@conference{
author = "Korać Jačić, Jelena and Stanković, Dalibor and Stanić, Marina and Bajuk-Bogdanovic, Danica and Žižić, Milan and Bogdanović Pristov, Jelena and Popovic Bijelic, Ana and Spasojević, Ivan",
year = "2017",
abstract = "Adrenaline (Adr) is catecholamine that is released by the sympathetic nervous system and
adrenal medulla. It is involved in several physiological functions, including regulation of
blood pressure, vasoconstriction, cardiac stimulation, and regulation of the blood glucose
levels 1
. Transients of high levels of Adr in the bloodstream have been recognized for a
long time as a cause of cardiovascular problems that develop under chronic exposure to
psychosocial and physical stress 2,3. A number of studies have found a connection between
the excess of Adr, cardiotoxic effects, and oxidative stress, that is irrespective of
adrenergic receptors stimulation 2-4. The mechanism behind this involves Adr (coordinate
and redox) interactions with iron, which are still not clear. Two main concepts have been
proposed - Adr autooxidation and redox interactions with iron, the most abundant
transition metal in human plasma 5
. Fe3+ is known to build complexes with catechols 6
, but
data on Fe3+ coordinate interactions with Adr at physiological pH are missing. In addition
to its (patho)physiological role, Adr is of interest from the aspect of development of
catecholamine-rich biopolymers with adhesive properties and metelloorganic frameworks
7,8. The adhesion and other properties materials are based on the cross-linking via
coordinate bonds with Fe3+ at pH > 7. Finally, ligands might dramatically alter the redox
potential of Fe3+/Fe2+ couple 9
. It has been shown that specific ligands with high affinity
for Fe3+, including some catechols, might promote the oxidation and increase the reactivity
of Fe2+ with molecular oxygen 10.
The aim of our study was to examine the nature of Adr interactions with Fe3+ and Fe2+:
stoichiometry, sites of coordinate bonds formation and structure of complex(es), and redox
activity, at pH 7.4 and different concentration ratios. The coordinate and redox interactions
were investigated using UV/Vis spectrophotometry, low temperature EPR, Raman
143
spectroscopy, cyclic voltammetry, and oximetry. The stability of Adr in the studied
reactions was monitored by HPLC.
At pH 7.4, Adr forms complexes with Fe3+, in the 1:1, and 3:1 stoichiometry, depending on
(high or low) Adr/Fe3+ concentration ratio. The high-spin Fe3+ 1:1 and 3:1 complexes show
different symmetries, with the 3:1 complex displaying higher EPR spectral anisotropy.
Raman spectroscopy showed that oxygen atoms on the catechol ring represent the sites of
coordinate bond formation in the bidentate Adr-Fe3+ complex. The bonds appear to be
stronger in the 1:1 complex, and not to share the same plane with the ring. On the other
hand, Adr and Fe2+ build a complex that acts as a strong reducing agent. In the presence of
O2, this leads to the production of H2O2, and to a facilitated formation of Adr/Fe3+
complexes. Adr is not oxidized in this process, i.e. iron is not an electron shuttle but
electron donor. Catalyzed oxidation of Fe2+ in the presence of Adr represents a plausible
chemical basis of stress-related damage of heart cells. In addition, our results imply that
the application/pre-binding of Fe2+ followed by oxidation at pH > 7 might be a simple
alternative strategy for promotion of cross-linking in catecholamine-rich biopolymers
frameworks.",
publisher = "Biohemijsko društvo Srbije",
journal = "Serbian Biochemical Society, Seventh Conference. "Biochemistry of Control in Life and Technology"",
title = "Ligand and redox - interactions of adrenaline with iron at physiological pH",
pages = "144-143",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2838"
}
