Abbreviations ................................................ xxix
1. Oxygen is a toxic gas—an introduction to oxygen
toxicity and reactive species ................................ 1
1.1. The history of oxygen: an essential air pollutant ....... 1
1.1.1. The paradox of photosynthesis .................... 5
1.1.2. Hyperoxia in history? ............................ 5
1.1.3. Oxygen in solution ............................... 5
1.2. Oxygen and anaerobes .................................... 6
1.2.1. Why does oxygen injure anaerobes? ................ 7
1.3. Oxygen and aerobes ...................................... 8
1.3.1. Oxygen transport in mammals ...................... 8
1.3.2. Oxygen sensing ................................... 9
1.3.3. Mitochondrial electron transport ................. 9
1.3.4. The evolution of mitochondria ................... 13
1.3.5. Bacteria electron transport chains .............. 13
1.4. Oxidases and oxygenases in aerobes ..................... 13
1.4.1. Cytochromes P450 ................................ 13
1.5. Oxygen toxicity in aerobes ............................. 15
1.5.1. Bacteria and plants ............................. 15
1.5.2. Oxygen toxicity in animals ...................... 16
1.5.3. Retinopathy of prematurity and brain damage ..... 18
1.5.4. Resuscitation of newborns ....................... 18
1.5.5. Factors affecting oxygen toxicity ............... 18
1.6. What causes the toxic effects of oxygen? ............... 19
1.7. So free radicals cause most oxygen toxicity? What
then are free radicals? ................................ 19
1.8. Oxygen and its radicals ................................ 21
1.8.1. Singlet oxygen .................................. 22
1.8.2. Superoxide radical .............................. 22
1.9. Saying it correctly: oxygen radicals, oxygen-derived
species, reactive oxygen species or oxidants? .......... 22
1.10.Sources of superoxide in aerobes ....................... 22
1.10.1.Enzymes ......................................... 23
1.10.2.Auto-oxidation reactions ........................ 23
1.10.3.Haem proteins ................................... 23
1.10.4.Mitochondrial electron transport ................ 24
1.10.5.Mitochondrial DNA (mtDNA) ....................... 26
1.10.6.Uncoupling proteins as antioxidants? ............ 27
1.10.7.Bacterial superoxide production ................. 27
1.10.8.Endoplasmic reticulum ........................... 27
1.10.9.Other cell membranes ............................ 28
1.10.10.Quantification ................................. 28
1.11.Artefacts in cell culture .............................. 28
2. The chemistry of free radicals and related 'reactive
species' .................................................... 30
2.1. Introduction ........................................... 30
2.2. How do radicals react? ................................. 30
2.3. Radical chemistry: thermodynamics versus kinetics ...... 31
2.3.1. Oxidation and reduction ......................... 31
2.3.2. Reaction rates and rate constants:
definitions ..................................... 35
2.3.3. Reaction rates and rate constants:
measurements .................................... 36
2.4. Chemistry of transition metals ......................... 38
2.4.1. Iron ............................................ 38
2.4.2. Copper .......................................... 40
2.4.3. Manganese ....................................... 40
2.4.4. The Fenton reaction ............................. 40
2.4.5. Iron chelators and Fenton chemistry: speed
it up or slow ................................... 41
2.4.6. Reaction of copper ions with H202 ............... 42
2.5. Chemistry of other biologically important radicals ..... 42
2.5.1. Hydroxyl radical ................................ 42
2.5.2. Carbonate radical ............................... 45
2.5.3. Superoxide radical .............................. 46
2.5.4. Peroxyl and alkoxyl radicals .................... 50
2.5.5. Sulphur radicals ................................ 52
2.5.6. Nitric oxide .................................... 53
2.6. Chemistry of biologically important non-radicals ....... 60
2.6.1. Peroxynitrite ................................... 60
2.6.2. Hydrogen peroxide ............................... 66
2.6.3. Hypochlorous acid ............................... 68
2.6.4. Singlet oxygen .................................. 69
2.6.5. Ozone ........................................... 74
3. Antioxidant defences: endogenous and diet derived ........... 79
3.1. Introduction ........................................... 79
3.1.1. The simplest defence: avoid 02 as much as
possible ........................................ 79
3.1.2. Other antioxidant defences ...................... 79
3.1.3. What is an antioxidant? A new definition ........ 80
3.2. Antioxidant defence enzymes: superoxide dismutases
(SODs) ................................................. 81
3.2.1. Copper-zinc SOD ................................. 81
3.2.2. Manganese SOD (sometimes called SOD2) ........... 87
3.2.3. Iron and cambialistic SODs ...................... 88
3.2.4. Nickel-containing SODs .......................... 91
3.2.5. Assaying SOD .................................... 91
3.2.6. Using SOD enzymes as probes for superoxide ...... 95
3.2.7. Superoxide and other metalloproteins ............ 95
3.3. Superoxide reductases .................................. 95
3.4. Superoxide dismutases; are they important in vivo? ..... 96
3.4.1. Gene knockout in bacteria and yeasts ............ 96
3.4.2. Transgenic animals .............................. 97
3.4.3. RNA interference ................................ 99
3.4.4. Induction experiments ........................... 99
3.4.5. SOD and oxygen toxicity in animals .............. 99
3.4.6. SOD and hibernation ............................ 100
3.5. The superoxide theory of oxygen toxicity:
variations and anomalies .............................. 100
3.5.1. Anaerobes with SOD and aerobes without SOD ..... 100
3.5.2. Manganese can replace SOD ...................... 100
3.6. Why is superoxide cytotoxic? .......................... 101
3.6.1. Direct damage by superoxide: not very super
but super enough? .............................. 101
3.6.2. Cytotoxicity of superoxide-derived species ..... 102
3.7. Antioxidant defence enzymes: catalases ................ 105
3.7.1. Catalase structure ............................. 106
3.7.2. The reaction mechanism of catalase ............. 107
3.7.3. Catalase inhibitors ............................ 108
3.7.4. Peroxidatic activity of catalase ............... 108
3.7.5. Photosensitization by catalase ................. 108
3.7.6. Subcellular location of catalase ............... 108
3.7.7. Manganese-containing catalases ................. 109
3.7.8. Acatalasaemia .................................. 109
3.8. Antioxidant defence enzymes: the glutathione
peroxidase family ..................................... 110
3.8.1. A family of enzymes ............................ 110
3.8.2. The role of selenium ........................... 112
3.8.3. Glutathione reductase .......................... 113
3.8.4. Watching GPx in action ......................... 113
3.9. Glutathione in metabolism and cellular redox state .... 114
3.9.1. Cofactor and redox agent ....................... 114
3.9.2. GSH as an antioxidant .......................... 115
3.9.3. Glutathione biosynthesis and degradation ....... 115
3.9.4. Defects in GSH metabolism: humans and
transgenic animals ............................. 116
3.9.5. The glutathione S-transferase superfamily ...... 118
3.9.6. Mixed disulphides involving glutathione:
pathological or protective? .................... 120
3.10.Protein-disulphide isomerase .......................... 121
3.11.Thioredoxin and peroxiredoxins: key players in
peroxide metabolism ................................... 122
3.11.1.Catalase, glutathione peroxidases and
peroxiredoxins: fitting it all together ........ 123
3.11.2.Selenium deficiency: reinterpretation of
an old paradigm ................................ 124
3.12.Other sulphur-containing compounds involved in
antioxidant defence ................................... 126
3.12.1.Trypanothione: an antioxidant defence in
some parasites ................................. 126
3.12.2.Ergothioneine .................................. 127
3.13.Antioxidant defence enzymes: other peroxidases ........ 127
3.13.1.Cytochrome с peroxidase: another specific
peroxidase ..................................... 127
3.13.2.NADH oxidase ................................... 128
3.13.3.'Non-specific' peroxidases ..................... 128
3.13.4.Horseradish peroxidase ......................... 128
3.13.5.Why do plants have so much peroxidase? ......... 129
3.13.6.Chloroperoxidase and bromoperoxidase ........... 130
3.13.7.Ascorbate peroxidase ........................... 130
3.13.8.Peroxidase 'mimics' ............................ 130
3.14.Antioxidant defence enzymes: co-operation ............. 130
3.14.1.The need for co-operation ...................... 130
3.14.2.Down's syndrome ................................ 132
3.15.Antioxidant defence: sequestration of metal ions ...... 132
3.15.1.Iron metabolism ................................ 132
3.15.2.Copper metabolism .............................. 138
3.15.3.Haem proteins: potential pro-oxidants .......... 139
3.15.4.Metal ion sequestration; why do it? ............ 140
3.15.5.Metal ion sequestration: when it goes wrong .... 141
3.16.Metal ions and antioxidant defence: intracellular
and extracellular strategies .......................... 144
3.16.1.Metallothioneins ............................... 144
3.16.2.Phytochelatins ................................. 145
3.16.3.Extracellular antioxidant defence .............. 145
3.17.Haem oxygenase ........................................ 148
3.18.Antioxidant protection by low-molecular-mass agents:
compounds synthesized in vivo ......................... 149
3.18.1.Bilirubin ...................................... 152
3.18.2.α-Keto acids ................................... 152
3.18.3.Melatonin ...................................... 152
3.18.4.Lipoic acid .................................... 154
3.18.5.Coenzyme Q ..................................... 155
3.18.6.Uric acid ...................................... 155
3.18.7.Histidine-containing dipeptides ................ 157
3.18.8.Trehalose (α-D-glucopyranosyl-l,l-α-D-
glucopyranoside) ............................... 158
3.18.9.Melanins: hair, skin, corals, fungi and fish ... 158
3.19.Gender affects antioxidant defence .................... 159
3.20.Antioxidant protection by low-molecular-mass agents:
compounds derived from the diet ....................... 160
3.20.1.Ascorbic acid (vitamin C) ...................... 160
3.20.2.Vitamin E ...................................... 166
3.21.Carotenoids: bright colours but not sparkling
antioxidants? ......................................... 174
3.21.1.Carotenoid chemistry ........................... 175
3.21.2.Metabolic roles of carotenoids ................. 177
3.21.3.Carotenoids and vitamin A as antioxidants ...... 177
3.22.Plant phenols ......................................... 179
3.22.1.Phenols in the diet ............................ 180
3.22.2.Are plant phenols antioxidants in vivo? ........ 182
3.22.3.Pro-oxidant effects of phenols? ................ 184
3.22.4.Herbal medicines ............................... 185
4. Cellular responses to oxidative stress: adaptation,
damage, repair, senescence and death ....................... 187
4.1. Introduction .......................................... 187
4.1.1. Defining oxidative stress and oxidative
damage ......................................... 187
4.2. Consequences of oxidative stress: proliferation,
adaptation, senescence, damage or death? .............. 188
4.2.1. Proliferation .................................. 188
4.2.2. Adaptation ..................................... 189
4.2.3. Cell injury and senescence ..................... 190
4.2.4. Poly(ADP-ribose)polymerase ..................... 191
4.3. Oxidative stress causes changes in cellular ion
metabolism ............................................ 191
4.3.1. Basic principles ............................... 191
4.3.2. Calcium ........................................ 192
4.3.3. Iron ........................................... 195
4.3.4. Copper ......................................... 198
4.4. Consequences of oxidative stress: cell death .......... 199
4.4.1. Apoptosis ...................................... 199
4.5. Redox regulation ...................................... 207
4.5.1. What is it and how does it work? ............... 207
4.5.2. Bacterial redox regulation: oxyR ............... 207
4.5.3. Bacterial redox regulation: soxRS .............. 208
4.5.4. Redox regulation in yeast ...................... 208
4.5.5. Redox regulation in animals: kinases and
phosphatases ................................... 208
4.5.6. Reactive species as mediators of the actions
of signalling molecules? ....................... 211
4.5.7. Intraorganelle communication? .................. 211
4.5.8. NF-kB .......................................... 213
4.5.9. AP-1 ........................................... 214
4.5.10.The antioxidant response element ............... 215
4.5.11.Getting it together: co-operation and
combination .................................... 215
4.5.12.Is it real? Physiological significance of
redox regulation in animals .................... 215
4.5.13.Lessons from an amoeba ......................... 216
4.6. Heat-shock and related 'stress-induced' proteins,
cross talk with ROS ................................... 217
4.7. Cytokines, hormones and redox-regulation of the
organism .............................................. 218
4.7.1. TNFα ........................................... 219
4.7.2. Interleukins ................................... 220
4.7.3. The acute-phase response ....................... 220
4.8. Mechanisms of damage to cellular targets by
oxidative stress: DNA ................................. 220
4.8.1. DNA structure .................................. 220
4.8.2. Damage to DNA by reactive species .............. 222
4.8.3. Damage to mitochondrial and chloroplast DNA .... 229
4.9. Consequences of damage to DNA by reactive species ..... 230
4.9.1. Mutation ....................................... 230
4.9.2. Misincorporation ............................... 232
4.9.3. Changes in gene expression ..................... 232
4.9.4. Having sex ..................................... 232
4.10.Repair of oxidative DNA damage ........................ 232
4.10.1.Reversing the chemical change .................. 232
4.10.2.Don't let it in: sanitization of the
nucleotide pool ................................ 233
4.10.3.Chop it out: excision repair ................... 233
4.10.4.Mismatch repair ................................ 234
4.10.5.Repair of 80HdG ................................ 234
4.10.6.Repair of double-strand breaks ................. 235
4.10.7.Mitochondrial DNA repair ....................... 235
4.10.8.Is DNA repair important? ....................... 235
4.10.9.Oxidative RNA damage ........................... 236
4.11.Mechanisms of damage to cellular targets by
oxidative stress: lipid peroxidation .................. 236
4.11.1.A history of peroxidation: from oils and
textiles to breast implants .................... 236
4.11.2.Targets of attack: membrane lipids and
proteins ....................................... 237
4.11.3.Targets of attack: dietary lipids, and
lipoproteins ................................... 238
4.11.4.How does lipid peroxidation begin? ............. 238
4.11.5.Propagation of lipid peroxidation .............. 242
4.11.6.Transition metals and lipid peroxidation ....... 243
4.11.7.Microsomal lipid peroxidation .................. 247
4.11.8.Acceleration of lipid peroxidation by species
other than oxygen radicals ..................... 248
4.12.Lipid peroxidation products: bad, good or
indifferent? .......................................... 249
4.12.1.General effects ................................ 249
4.12.2.Lipid hydroperoxides (ROOH) .................... 249
4.12.3.Isoprostanes, isoketals and cyclopentenone
compounds ...................................... 250
4.12.4.Cholesterol oxidation products (COPs) .......... 253
4.12.5.Decomposition products from lipid peroxides:
what do they do? ............................... 253
4.12.6.Peroxidation of other molecules ................ 258
4.12.7.Repair of lipid peroxidation ................... 258
4.12.8.Lipids as antioxidants? The plasmalogens ....... 259
4.12.9.Polyamines: antioxidants or pro-oxidants? ...... 260
4.13.Mechanisms of damage to cellular targets by
oxidative stress: protein damage ...................... 260
4.13.1.Does protein damage matter? .................... 260
4.13.2.How does damage occur? Is it random or
specific? ...................................... 261
4.13.3.Chemistry of protein damage .................... 261
4.13.4.Damage to specific amino-acid residues ......... 264
4.14.Dealing with oxidative protein damage ................. 264
4.14.1.Repair of methionine residues .................. 264
4.14.2.Removal: lysosomes and proteasomes ............. 265
4.15.Summary: oxidative stress and cell injury ............. 267
5. Measurement of reactive species ............................ 268
5.1. Introduction .......................................... 268
5.1.1. Trapping ....................................... 268
5.1.2. Fingerprinting: the biomarker concept .......... 268
5.1.3. Indirect approaches ............................ 269
5.2. ESR and spin trapping ................................. 270
5.2.1. What is ESR? ................................... 270
5.2.2. Measurement of oxygen .......................... 272
5.2.3. Spin trapping .................................. 272
5.2.4. DMPO, DEPMPO and PBN ........................... 273
5.2.5. Ex vivo trapping in humans ..................... 275
5.2.6. Further cautions in the use of spin traps ...... 276
5.2.7. Trapping thiyl radicals ........................ 277
5.2.8. Spin-trapping without ESR? ..................... 277
5.3. Other trapping methods, as exemplified by hydroxy
1-radical trapping .................................... 278
5.3.1. Aromatic hydroxylation ......................... 278
5.3.2. Use of hydroxyl-radical scavengers ............. 281
5.3.3. The deoxyribose assay .......................... 281
5.3.4. Measurement of rate constants for OH-
reactions ...................................... 281
5.3.5. Other trapping methods for hydroxyl radical .... 282
5.4. Detection of superoxide ............................... 282
5.4.1. The aconitase assay ............................ 285
5.4.2. Rate constants for reactions with O2- .......... 285
5.4.3. Triphenyl radical-based probes ................. 286
5.4.4. Histochemical detection ........................ 286
5.5. Detection of nitric oxide ............................. 286
5.5.1. Calibration .................................... 286
5.6. Detection of peroxynitrite and other reactive
nitrogen species ...................................... 286
5.6.1. Probes for peroxynitrite ....................... 286
5.6.2. Nitration assays ............................... 292
5.7. Detection of reactive halogen species ................. 293
5.8. Detection of hydrogen peroxide ........................ 295
5.9. Detection of singlet oxygen ........................... 296
5.9.1. Direct detection ............................... 301
5.9.2. Use of scavengers and traps .................... 301
5.9.3. Deuterium oxide (D20) .......................... 302
5.10.Studies of 'generalized' light emission
(luminescence/fluorescence) ........................... 302
5.11.Measurement of reactive species in cultured cells ..... 302
5.11.1.Dichlorofluorescin diacetate (DCFDA) ........... 304
5.11.2.Dihydrorhodamine 123 (DHR) ..................... 305
5.11.3.Dihydroethidium ................................ 305
5.11.4.Luminol and lucigenin .......................... 305
5.11.5.Alternative fluorescent probes for
superoxide ..................................... 307
5.11.6.Measuring the light output of fluorescent
probes ......................................... 307
5.11.7.Effects of reactive species on other probes .... 308
5.12.Biomarkers: the promise of urate oxidation? ........... 308
5.13.Biomarkers of oxidative DNA damage .................... 309
5.13.1.Characterizing DNA damage: why bother to do
it? ............................................ 309
5.13.2.Characterizing DNA damage: what to measure? .... 309
5.13.3.Characterizing DNA damage: how to measure it ... 311
5.13.4.Steady-state damage: the artefact problem ...... 312
5.13.5.Overcoming the artefact ........................ 313
5.13.6.Interpreting the results: measure DNA levels
or urinary excretion? What do the levels
mean? .......................................... 314
5.13.7.Reactive nitrogen and chlorine species ......... 315
5.13.8.Gene-specific oxidative damage ................. 316
5.13.9.DNA-aldehyde adducts ........................... 316
5.14.Biomarkers of lipid peroxidation ...................... 316
5.14.1.Why measure lipid peroxidation? ................ 317
5.14.2.How to measure lipid peroxidation: general
principles ..................................... 317
5.14.3.Loss of substrates ............................. 317
5.14.4.Measurement of intermediates ................... 318
5.14.5.Measurement of end-products: peroxides ......... 319
5.14.6.Measurement of end products: isoprostanes,
isofurans and isoketals ........................ 319
5.14.7.Measurement of end products: aldehydes ......... 322
5.14.8.Measurement of end products: breath analysis ... 325
5.14.9.The TBA assay (thiobarbituric acid or 'that
bloody assay') ................................. 326
5.14.10.Measuring lipid peroxidation: light
emission ....................................... 329
5.14.11.A summary: what is the best method to measure lipid
peroxidation in tissues, cells and body fluids? ....... 329
5.14.12.Visualizing lipid peroxidation ................ 330
5.14.13.Probes of lipid peroxidation/ membrane
reactive species ............................... 330
5.15.Biomarkers of protein damage by reactive species ...... 333
5.15.1.Damage by reactive oxygen species .............. 333
5.15.2.Damage by reactive halogen and nitrogen
species ........................................ 333
5.15.3.The carbonyl assay ............................. 336
5.16.Is there a single biomarker of oxidative stress
or oxidative damage? .................................. 336
5.17.Assays of total antioxidant capacity .................. 337
5.17.1 What do changes in total antioxidant
capacity mean? ................................. 337
6. Reactive species can pose special problems needing
special solutions: some examples ........................... 341
6.1. Introduction .......................................... 341
6.2. The gastrointestinal tract ............................ 341
6.2.1. Threatening your guts .......................... 341
6.2.2. Defending your guts ............................ 342
6.3. The respiratory tract ................................. 344
6.3.1. The challenges ................................. 344
6.3.2. Defending the respiratory tract ................ 345
6.3.3. Asthma and antioxidants ........................ 346
6.4. Erythrocytes .......................................... 346
6.4.1. What problems do erythrocytes face? ............ 346
6.4.2. Solutions: antioxidant defences ................ 347
6.4.3. Solutions: diet-derived antioxidants ........... 349
6.4.4. Erythrocyte peroxidation in health and
disease ........................................ 349
6.4.5. Glucose-6-phosphate dehydrogenase (G6PDH)
deficiency ..................................... 350
6.4.6. Solutions: destruction ......................... 350
6.5. Erythrocytes as targets for toxins .................... 350
6.5.1. Hydrazines ..................................... 350
6.5.2. Sulphur-containing haemolytic drugs ............ 353
6.5.3. Favism ......................................... 353
6.6. Bloodthirsty parasites: problems for them and
for us ................................................ 353
6.6.1. Malaria, oxidative stress and an ancient
Chinese herb ................................... 354
6.7. Oxidation in plants: peroxides and phytoprostanes ..... 356
6.7.1. Sources of ROS in plants ....................... 356
6.8. The origins of life: chloroplasts ..................... 356
6.8.1. Structure and genetics ......................... 356
6.8.2. Trapping of light energy ....................... 357
6.8.3. The water splitting mechanism: a radical
process and the reason for this book ........... 360
6.8.4. What problems do green leaves face? ............ 361
6.8.5. Solutions: minimizing the problem .............. 363
6.8.6. The xanthophyll cycle .......................... 364
6.8.7. Solutions: antioxidant defence enzymes
control, but do not eliminate, reactive
species ........................................ 365
6.8.8. Ascorbate and glutathione ...................... 366
6.8.9. Plant tocopherols .............................. 367
6.8.10.Solutions: repair and replacement .............. 367
6.8.11.The special case of the root nodule ............ 368
6.9. Plants as targets for stress and toxins ............... 368
6.9.1. Inhibition of electron transport and
carotenoid synthesis ........................... 368
6.9.2. Bipyridyl herbicides ........................... 368
6.9.3. Environmental stress: air pollutants (ozone,
sulphur dioxide, nitrogen dioxide) ............. 371
6.9.4. Environmental stress: heat and cold ............ 371
6.9.5. Coral reef bleaching and toxic algal blooms:
examples of plant-dependent oxidative
stress? ........................................ 373
6.10.The eye ............................................... 373
6.10.1.What problems does the eye face? ............... 373
6.10.2.Solutions ...................................... 377
6.10.3.Toxins, inflammation and the eye ............... 379
6.10.4.The thorny question of ocular carotenoids:
a Chinese herb good for the eyes? .............. 379
6.10.5.Antioxidants, cataract and macular
degeneration ................................... 379
6.11.Reproduction and oxidative stress ..................... 380
6.11.1.Preconception: spermatozoa have problems ....... 380
6.11.2.The female story ............................... 381
6.11.3.Spermatozoa: the solutions ..................... 381
6.11.4.Spermatozoa as targets for toxins .............. 381
6.11.5.Problems of the embryo ......................... 382
6.11.6.Problems of pregnancy: normal and abnormal
02 ............................................. 382
6.11.7.The embryo/foetus as a target for toxins ....... 384
6.11.8.Birth .......................................... 385
6.12.The skin .............................................. 387
6.12.1.Problems of the skin ........................... 388
6.12.2.The solutions .................................. 390
6.12.3.Wounds and burns ............................... 391
6.13.Exercise: a cause of or a protection against
oxidative stress? ..................................... 392
6.13.1.Exercise, lack of exercise and oxidative
damage ......................................... 392
6.13.2.Exercise, health and free radicals ............. 393
6.13.3.Muscle as a target for toxins .................. 394
7. Reactive species can be useful: some more examples ......... 395
7.1. Introduction .......................................... 395
7.2. Radical enzymes: ribonucleotide reductase and its
colleagues ............................................ 395
7.2.1. The enzyme mechanism ........................... 395
7.2.2. Inhibitors of RNRs ............................. 396
7.2.3. Class III ribonucleotide reductases and other
'sons of SAM' enzymes .......................... 397
7.2.4. Class II ribonucleotide reductases and other
cobalamin radical enzymes ...................... 397
7.3. Pyruvate-formate lyase: a similar mechanism ........... 397
7.3.1. Pyruvate-ferredoxin oxidoreductase ............. 398
7.4. Assorted oxidases ..................................... 398
7.4.1. Galactose oxidase .............................. 398
7.4.2. Indoleamine dioxygenase ........................ 399
7.5. Useful peroxidases .................................... 399
7.5.1. Thyroid hormone synthesis ...................... 399
7.5.2. An 'antimolestation' spray ..................... 401
7.5.3. Thick coats .................................... 401
7.5.4. Making and degrading lignin .................... 401
7.6. Light production ...................................... 403
7.6.1. Green fluorescent protein: another example
of autocatalytic oxidation ..................... 403
7.7. Phagocytosis .......................................... 405
7.7.1. Phagocyte recruitment, adhesion, activation
and disappearance .............................. 407
7.7.2. How do phagocytes kill? ........................ 412
7.7.3. The enigma of myeloperoxidase .................. 417
7.8. Other phagocytes: similar but different ............... 420
7.9. What do phagocyte-derived reactive species do to
the host? ............................................. 421
7.9.1. Extracellular RS: what can they do? ............ 421
7.9.2. Signalling ..................................... 422
7.9.3. Damage to the phagocyte ........................ 422
7.9.4. Damage by phagocytes can be severe: the
tragedy of chronic inflammation ................ 423
7.9.5. What does it all mean? Are RS both pro- and
anti-inflammatory? ............................. 424
7.9.6. Defeating the system: bacterial and fungal
avoidance strategies ........................... 424
7.10.NAD(P)H oxidases in other cell types .................. 425
7.10.1.The gastrointestinal tract ..................... 426
7.10.2.С elegans ...................................... 426
7.10.3.Blood vessel walls ............................. 426
7.10.4.Lymphocytes .................................... 427
7.10.5.Reactive species, renal function and oxygen
sensing ........................................ 427
7.10.6.Platelets ...................................... 428
7.10.7.Osteoclasts .................................... 428
7.10.8.Other redox systems ............................ 428
7.11.Even plants use reactive species ...................... 428
7.11.1.The hypersensitive response .................... 429
7.11.2.Germination and senescence ..................... 430
7.11.3.Plant lipoxygenases ............................ 431
7.11.4.The injury response and oxylipid signalling .... 431
7.12.Animal lipoxygenases and cyclooxygenases:
stereospecific lipid peroxidation ..................... 432
7.12.1.Eicosanoids: prostaglandins and leukotrienes ... 432
7.12.2.Prostaglandins and thromboxanes ................ 433
7.12.3.Prostaglandin synthesis ........................ 434
7.12.4.Regulation by 'peroxide tone' .................. 434
7.12.5.Prostaglandins from isoprostanes? Cross-talk
of the systems ................................. 436
7.12.6.Levuglandins ................................... 436
7.12.7.Prostacyclins and thromboxanes ................. 436
7.12.8.Leukotrienes and other lipoxygenases
products ....................................... 438
8. Reactive species can be poisonous: their role in
toxicology ................................................. 440
8.1. Introduction .......................................... 440
8.1.1. What is toxicology? ............................ 440
8.1.2. Principles of toxin metabolism ................. 440
8.1.3. How can reactive species contribute to
toxicity? ...................................... 441
8.2. Carbon tetrachloride .................................. 442
8.2.1. Carbon tetrachloride synthesis: a free-
radical chain reaction ......................... 442
8.2.2. Toxicity of CC14 ............................... 444
8.2.3. How does CC14 cause damage? .................... 444
8.3. Other halogenated hydrocarbons ........................ 445
8.3.1. Chloroform and bromotrichloromethane ........... 446
8.3.2. Pentachlorophenol and related environmental
pollutants ..................................... 446
8.4. Redox-су cling toxins: bipyridyl herbicides ........... 447
8.4.1. Toxicity to bacteria ........................... 447
8.4.2. Toxicity to animals ............................ 447
8.4.3. Why is paraquat toxic to the lung? ............. 448
8.5. Diabetogenic drugs .................................... 449
8.5.1. Alloxan ........................................ 449
8.5.2. Streptozotocin ................................. 451
8.6. Redox-cycling toxins: diphenols and quinones .......... 451
8.6.1. Interaction with 02 and superoxide ............. 451
8.6.2. Interaction with metals ........................ 451
8.6.3. Mechanisms of toxicity ......................... 453
8.6.4. Quinone reductase .............................. 453
8.6.5. Catechol oestrogens ............................ 454
8.6.6. Substituted dihydroxyphenylalanines and
'manganese madness' ............................ 454
8.6.7. Neurotoxicity of 6-hydroxydopamine ............. 455
8.6.8. Benzene and its derivatives .................... 456
8.6.9. Toxic-oil syndrome and a new society ........... 456
8.7. Redox-cycling agents: toxins derived from
Pseudomonas aeruginosa ................................ 457
8.8. Alcohols .............................................. 457
8.8.1. Ethanol ........................................ 457
8.8.2. Allyl alcohol and acrolein ..................... 461
8.9. Other recreational drugs .............................. 461
8.10.Paracetamol (acetaminophen), a glutathione-
depleting toxin ....................................... 461
8.11.Air pollutants ........................................ 463
8.11.1.Ozone, a non-radical reactive species .......... 464
8.11.2.Nitrogen dioxide ............................... 464
8.11.3.Sulphur dioxide ................................ 466
8.12.Toxicity of mixtures: cigarette smoke and other
'toxic smokes' ........................................ 467
8.12.1.Chemistry of tobacco smoke ..................... 467
8.12.2.Mechanisms of damage by cigarette smoke ........ 469
8.12.3.How does the respiratory tract defend
itself? ........................................ 470
8.12.4.Adaptation ..................................... 470
8.12.5.Environmental tobacco smoke (ETS) .............. 471
8.12.6.Other tobacco usage ............................ 471
8.12.7.Fire smoke ..................................... 471
8.13.Diesel exhaust ........................................ 471
8.14.Toxicity of asbestos and similar particulates ......... 472
8.15.Toxicity of metals .................................... 472
8.15.1.Cause or consequence? .......................... 472
8.15.2.Arsenic ........................................ 473
8.15.3.Nickel ......................................... 474
8.15.4.Chromium ....................................... 474
8.15.5.Cobalt ......................................... 475
8.15.6.Cadmium ........................................ 475
8.15.7.Mercury ........................................ 475
8.15.8.Lead ........................................... 476
8.15.9.Vanadium ....................................... 476
8.15.10.Titanium ...................................... 477
8.15.11.Aluminium ..................................... 477
8.15.12.Zinc .......................................... 478
8.16.Antibiotics ........................................... 478
8.16.1.Tetracyclines as pro- and antioxidants ......... 478
8.16.2.Quinone antibiotics ............................ 480
8.16.3.Aminoglycoside nephrotoxicity and
ototoxicity .................................... 481
8.17.Noise and stress ...................................... 481
8.18.Nitro and azo compounds ............................... 482
8.18.1.Nitro radicals and redox cycling ............... 482
8.18.2.Further reduction of nitro radicals ............ 482
8.18.3.Azo compounds .................................. 484
8.19.Ionizing radiation .................................... 484
8.19.1.The oxygen effect .............................. 484
8.19.2.Antioxidants and radiotherapy .................. 485
8.19.3.Hypoxic-cell sensitizers ....................... 486
8.19.4.Food irradiation ............................... 486
8.20.Summary and conclusion ................................ 486
9. Reactive species and disease: fact, fiction or
filibuster? ................................................ 488
9.1. Setting the scene ..................................... 488
9.2. Does oxidative stress matter? ......................... 488
9.2.1 Establishing importance ......................... 491
9.3. Atherosclerosis ....................................... 494
9.3.1. What is atherosclerosis? ....................... 494
9.3.2. Predictors of atherosclerosis .................. 496
9.3.3. What initiates atherosclerosis? ................ 497
9.3.4. LDL oxidation and the foam cell ................ 497
9.3.5. Mechanisms of LDL oxidation .................... 499
9.3.6. Other aspects of the involvement of RS in
atherosclerosis ................................ 501
9.3.7. Does evidence support the 'oxidative
modification hypothesis' of atherosclerosis? ... 501
9.3.8. Chemistry of LDL oxidation: is in vitro LDL
oxidation a relevant model? .................... 502
9.3.9. The role of high-density lipoproteins .......... 507
9.3.10.Lipoprotein (a) ................................ 508
9.3.11.Unanswered questions ........................... 508
9.4. Diabetes .............................................. 508
9.4.1. Can oxidative stress cause diabetes? ........... 509
9.4.2. Oxidative stress in diabetic patients .......... 509
9.4.3. How does the oxidative stress originate? ....... 510
9.4.4. Non-enzymatic glycation and glycoxidation ...... 510
9.4.5. Other mechanisms of glucose toxicity: aldose
reductase ...................................... 513
9.4.6. How important is oxidative stress in
diabetes? ...................................... 514
9.5. Ischaemia-reperfusion ................................. 514
9.5.1. Reoxygenation injury ........................... 515
9.5.2. A role for xanthine oxidase? ................... 516
9.5.3. Intestinal ischaemia-reoxygenation ............. 516
9.5.4. Cardiac ischaemia-reoxygenation ................ 517
9.5.5. Angioplasty, restenosis and bypass grafting .... 521
9.5.6. Ischaemic preconditioning ...................... 521
9.5.7. Shock-related ischaemia-reoxygenation .......... 522
9.5.8. The eye ........................................ 522
9.5.9. Plants ......................................... 523
9.5.10.Chemical ischaemia-reperfusion: carbon
monoxide poisoning ............................. 523
9.5.11.Freezing injury ................................ 523
9.5.12.Sleep apnoea ................................... 523
9.6. Organ preservation, transplantation and reattachment
of severed tissues .................................... 524
9.6.1. Heart and kidney ............................... 524
9.6.2. Liver .......................................... 524
9.6.3. Limbs, digits and sex organs ................... 525
9.6.4. Organ preservation fluids ...................... 525
9.6.5. Other examples ................................. 526
9.7. Lung damage, shock and ARDS ........................... 526
9.7.1. Oxidative stress in ARDS: does it occur and
does it matter? ................................ 527
9.8. Cystic fibrosis ....................................... 527
9.8.1. Cystic fibrosis and carotenoids ................ 529
9.9. Chronic inflammatory diseases: more examples .......... 530
9.9.1. Are RS important mediators of autoimmune
diseases? ...................................... 531
9.10.Rheumatoid arthritis .................................. 532
9.10.1.The normal joint ............................... 532
9.10.2.The RA joint ................................... 533
9.10.3.Does increased oxidative damage occur in RA? ... 535
9.10.4.What is the origin of the oxidative stress? .... 535
9.10.5.Does oxidative damage matter in RA? ............ 536
9.10.6.Drugs for the treatment of RA: antioxidant,
pro-oxidant or neither? ........................ 536
9.10.7.Iron and rheumatoid arthritis .................. 540
9.11.Inflammatory bowel disease ............................ 540
9.11.1.The salazines .................................. 541
9.12.Inflammation of other parts of the gastrointestinal
tract ................................................. 541
9.12.1.Pancreas ....................................... 541
9.12.2.Oesophagus and stomach ......................... 542
9.12.3.Liver .......................................... 542
9.13.Oxidative stress and cancer: a complex relationship ... 543
9.13.1.The cell cycle ................................. 543
9.13.2.Tumours ........................................ 544
9.13.3.Carcinogenesis ................................. 544
9.13.4.Genes and cancer ............................... 547
9.13.5.Reactive species and carcinogenesis ............ 550
9.13.6.Chronic inflammation and cancer: a close
link but is it due to RS? ...................... 554
9.13.7.Changes in antioxidant defences in cancer ...... 555
9.13.8.Transition metals and cancer ................... 556
9.14.Carcinogens: oxygen and others ........................ 557
9.14.1.Carcinogen metabolism .......................... 557
9.14.2.Carcinogens and oxidative DNA damage ........... 561
9.14.3.Reactive nitrogen species and cancer ........... 564
9.15.Cancer chemotherapy ................................... 564
9.15.1.Oxidative stress and chemotherapy .............. 564
9.15.2.The anthracyclines and other quinones .......... 566
9.15.3.Bleomycin ...................................... 569
9.15.4.Should cancer patients consume antioxidants? ... 570
9.16.Oxidative stress and disorders of the nervous
system: setting the scene ............................. 571
9.16.1.Introduction to the brain ...................... 571
9.16.2.Energy metabolism .............................. 572
9.16.3.Glutamate, calcium and nitric oxide ............ 574
9.16.4.Excitotoxicity ................................. 575
9.16.5.Why should the brain be prone to oxidative
stress? ........................................ 576
9.16.6.Antioxidant defences in the brain .............. 578
9.17.Oxidative stress in brain ischaemia, inflammation
and trauma ............................................ 582
9.17.1.Inflammation: a common feature ................. 582
9.17.2.Multiple sclerosis ............................. 582
9.17.3.Brain ischaemia ................................ 582
9.17.4.Traumatic injury ............................... 586
9.18.Oxidative stress and neurodegenerative diseases:
some general concepts ................................. 586
9.19.Parkinson's disease ................................... 590
9.19.1.Genetics or environment? ....................... 590
9.19.2.Treatment ...................................... 591
9.19.3.Toxins and PD .................................. 592
9.19.4.Oxidative stress and mitochondrial defects
in PD ......................................... 595
9.19.5.What does it all mean? ......................... 596
9.20.Alzheimer's disease ................................... 597
9.20.1.Definition and pathology ....................... 597
9.20.2.Genetics of AD ................................. 599
9.20.3.Mechanisms of neurodegeneration ................ 600
9.20.4.Cause or consequence? .......................... 601
9.20.5.An old red herring: aluminium in AD ............ 603
9.20.6.Other amyloid diseases ......................... 603
9.21.Amyotrophic lateral sclerosis (ALS) ................... 603
9.21.1.Familial ALS (FALS) and superoxide
dismutase ...................................... 604
9.21.2.Oxidative damage and excitotoxicity in ALS ..... 605
9.22.Other neudegenerative diseases ........................ 606
9.22.1.Friedreich's ataxia ............................ 606
9.22.2.Huntington's disease ........................... 606
9.22.3.Prion diseases ................................. 607
9.22.4.Neuronal ceroid lipfuscinoses .................. 608
9.22.5.Tardive dyskinesia ............................. 609
9.22.6.Cycads, flying foxes, guam and lathyrism:
now all history? ............................... 609
9.23.Oxidative stress and viral infections ................. 609
9.23.1.Reactive species, antioxidants and HIV ......... 611
9.23.2.Redox regulation of viral expression ........... 611
9.23.3.Side-effects of therapy ........................ 613
9.24.Conclusion ............................................ 613
10.Ageing, nutrition, disease and therapy: a role for
antioxidants? .............................................. 614
10.1.Introduction .......................................... 614
10.2.An introduction to theories of ageing ................. 614
10.2.1.General principles ............................. 614
10.3.What theories of ageing exist? ........................ 616
10.3.1.Do genes influence ageing? The story of C.
elegans ........................................ 616
10.3.2.Genes and human longevity ...................... 620
10.3.3.Premature human ageing ......................... 621
10.3.4.Mechanisms of caloric restriction .............. 622
10.3.5.Telomeres and cellular senescence .............. 623
10.4.Oxidative damage: a common link between all the
theories of aging? .................................... 624
10.4.1.Introduction to the free radical theory of
ageing ......................................... 624
10.4.2.Testing the theory: altering antioxidant
levels ......................................... 627
10.4.3.'Rapidly-ageing' mice .......................... 629
10.4.4.Does antioxidant protection fail with age? ..... 629
10.4.5.Does oxidative damage increase with age? ....... 629
10.4.6.Lipofuscin and ceroid; fluorescent 'red
herrings'? ..................................... 630
10.4.7.Oxidative stress, oxidative damage and
signal transduction ............................ 631
10.4.8.The oxidative damage theory of ageing:
summing it up .................................. 631
10.5.Nutrition, health and oxidative damage ................ 632
10.5.1.Learning from epidemiology ..................... 632
10.5.2.Epidemiology and antioxidants .................. 634
10.5.3.Problems of interpretation ..................... 636
10.5.4.The gold standard of intervention trials:
hope unfulfilled ............................... 640
10.5.5.The need for biomarkers ........................ 640
10.5.6.Some intervention trials: a state of CHAOS ..... 641
10.5.7.Some rays of hope and a gender bias ............ 643
10.5.8.Lycopene, other carotenoids and human
disease ........................................ 643
10.5.9.Other dietary factors and oxidative damage ..... 643
10.5.10.Iron, ageing and disease: another gender
gap ............................................ 645
10.5.11.Antioxidants, epidemiology and
neurodegenerative disease ...................... 645
10.5.12.What does it all mean? Some dietary advice .... 646
10.6.Antioxidants and the treatment of disease ............. 646
10.6.1.Therapeutic antioxidants ....................... 647
10.6.2.Approaches to antioxidant characterization ..... 647
10.6.3.Superoxide dismutases and catalases ............ 648
10.6.4.SOD/catalase mimetics .......................... 650
10.6.5.Spin traps/nitroxides .......................... 653
10.6.6.Vitamins С and E and their derivatives ......... 658
10.6.7.Other chain-breaking antioxidants .............. 665
10.6.8.The lazaroids .................................. 665
10.6.9.Thiol compounds ................................ 666
10.6.10.Glutathione peroxidase 'mimetics' ............. 668
10.6.11.Mitochondrially-targeted antioxidants ......... 668
10.7.Iron chelators ........................................ 669
10.7.1.Desferoxamine .................................. 669
10.7.2.Other iron-chela ting agents ................... 675
10.8.Inhibitors of the generation of reactive species ...... 676
10.8.1.Xanthine oxidase (XO) inhibitors ............... 676
10.8.2.Inhibitors of phagocyte RS generation .......... 677
Appendix:Some basic chemistry ................................. 678
Al. Atomic structure .................................. 678
A2. Bonding between atoms ............................. 681
A2.1. Ionic bonding ............................... 681
A2.2. Covalent bonding ............................ 684
A2.3. Non-ideal character of bonds ................ 685
A2.4. Hydrocarbons and electron derealization ..... 686
A3. Moles and molarity ................................ 687
A4. pH and pKa ........................................ 687
References .................................................... 689
Index ......................................................... 777
|
