Mitragynine inhibits the COX-2 mRNA expression and prostaglandin E2 production induced by lipopolysaccharide in RAW264.7 macrophage cells

Ethopharmacological relevanceMitragyna speciosa Korth (Rubiaceae) is one of the medicinal plants used traditionally to treat various types of diseases especially in Thailand and Malaysia. Its anti-inflammatory and analgesic properties in its crude form are well documented. In this study, the cellular mechanism involved in the anti-inflammatory effects of mitragynine, the major bioactive constituent, was investigated.Materials and methodsThe effects of mitragynine on the mRNA and protein expression of COX-1 and COX-2 and the production of prostaglandin E2 (PGE2) were investigated in LPS-treated RAW264.7 macrophage cells. Quantitative RT-PCR was used to assess the mRNA expression of COX-1 and COX-2. Protein expression of COX-1 and COX-2 were assessed using Western blot analysis and the level of PGE2 production was quantified using Parameter™ PGE2 Assay (R&D Systems).ResultsMitragynine produced a significant inhibition on the mRNA expression of COX-2 induced by LPS, in a dose dependent manner and this was followed by the reduction of PGE2 production. On the other hand, the effects of mitragynine on COX-1 mRNA expression were found to be insignificant as compared to the control cells. However, the effect of mitragynine on COX-1 protein expression is dependent on concentration, with higher concentration of mitragynine producing a further reduction of COX-1 expression in LPS-treated cells.ConclusionsThese findings suggest that mitragynine suppressed PGE2 production by inhibiting COX-2 expression in LPS-stimulated RAW264.7 macrophage cells. Mitragynine may be useful for the treatment of inflammatory conditions.

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