Scavenging of reactive oxygen species by the plant phenols genistein and oleuropein

Authors

  • Irena Kruk,

    1. Institute of Physics, Technical University of Szczecin, Al. Piastów 48[sol ]49, 70-311 Szczecin, Poland
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  • Hassan Y. Aboul-Enein,

    Corresponding author
    1. Pharmaceutical Analysis Laboratory, Biological and Medical Research Department (MBC 03-65), King Faisal Specialist Hospital and Research Centre, PO Box 3354, Riyadh 11211, Saudi Arabia
    • Pharmaceutical Analysis Laboratory, Biological and Medical Research Department (MBC-03), King Faisal Specialist Hospital and Research Centre, PO Box 3354, Riyadh 11211, Saudi Arabia.
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  • Teresa Michalska,

    1. Institute of Physics, Technical University of Szczecin, Al. Piastów 48[sol ]49, 70-311 Szczecin, Poland
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  • Krzysztof Lichszteld,

    1. Institute of Physics, Technical University of Szczecin, Al. Piastów 48[sol ]49, 70-311 Szczecin, Poland
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  • Aleksandra Kładna

    1. Department of Medical History and Ethics, Pomeranian Medical Academy, Rybacka 1, 70-204 Szczecin, Poland
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Abstract

The plant-derived phenolic compounds genistein and oleuropein are known to exhibit several biological properties, many of which may result from their antioxidant and free radical scavenger activity. In this paper we report the results of a complex study of antioxidant activity of genistein and oleuropein, using electron spin resonance (ESR), chemiluminescence, fluorescence and spectrophotometric techniques. Different reaction systems were applied to study the inhibitory effect of the phenolic compounds studied: (a) the potassium superoxide[sol ]18-crown-6 dissolved in DMSO system, which generates superoxide radical (O2·) and hydrogen peroxide (H2O2); (b) the Co(II)–EDTA–H2O2 system (the Fenton-like reaction), which generates hydroxyl radical (HO·); (c) 2,2′-azobis(2-amidino-propane)dichloride (AAPH) as the peroxyl radical (ROO·) generator, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical test. Results showed that genistein and oleuropein decreased the chemiluminescence sum from the O2· generating system, an inhibitory effect that was dependent on their concentration. These compounds also reacted with ROO radicals and they showed activity about two-fold greater than the standard Trolox. The antioxidant effects were studied at different concentrations and reflected in protection against the fluorescence decay of β-phycoerythrin (β-PE), due to ROO· attack on this protein. Using the Fenton-like reaction and the spin trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the phenolic compounds examined were found to inhibit DMPO–·OH radical formation in the range 10–90% at concentrations of 0.1 mmol[sol ]L to 2 mmol[sol ]L. Furthermore, these compounds also inhibited HO·-dependent deoxyribose degradation; about 20% and 60% inhibitions were observed in the presence of 0.5 mmol[sol ]L genistein and oleuropein, respectively. It was also demonstrated that genistein had a weaker DPPH radical scavenging activity than oleuropein. Our results confirm good scavenging activity towards O2·, HO· and ROO· and the antioxidant effect of genistein and oleuropein. Copyright © 2005 John Wiley & Sons, Ltd.

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