New diterpenoids and sesquiterpenoids from Siegesbeckia pubescens Makino and their anti-inflammatory activity

Abstract

Six undescribed terpenoids were isolated from the aboveground parts of Siegesbeckia pubescens Makino. These compounds include four diterpenoids (1–4) and two sesquiterpenoids (5–6), as well as thirteen known compounds (7–19). The structures of new compounds were determined through spectroscopic analysis, DP4+ Analysis and ECD calculation. The protective effect of all compounds against lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 cells was tested. The result showed that compounds 2–9, 12–15 and 17–19 significantly inhibited the production of nitric oxide (NO) in LPS-induced RAW 264.7 cells, among which compound 18 demonstrated the best inhibitory activity against NO release. The potential anti-inflammatory mechanism was investigated through molecular docking. The molecular docking results showed that the active compounds had a strong binding affinity with the key targets. In conclusion, Siegesbeckia pubescens Makino has demonstrated multi-component, multi-target and multi-pathway therapeutic characteristics in the treatment of inflammation. These findings provide a valuable theoretical basis for the clinical application of this plant.