A new flavonoid from the aerial parts of Andrographis paniculata.

A new flavonoid, 7,8-dimethoxy-2'-hydroxy-5-O-β-d-glucopyranosyloxyflavone (1), along with 15 known flavonoids (2-16), was isolated from the aerial parts of Andrographis paniculata Nees. Their structures were elucidated on the basis of chemical and spectroscopic analyses. Most of them have uncommon O-substitution patterns involving 5-, 7-, 8-, 2'-, 3'-, 4'- and 5'-O-substituents. The antiproliferative effects of these flavonoids against human leukaemia HL-60 cells were investigated. Among them, 13 was the most active, displaying potent antiproliferative activity with IC50 of 3.50 μM. The structure-activity relationships of these isolated compounds were discussed.