1. Nitric Oxide and Lipid Peroxidation
Valerie B. O’Donnella, Neil Hoggb
and Victor M. Darley Usmarc
aDept of Med. Biochem.
University of Wales
College of Medicine,
Heath Park,
Cardiff CF14 4XN, UK.
Ph:
Fax:
bBiophysics Research Institute, Medical College of Wisconsin, Milwaukee, WI USA.
cDepartment of Pathology, University of Alabama at Birmingham, AL USA
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 1

2. Nitric Oxide is a Free Radical
N=O
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 2

3. Nitric oxide is not particularly oxidizing
Nitric oxide is not particularly oxidizing. Nitric oxide is (infinitely) stable*. Nitric oxide does not rapidly react with organic molecules.
*In the absence of dioxygen.
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4. The Nitric Oxide ‘Radical’ and some of its stable end-products
•N=O…nitric oxide
-O-N=O…nitrite
RO-N=O…alkyl nitrite
RS-N=O…nitrosothiol
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5. Reactions of •NO with Other Free Radicals
Oxidation of NO to nitrite:
4 NO+ O=O +2H2O  4HNO2
Nitric oxide reaction with organic peroxyl radicals:
NO+ ROO  ROONO  ??
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6. LOO is the central and rate-limiting species
Lipid Peroxidation
LOO + LH + O2  LOO + LOOH
LOO is the central and rate-limiting species
of lipid peroxidation
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7. Non-enzymatic lipid oxidation
Initiation
Propagation L
LOOH
LOO
Metal or
enzyme LH
AOO O2
LOH
GPx
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8. Lipid peroxidation products in an atherosclerotic lesion are both enzymatically and non-enzymatically produced.
Foam cell
15-LOX 
Necrotic core
lipid hydroxides, hydroperoxides, aldehydes,
epoxides, ketones, ceroid, isoprostanes
Fibrous cap
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9. Location of lipid oxidation enzymes
in the vasculature
LOX: lipoxygenase
PGHS: prostaglandin H synthase
Smooth muscle:
12-LOX
Monocyte:
PGHS-1,2
5, 15-LOX
Platelet:
PGHS-1
12-LOX
Neutrophil:
PGHS-1,2
5,12-LOX
Endothelium
PGHS-1
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10. Lipid oxidation enzymes are upregulated during vascular disease.
* Inhibition of 12-LOX restores blood pressure in Angiotensin-
II dependent hypertensive rats.
* Increased products of PGHS in hypertensive rats, and PGHS
inhibition restores blood pressure in humans and rats.
* Smooth muscle 12-LOX  in hypertension
* Platelet 12-LOX  in hypertension
* Foam cell/macrophage 15-LOX  in atherosclerosis.
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11. Nitric oxide reaction with lipid peroxyl radicals
NO
LOO
LOONO
H2O
[LO NO2]
LOOH + NO2-
LO NO2
NO
[L(O) NO2]
NO
LONO
NO2-
L(O)NO2
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12. Reactions between NO-derived reactive
nitrogen species and unsaturated lipid LH
NO2
NO O2
O2-
ONOO- L
LOO
LOONO
NO2, ONOO-
LNO2
LOOH
HONO
L(O)NO2
e-, H+
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 12

13. Nitric oxide inhibition of lipid oxidation coincides
with fast rates of NO uptake during ABAP-dependent
linoleate oxidation.
(A)
(B)
0.6
200
ABAP
0.2
Oxygen (µM)
NO (µM)
100
-0.2
[ NO] = 0.9 µM added at vertical lines to
7.3 mM linoleate in 0.5% cholate, 11 mM ABAP
-0.6
400
800
1200
Time/s
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 13

14. Mechanism of Inhibition of LDL
Oxidation by NO
LOO + NO  LOONO
LOOH
LO + NO2  LONO2
OLOO + NO
OLOONO  OLONO2
Two NO consumed for each LOO
4 NO + 2LOO + H2O HNO2 + LONO2 + LONO
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15. •NO2 •NO2 •NO2 •NO •NO Cholesteryl Ester Triglyceride Phospholipid
Apolipoprotein B O2 LH
Oxidant
•NO2 O2 L•
•NO2 LH
LOO•
LNO2
•NO2 L•
•NO
LOOH
-Tocopherol
L(O)NO2
Cholesterol
•NO
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16. NO and LDL Oxidation: The effect of HPODE
Lag time of LDL (125 g/ml) oxidation by Cu(II) (20 M) with and without HPODE (5 M)
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 16

17. Comparison of nitric oxide and tocopherol
inhibition of linoleate oxidation.
100
200
300
400
600
800
1000
1200
Time/s
[Oxygen]/µM T
inh
ABAP a
-tocopherol (1 µM)
NO (1 µM)
Oxidation of linoleate (7.3 mM) by ABAP (11 mM)
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18. Nitric oxide is consumed by rabbit 15-lipoxygenase
during oxidation of linoleate.
Add figure caption
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19. Site of lipoxygenase inhibition by NO
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 19

20. Activation of LOX inhibits activation of sGC by NO50
100
cGMP (% control)
control
AA, 5 µM
LOX
AA, 5 µM, LOX **
NO
Lox
sGC
cGMP
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 20

21. Further Reading:
Darley-Usmar, VM et al., (1992) Free Radic. Res. Commun. 17, 9-20
Graham, A et al., (1993) FEBS Lett. 330,
Rubbo, H et al., (1994) J. Biol. Chem. 265,
Hogg, N et al., (1995) J. Lipid Res. 36,
Struck, N et al., (1995) FEBS Lett 361,
O’Donnell, VB et al., (1997) Biochemistry 36,
O’Donnell, VB et al., (1999) Chem. Res. Toxicol. 12, 83-92
O’Donnell, VB et al., (1999) J. Biol. Chem. 274,
Hogg, N & Kalyanaraman, B (1999) Biochim. Biophys. Acta. 1411,
Rubbo, H et al., (2000) J. Biol. Chem. 275,
O’Donnell, VB & Freeman, BA (2001) Circ. Res. 88, 16-25
NO & LPO Society For Free Radical Biology and Medicine O’Donnell et al. 21