Recent Advances in Polyphenol Research, Volume 6

Heidi Halbwirth, Karl Stich, Véronique Cheynier, Stéphane Quideau

• Publisher: Wiley-Blackwell
• Year: 2019
• ISBN:
  9781119427919
• Edition: 1
• Topic: Scienze biologiche
• Subtopic: Biologia

Plantpolyphenols are secondary metabolites that constitute one of the most common and widespread groups of natural products. They are crucial constituents of a large and diverse range of biological functions and processes, and provide many benefits to both plants and humans. Manypolyphenols, from their structurally simplest representatives to their oligo/polymeric versions, are notably known as phytoestrogens, plant pigments, potent antioxidants, and protein interacting agents.

This sixth volume of the highly regarded Recent Advances inPolyphenol Research series is edited by Heidi Halbwirth, Karl Stich, Véronique Cheynier and Stéphane Quideau, and is a continuance of the series' tradition of compiling a cornucopia of cutting-edge chapters, written by some of the leading experts in their respective fields of polyphenol sciences. Highlighted herein are some of the most recent and pertinent developments in polyphenol research, covering such major areas as:

• Chemistry and physicochemistry
• Biosynthesis, genetics & metabolic engineering
• Roles in plants and ecosystems
• Food, nutrition & health
• Applied polyphenols

This book is a distillation of the most current information, and as such, will surely prove an invaluable source for chemists, biochemists, plant scientists, pharmacognosists and pharmacologists, biologists, ecologists, food scientists and nutritionists.

1
The Lignans: A Family of Biologically Active Polyphenolic Secondary Metabolites

Anna K.F. Albertson and Jean‐Philip Lumb

Department of Chemistry, McGill University, Montreal, Québec, Canada

1.1 Introduction

Nature has long served as an important source of therapeutics, and lignans represent a large class of pharmacologically active compounds (Cunha et al. 2012). This family of molecules demonstrates a wide range of biological activities, which plants use as a front‐line chemical defence against pathogens (Figure 1.1). Additionally, the anticancer, antimiotic, antiangiogenesis and antiviral properties possessed by lignans have made them appealing drug candidates, as well as starting points for drug discovery. Lignans currently employed for healthcare include (−)‐podophyllotoxin (1), a treatment for warts, and its derivatives (−)‐etoposide (2) and (−)‐teniposide (3), two potent chemotherapeutic agents (Liu et al. 2007). Other members of this class with promising biological activities include (+)‐gomisin J (4) and (+)‐pinoresinol (5). Due to the established benefits of the lignans, both their biosynthesis and synthetic strategies to access them have been areas of extensive research.

Figure 1.1 Selected biologically active lignan natural products.

In addition to their varied biological activities, lignans comprise a vast array of structurally distinct skeletons (Figure 1.2), including 6‐ and 8‐membered carbocycles (6, 7), linear dibenzylbutanes (8), and diversely oxidized tetrahydrofurans (9–11). Remarkably, their biosynthesis originates from a regio‐ and stereoselective, oxidative coupling of relatively simple monolignols (propenyl phenols) (12), to form the key 8–8 bond that serves to characterize all lignan natural products. Subsequent transformations, including cyclization and oxidation of the parent scaffold, convert the initially formed dimer to various family members, imparting unique functionalities. While this blueprint has served as a key source of inspiration for decades of biomimetic synthetic approaches to the lignans, issues of selectivity in the oxidative coupling have led researchers to alternative, target‐oriented routes, which are often specific for an individual structural class. In this review, we summarize these recent efforts from 2009 to 2016, and provide an overview of contemporary research efforts interrogating the lignans. Previous reviews on this subject cover 2000–2004 (Saleem et al. 2005), 2005–2008 (Pan et al. 2009), and 2009–2015 (Teponno et al. 2016).

Figure 1.2 Structural classes of lignans.

1.2 Biosynthesis of Lignans

Due to their biological activity and fundamental importance to plant biology, significant efforts have been made to elucidate lignan biosynthesis (Suzuki and Umezawa 2007; Umezawa 2009; Petersen et al. 2010). Lignans originate from cinnamic acids, which are themselves biosynthesized from phenylalanine (Scheme 1.1). The shikimate pathway, which produces several aromatic amino acids including phenylalanine (16), is preceded by the synthesis of shikimic acid (15) from phosphoenolpyruvate (13) and erythrose‐4‐phosphate (14). The conversion of phenylalanine to cinnamic acid (17) is carried out by phenylalanine ammonia‐lyase (PAL). Substitution of the aromatic ring is performed by cinnamate hydroxylases (C4H and C3H), to access coumaric acid (18) and caffeic acid (19). The methyl ethe...

Table of contents

• Cover
• Table of Contents
• Contributors
• Preface
• Acknowledgements
• 1 The Lignans: A Family of Biologically Active Polyphenolic Secondary Metabolites
• 2 Anthocyanin Accumulation is Controlled by Layers of Repression
• 3 The Subtleties of Subcellular Distribution: Pointing the Way to Underexplored Functions for Flavonoid Enzymes and EndProducts
• 4 Transcriptional and Metabolite Profiling Analyses Uncover Novel Genes Essential for Polyphenol Accumulation
• 5 Dietary (Poly)Phenols and Vascular Health
• 6 Cellular‐Specific Detection of Polyphenolic Compounds by NMR‐and MS‐Based Techniques: Application to the Representative Polycyclic Aromatics of Members of the Hypericaceae, the Musaceae and the Haemodoraceae
• 7 Metabolomics Strategies for the Dereplication of Polyphenols and Other Metabolites in Complex Natural Extracts
• 8 Polyphenols from Plant Roots: An Expanding Biological Frontier
• 9 Biosynthesis of Polyphenols in Recombinant Micro‐organisms: A Path to Sustainability
• 10 Revisiting Wine Polyphenols Chemistry in Relation to Their Sensory Characteristics
• 11 Advances in Bio‐based Thermosetting Polymers
• 12 Understanding the Misunderstood: Products and Mechanisms of the Degradation of Curcumin
• 13 How to Model a Metabolon: Theoretical Strategies
• Index
• End User License Agreement