Zanthoxylum rhetsa Stem bark extract inhibits LPS-induced COX-2 and iNOS expression in RAW 264.7 cells via the NF-κB inactivation

The methanol extract of Zanthoxylum rhetsa (MZRR) were evaluated for its ability to suppress the formation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)- activated RAW 264.7 macrophages. MZRR presented an inhibition of LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7 macrophages. Western blotting and RT-PCR analyses demonstrated that MZRR significantly inhibited the protein and mRNA expressions of iNOS and COX-2 in LPSactivated macrophages in a dose-dependent manner. LPS-induced COX-2, iNOS, and nuclear factor kappa beta (NF-κB) activity were also decreased in the presence of MZRR. The production of tumor necrosis factor-α (TNF- α), the mRNA expression levels of pro-inflammatory cytokines, including TNF-α and IL-1β, were reduced after MZRR administration in a dose dependent-manner. These results suggest that the MZRR extract involved in the inhibition of iNOS and COX-2 via the NF-κB pathway, revealing a partial molecular basis for anti-inflammatory properties of the MZRR extract.