Notes and references
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Fig. 3 Cyclic voltammograms for 5-modified glassy carbon electrodes
immersed into O2-saturated 0.10 M Et4NClO4/MeCN solution. Scan
rate: 50 mV sÀ1
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M. Filipovic, F. W. Heinemann and I. Ivanovic
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´ ´
of a microparticulate deposit of the complex on a glassy
carbon electrode. As can be seen in Fig. 3, in contact with
O2-saturated MeCN solutions, 5-modified electrodes producÀe
a sharp decrease of the anodic peak of the reversible O2/O2
couple, thus denoting that the superoxide ion electrochemically
generated upon reduction of dissolved O217 rapidly reacts with
the manganese complex with concomitant abrupt decrease of
´
-
´
6 D. Salvemini, Z.-Q. Wang, J. L. Zweier, A. Samouilov,
H. Macarthur, T. P. Misko, M. G. Currie, S. Cuzzocrea,
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À
the anodic signal. The O2/O2 couple is accompanied by an
anodic wave at +0.70 V vs. AgCl/Ag, corresponding to the
solid state oxidation of the parent MnII complex (Fig. S3,
ESIw). All these features denote the existence of a significant
reactivity of the studied species with superoxide ion even under
electrochemical activation conditions.
7 B. Verdejo, S. Blasco, E. Garcı
C. Soriano, S. Tatay, H. R. Jimenez, A. Dome
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Table 1 also collects results of preliminary in vitro studies of
the SOD activity using the nitro blue tetraazolium (NBT)
reduction method18 along with the reported data for the
relevant MnSOD mimic M40403.
9 E. Garcı
and J. Gonza
10 B. Verdejo, A. Ferrer, S. Blasco, C. E. Castillo, J. Gonza
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lez, Patent Application Number P20093071L.
´
lez,
´
The values obtained are very promising ranking amongst
the best values found in the literature.19 As a matter of
fact the Kcat of MnII–3 parallels the value reported for the
pentaazamacrocycle M40403 that is one of the MnII mimics
that has up to now shown more potential.
´
11 P. Gans, A. Sabatini and A. Vacca, Talanta, 1996, 43,
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12 W. B. Greenleaf, J. Jefferson, P. Perry, A. S. Hearn, D. E. Cabelli,
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D. N. Silverman, Biochemistry, 2004, 43, 7038.
The one order of magnitude difference in SOD activity
between the manganese complexes of the two quinoline-
containing ligands MnII–2 and MnII–3 deserves to be
emphasized. The water molecule directly bound to manganese
is a feature also observed in the native enzyme,13 which seems to
play a very significant role in the proton transfer steps of the
mechanistic cycle and in the regulation of the electrode potential.
Preliminary studies with Candida albicans SC5314 in the
presence of concentrations up to 0.5 mM of the here reported
complexes do not reveal toxicity and show normal growth.
Studies of the protective effects of these SOD mimics using
Saccharomyces cerevisiae ATCC96687 and ATCC96688 deficient
in Sod1p and Sod2p, respectively, are currently being carried
out.20
13 D. M. Stanbury, Adv. Inorg. Chem., 1989, 33, 70.
14 I. Batinic-Haberle, I. Spasojevic, R. D. Stevens, B. Bondurant,
A. Okado-Matsumoto, I. Fridovich, Z. Vujaskovic and
M. W. Dewhirst, Dalton Trans., 2006, 617.
15 C. Muscoli, S. Cuzzocrea, D. P. Riley, J. L. Zweier,
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16 F. Scholz, U. Schroder and R. Gulaboski, Electrochemistry of
¨
Immobilized Particles and Droplets, Springer, Berlin-Heidelberg,
2005.
17 (a) P. Cofre and D. T. Sawyer, Anal. Chem., 1986, 58, 1057;
(b) P. S. Singh and D. H. Evans, J. Phys. Chem. B, 2006, 110, 637.
18 (a) C. Beauchamp and I. Fridovich, Anal. Biochem., 1971, 44, 276;
(b) L. W. Oberley and D. R. Spitz, in Handbook of Methods of
Oxygen Radical Research, ed. R. A. Grenwald, CRC Press, Boca
Raton, USA, 1986, pp. 218; (c) J. Y. Zhou and B. Prognon,
´
J. Pharm. Biomed. Anal., 2006, 40, 1143.
19 O. Iranzo, Bioorg. Chem., 2011, 39, 73–87.
We would like to thank MCINN (Spain) for financial
support (Projects CONSOLIDER INGENIO CSD-2010-
00065 and CTQ2009-14288-C04-01).
´
20 M. Gonza
S. Garcı
2005, 44, 9424.
´
lez-Alvarez, G. Alzuet, J. Borra
´
s, L. del Castillo Agudo,
´
a-Granda and J. M. Montejo-Bernardo, Inorg. Chem.,
c
This journal is The Royal Society of Chemistry 2011
5990 Chem. Commun., 2011, 47, 5988–5990