Soybeans are a main source of plant lipoxygenases and also important sources of isoflavone, including free genistein, daidzein, glycitein and their acetyl, malonyl and glucosilated forms. The enzymatic extract from soybeans (LE) rich in lipoxygenase was checked for the presence of polyphenols through LC-UV-DAD and LC-ESI –MS analysis. LE contains malonyl daidzin and genistein but the amounts in which these are present are very low.