Antioxidant activities of lutonarin isolated from young barley leaves

Abstract

Lutonarin was isolated from young barley (Hordeum vulgare L. var. nudum Hook) leaves. It has been suggested that lutonarin found in plants, especially in leaves, plays a role in removing reactive oxygen species 6). In this study, we examined the antioxidative effects of lutonarin and related flavones against the free radical DPPH and Fenton's reaction in vitro. The DPPH radical-scavenging activity was higher in the flavones with a catechol struc-ture in the B-ring of the flavone compared to those in which the B-ring contained only a single hydroxyl mole-cule. Furthermore, the higher DPPH radical scavenging activity of saponarin compared to apigenin suggests that the 6-C-and/or 7-O-glucosyl moiety in saponarin stimu-lates its radical scavenging activity. In a comparison of lutonarin with luteolin, the inhibitory action against the oxidation of ethyl linoleate by Fenton's reaction appeared to be weakened by the 6-C-and/or 7-O-glucosyl moiety.