Structure elucidation of three new acetylated flavonoid glycosides from Centaurium spicatum

Three new acetylated flavonol glycosides, quercetin 3-O-(2,3,4-triacetyl-al pha -rhamnopyranosyl)-(1 --> 6)-beta -galactopyranoside, quercetin 3-O-[(2, 3,4-triacetyl-alpha -rhamnopyranosyl)-(1 --> 6)]-4-acetyl-beta -galactopyra noside and quercetin 3-O-[(2,3,4-triacetyl-alpha -rhamnopyranosyl)-(1 --> 6 )1-4-acetyl-beta -galactopyranoside, were isolated from Centaurium spicatum (L.) Fritsch (Gentianaceae). Structure elucidation, especially the localiz ation of the acetyl groups, and complete H-1 land C-13 NMR assignments of t hese biologically active compounds were carried out using one- and two-dime nsional NMR methods, including H-1 and C-13 NMR, DEPT-135 and DEPT-90 and g radient-assisted experiments such as DQF-COSY, TOCSY, HSQC and HMBC experim ents. Copyright (C) 2001 John Wiley & Sons, Ltd.