afzelechin and 1-1-diphenyl-2-picrylhydrazyl

The rhizomes of Astilbe rivularis, commonly known as 'Thulo Okhati' are widely used in Nepal as tonic for uterine and menstrual disorders. In our preliminary study, the 70% MeOH extract of the rhizomes showed potent antioxidant activity. Hence, present study was aimed for the isolation of potent antioxidant constituents. Bergenin (1), 11-O-galloylbergenin (2), (+)-catechin (3), (-)-catechin (4), (-)-afzelechin (5), (-)-epiafzelechin (6) and 2-(β-D-glucopyranosyloxy)-4-hydroxylbenzenacetonitrile (7) were isolated from the rhizomes. Structures of these compounds were elucidated on the basis of spectroscopic methods. All these isolated compounds were evaluated for their in vitro antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. 11-O-Galloylbergenin (2), (+)-catechin (3), (-)-catechin (4), (-)-afzelechin (5) and (-)-epiafzelechin (6) showed potent antioxidant activity.

Topics: Antioxidants; Benzopyrans; Biphenyl Compounds; Catechin; Drug Evaluation, Preclinical; Flavonoids; Gallic Acid; Magnetic Resonance Spectroscopy; Molecular Structure; Nepal; Phenols; Picrates; Plant Extracts; Rhizome; Saxifragaceae

Chemical investigation of the aerial parts of Atraphaxis frutescens resulted in the isolation of five 7-methoxyflavonols with pyrogallol B-ring moieties (1-5), a fisetinidol glucoside (13), and a benzyl glycoside (18), together with 26 known compounds including flavonoids, phenylpropanoid amides, anthraquinone glycosides, lignans, and a benzyl derivative. The principal chemical structural feature of the isolated compounds was either a pyrogallol or catechol B-ring moiety, and they showed potent 1,1-diphenyl-2-picrylhydrazyl radical scavenging activities. To assess the effects of these antioxidants on biological enzymes, their inhibitory effects against an insect phenoloxidase and a mushroom tyrosinase were evaluated. This study indicated that insect phenoloxidase was inhibited by phenylpropanoid amides and that mushroom tyrosinase was inhibited by the characteristic 7-methoxyflavonol 3-O-rhamnopyranosides.

Topics: Agaricales; Animals; Antioxidants; Aphids; Biphenyl Compounds; Catechol Oxidase; Flavonols; Glucosides; Molecular Structure; Mongolia; Monophenol Monooxygenase; Nuclear Magnetic Resonance, Biomolecular; Phenols; Picrates; Plant Components, Aerial; Polygonaceae

The EtOAc-soluble fraction from a methanolic extract of Hovenia dulcis Thunb. exhibited neuroprotective activity against glutamate-induced neurotoxicity in mouse hippocampal HT22 cells. The neuroprotective activity-guided isolation resulted in 8 phenolic compounds (1-8), such as vanillic acid (1), ferulic acid (2), 3,5-dihydroxystilbene (3), (+)-aromadendrin (4), methyl vanillate (5), (-)-catechin (6), 2,3,4-trihydrobenzoic acid (7), and (+)-afzelechin (8). Among these, compounds 6 and 8 had a neuroprotective effect on the glutamate-induced neurotoxicity in HT22 cells. Furthermore, compound 6 had a DPPH free radical scavenging effect with an IC50 value of 57.7 microM, and a superoxide anion radical scavenging effect with an IC50 value of 8.0 microM. Both compounds 6 and 8 had ABTS cation radical scavenging effects with IC50 values of 7.8 microM and 23.7 microM, respectively. These results suggest that compounds 6 and 8 could be neuroprotectants owing to their free radical scavenging activities.

Topics: Animals; Benzopyrans; Benzothiazoles; Biphenyl Compounds; Catechin; Cell Line; Flavonoids; Free Radical Scavengers; Glutamic Acid; Inhibitory Concentration 50; Mice; Neurons; Neuroprotective Agents; Phenols; Picrates; Plant Bark; Plant Extracts; Plants, Medicinal; Rhamnaceae; Sulfonic Acids; Superoxides; Tannins