PHENOLIC ANTIOXIDANTS OF DRIED SOYBEANS

Abstract

ABSTRACT Whole dried soybean seeds were investigated to determine the nature of their antioxidant activity. Activity was measured by rates of carotene bleaching in the coupled oxidation of linoleic acid and β‐carotene. Methanolic extracts of the soybeans were found to possess potent antioxidant ability. Paper and Sephadex column chromatography gave incomplete resolution of individual components. Therefore, thin‐layer chromatography of the whole methanolic extract rather than individual column fractions was used in isolating this component. Three fluorescent bands were found to possess the major activity. The most potent complex was further analyzed. Thin‐layer chromatography was used to separate the complex into four fluorescent components. One compound was determined to be responsible for the antioxidant activity exhibited by the parent band. Further analysis of this component by paper chromatography, chromogenic spray reagent tests, and ultraviolet spectral analyses indicated that the antioxidant was an isoflavone pentoside.