Flavonoids from Andrographis viscosula

Abstract

Phytochemical investigation of the whole plant of Andrographis viscosula has led to the isolation of three new 2′-oxygenated flavonoids, (2R)-5-hydroxy-7,2′,3′-trimethoxyflavanone (1), 7,2′,5′- trimethoxyflavone (2), 5,7,2′,3′-tetramethoxyflavone (3), and eight known flavones, 5,7,2′-trimethoxyflavone (4), 5,7,2′,4′, 5′-pentamethoxyflavone (5), echioidinin (6), 5,2′,6′- trihydroxy-7-methoxyflavone (7), 5-hydroxy-7,2′-dimethoxyflavone (8), echioidin (9), echioidinin 5-O-glucoside (10), and 5,2′,6′- trihydroxy-7-methoxyflavone 2′-O-glucoside (11). The structures of 1-11 were elucidated by physical and spectral methods, including extensive 2D NMR studies. The presence of 2′-oxygenated flavonoids is apparently restricted to Andrographis species in Acanthaceae. Therefore, 2′-oxygenated flavonoids are regarded as chemotaxonomic markers of Andrographis genus in the Acanthaceae family. © 2003 Pharmaceutical Society of Japan.