title: Bioactivity-guided fractionation of Coronopus didymus: A free radical scavenging perspective.
abstract: The whole plant aqueous extract of Coronopus didymus Linn. was fractionated on the basis of polarity and resulting fractions were evaluated for free radical scavenging ability. The most non-polar fraction (CDF1) was found to be more active than other fractions in scavenging DPPH, ABTS(-), nitric oxide and hydroxyl radicals in steady-state conditions. Stop-flow spectrometric studies showed 58.13% inhibition of 100 microM DPPH at a concentration of 150 microg/ml of CDF1 in 1000 s and 32.31% scavenging of 960 microM ABTS(-) at a concentration of 300 microg/ml of CDF1 in 100 s. The reaction of CDF1 with hydroxyl radicals produced by pulse radiolysis showed a transient spectrum with absorption peaks at 320, 390 and 400 nm, indicating the presence of flavonoids/related components. Competition kinetics with potassium thiocyanate against scavenging of hydroxyl radicals showed a reactivity of 0.1326 against thiocyanate. CDF1 also protected against Fenton reagent-induced calf thymus DNA damage at a concentration of 400 mg/ml indicating it to be the most potent fraction.
authors.affiliation: Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal - 576104, India.
authors.forename: K R
authors.initials: KR
authors.lastname: Prabhakar
authors.forename: V P
authors.initials: VP
authors.lastname: Veeresh
authors.forename: K
authors.initials: K
authors.lastname: Vipan
authors.forename: M
authors.initials: M
authors.lastname: Sudheer
authors.forename: K I
authors.initials: KI
authors.lastname: Priyadarsini
authors.forename: R B S S
authors.initials: RB
authors.lastname: Satish
authors.forename: M K
authors.initials: MK
authors.lastname: Unnikrishnan
mesh_terms: D000818:Animals; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D019607:Brassicaceae / Q000737:chemistry*; D002417:Cattle; D005591:Chemical Fractionation; D004249:DNA Damage / Q000187:drug effects; D016166:Free Radical Scavengers / Q000032:analysis / Q000494:pharmacology*; D017665:Hydroxyl Radical / Q000037:antagonists & inhibitors; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D010851:Picrates / Q000037:antagonists & inhibitors; D010936:Plant Extracts / Q000494:pharmacology*; D013451:Sulfonic Acids / Q000037:antagonists & inhibitors
chemical_list: D052160:Benzothiazoles; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; D010936:Plant Extracts; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D009569:Nitric Oxide; D017665:Hydroxyl Radical; C004931:1,1-diphenyl-2-picrylhydrazyl