C O M M U N I C A T I O N S
The effects of the chelators on the generation of H2O2 by Cu-
bound Aꢀ was examined in cell-free solutions using a horseradish
peroxidase (HRP)/Amplex Red assay.6,7 Samples containing CuII,
Aꢀ, and either 1 or 2 show 70% lower [H2O2] (Figure S7), revealing
that 1 and 2 can reduce H2O2 production by Cu-Aꢀ. As expected,
the sample containing Aꢀ, CuII, and phen in the presence of
ascorbate as a reducing agent produces a significant amount of
H2O2, compared to that of Cu-Aꢀ, since the CuI/II redox cycle can
be supported by phen.29 Lastly, the ability of 1 and 2 to modulate
the Cu-induced Aꢀ aggregation was investigated in human neuro-
blastoma cells (SK-N-BE(2)-M17). The bifunctional molecules 1
and 2 exhibit less toxicity than the clinically available compound
CQ in the presence of CuII (Figure 4). Also, 2 shows no toxicity
up to 200 µM (Figure S8). Importantly, toxicity arising from Cu-
Aꢀ is diminished upon incubation with 2, affording ca. 90% cell
survival. This is a better survival rate than that for other chelators
including CQ (Figure 4). These observations suggest that 2 may
be a good candidate to be further studied in vitro and in vivo.
Supporting Information Available: Experimental procedures,
preparation and characterization of 1 and 2, Table S1, Scheme S1, and
Figures S1-S8. This material is available free of charge via the Internet
References
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(18) Abbreviatios: 1 ) 2-(4-(dimethylamino)phenyl)imidazo[1,2-a]pyridine-8-
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CQ ) clioquinol; EDTA ) 2,2′,2′′,2′′′-(ethane-1,2-diyldinitrilo)tetraacetic
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In summary, to specifically target divalent metal ions in Aꢀ
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aggregates and promote their disaggregation. Furthermore, studies
of our chelators in living cells demonstrate their ability to regulate
the cytotoxicity of Cu-induced Aꢀ species and prompt further
investigations in vitro and in vivo. Our approach shown herein may
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tools to elucidate metal-associated events in AD and as potential
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Acknowledgment. This research was supported by the Uni-
versity of Michigan (to M.H.L.) and NIH (DK078885, to A.R).
We thank Dr. Jeffrey Brender and Ravi Nanga for assistance with
NMR and Akiko Kochi and Thu Truong for experimental assistance.
We are grateful to Professor Jason Gestwicki, Ashley Reinke, and
Dr. Christopher Evans for helpful discussions and suggestions.
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(26) For 2, competitive binding experiment with ThT to Aꢀ aggregates was not
performed due to the interference of the absorption of 2 with the window
for fluorescence analysis.27
(27) The absorptions of chelators and their corresponding metal complexes
(Figure S4) interfere with the windows for fluorescence (ThT) and/or
turbidity assays.9-13,17,28
Note Added after ASAP Publication. Due to a production error,
some of the changes requested by the author were not included in the
version published ASAP October 30, 2009; the corrected version
published ASAP November 2, 2009.
(28) Reinke, A. A.; Seh, H. Y.; Gestwicki, J. E. Bioorg. Med. Chem. Lett. 2009,
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(29) Lei, Y.; Anson, F. C. Inorg. Chem. 1994, 33, 5003.
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