INHIBITORY EFFECTS OF ISOFLAVONES ON SOYBEAN LIPOXYGENASE-1 ACTIVITY

ABSTRACT Considering the fundamental and practical aspects regarding the lipoxygenase (LOX) inhibition by phytochemicals, we studied the inhibition of pure soybean LOX-1 by an extract rich in isoflavones, with controlled concentration of genistein and daidzein (2 and 1.8 mM, respectively). Our results showed that genistein was almost twice more potent inhibitor than daidzein at similar concentration with concentration that induces 50% LOX inhibition values of 5.33 µM versus 11.53 µM. Genistein and daidzein proved to be noncompetitive with inhibition constants Ki of 33.65 and 43.45 µM, respectively. The inhibitory efficiency of the genistein and daidzein depended both on their concentration and on the substrate's concentration. PRACTICAL APPLICATIONS The aim of the present article is to study the inhibition of a pure soybean lipoxygenase by an extract rich in soybean isoflavones (mainly, genistein and daidzein), with a view to obtain the soybean products both, free of undesirable off flavor and suplemented with bioactive compounds (like isoflavones) with antioxidant and anticancer properties. These data can have practical applications for food industry, as the addition of such extracts to soybean meals can prevent the formation of off flavors, during soybean processing. Furthermore, the study offers the background for futher in vitro soybean LOX-1 inhibition experiments by using natural extracts rich in isoflavones.