kaempferol and 1-1-diphenyl-2-picrylhydrazyl

Together with the sweet principle component glycyphyllin A (3), seven phenolic compounds including two new dihydrochalcone rhamnopyranosides, glycyphyllin B (1) and glycyphyllin C (2), and five known flavonoids, catechin (4), kaempferol-3-O-β-D-glucopyranoside (5), quercetin-3-O-β-D-glucopyranoside (6), kaempferol-3-O-β-neohesperidoside (7), and 2R,3R-dihydrokaempferol-3-O-β-D-glucopyranoside (8), have been isolated from the ethanolic extract of the leaves of Smilax glyciphylla for the first time. The structures of these compounds were characterized by spectroscopic methods including UV, MS, and 1D and 2D NMR. In vitro antioxidant capacity tests employing FRAP and DPPH assays indicated that 1, 4, and 6 exhibited potent antioxidant activity and are the key phenolics responsible for the antioxidant activity of the leaf extract of S. glyciphylla.

Topics: Antioxidants; Australia; Biphenyl Compounds; Flavonoids; Glycosides; Kaempferols; Nuclear Magnetic Resonance, Biomolecular; Oxidation-Reduction; Phenols; Picrates; Plant Leaves; Smilax

Activity-guided fractionation of Theobroma grandiflorum ("cupuaçu") seeds resulted in the identification of two new sulfated flavonoid glycosides, theograndins I (1) and II (2). In addition, nine known flavonoid antioxidants, (+)-catechin, (-)-epicatechin, isoscutellarein 8-O-beta-d-glucuronide, hypolaetin 8-O-beta-d-glucuronide, quercetin 3-O-beta-d-glucuronide, quercetin 3-O-beta-d-glucuronide 6' '-methyl ester, quercetin, kaempferol, and isoscutellarein 8-O-beta-d-glucuronide 6' '-methyl ester, were identified. Theograndin II (2) displayed antioxidant activity (IC(50) = 120.2 microM) in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assay, as well as weak cytotoxicity in the HCT-116 and SW-480 human colon cancer cell lines with IC(50) values of 143 and 125 microM, respectively. While 1 was less active as an antioxidant than 2, the known compounds were more potent in the DPPH assay (IC(50) range 39.7-89.7 microM).

Topics: Antineoplastic Agents, Phytogenic; Antioxidants; Biphenyl Compounds; Catechin; Colonic Neoplasms; Drug Screening Assays, Antitumor; Flavonoids; French Guiana; Glycosides; Humans; Inhibitory Concentration 50; Malvaceae; Molecular Structure; Picrates; Seeds; Tumor Cells, Cultured

Analysis of a methanolic extract of Tagetes lucida leaves has resulted in the isolation of a new flavonol glycoside, quercetagenin 3,4'-dimethyl ether 7-O-beta-D-glucopyranoside (1), two new phenolic acids, 3-(2-O-beta-D-glucopyranosyl-4-methoxyphenyl)propanoic acid (2) and its methylester (3), and known flavonols, aromatic acids, and 7-methoxycoumarin. Using the DPPH degrees test, the extract and some of its constituents showed a significant free-radical-scavenging effect in comparison to alpha-tocopherol and standard flavonols.

Topics: Antioxidants; Biphenyl Compounds; Chromatography, High Pressure Liquid; Flavonoids; Free Radical Scavengers; Glycosides; Guatemala; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Picrates; Plant Leaves; Plants, Medicinal; Spectrophotometry, Ultraviolet; Tagetes; Tocopherols