Nine new ent-labdane diterpenoids from the aerial parts of Andrographis paniculata

Nine new ent-labdane-type diterpenoids (1-9), mostly in the form of the corresponding 16,15-lactones, were isolated from the 85%-EtOH extract of the aerial parts of Andrographis paniculata NEES., together with nine known compounds (10-18). Their structures were deduced by in-depth NMR spectroscopy and high-resolution mass spectrometry.