Characterization of Antioxidant Constituents from Perilla Cake

摘要

The antioxidant capacity of the hot water extract of defatted Perilla cake were evaluated using DPPH and ABTS+ radical scavenging assays. The extracts of four solvent fractions (hexane layer, EtOAc layer, w-BuOH layer, and residue) of the hot water extract were also investigated. In particular, the radical scavenging activity of the EtOAc-soluble portion from defatted Perilla cake was higher than those of the other solvent-soluble layers. This paper reports the chromatographic isolation and characterization of ten phenolic constituents of previously known structures, rosmarinic acid 3-O-glucoside (1), rosmarinic acid (2), caffeic acid (3), /7-coumaric acid (4), vanillic acid (5), vanillin (6), protocatechuic acid (7), protocatechuic aldehyde (8), p-hydroxybenzoic acid (9), and beta-hydroxybenzaldehyde (10). The chemical structures of these isolated compounds were identified by neclear magnetic resonance (NMR) spectroscopy and mass spectrometry methods. Among the compounds tested, rosmarinic acid (2) and protocatechuic aldehyde (8) showed the most potent DPPH radical scavenging activities with IC_(50) values of 34.1±0.8 and 74.2±1.2 uM, respectively. In addition, these two compounds showed significant ABTS+ radical scavenging capacities. These results suggest that the radical scavenging activities of defatted Perilla cake are closely correlated with the presence of phenolic compounds.