Original Contribution
TRIMETAZIDINE PROTECTS LOW-DENSITY LIPOPROTEINS FROM
OXIDATION AND CULTURED CELLS EXPOSED TO H
2
O
2
FROM DNA
DAMAGE
ALEXANDROS TSELEPIS,* PASCHALIS-THOMAS DOULIAS,
†
EVAGGELIA LOURIDA,* GEORGIOS GLANTZOUNIS,
‡
EVANGELOS TSIMOYIANNIS,
‡
and DIMITRIOS GALARIS
†
*Laboratory of Biochemistry, Department of Chemistry and
†
Laboratory of Biological Chemistry, School of Medicine, University
of Ioannina, Ioannina, Greece; and
‡
Department of Surgery, “G. Hatzikosta” General Hospital, Ioannina, Greece
(Received 2 November 2000; Accepted 8 March 2001)
Abstract—Trimetazidine is a well-established anti-ischemic drug, which has been used for long time in the treatment
of pathological conditions related with the generation of reactive oxygen species. However, although extensively
studied, its molecular mode of action remains largely unknown. In the present study, the ability of trimetazidine to
protect low-density lipoproteins (LDL) from oxidation and cultured cells from H
2
O
2
-induced DNA damage was
investigated. Trimetazidine, tested at concentrations 0.02 to 2.20 mM, was shown to offer significant protection to LDL
exposed to three different oxidizing systems, namely copper, Fe/ascorbate, and met-myoglobin/H
2
O
2
. The oxidizability
of LDL was estimated by measuring, (i) the lag period, (ii) the maximal rate of conjugated diene formation, (iii) the total
amount of conjugated dienes formed, (iv) the electrophoretic migration of LDL protein in agarose gels (REM), and (v)
the inactivation of the enzyme PAF-acetylhydrolase present in LDL. In addition, the presence of trimetazidine decreased
considerably the DNA damage in H
2
O
2
-exposed Jurkat cells in culture. H
2
O
2
was continuously generated by the action
of glucose oxidase at a rate of 11.8 1.5 M per min (60 ng enzyme per 100 l), and DNA damage was assessed by
the single cell gel electrophoresis assay (also called comet assay). The protection offered by trimetazidine in this system
(about 30% at best) was transient, indicating modification of this agent during its action. These results indicate that
trimetazidine can modulate the action of oxidizing agents in different systems. Although its mode of action is not
clarified, the possibility that it acts as a lipid barrier permeable transition metal chelator is considered. © 2001 Elsevier
Science Inc.
Keywords—LDL, Oxidized-LDL, PAF-acetylhydrolase, Hydrogen peroxide, Single cell gel electrophoresis (comet
assay), Glucose oxidase, Jurkat cells, Free radicals
INTRODUCTION
Reactive oxygen species (ROS) of various kinds are
continuously generated in aerobic organisms but their
rate of production and steady state concentrations are
considerably increased under a variety of pathological
conditions [1]. Examples of pathological conditions in
which ROS have been proposed to be implicated are
cardiovascular diseases (mainly of atheroslerotic origin),
ischemia/reperfusion syndromes, neurodegenerative dis-
eases such as Parkinson’s and Alzheimer’s, and many
others including AIDS and cancer [1–3]. It is well known
that ROS are able to induce damage to all the basic
constituents of the cell, i.e., lipids, proteins, DNA, and
other. However, the molecular mechanisms underlying
the induction of damage remain partly controversial or
even elusive. It seems likely that redox active transition
metal ions are mainly involved in mediating ROS-in-
duced damage to cell constituents and consequently cell
toxicity.
Organisms have evolved effective protective mecha-
nisms in order to withstand oxidative stress, but these
defenses are often overwhelmed leading to development
of serious diseases. In such cases the administration of
exogenous protective compounds (e.g., therapeutic
agents, food constituents, and others) may be beneficial.
Address correspondence to: Dimitrios Galaris, Ph.D., Laboratory of
Biological Chemistry, University of Ioannina Medical School, 451 10
Ioannina, Greece; Tel: +30 (651) 97562; Fax: +30 (651) 97868;
E-Mail: dgalaris@cc.uoi.gr.
Free Radical Biology & Medicine, Vol. 30, No. 12, pp. 1357–1364, 2001
Copyright © 2001 Elsevier Science Inc.
Printed in the USA. All rights reserved
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