Extraction solvents such as methanol, ethanol, and acetone have been universally used for the extraction of phenolic compounds in plant . Aqueous mixtures of these organic solvents have been also used as an effective extractant, depending on the type and concentration of extraction solvent used. Therefore, it is important to apply an appropriate extraction solvent in order to obtain high content of phenolic compounds from rice bran. There are few studies on antioxidant activity of pigmented rice bran available, but no published report on the effect of extraction solvent with various organic solvents.
In this study, we used aqueous mixtures of acetone, methanol, and ethanol prepared with varying concentrations (0% to 100%) in order to choose the optimum solvent concentration for the extraction of antioxidant compounds from pigmented rice bran. We determined antioxidant activities by measuring DPPH radical scavenging ability, ABTS radical cation scavenging ability, reducing power, and chelating ability of pigmented rice bran extracts from various aqueous mixtures. The composition of phenolic acids was also analyzed.