Jaboticabin and flavonoids from the ripened fruit of black rasberry (Rubus coreanum)

The ethyl acetate (EtOAc) layer of ripened fruits of black raspberry (Rubus coreanum) had higher DPPH radical scavenging activity than was detected in other layers. Six phenolic compounds were purified and isolated from the EtOAc layer of ripened black raspberry fruits via octadecyl silane (ODS)-column chromatography and amide column-HPLC using a guided DPPH radical scavenging assay. These compounds were identified as 4-hydroxybenzoic acid (1), 2-O-(3',4'-dihydroxybenzoyl)-4,6-dihydroxyphenylmethylacetate (2, jaboticabin), phloridzin (3), kaempferol 3-O-beta-d-glucopyranoside (4), quercetin 3-O-beta-d-glucuronic acid methyl ester (5), and quercetin (6), based on MS and NMR analysis. Three compounds (1, 5, and 6) had been identified previously in this plant, but other compounds (2-4) were newly isolated from this plant. Compound 2, 5, and 6 evidenced higher DPPH radical scavenging activity than alpha-tocopherol at the same concentration.