title: 5, 6-Dihydropyranobenzopyrone: a previously undetermined antioxidant isolated from Polygonum amplexicaule.
abstract: OBJECTIVE
  To study the chemical constituents and their bioactivity of Polygonum amplexicaule.
  
  
  METHODS
  The isolation of compounds was achieved by chromatographic techniques and structure of the isolates was established by UV, IR, HRESI-MS and NMR including 1D and 2D experiments.
  
  
  RESULTS
  Bioassay-guided fractionation of an ethanolic extract of Polygonum amplexicaule led to the isolation of a hitherto unidentified compound, 5, 6-dihydropyranobenzopyrone (1) along with nine previously known compounds (2-10). Compounds 2-10 were identified as amplexicine (2), catechin (3), rutin (4), quercetin-3-O-β-D-galactopyranoside (5), chlorogenic acid (6), galloyl glucose (7), caffeic acid (8), gallic acid (9) and scopletin (10).
  
  
  CONCLUSIONS
  Compound 1 is new. Compounds 1-10 exhibited considerable antioxidant activity in a 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay.
authors.affiliation: National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS 38677, United States. mtantry@olemiss.edu
authors.forename: Mudasir A
authors.initials: MA
authors.lastname: Tantry
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Radwan
authors.forename: Seema
authors.initials: S
authors.lastname: Akbar
authors.forename: Ikhlas A
authors.initials: IA
authors.lastname: Khan
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000378:metabolism; D003374:Coumarins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D015394:Molecular Structure; D010851:Picrates / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D028502:Polygonum / Q000737:chemistry*
chemical_list: C582404:5,6-dihydropyranobenzopyrone; D000975:Antioxidants; D001713:Biphenyl Compounds; D003374:Coumarins; D010851:Picrates; D010936:Plant Extracts; C004931:1,1-diphenyl-2-picrylhydrazyl