Phenolic Antioxidants Isolated from Mulberry Leaves

In this study, the crude methanol extract of mulberry leaves was fractionated with chloroform, ethyl acetate, nbutanol, and water, successively. The antioxidant activities of the fractions were examined with the 2-deoxyribose oxidation and linoleic acid peroxidation methods. The ethyl acetate fraction showed the strongest antioxidant activity. From it we isolated chlorogenic acid, caffeic acid, quercetin 3-O-β-D-glucopyranoside, and kaempferol 3-O-β-D-glucopyranoside with preparatory octadecyl silane-high performance liquid chromatography (ODS-HPLC), and identified the compounds by nuclear magnetic resonance (NMR) and fast atom bombardment mass (FAB-MS) analyses. Overall, quercetin 3-O-β-D-glucopyranoside showed the strongest antioxidant activity by both the 2-deoxyribose oxidation and rat liver microsome peroxidation methods.