Chemistry Reference
In-Depth Information
Reactive oxygen species (ROS)
Superoxide,
O
−•
Hydrogen peroxide, H
2
O
2
Hydroxyl,
•
OH
Hypobromous acid, HOBr
a
Hydroperoxyl,
HO
•
(protonated
superoxide)
Hypochlorous acid, HOCl
b
Carbonate,
CO
−•
Ozone, O
3
c
Peroxyl,
RO
•
Singlet
O g
2
1
∆
Alkoxyl, RO
•
Organic peroxides, ROOH
Carbon dioxide radical,
CO
−•
Peroxynitrite, ONOO
−
d
Singlet
O
g
2
Peroxynitrate, O
2
NOO
−
d
Peroxynitrous acid, ONOOH _
Peroxomonocarbonate,
HOOCO
−
Nitrosoperoxycarbonate, ONOOCO
2
1
∑
+
Reactive nitrogen species (RNS)
Nitric oxide, NO
•
Nitrous acid, HNO
2
Nitrogen dioxide, NO
2
c
Nitrosyl cation, NO
+
Nitrate,
NO
•
Nitroxyl anion, NO
−
Dinitrogen tetroxide, N
2
O
4
Dinitrogen trioxide, N
2
O
3
Peroxynitrite, ONOO
−
d
Peroxynitrate, O
2
NOO
−
Peroxynitrous acid, ONOOH
d
Nitronium cation,
NO
+
Alkyl peroxynitrites, ROONO
Alkyl peroxynitrates, RO
2
ONO
Nitryl chloride, NO
2
Cl
Peroxyacetyl nitrate,
CH C O OONO
3
−
c
(
)
2
Reactive chlorine species (RCS)
Atomic chlorine, Cl
•
Hypochlorous acid, HOCl
b
Nitryl chloride, NO
2
Cl
e
Chloramines
Chlorine gas (Cl
2
)
Bromine chloride (BrCl)
a
Chlorine dioxide (ClO
2
)
Reactive bromine species (RBS)
Atomic bromine, Br
•
Hypobromous acid (HOBr)
Bromine gas (Br
2
)
Bromine chloride (BrCl)
“ROS” is a collective term that includes both oxygen radicals and certain nonradicals that are oxidizing agents
and/or are easily converted into radicals (HOCl, HOBr, O
3
, ONOO
−
,
1
O
2
, H
2
O
2
).
All oxygen radicals are ROS, but not all ROS are oxygen radicals. Peroxynitrite and H
2
O
2
are frequently erro-
neously described in the literature as free radicals, for example. “RNS” is a similar collective term that includes
NO and NO
2
as well as nonradicals such as HNO
2
and N
2
O
4
.
“Reactive” is not always an appropriate term: H
2
O
2
, NO
•
, and
O
•−
react fast with few molecules, whereas
•
OH
reacts fast with almost everything. Species such as
RO
•
,
NO
•
, RO
•
, HOCl, HOBr,
CO
•
,
CO
•
,
NO
•
, ONOO
−
,
NO
+
, and O
3
have intermediate reactivities.
a
HOBr and BrCl could also be regarded as RBS.
b
HOCl and HOBr are often included as ROS, although HOCl is also an RCS.
c
Oxidizing species formed in polluted air that are toxic to plants and animals.
NO
•
is also produced
in vivo
by
myeloperoxidase and from ONOO
−
[19]. Ozone might also be produced
in vivo
, although the chemistry involved
is unclear [20].
d
ONOO
−
, O
2
NOO
−
, and ONOOH are often included as ROS but are also classifiable as RNS.
e
NO
2
Cl can also be regarded as a RNS.
Adapted from Halliwell [18] with the permission of the International Society of Neurochemistry.
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