title: Bioassay-guided isolation of cytotoxic flavonoids from aerial parts of Coronopus didymus.
abstract: BACKGROUND
  Coronopus didymus Linn. (Brassicaceae) is a medicinal plant used traditionally as antipyretic, expectorant, to purify blood and for alleviating symptoms of pain, inflammations, malaria, wounds and cancer.
  
  
  OBJECTIVE
  The present study was designed to isolate and identify the cytotoxic compounds responsible for anticancer activity from this traditionally useful medicinal plant.
  
  
  METHODS
  Bioassay-guided fractionation of the ethanolic extract of aerial parts of C. didymus allowed the isolation of compounds responsible for anticancer activity. Their structures were elucidated by UV Spectroscopy (with shift reagents), ESI-MS and NMR spectral data. Preliminary anticancer activity of ethanolic extract, different fractions and isolated compounds was assessed through MTT in vitro cytotoxicity assay in a dose dependent manner against human cancer cell lines (HeLa and LN18) and normal 293T cells.
  
  
  RESULTS
  Three flavonoids namely 5,7,4'-trihydroxy-3'-methoxyflavone-4'-O-β-D-glucoside (1), 5,7,4'-trihydroxy-3'-methoxyflavone-4'-O-(6''-acetyl)-β-D-glucoside (2) and 5,7,4'-trihydroxy-3'-methoxy flavone (3), were isolated from aerial parts. Compound 1 was identified for the first time from the genus Coronopus. All the compounds 1-3 showed promising activity against HeLa cells with IC50values of 43.50, 0.63 and 3.67 µM, respectively. Significant result was also obtained with compound 3 against LN18 cells with IC50value of 46.63 µM.
  
  
  CONCLUSIONS
  The cytotoxic activity of the crude extract and fractions which may largely be due to its major isolated constituents, flavonoids 1-3, against both HeLa and LN18 cells provides a scientific basis for the ethnopharmacological use of C. didymus as anticancer agent.
authors.affiliation: Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan; Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
authors.forename: Hafiza
authors.initials: H
authors.lastname: Noreen
authors.affiliation: Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan. Electronic address: farman@qau.edu.pk.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Farman
authors.affiliation: Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
authors.forename: James S O
authors.initials: JS
authors.lastname: McCullagh
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology*; D001681:Biological Assay; D019607:Brassicaceae / Q000737:chemistry*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D015394:Molecular Structure; D035261:Plant Components, Aerial / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D010936:Plant Extracts
keywords: Anticancer activity; Coronopus didymus; Cytotoxicity; Flavones; HeLa and LN18 cell lines