Identification and Evalutation of Antioxidant Phenolic Compounds in Parsley (Petroselinum crispum var. neapolitanum) and Radish (Raphanus sativus L.) Sprout

摘要

Free phenolic antioxidant compounds (i.e., caffeic acid in parsley and ferulic acid, methyl ferulate, isoferulic acid, sinapic acid, and methyl sinapate in radish sprout) in parsley and radish sprout were separated and identified by chromatographic techniques. Their antioxidant capacities were determined by the DPPH radical scavenging and the β-carotene-linoleic acid assays. Caffeic acid had a lower EC_(50) value than two antioxidant standards, BHT and α-tocopherol in the DPPH' scavenging assay, but its inhibitory efficacy againstrnthe discoloration of β-carotene was much weaker than that of the standards and other phenolics, except isoferulic acid, in the β-carotene-linoleic acid assay. All phenolic constituents in the radish sprout had lower antioxidant activities than the standard antioxidants in both assays, but the crude methanolic extract of radish sprout showed a stronger free radical scavenging capacity than the parsley extract in the DPPH' assay. It was also found that the methylation of hydroxyl group on phenol ring decreased the free radical scavenging activity.