Two New 2'-Oxygenated Flavones from Andrographis elongata

Abstract

Two new 2'-oxygenated flavones, 5,2',6'-trihydroxy-7-methoxyflavone (3) and skullcapflavone I 2'-O-β-D-(4''-E-cinnamyl) glucopyranoside (5), together with three known flavones, 7-O-methylwogonin (1), skullcapflavone I (2) and skullcapflavone I 2'-O-β-D-glucopyranoside (4) were isolated from the whole plant of Andrographis elongata, and the structures were elucidated by FAB-MS and one- and two-dimensional (1D- and 2D)-NMR spectral studies including ¹H-¹H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and rotating frame Overhauser enhancement spectroscopy (ROESY) experiments, and chemical studies.