Hydroxyl radical scavenging activities of isoquinoline alkaloids isolated from Coptis chinensis

Abstract

The hydroxyl radical (?OH) scavenging and ferrous ion chelating activities of four isoquinoline alkaloids isolated from Coptis chinensis Franch were studied for the identification of their structural characteristics to scavenge ?OH. The ?OH was generated via Fe(II)-catalazed Fenton reaction in this study and the reliable measurement of ?OH scavenging activities of isoquinoline alkaloids were achieved using electron spin resonance (ESR) spectrometry method. At the 1 mM concentration, berberrubine (85%) showed the strongest ?OH scavenging activity and the next were in the decreasing order of coptisine (79%), berberine (23%), and palmatine (22%). The ferrous ion chelating effects of the alkaloids showed similar pattern with their ?OH scavenging effects. These results suggest that ?OH scavenging effects of the alkaloids were closely related to their ferrous ion chelating activities. In addition, metal chelating functional groups such as hydroxy group at C-9 and methylenedioxy group at C-9 and C-10 were thought to contribute to the ?OH scavenging activities of the isoquinoline alkaloids. ? 2009 The Pharmaceutical Society of Korea.