Anticomplement and Antioxidant Activities of New Acetylated Flavonoid Glycosides from Centaurium spicatum

Abstract

In addition to the three acetylated flavonol glycosides, quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1→6)]-β- galactopyranoside, quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)- (1→6)]-3-acetyl-β-galactopyranoside, and quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1→6)]-4-acetyl-β- galactopyranoside, which have recently been isolated from Centaurium spicatum (L.) Fritsch (Gentianaceae), a new pentaacetylated flavonoid glycoside was isolated from the same plant. Structure elucidation, especially the localization of the acetyl groups, and complete 1H- and 13C-NMR assignments, was carried out using one- and two-dimensional NMR methods, including 1H- and 13C-NMR, DEPT-135 and DEPT-90, and gradient-assisted experiments such as DQF-COSY, TOCSY, HSQC and HMBC. The structure of the new flavonoid glycoside was established as quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1→6)]-3, 4-diacetyl-β-galactopyranoside. The anticomplement and antioxidant activities of these compounds were evaluated. The triacetylated flavonoid glycoside showed the highest activity in the two assays.