A New Geranylated Chalcone from Andrographis lobelioides.

A new Omicron-geranylated chalcone, 2'-hydroxy-2-methoxy-4'-Omicron-[(E)-3,7-dimethyl-2,6-octadienyl] chalcone (1), together with three known flavones, 5-hydroxy7,2'-dimethoxyflavone (2), skullcapflavone I (3) and echioidin (4), were isolated from the leaves of Andrographis lobelioides. The structure of 1 and the known compounds (2-4) were achieved by extensive 1D and 2D NMR spectral and chemical studies.