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Effects of citrinin on iron‐redox cycle
Author(s) -
Da Lozzo Eneida Janiscki,
Mangrich Antonio Salvio,
Rocha Maria Eliane Merlin,
de Oliveira Maria Benigna Martinelli,
Carnieri Eva Gunilla Skare
Publication year - 2002
Publication title -
cell biochemistry and function
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 61
eISSN - 1099-0844
pISSN - 0263-6484
DOI - 10.1002/cbf.931
Subject(s) - citrinin , chemistry , hydrogen peroxide , redox , photochemistry , ascorbic acid , chelation , reducing agent , nuclear chemistry , inorganic chemistry , organic chemistry , mycotoxin , food science
The ability of the mycotoxin citrinin to act as an inhibitor of iron‐induced lipoperoxidation of biological membranes prompted us to determine whether it could act as an iron chelating agent, interfering with iron redox reactions or acting as a free radical scavenger. The addition of Fe 3+ to citrinin rapidly produced a chromogen, indicating the formation of citrinin‐Fe 3+ complexes. An EPR study confirms that citrinin acts as a ligand of Fe 3+ , the complexation depending on the [Fe 3+ ]:[citrinin] ratios. Effects of citrinin on the iron redox cycle were evaluated by oxygen consumption or the o ‐phenanthroline test. No effect on EDTA‐Fe 2+ →EDTA‐Fe 3+ oxidation was observed in the presence of citrinin, but the mycotoxin inhibited, in a dose‐dependent manner, the oxidation of Fe 2+ to Fe 3+ by hydrogen peroxide. Reducing agents such as ascorbic acid and DTT reduced the Fe 3+ ‐citrinin complex, but DTT did not cause reduction of Fe 3+ ‐EDTA, indicating that the redox potentials of Fe 3+ ‐citrinin and Fe 3+ ‐EDTA are not the same. The Fe 2+ formed from the reduction of Fe 3+ ‐citrinin by reducing agents was not rapidly reoxidized to Fe 3+ by atmospheric oxygen. Citrinin has no radical scavenger ability as demonstrated by the absence of DPPH reduction. However, a reaction between citrinin and hydrogen peroxide was observed by UV spectrum changes of citrinin after incubation with hydrogen peroxide. It was also observed that citrinin did not induce direct or reductive mobilization of iron from ferritin. These results indicate that the protective effect on iron‐induced lipid peroxidation by citrinin occurs due to the formation of a redox inactive Fe 3+ ‐citrinin complex, as well as from the reaction of citrinin and hydrogen peroxide. Copyright © 2001 John Wiley & Sons, Ltd. Abbreviations used: DPPH diphenylpicrylhydrazylDMPO 5,5‐dimenthyl‐1‐pyrroline‐ N ‐oxideEDTA ethylene diaminetetraacetic acidDTT dithiothreitolEPR electron paramagnetic resonance spectroscopy