In the present study, we have demonstrated photo-
controllable ONOOÀ generation from a novel 2,6-dimethyl-
nitrobenzene bearing a conjugated phenol moiety (1). NO
release from 1 was detected by means of an ESR spin trapping
method. ONOOÀ generation in response to photoirradiation
of 1 was detected with an ONOOÀ-specific fluorescent probe,
HKGreen-3. The results of the DNA strand break assay with 1
indicate that 1 shows ONOOÀ-like DNA cleavage reactivity.
To our knowledge, this is the first example of a photocontrol-
lable ONOOÀ generator. It is expected be a useful tool for
time- and site-specific generation of ONOOÀ.
This work was supported by JST PRESTO program (H.N.),
Grants-in-Aid for Scientific Research on Innovative Areas
(Research in a Proposed Research Area) (No. 21117514
to H.N.), and Grants-in-Aid for Scientific Research
(No. 22590103 to H.N.) from Ministry of Education, Culture,
Sports Science and Technology Japan.
Fig. 5 Detection of 2, the photo-decomposition product of 1, using
reverse-phase HPLC: (a) a solution of 1 (100 mM) was examined by
means of HPLC; (b) an irradiated (15 min) solution of 1 (100 mM) was
examined by means of HPLC.
Notes and references
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under physiological conditions, so would not generate an
À
ꢀ
excess amount of O2
.
À
As ONOOÀ eventually decomposes to NO2 or NO3À, the
À
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À
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We also examined DNA cleavage by photoirradiation in the
presence of 1 in vitro. It is known that ONOOH (pKa = 6.8,
protonated form of ONOOÀ) decays by homolysis of its
peroxo bond, generating ꢀOH and nitrogen dioxide (ꢀNO2),
and shows OH-like DNA cleavage reactivity. So, we
conducted a DNA cleavage assay under various pH conditions
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photoirradiation in the presence of 1, and the activity was
found to be diminished at high pH (pH = 8.0), like that of
ONOOÀ (Fig. 6). From these results, it was suggested that
ONOOÀ generated from 1 in response to photoirradiation
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c
This journal is The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 6449–6451 6451