title: Flavonoid Glycosides from Siparuna gigantotepala Leaves and Their Antioxidant Activity.
abstract: Two new flavonol glycosides were isolated from the leaves of Siparuna gigantotepala. Their structures were determined to be kaempferol 3-O-β-xylopyranosyl-(1→2)-α-arabinofuranoside (1) and kaempferol 3,7-di-O-methyl-4'-O-α-rhamnopyranosyl-(1→2)-β-glucopyranoside (2). In addition, three known flavonol glycosides, rutin (3), kaempferol 3-O-rutinoside (4), and kaempferol 3,7-di-O-methyl-4'-O-rutinoside (5), and three flavonol aglycones, quercetin (6), kaempferol 3,7-dimethyl ether (7), and kaempferol 3,7,4'-trimethyl ether (8), were also isolated and are reported here for the first time in this species. The structures of compounds 1 and 2 were established on the basis of their LC-MS and one- and two-dimensional (1D)- and (2D)-NMR spectroscopic analyses, combined with acid methanolysis and silylation of sugar moieties for GC-MS. Evaluation of the antioxidant activity, conducted in the 96-well plate format, showed that the flavonoids isolated possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and moderate oxygen radical absorption capacity.
authors.affiliation: Research Group on Natural Products and Food (GIPNA), Department of Chemistry, Faculty of Natural and Exact Sciences, Ed. 320, Of 2096. Ciudad Universitaria-Meléndez, Universidad del Valle.
authors.forename: Harlen Gerardo
authors.initials: HG
authors.lastname: Torres Castañeda
authors.forename: Ana Julia
authors.initials: AJ
authors.lastname: Colmenares Dulcey
authors.forename: José Hipólito
authors.initials: JH
authors.lastname: Isaza Martínez
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D006027:Glycosides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D015394:Molecular Structure; D029585:Monimiaceae / Q000737:chemistry*; D010851:Picrates / Q000037:antagonists & inhibitors / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D005419:Flavonoids; D006027:Glycosides; D010851:Picrates; D017382:Reactive Oxygen Species; C004931:1,1-diphenyl-2-picrylhydrazyl