Ginsenosides compound K and Rh(2) inhibit tumor necrosis factor-alpha-induced activation of the NF-kappaB and JNK pathways in human astroglial cells.

Ginsenosides, the main component of Panax ginseng, have been known for the anti-inflammatory and anti-proliferative activities. In this study, we investigated the molecular mechanisms responsible for the anti-inflammatory effects of ginsenosides on activated astroglial cells. Among 13 different ginsenosides, intestinal bacterial metabolites Rh(2) and compound K (C-K) showed a significant inhibitory effect on tumor necrosis factor-alpha (TNF-alpha)-induced expression of intercellular adhesion molecule-1 in human astroglial cells. Pretreatment with C-K or Rh(2) suppressed TNF-alpha-induced phosphorylation of IkappaBalpha kinase and the subsequent phosphorylation and degradation of IkappaBalpha. Additionally, the same treatment inhibited TNF-alpha-induced phosphorylation of MKK4 and the subsequent activation of the JNK-AP-1 pathway. The inhibitory effect of ginsenosides on TNF-alpha-induced activation of the NF-kappaB and JNK pathways was not observed in human monocytic U937 cells. These results collectively indicate that ginsenoside metabolites C-K and Rh(2) exert anti-inflammatory effects by the inhibition of both NF-kappaB and JNK pathways in a cell-specific manner.