Anti-inflammatory activity of ginsenosides in LPS-stimulated RAW 264.7 cells

Ginsenosides, the main active constituents of Panax ginseng Meyer (P. ginseng), have potential therapeutic effects. All tested ginsenosides except ginsenoside F1 have previously been reported in inflammation studies using the RAW 264.7 macrophage cell line. We examined the anti-inflammatory effects of single sugar moiety ginsenosides such as compound K (CK), Rh2, Rh1, and F1 that were isolated from P. ginseng through in silico docking studies. We investigated their biological activity predictions, including absorption, distribution, metabolism, excretion, and toxicity and PASS properties, on the suppression of NF-κB, followed by in vitro validation in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The molecular docking results of our study showed that all treated ginsenosides are non-toxic and may be drug-like molecules. The molecular binding interactions of these ginsenosides with the active residues of NF-κB noticeably support their anti-inflammatory activity. CK and Rh1 significantly reduced the production of nitric oxide, cyclooxygenase-2 (COX-2), and pro-inflammatory cytokines such as prostaglandin E2 and tumor necrosis factor alpha (TNF-α) in a dose-dependent manner. Real-time PCR and Western blot analyses further confirmed that protopanaxadiols (PPDs) and protopanaxatriols (PPTs) inhibitory effects may have been due to the down-regulation of TNF-α, inducible nitric oxide synthase, COX2, nuclear factor kappa B (NF-κB), and I kappa B kinase. The expression of co-stimulatory molecules such as ROS was also inhibited by CK and Rh1 in a dose-dependent manner. Furthermore, activation of NF-κB in LPS-stimulated RAW 264.7 macrophages was significantly suppressed by CK and Rh1. Taken together, these results provide evidence that PPD- and PPT-type ginsenosides including CK and Rh1 may exhibit strong anti-inflammatory effects by inhibiting pro-inflammatory mediators through down-regulation of NF-κB.