Inhibition of Lipopolysaccharide-Induced iNOS, COX-2, and TNF-α Expression by Aqueous Extract of Orixa Japonica in RAW 264.7 Cells via Suppression of NF-κB Activity

Abstract

Purpose: To investigate the anti-inflammatory effects of aqueous extract of Orixa japonica (AEOJ) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Methods: The expression of mRNA and protein using RT-PCR and Western blot analysis was investigated. The level of nitric oxide (NO) production was analyzed using Griess reaction. Release of prostaglandin E2 (PGE2) and tumor necrosis factor-α (TNF-α) was determined using sandwich ELISA. Results: AEOJ potently inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor-α (TNF-α) in LPS-stimulated RAW 264.7 cells. Consistent with these findings, AEOJ was also found to significantly reduce LPS-induced expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and TNF-α at the transcriptional level. Additionally, AEOJ attenuated LPSinduced NF-κB activity via the inhibition of IκB phosphorylation and degradation. It was also found that the NF-κB inhibitor N-acetyl cysteine (NAC) attenuated LPS-induced gene expression of iNOS, COX-2, and TNF-α. These results indicate that AEOJ attenuates LPS-induced inflammatory mediators such as NO, PGE2, and TNF-α via suppression of NF-κB activity. Conclusion: These results suggest that AEOJ has a potential activity to alleviate LPS-induced inflammation. © Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria.