Inhibitory effect of moschamine isolated from Carthamus tinctorius on LPS-induced inflammatory mediators via AP-1 and STAT1/3 inactivation in RAW 264.7 macrophages

Abstract

Seeds of Carthamus tinctorius L. (Compositae) have been used in Korean traditional medicines for the treatment of cardiovascular and bone diseases. In this study, we investigated the anti-inflammatory effects of known serotonin derivatives (1–9) isolated from the ethyl acetate (EtOAc) soluble fraction from the seeds of C. tinctorius. Compound 2, identified as moschamine, most potently inhibited lipopolysaccharide (LPS)-induced production of prostaglandin E2 (PGE2) and nitric oxide (NO) in RAW 264.7 macrophages. Moschamine concentration-dependently inhibited LPS-induced PGE2 and NO production in RAW 264.7 macrophages. Consistent with these findings, moschamine suppressed the protein and mRNA levels of cyclooxygenase-2 (COX-2), microsomal prostaglandin E2 synthase (mPGES)-1, and inducible NO synthase (iNOS), interleukin (IL)-6, and IL-1β. In addition, pretreatment of moschamine significantly inhibited LPS-stimulated the transcriptional activity of activator protein-1 (AP-1) and the phosphorylation of signal transducer and activator of transcription (STAT)1/3 in RAW 264.7 macrophages. Moreover, moschamine inhibited LPS-induced the phosphorylation of p38 mitogen-activated protein kinase (p38) and extracellular signal-regulated kinase (ERK), but it had no effect on c-Jun N-terminal kinase (JNK). These results suggest that the mechanism of anti-inflammatory activity of moschamine is associated with the downregulation of COX-2, mPGES-1, iNOS, IL-6, and IL-1β expression through the suppression of AP-1 and STAT1/3 activation in LPS-induced RAW 264.7 macrophages.