Active components from Artemisia iwayomogi displaying ONOO- scavenging activity

Peroxynitrite (ONOO-) is one of cytotoxic species produced by the reaction between superoxide (.O-2(-)) and nitric oxide (NO). The main aim of this study was to identify ONOO- scavenging constituents from herbs. Methanolic extracts derived from one hundred thirty eight herbs were screened out for their ONOO- scavenging activities. Twenty herbs showed excellent ONOO- scavenging activity in a dose dependent manner. Of them, Artemisia iwayomogi, which showed the highest activity, was fractioned with several solvents. The ONOO- scavenging activity of fractions was in order of ethyl acetate (EtOAc) > n-butanol (BuOH) > dichloromethane (CH2Cl2) > water (H2O) fraction. The EtOAc and the n-BuOH fractions were further purified to isolate active principles by column chromatography. Apigenin 7-methylether (genkwanin), apigenin 7,4'-di-O methylether, jaceosidin, and scopoletin from the EtOAc fraction and chlorogenic acid, 2,4-dihydroxy 6-methoxy acetophenone 4-O-beta-D-glucoside, quebrachitol, and scopolin from the n-BuOH fraction were identified. The scavenging activities of chlorogenic acid (IC50 = 0.52 +/- 0.04 muM), genkwanin (IC50 = 1.01 +/- 0.10 muM), and scopoletin (IC50 = 1.03 +/- 0.15 muM) were higher than or comparable to a well-known ONOO- scavenger, penicillamine (IC50 = 1.76 +/- 0.18 muM), suggesting that those compounds might be developed as effective ONOO- scavengers for, prevention of the ONOO--involved diseases. Copyright (C) 2004 John Wiley Sons, Ltd.