Recent advances in polyphenol research. Volume 3

Plant polyphenols are secondary metabolites that constitute one of the most common and widespread groups of natural products. They express a large and diverse panel of biological activities including beneficial effects on both plants and humans. Many polyphenols, from their structurally simplest representatives to their oligo/polymeric versions (also referred to as vegetable tannins) are notably known as phytoestrogens, plant pigments, potent antioxidants, and protein interacting agents. Sponsored by Groupe Polyphénols, this publication, which is the third volume in this highly regarded Recent Advances in Polyphenol Research series, is edited by Véronique Cheynier, Pascale Sarni-Manchado, and Stéphane Quideau (the current President of Groupe Polyphénols). Like their predecessors, they have once again put together an impressive collection of cutting-edge chapters written by expert scientists internationally respected in their respective field of polyphenol sciences. This Volume 3 provides the latest information and opinion on the following major research topics about polyphenols: Organic chemistry and physical chemistry. Biosynthesis, genetics and metabolic engineering. The role of polyphenols in plants and ecosystems. Health and nutrition. Analysis and metabolomics. Chemists, biochemists, plant scientists, pharmacognosists and pharmacologists, biologists, ecologists, food scientists and nutritionists will all find this book an invaluable resource. Libraries in all universities and research institutions where these disciplines are studied and taught should have copies on their bookshelves.

Contributors

Preface x

1 Plant Phenolics: A Biochemical and Physiological Perspective 1

Vincenzo Lattanzio, Angela Cardinali and Vito Linsalata

1.1 The general phenolic metabolism in plants 1

1.2 Effect of non-freezing low temperature stress on phenolic metabolism in crop plants 6

1.3 Plant phenolics as defence compounds 11

1.3.1 Phenolic-mediated induced resistance of apples against fungal pathogens 12

1.3.2 Contribution of vigna phenolics to plant protection against insects 16

1.4 Diversion of carbon skeletons from primary to phenolic-related secondary metabolism 19

1.4.1 Metabolic costs of adaptive responses to adverse environmental conditions 21

1.4.2 Transduction pathway between nutrient depletion and enhanced polyphenol content 24

References 26

2 Polyphenols: From Plant Adaptation to Useful Chemical Resources 41

Alain-Michel Boudet

2.1 The emergence of phenolic metabolism and the adaptation of plants to a terrestrial environment 41

2.2 The shikimate pathway: a complex and subtle interface between primary metabolism and phenolic metabolism 47

2.2.1 Quinic acid, a specific component of higher plants 49

2.2.2 The postchorismate branch of the shikimate pathway leading to phenylalanine: one or two metabolic routes in plants? 53

2.2.2.1 Intracellular location of enzymes 54

2.2.2.2 Complex and new regulatory mechanisms in the shikimate pathway 55

2.3 Plant (poly)phenols: a diversified reservoir of useful chemicals 56

2.3.1 The health-promoting properties of polyphenols 57

2.3.2 A new time for lignocellulosics utilization through biotechnology 58

2.3.2.1 Biomass pretreatment and enzymatic conversion of polysaccharides 59

2.3.2.2 Lignins: degradation, bioconversion 60

2.3.2.3 The fermentation step towards the production of bioalcohols 61

2.3.2.4 Biorefinery pilot plants 61

2.3.2.5 Quality and availability of the upstream resource 61

2.3.2.6 Future prospects 62

2.3.3 Chemical and catalytic valorization of polyphenols 63

2.4 Concluding remarks 63

Acknowledgments 64

References 64

3 Fifty Years of Polyphenol-Protein Complexes 71

Ann E. Hagerman

3.1 Introduction 71

3.2 Precipitable complexes 74

3.3 Soluble complexes 76

3.4 Proline-rich proteins 78

3.5 Mechanisms of binding 79

3.6 Stoichiometry of binding 80

3.7 Protein conformation 82

3.8 Covalent tannin-protein complexes 83

3.9 Conclusions 90

Acknowledgments 91

References 91

4 Chemistry of Flavonoids in Color Development 99

Kumi Yoshida, Kin-ichi Oyama and Tadao Kondo

4.1 Introduction 99

4.2 Synthetic studies on anthocyanins toward polyacylated pigments 103

4.2.1 Previously reported syntheses of anthocyanins 103

4.2.2 Synthesis of anthocyanin using biomimetic oxidation 105

4.2.3 Transformation of flavonol derivatives to anthocyanins via a flavenol glycoside 107

4.3 Synthesis of copigments for studying blue color development 109

4.3.1 Copigmentation in metalloanthocyanins 110

4.3.2 Synthesis of glycosylated flavones 112

4.3.3 Chiral recognition in metalloanthocyanin formation 114

4.3.4 Synthesis of acylquinic acid derivatives for studies on hydrangea coloration 118

4.4 Conclusion 122

Abbreviations 123

Acknowledgments 124

References 124

5 Colouring up Plant...