Four new pyrrole alkaloids from the rhizomes of Amomum koenigii

Four new pyrrole alkaloids, named amokoens A–D ( 1 – 4 ), together with three known compounds ( 5 – 7 ) were isolated from the rhizomes of Amomum koenigii . Their structures and absolute configurations were established by spectroscopic data, including 1D and 2D NMR, and the optical rotation calculations. All the isolates were evaluated for their effects on nitric oxide (NO) production in lipopolysaccharide-induced RAW264.7 macrophages. Compounds 1 – 7 inhibited NO production ranging from 27.1 to 82.4% at a concentration of 100 μ M, and compounds 5 and 6 showed efficacious inhibitory activities with IC 50 values of 42.2 and 69.3 µ M, respectively.