Polyphenolic compounds in clove and pimento and their antioxidative activities

Abstract

Two new polyphenolic glucosides, 60-O-acetylisobiflorin (1) and (2S)-3-(4-hydroxy-3-methoxyphenyl)-propane- 1,2-diol 1-O-(60-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 galloand 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 39,270μmol TE (trolox equivalent)/g].