Platelet-Activating Factor (PAF) Receptor Binding Antagonist Activity of the Methanol Extracts and Isolated Flavonoids from Chromolaena odorata (L.) KING and ROBINSON

抄録

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 μg/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 μg/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 μM.