Nuclear Factor-κB/Signal Transducers and Activators of Transcription-1-Mediated Inflammatory Responses in Lipopolysaccharide-Activated Macrophages Are a Major Inhibitory Target of Kahweol, a Coffee Diterpene

Diterpene kahweol, one of the major components in coffee, has anti-cancer, anti-oxidative, and anti-inflammatory activity. In this study, we explored the molecular mechanism of the anti-inflammatory activity of kahweol. Lipopolysaccharide (LPS)-activated RAW264.7 cells were used to explore the modulatory role of kahweol on nitric oxide (NO) and prostaglandin E-2 (PGE(2)) production and the activation of signaling proteins and transcription factors using immunoblotting and reverse transcription-polymerase chain reaction (RT-PCR). Kahweol diminished both the production of NO and PGE(2) and the mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2. Interestingly, this compound suppressed the phospho-signal transducers and activators of transcription (STAT)-1 and p65/nuclear factor (NF)-kappa B levels in the nucleus but not c-Jun and c-fos. In conjunction, the phosphorylation of Akt and Janus kinase (JAK)2 also decreased. Therefore, our data suggest that kahweol in coffee may be an anti-inflammatory modulator with NF-kappa B/STAT-1-targeted inhibitory properties in LPS-activated RAW264.7 cells.