α-Cyperone, isolated from the rhizomes of Cyperus rotundus, inhibits LPS-induced COX-2 expression and PGE₂ production through the negative regulation of NFκB signalling in RAW 264.7 cells

Ethnopharmacological relevance: The rhizomes of Cyperus rotundus (Cyperaceae) have been used in Asian traditional medicine for the treatment of several inflammatory diseases. However, the anti-inflammatory effects of α-cyperone, a major active compound of Cyperus rotundus, are poorly understood. Materials and methods: PGE₂ and cytokines released from cells were measured using an EIA assay kit. The expression of iNOS, COX-2, TNF-α, and IL-6 was measured by real-time RT-PCR and/or Western blot analysis. A luciferase assay was performed to measure the effect of α-cyperone on NFκB activity. Results: The n-hexane fraction of the 80% EtOH extract from the rhizomes of Cyperus rotundus was found to inhibit both NO and PGE₂ production in RAW 264.7 cells. α-Cyperone isolated from the n-hexane fraction significantly inhibited PGE₂ production by suppressing the LPS-induced expression of inducible COX-2 at both the mRNA and the protein levels. In contrast, α-cyperone had little effect on NO production and iNOS expression. Additionally, α-cyperone downregulated the production and mRNA expression of the inflammatory cytokine IL-6. Moreover, treatment with α-cyperone suppressed the transcriptional activity of NFκB and the nuclear translocation of the p65 NFκB subunit in LPS-induced RAW 264.7 cells. Conclusion: The anti-inflammatory activity of α-cyperone is associated with the down-regulation of COX-2 and IL-6 via the negative regulation of the NFκB pathway in LPS-stimulated RAW 264.7 cells.