Anti-inflammatory Triterpenoid Saponins from the Stem Bark of Kalopanax pictus

Five new compounds, 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), 3-O-[2,3-di-O-acetyl-α-l-arabinopyranosyl]hederagenin 28-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (4), and 3-O-[3,4-di-O-acetyl-α-l-arabinopyranosyl]hederagenin 28-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (5), as well as 10 known compounds (6–15), were isolated from the stem bark of Kalopanax pictus. Compounds 1–5 and 7–14 inhibited TNFα-induced NF-κB transcriptional activity in HepG2 cells in a dose-dependent manner, with IC50 values ranging from 0.6 to 16.4 μM. Furthermore, the transcriptional inhibitory function of these compounds was confirmed on the basis of decreases in COX-2 and iNOS gene expression in HepG2 cells. The structure–activity relationship of the compounds with respect to anti-inflammatory activity is also discussed.