Methanol extract of Guettarda speciosa Linn. inhibits the production of inflammatory mediators through the inactivation of Syk and JNK in macrophages

초록

Guettarda speciosa Linn. (G. speciosa, Rubiaceae) has been used as a traditional medicinal plant in Asia for the treatment of various inflammatory conditions, including cough, fever and maternal postpartum infection. However, the mechanisms underlying the anti-inflammatory action of G. speciosa extracts have remained elusive. In the present study, the anti-inflammatory effects of the methanol extract of G. speciosa (MGS) were investigated in murine macrophages by measuring the production of inflammatory mediators and the underlying mechanisms of action by performing immunoblotting analysis of proteins that are potentially involved. MGS reduced nitric oxide (NO) production through regulation of the expression of inducible NO synthase (iNOS) in lipopolysaccharide-activated RAW 264.7 cells; however, cyclooxygenase-2, the enzyme responsible for prostaglandin E-2 production, was not affected at the mRNA or protein level. MGS reduced interleukin-6 (IL-6) production, but had no effect on tumor necrosis factor (TNF)-alpha production. In addition, MGS suppressed the transcription of IL-6, but not that of IL-1 beta and TNF-alpha. The effect of MGS on proinflammatory mediators resulted from the inhibition of the activation of spleen tyrosine kinase and c-Jun N-terminal kinase. In conclusion, the present study suggested that MGS may be a potential candidate for development as a therapeutic for alleviating inflammation.

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