Triterpenoid saponin, oleanolic acid 3-O-β-d-glucopyranosyl(1 → 3)-α-l-rhamnopyranosyl(1 → 2)-α-l-arabinopyranoside (OA) from Aralia elata inhibits LPS-induced nitric oxide production by down-regulated NF-κB in raw 264.7 cells

It is well known that the pro-inflammatory mediators such as nitric oxide (NO) and prostaglandin (PG)E₂ are involved in several inflammatory diseases and lipopolysaccharide (LPS) can stimulate these inflammatory responses. Oleanolic acid 3-O-β-d-glucopyranosyl(1 → 3)-α-l-rhamnopyranosyl(1 → 2)-α-l-arabinopyranoside (OA) was purified from edible plant Aralia elata. OA inhibited LPS-induced NO and PGE₂ production in raw 264.7 murine macrophages in a dose-dependent manner and RT-PCR analysis indicated OA inhibited mRNA transcriptions of iNOS and COX-2 genes in LPS-induced cells. EMSA and Western blot analysis revealed that OA drastically reduced NF-κB translocation by the inhibition effects of LPS-induced phosphorylation of IκBα. In addition, it was found that OA inhibited the phosphorylation of ERK1/2, p38 and JNK MAPK, and the treatment of U0126 in LPS-induced raw 264.7 cells showed significant inhibition activity on the NO production and the phosphorylation of IκBα. Taken together, it is suggested that OA from A. elata has an anti-inflammatory activity via down-regulation of NF-κB.