Bioassay-directed fractionation of an antioxidant methanol ext. of the leaves of Chrozophora senegalensis using DPPH assay led to the isolation of 3 new flavonoid glycosides, quercetin 3-O-(6''-caffeoyl)-β-D-glucopyranoside-3'-O-β-D-glucopyranoside (1), quercetin 3-Me ether-7-O-α-L-rhamnopyranosyl-(1→6)-(2''-p-coumaroyl)-β-D-glucopyranoside (2), acacetin 7-O-(6''-p-coumaroyl)-β-D-glucopyranoside (3), along with five known flavonoids, one phenolic deriv., and 3 megastigmane glycosides. Their structures were established on the basis of detailed spectral anal. All isolated compds. were tested for their antioxidant activity on DPPH stable radical, superoxide anion, metal chelating activity, and DNA cleavage induced by the photolysis of H2O2. Quercetin 3-O-(6''-caffeoyl)-β-D-glucopyranoside-3'-O-β-D-glucopyranoside (1), quercetin 3'-Me ether-3-O-α-L-rhamnopyranoside (4), and 4'''-Me ether amenthoflavone (9) exhibited the highest antioxidant capacity being also able to modulate hydroxyl radical formation more efficiently than other compds. acting as direct hydroxyl radical scavengers and chelating iron.
New flavonoid glycosides from Chrozophora senegalensis and their antioxidant activity
BRACA, ALESSANDRA;
2006-01-01
Abstract
Bioassay-directed fractionation of an antioxidant methanol ext. of the leaves of Chrozophora senegalensis using DPPH assay led to the isolation of 3 new flavonoid glycosides, quercetin 3-O-(6''-caffeoyl)-β-D-glucopyranoside-3'-O-β-D-glucopyranoside (1), quercetin 3-Me ether-7-O-α-L-rhamnopyranosyl-(1→6)-(2''-p-coumaroyl)-β-D-glucopyranoside (2), acacetin 7-O-(6''-p-coumaroyl)-β-D-glucopyranoside (3), along with five known flavonoids, one phenolic deriv., and 3 megastigmane glycosides. Their structures were established on the basis of detailed spectral anal. All isolated compds. were tested for their antioxidant activity on DPPH stable radical, superoxide anion, metal chelating activity, and DNA cleavage induced by the photolysis of H2O2. Quercetin 3-O-(6''-caffeoyl)-β-D-glucopyranoside-3'-O-β-D-glucopyranoside (1), quercetin 3'-Me ether-3-O-α-L-rhamnopyranoside (4), and 4'''-Me ether amenthoflavone (9) exhibited the highest antioxidant capacity being also able to modulate hydroxyl radical formation more efficiently than other compds. acting as direct hydroxyl radical scavengers and chelating iron.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
