Flavonoids

"In this book, two of the primary sources of flavonoids, i.e. plants and fruits (oranges to be specific) are comprehensively reviewed, along with their flavonoid content and antioxidant activity (including action against COVID-19) and toxicity. Besides, a general overview of the analytical techniques for flavonoids determination in their natural sources is provided. Finally, a detailed description of flow techniques and their evolution, together with their role in the automation of the sample pretreatment and its combination with separation techniques, is also included"--

About 1958, the late Professor R. E. ALSTON and Professor B. L. TURNER, both of the Department ofBotany, The University ofTexas at Austin, initiated a general systematic investigation ofthe legurne genus Baptisia. They found that flavonoid patterns, as revealed by two-dimensional paper chromatography, were valid criteria for the recognition of the Baptisia species and for the documentation of their numerous natural hybrids. Later, they showed that the flavonoid chemistry could be used for the analysis of gene flow among populations. At that time no attempt was made to even partially identify the flavonoids which were detected chromatographically. Neverthe1ess, it soon became apparent that the full value of the chemical data for systematic purposes required knowledge of the structures of the flavonoids. In 1962, one of us (T.J.M.) in collaboration with Drs. ALSTON and TURNER beg an the chemical analysis of the more than 60 flavonoids which had been chromatographi cally detected in the 16 Baptisia species. In the intervening years, a number of chemists and botanists, inc1uding Drs. K. BAETCKE, B. BREHM, M. CRANMER, D. HORNE, J. KAGAN, B. KROSCHEWSKY, J. MCCLURE, H. RÖSLER, and J. WALLACE, participated in the devel opment of techniques and procedures for the rapid identification of known flavonoids and in the structure determination of new flavonoids. In addition, the flavonoid chem istry of many plants other than Baptisia was investigated.

Advances in the flavonoid field have been nothing short of spectacular over the last 20 years. While the medical field has noticed flavonoids for their potential antioxidant, anticancer and cardioprotectant characteristics, growers and processors in plant sciences have utilized flavonoid biosynthesis and the genetic manipulation of the flavonoid pa

This is the only book of its kind to provide an overview of the science of flavonoids in plants.

Flavonoids are ubiquitously present in plant-based foods and natural health products. The molecule of flavonoids is characterized by a 15-carbon skeleton of C6–C3–C6, with the different structural configuration of subclasses. The major subclasses of flavonoids with health-promotional properties are the flavanols or catechins (e.g., epigallocatechin 3-gallate from green tea), the flavones (e.g., apigenin from celery), the flavonols (e.g., quercetin glycosides from apples, berries, and onion), the flavanones (e.g., naringenin from citrus), the anthocyanins (e.g., cyanidin-3-O-glucoside from berries), and the isoflavones (e.g., genistein from soya beans). Scientific evidence has strongly shown that regular intake of dietary flavonoids in efficacious amounts reduces the risk of oxidative stress- and chronic inflammation-mediated pathogenesis of human diseases such as cardiovascular disease, certain cancers, and neurological disorders. The physiological benefits of dietary flavonoids have been demonstrated to be due to multiple mechanisms of action, including regulating redox homeostasis, epigenetic regulations, activation of survival genes and signaling pathways, regulation of mitochondrial function and bioenergetics, and modulation of inflammation response. The role of flavonoids on gut microbiota and the impact of microbial metabolites of flavonoids on optimal health has begun to unravel. The complex physiological modulations of flavonoid molecules are due to their structural diversity. However, some flavonoids are not absorbed well, and their bioavailability could be enhanced through structural modifications and applications of nanotechnology, such as encapsulation. This Special Issue consists of four review articles on flavonoids and 15 original research articles, which cover the latest findings on the role of dietary flavonoids and their derivatives in disease prevention and treatment.

The flavonoids, one of the most numerous and widespread groups of natural constituents, are important to man not only because they contribute to plant colour but also because many members (e.g. coumestrol, phloridzin, rotenone) are physiologically active. Nearly two thousand substances have been described and as a group they are universally distributed among vascular plants. Although the anthocyanins have an undisputed function as plant pigments, the raison d'etre for the more widely distributed colourless flavones and flavonols still remains a mystery. It is perhaps the challenge of discovering these yet undisc10sed functions which has caused the considerable resurgence of interest in flavonoids during the last decade. This book attempts to summarize progress that has been made in the study of these constituents since the first comprehensive monograph on the chemistry of the flavonoid compounds was published, under the editorship of T. A. Geissman, in 1962. The present volume is divided into three parts. The first section (Chapters 1-4) deals with advances in chemistry, the main emphasis being on spectral techniques to take into account the re cent successful applications of NMR and mass spectral measurements to structural identifications. Recent developments in isolation techniques and in synthesis are also covered in this section. Advances in chemical knowledge of individual c1asses of flavonoid are mentioned inter aha in later chapters of the book.

Offering a wide ranging view of this important class of plant pigments, after a brief examination of the history & literature of flavonoids, this book explores structural variation of all subclasses of flavonoids, techniques for isolation, purification, & determination of structures, chemical syntheses, biosynthesis & genetics, patterns of distribution in the plant kingdom, & uses. Lastly, the functions of flavonoids in nature are investigated, as well as ways in which these compounds may have a more direct impact upon the human race. Contents: Introduction & Historical Perspective * Structural Variation * Occurrence & Distribution of Flavonoids * Extraction, Purification, & Identification of Flavonoids * Synthesis & Interconversions of Flavonoids * Biosynthesis & Genetics * Flavonoid Functions in Nature * Human Uses of Flavonoids

Chemoprevention is currently regarded as one of the most promising avenues for the control of cancer, with human epidemiological and animal studies indicating that the risk of cancer may be modified by changes in diet. Over 100 papers are collected in this volume, the proceedings of the International Conference on Food Factors: Chemistry and Cancer Prevention, held in Hamamatsu, Japan, in December 1995. Special emphasis is placed on chemical, biological, and molecular properties of phytochemicals in teas, fruit, vegetables, herbs, and spices, and on their potential for cancer prevention. Also discussed are the cancer-preventive effects of vitamins, lipids, carotenoids, flavonoids, and other components of diet. The findings presented here will be invaluable to all who are interested in diet and cancer prevention, and especially to biochemists, pharmacologists, food scientists, and nutritionists.