Effects of citrinin on iron-redox cycle

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http://www3.interscience.wiley.com/cgi-bin/abstract/85514985/ABSTRACT

Cell Biochemistry and Function

Volume 20, Issue 1 , Pages 19 - 29

Published Online: 8 Oct 2001

Copyright © 2002 Wiley & Sons, Ltd.

Research Article

Effects of citrinin on iron-redox cycle

Eneida Janiscki Da Lozzo 1, Salvio Mangrich 2, Eliane

Merlin Rocha 1, Benigna elli de Oliveira 1, Eva Gunilla

Skare Carnieri 1 *

1Departamento de Bioquímica da Universidade Federal do Paraná,

Curitiba, Brasil

2Departamento de Química da Universidade Federal do Paraná,

Curitiba, Brasil

email: Eva Gunilla Skare Carnieri (carnieri@...)

*Correspondence to Eva Gunilla Skare Carnieri, Departamento de

Bioquímica da Universidade Federal do Paraná, CP 19046, CEP 81531-

990, Curitiba, PR, Brasil.

Funded by:

CNPq

Keywords

citrinin, iron chelation; iron redox cycle; iron-dependent lipid

peroxidation

Abstract

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 Fe3+ to citrinin rapidly produced a

chromogen, indicating the formation of citrinin-Fe3+ complexes. An

EPR study confirms that citrinin acts as a ligand of Fe3+, the

complexation depending on the [Fe3+]:[citrinin] ratios. Effects of

citrinin on the iron redox cycle were evaluated by oxygen

consumption or the o-phenanthroline test. No effect on EDTA-Fe2+EDTA-

Fe3+ oxidation was observed in the presence of citrinin, but the

mycotoxin inhibited, in a dose-dependent manner, the oxidation of

Fe2+ to Fe3+ by hydrogen peroxide. Reducing agents such as ascorbic

acid and DTT reduced the Fe3+-citrinin complex, but DTT did not

cause reduction of Fe3+-EDTA, indicating that the redox potentials

of Fe3+-citrinin and Fe3+-EDTA are not the same. The Fe2+ formed

from the reduction of Fe3+-citrinin by reducing agents was not

rapidly reoxidized to Fe3+ 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 Fe3+-citrinin complex, as well as from

the reaction of citrinin and hydrogen peroxide. Copyright © 2001

Wiley & Sons, Ltd.Abbreviations used:

DPPH diphenylpicrylhydrazyl

DMPO 5,5-dimenthyl-1-pyrroline-N-oxide

EDTA ethylene diaminetetraacetic acid

DTT dithiothreitol

EPR electron paramagnetic resonance spectroscopy

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