Anti-inflammatory constituents isolated from the flowers of Hosta plantaginea via suppression of the NF-κB signaling pathway in LPS-stimulated RAW 264.7 macrophages

Hosta plantaginea (Lam.) Aschers flower is traditionally used in China as an important herbal medicine for the treatment of inflammatory disease. The present study isolated one new compound, namely (3R)-dihydrobonducellin (1), and five known ones, p-hydroxycinnamic acid (2), paprazine (3), thymidine (4), bis(2-ethylhexyl) phthalate (5), and dibutyl phthalate (6) from H. plantaginea flowers. These structures were elucidated from spectroscopic data. Among them, compounds 1–4 remarkably suppressed nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells with half maximal inhibitory concentration (IC(50)) values of 19.88 ± 1.81, 39.80 ± 0.85, 19.03 ± 2.35, and 34.63 ± 2.38 μM, respectively. Furthermore, compounds 1 and 3 (20 μM) significantly decreased levels of tumor necrosis factor α (TNF-α), prostaglandin E2 (PGE2), interleukin 1β (IL-1β), and IL-6. Additionally, compounds 1 and 3 (20 μM) prominently reduced the phosphorylation protein level of nuclear factor kappa-B (NF-κB) p65. The present findings indicated that compounds 1 and 3 may be new candidates against inflammation via blocking the NF-κB signaling pathway.