Diterpenoid Lactones with Anti-Inflammatory Effects from the Aerial Parts of Andrographis paniculata

Andrographis paniculata (AP) has been widely used in China for centuries to treat various diseases, and especially to treat inflammation. Diterpenoid lactones are the main anti-inflammatory components of AP. However, systematic chemical composition and biological activities, as well as key pharmacophores, of these diterpenoid lactones from AP have not yet been clearly understood. In this study, 17 diterpenoid lactones, including 2 new compounds, were identified by spectroscopic methods, and most of them attenuated the generation of TNF-alpha and IL-6 in LPS-induced RAW 274.7 cells examined by ELISA. Pharmacophores of diterpenoid lactones responsible for the anti-inflammatory activities were revealed based on the quantitative structure-activity relationship (QSAR) models. Moreover, new compounds (AP-1 and AP-4) exerted anti-inflammatory activity in LPS microinjection-induced zebrafish, which might be correlated with the inhibition of the translocation of NF-kappa B p65 from cytoplasm to nucleus. Our study provides guidelines for future structure modification and rational drug design of diterpenoid lactones with anti-inflammatory properties in medical chemistry.