title: Platelet-activating factor (PAF) receptor binding antagonist activity of the methanol extracts and isolated flavonoids from Chromolaena odorata (L.) King and Robinson.
abstract: The leaf, stem and root extracts of Chromolaena odorata were evaluated for their effect on platelet-activating factor (PAF) receptor binding on rabbit platelets using 3H-PAF as a ligand. The leaf extract demonstrated high PAF receptor binding inhibitory activity of 79.2+/-2.1% at 18.2 microg/ml. A total of eleven flavonoids were subsequently isolated from the active leaf extract and evaluated for their effects on PAF receptor binding. Eight of the flavonoids exhibited >50% inhibition on the binding activity at 18.2 microg/ml. These flavonoids were identified as eriodictyol 7,4'-dimethyl ether, quercetin 7,4'-methyl ether, naringenin 4'-methyl ether, kaempferol 4'-methyl ether, kaempferol 3-O-rutinoside, taxifolin 4'-methyl ether, taxifolin 7-methyl ether and quercetin 4'-methyl ether. Their IC50 values ranged from 19.5 to 62.1 microM.
authors.affiliation: Forest Research Institute Malaysia, Selangor Darul Ehsan. lingsk@frim.gov.my
authors.forename: Sui Kiong
authors.initials: SK
authors.lastname: Ling
authors.forename: Mazura Md
authors.initials: MM
authors.lastname: Pisar
authors.forename: Salbiah
authors.initials: S
authors.lastname: Man
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects; D036604:Chromolaena / Q000033:anatomy & histology / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D000432:Methanol / Q000378:metabolism*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors*; D011817:Rabbits; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors*
chemical_list: D005419:Flavonoids; D010936:Plant Extracts; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D000432:Methanol