Inhibition of lipoxygenase by soy isoflavones: Evidence of isoflavones as redox inhibitors

Hydroperoxides, the products of lipoxygenase mediated pathways, play a major role in the manifestation of chronic inflammatory diseases. Soy isoflavones act as antioxidants due to their ability to scavenge free radicals. Isoflavones inhibit the activity of soy lipoxygenase-1 and 5-lipoxygenase, from...

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Bibliographic Details
Published in:Archives of biochemistry and biophysics 2007-05, Vol.461 (2), p.176-185
Main Authors: Mahesha, H.G., Singh, Sridevi Annapurna, Rao, A.G. Appu
Format: Article
Language:English
Subjects:
Daidzein
Daidzin
Genistein
Genistin
Glycine max - enzymology
Humans
Inhibition studies
Isoflavones - physiology
Lipoxygenase
Lipoxygenase Inhibitors - pharmacology
Oxidation-Reduction
Redox inhibitor
Spectroscopic measurements
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Summary:Hydroperoxides, the products of lipoxygenase mediated pathways, play a major role in the manifestation of chronic inflammatory diseases. Soy isoflavones act as antioxidants due to their ability to scavenge free radicals. Isoflavones inhibit the activity of soy lipoxygenase-1 and 5-lipoxygenase, from human polymorph nuclear lymphocyte in a concentration dependent manner. Spectroscopic and enzyme kinetic measurements have helped to understand the nature and mechanism of inhibition. Genistein is the most effective inhibitor of soy lipoxygenase 1 and 5-lipoxygenase with IC 50 values of 107 and 125 μM, respectively. Genistein and daidzein are noncompetitive inhibitors of soy lipoxygenase 1 with inhibition constants, K i, of 60 and 80 μM, respectively. Electron paramagnetic resonance and spectroscopic studies confirm that isoflavones reduce active state iron to ferrous state and prevent the activation of the resting enzyme. A model for the inhibition of lipoxygenase by isoflavones is suggested.
ISSN:0003-9861
1096-0384
DOI:10.1016/j.abb.2007.02.013