| Summary: | Compound K, a major metabolite of ginsenosides Rb1, which is produced by human intestinal bacteria after oral administration, is one of the main pharmacologic compounds found in ginseng. In our previous study, we demonstrated that compound K inhibited the production of nitric oxide (NO) and prostaglandin E2 in lipopolysaccharide (LPS)-treated RAW264.7 cells. However, the mechanisms by which compound K may be effective against inflammation remain unknown. In the present study, compound K significantly inhibited LPS-induced NO production by suppression of inducible NO synthase (iNOS) in LPS-treated RAW264.7 cells. Compound K also inhibited LPS-induced cyclooxygenase-2 (COX-2) expression at both the mRNA and protein levels. It effectively suppressed both the release and mRNA expression levels of pro-inflammatory cytokines such as interleukin-1β (IL-1β) and IL-6. The anti-inflammatory effects of compound K appeared to occur via inhibition of LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs) and inhibition of NF-κB translocation from the cytosol to the nucleus by suppressing phosphorylation of inhibitory kappa B-α (IκB-α). Furthermore, we showed that compound K inhibited LPS-induced NO generation in an experimental zebrafish model. Considering these results, compound K could potentially be developed as a natural anti-inflammatory agent.
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