Inhibitory mechanism of saponins derived from roots of Platycodon grandiflorum on anaphylactic reaction and IgE-mediated allergic response in mast cells

The purpose of this study was to investigate the protective effects of saponins isolated from the root of Platycodi Radix (Changkil saponins: CKS) anti-allergic effects in mice and mast cells. Oral administration of CKS inhibited the dinitrophenyl (DNP)–IgE antibody-induced systemic PCA reaction in mice. CKS reduced the β-hexosaminidase and histamine release from anti-DNP–IgE-sensitized RBL–2H3 cells. In addition, CKS inhibited the IgE antibody-induced increases in IL-4 and TNF-α production and expression in RBL-2H3 cells. In order to explore the inhibitory mechanism of CKS in PCA and mast cell degranulation, we examined the activation of intracellular signaling molecules. CKS suppressed DNP–IgE antibody-induced Syk phosphorylation. Further downstream, CKS also inhibited the phosphorylation of Akt and MAP kinases. Taken together, the in vivo/in vitro anti-allergic effects of CKS suggest possible therapeutic applications for this agent in allergic diseases through the inhibition of inflammatory cytokines and Syk-dependent signaling cascades.