Inhibitory effects of oleanane-type triterpenes and saponins from the stem bark of Kalopanax pictus on LPS-stimulated pro-inflammatory cytokine production in bone marrow-derived dendritic cells

Kalopanax pictus (Araliaceae) is a deciduous tree distributed in Korea, Japan, and China. The stem bark of K. pictus has been functionally used as a traditional crude drug for the treatment of various inflammatory diseases. In the present study, we describe the inhibitory effects of oleanane-type triterpenes and saponins isolated from the stem bark of K. pictus on production of pro-inflammatory cytokines in LPS-stimulated bone marrow-derived dendritic cells. Of the compounds tested, 16,23,29-trihydroxy-3-oxo-olean-12-en-28-oic acid (1), 4,23,29-trihydroxy-3,4-seco-olean-12-en-3-oate-28-oic acid (2), 3β,6β,23-trihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (3), nipponogenin E (6), 3β,6β,23-trihydroxyolean-12-en-28-oic acid (7), and caulophyllogenin (19) significantly inhibited the production of IL-12 p40 and IL-6 with IC₅₀ values ranging from 3.3 to 9.1 μM. Compounds 2, 3, 7, and 19 significantly suppressed the secretion of TNF-α with IC₅₀ ranging from 8.8 to 20.0 μM. These data provide scientific support for the use of K. pictus stem bark and its triterpene and saponin components in the inhibition of pro-inflammatory cytokine secretion, including IL-12 p40, IL-6, and TNF-α, and for prevention and treatment of inflammatory diseases.