively, besides significantly (p < 0.05) diminished nitrate and ROS generation, when compared with LPS control. Moreover, MERA down-regulated the mRNA expressions of inflammatory marker genes like TNF-α, IL-6, and COX-2 against LPS stimulation. Our results demonstrate that MERA is able to attenuate inflammatory response, possibly via ROS and NO suppression, inhibiting the production of arachidonic acid metabolites and modulation of proinflammatory mediators and cytokines release.