Phenolic compound biochemistry /

CHAPTER I
Families of Phenolic Compounds and Means of Classification
1. Definitions 1
2. Classification 2
3. Classes of phenolic compounds 3
3.1 Simple phenolics 3
3.2 Phenolic acids and aldehydes 4
3.3 Acetophenones and phenylacetic acids 4
3.4 Cinnamic acids 5
3.5 Coumarins 6
3,6 Flavonoids 7
3.6.1 Chalcones 8
3.6.2 Aurones 8
3.6.3 Flavonoids 9
3.6.3,1 Flavanones 10
3.6.3,2 Flavanonols 10
3.6.3.3 Leucoanthocyanidins 11
3,6.3.4 Flavones 12
3 6.3.5 Anthocyanidins and deoxyanthocyandins 12
3.6.3.6 Anthocyanins 15
3.7 Biflavonyis 15
3.8 Benzophenones. xanthones and stilbenes 16
3.9 Benzoquinones, anthraquinones and naphthaquinones 17
3.10 Betacyanins 17
3.11 Lignans 18
3112 Lignin 20
3 13 Tannins 23
3.13.1 Condensed tannins 24
3.13.2 Gallotannins 25
3.13.3 Ellagitannins 26
3.1-3.4 Complex tannins 29
3.14 Phlobaphenes 30
4. References 32
CHAPTER 2
Chemical Properties of Phenolic Compounds
1.1 The benzene ring 35
1.2 Planar versus non-planar bonds 38
1.3 The acidic nature of the phenolic hydroxyl group 38
1.3 1 Tbhe effects of substituents on acidity 39
1.3.2 Use of acidity in separations 40
1.4 Hydrogen bonding and the phenolic hydroxyl group 40
1.4.1 Intra- and inter-molecular hydrogen bonds 41
1.4,2 Stabilit of the hydrogen bond ring 41
.5 Metal complexes 43
1.6 Esterification 45
1.7 Ethers and glycosides 47
1.8 Oxidation of the phenolic hydroxyl group 48
1.8.1 Auto-oxidation of phenolic compounds 48
1.8.2 Enzymatic oxidation of the phenolic hydroxyl group 50
1.8.2.1 E.C. 110.3 50
1.8.22 E.C. 11418.1 53
1 8.2.3 E.C. LIL 1. 53
1.9 Reactive oxygen species and antioxidants 58
2. References 61
CHAPTER 3
Biosynthesis of Phenolic Compounds
1. Introduction 63
2. Protein isolation and purification 64
3. Gene cloning strategies 67
3.1 Insertional mutagenesis 70
3.2 Map-based cloning 72
3.3 The candidate-gene approach 72
3.4 QTL mapping 73
4. Isolation and characterization of recombinant proteins 74
5. Carbohydrate catabolism 76
5.1 Glycolysis 77
5.2 The pentose phosphate pathway 77
6. The shikirnate pathway 81
7. The general phenylpropanoid pathway 84
8. Biosynthesis of phenolic acids 86
8.1 Salicylic acid 86
8.2 Gallic acid 88
9. Biosynthesis of flavonoids and condensed tannins 90
9.1 Structural genes and enzymes 90
9.2 Regulatory genes 96
10. Monolignol biosynthesis 102
11. Lignan biosynthesis 107
12. Lignin biosynthesis 112
12.1 Genetic control of lignification 112
12.2 Monolignol transport and polymerization 116
12.3 Modification of lignin for agro-industrial applications 120
12.3.1 Pulp and paper industry 121
12.3.2 Forage and silage quality 123
12.3.3 Ethanol production from ligno-cellulosic biomass 124
13. Hydroxycinnamic acid biosynthesis 125
14. Biosynthesis of sinapoyl esters 126
15. Coumarin biosynthesis 129
16. Stilbene biosynthesis 129
17. Biosynthesis of gallotannins and ellagitannins 130
18. References 134
CHAPTER 4
Isolation and Identification of Phenolic Compounds
1. Introduction 151
2. Isolation of phenolic compounds 151
2.1 Total phenolic content: the Folin-Ciocalteu reagent 152
2.2 Determining the content of condensed tannins 154
2.2.1 The butanol-HC1 assay 154
2.2.2 The vanillin assay 154
2.2.3 Precipitation of condensed tannins with formaldehyde 155
2.3 Determining the content of gallotannins 155
2.3.1 The potassium iodate assay 155
2.3.2 The rhodanine assay 156
2.4 Determining the content of ellagitannins 157
2.4.1 Nitrous acid oxidation 157
2.4.2 The NaNO2/HCI assay 158
2.5 Determining lignin content 159
2.5.1 Klason lignin 1 60
2.152 Acid detergent lignin 161
2.5.3 Thioglycolic acid lignin 162
2.5.4 Acety lbronide lignin 164
3. Identification and characterization of phenolic compounds 166
3. Thin layer chromatography 166
3.2 Liquid chromatography: HPLC and LC-MS 169
3.3 Gas chromatography 170
3.4 Methods for the identification of lignin subunit composition 171
314,1 The nitrobenzene oxidation 172
3.4.2 Thioacidolysis 173
3.4.3 Derivatiation Followed by Reductive Cleavage 176
3.4.4 Analytical pyrolysis 178
3.4.5 Nuclear magnetic resonance 178
3.4.6 Fourier-transform infrared spectroscopy and near 181
infrared reflectance spectroscopy
4. Visualization of phenolic compounds in planta using 183
histochemnical stains
4.1 An overview of histochemical staniing protocols 183
4.2 Visualizing plant-pathogen interactions involving phenolics 185
with histochemical stains
5. References 190
CHAPTER 5
Analysis of Phenolic Compounds with Mass Spectrometry
1. The principles of mass spectrometry 197
1l ionization 197
1.2 Mass Analysis 198
1.3 Detectors 199
1.4 Sample introduction 200
2. New developments in mass spectrometry 202
2.1 Fast atom bombardment 202
2.2 Plasma desorption ionization 203
2.3 Electrospray ionization 204
2.4 Matrix-assisted laser desorption ionization 206
3. Quantitation 208
4. References 210
CHAPTER 6
The Role of Phenois in Plant Defense
1. Preformed antimicrobial and insecticidal metabolites 211
"1.1 Chlorogenic acid 213
12 Phloridzin and phloretin 214
1.3 Cyanogenic glycosides 215
1.4 Tuliposides 216
1.5 Protocatechuic acid 217
1.6 Lignin 217
1.7 C-glycosyl flavones 217
2. Compounds formed in response to pathogen attack 222
21 3-Deoxyanthocyanidins 222
2.2 Pisatin 224
2.3 Stilbenes 224
2 4 Salicylic acid 225
2.5 Lignin 227
3. References 230
CHAPTER 7
Phenolic Compounds and their Effects on Human Health
I Introduction 235
2 Antioxidant properties 237
3. Disease prevention 246
4. Activity against toxins 251
5. References 253