Polyphenolic Compounds in Clove and Pimento and Their Antioxidative Activities

Abstract

Two new polyphenolic glucosides, 6′-O-acetylisobiflorin (1) and (2S)-3-(4-hydroxy-3-methoxyphenyl)-propane-1,2-diol 1-O-(6′-O-galloyl)-β-D-glucoside (2), were respectively isolated from the flower buds of Syzygium aromaticum and berries of Pimenta dioica. Each structure was elucidated on the basis of spectral analyses (NMR, MS and [α]_D) and chemical conversion. A total of twenty-seven known compounds from the plants were also characterized. The antioxidative activity of their extracts and the twenty-nine isolates including gallo- and ellagitannins was estimated by oxygen radical absorbance capacity (ORAC) assay, and eugenol (3), which was the most abundant ingredient in each plant extract, showed the most potent antioxidative activity [ORAC value of 39,270 μmol TE (trolox equivalent)/g].

• clove
• pimento
• polyphenol
• antioxidant
• oxygen radical absorbance capacity (ORAC)