Neuroprotective Effects of Phytochemicals in Neurological Disorders

Tahira Farooqui, Akhlaq A. Farooqui, Tahira Farooqui, Akhlaq A. Farooqui

• Publisher: Wiley-Blackwell
• Year: 2017
• Print ISBN: 9781119155140
• eBook ISBN: 9781119155188
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Neuroscience
• Index: Biological Sciences

Phytochemicals are naturally occurring bioactive compounds found in edible fruits, plants, vegetables, and herbs. Unlike vitamins and minerals, phytochemicals are not needed for the maintenance of cell viability, but they play a vital role in protecting neural cells from inflammation and oxidative stress associated with normal aging and acute and chronic age-related brain diseases. Neuroprotective Effects of Phytochemicals in Neurological Disorders explores the advances in our understanding of the potential neuroprotective benefits that these naturally occurring chemicals contain.

Neuroprotective Effects of Phytochemicals in Neurological Disorders explores the role that a number of plant-based chemical compounds play in a wide variety of neurological disorders. Chapters explore the impact of phytochemicals on neurotraumatic disorders, such as stroke and spinal cord injury, alongside neurodegenerative diseases such as Alzheimer's and Parkinson's Disease, as well as neuropsychiatric disorders such as depression and schizophrenia. The chapters and sections of this book provide the reader with a big picture view of this field of research.

Neuroprotective Effects of Phytochemicals in Neurological Disorders aims to present readers with a comprehensive and cutting edge look at the effects of phytochemicals on the brain and neurological disorders in a manner useful to researchers, neuroscientists, clinical nutritionists, and physicians.

1
Use of Phytochemicals against Neuroinflammation

Wei‐Yi Ong,^1,2 Tahira Farooqui,³ Christabel Fung‐Yih Ho,¹ Yee‐Kong Ng,¹ and Akhlaq A. Farooqui ⁴

¹ Department of Anatomy, National University of Singapore, Singapore

² Neurobiology and Ageing Research Programme, National University of Singapore, Singapore

³ Department of Entomology, Ohio State University, Columbus, OH, USA

⁴ Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, OH, USA

1.1 Introduction

Neuroinflammation and oxidative stress are closely associated with the pathogenesis of neurotraumatic and neurodegenerative diseases, such as stroke and Alzheimer’s disease (AD). During the inflammatory reaction, secretion of proinflammatory cytokines and chemokines amplifies and maintains inflammatory responses. It involves the enzymatic activity of cytosolic phospholipase A₂ (cPLA₂) and secretory phospholipase A₂ (sPLA₂), which release arachidonic acid from glycerophospholipids, and of cyclooxygenase (COX) and 5‐lipoxygenase (5‐LOX), which oxidize arachidonic acid to proinflammatory eicosanoids. This is followed by the formation of the prostaglandin D2 (PGD2) and of docosahexaenoic acid (DHA)‐derived resolvins and protectins, which facilitate the resolution of inflammation. Acute neuroinflammation is a protective process that isolates the injured brain tissue from uninjured areas, destroys injured cells, and rebuilds the extracellular matrix. Without it, brain tissue would rapidly be damaged by the effects of injury and infections, including those of microbial, viral, and prion origin. Acute neuroinflammation involves the recruitment of lymphocytes, monocytes, and macrophages of the hematopoietic system and glial cells of the central nervous system (CNS). Microglia are recruited to the site of injury to protect and repair the injured tissue via the secretion of cytokines, chemokines, and lipid mediators such as resolvins and neuroprotectins, while astrocytes react by forming a glial scar. Chronic neuroinflammation, on the other hand, lingers for years, and causes damage to brain tissues. It is closely associated with the activity of microglia and astrocytes and with the assembly and activation of the inflammasome: a multiprotein oligomer consisting of caspase 1, PYCARD, NALP, and sometimes caspase 5 (also known as caspase 11 or ICH‐3). Once activated, the inflammasome binds to and appositions together many p45 pro‐caspase‐1 molecules to induce their autocatalytic cleavage to p20 and p10 subunits. Caspase‐1 then assembles into its active form (consisting of two heterodimers with a p20 and p10 subunit each), in order to carry out a variety of processes, including cleavage of pro‐interleukin (IL)‐1β into IL‐1β, cleavage of pro‐IL‐18 into IL‐18 to induce interferon gamma (IFN‐γ) secretion, and activation of lipid biosynthesis [1]. Inflammasomes orchestrate the activation of precursors of proinflammatory caspases, which, in turn, cleave precursor forms of IL‐1β, IL‐18, and IL‐33 into their active forms. These lead to further stimulation of PLA₂, COX‐2, and LOX; generation of eicosanoids, lysophosphatidylcholine (lyso‐PtdCho), and platelet‐activating factor (PAF); production of reactive oxygen species (ROS), proteinases, and complement proteins; and a potent inflammatory response. Alterations in the expression of inflammasome mediators may lead to neurodegeneration in neurotraumatic, neurodegenerative, and neuropsychiatric diseases. Based on this, it has been suggested that regulation of the inflammasome machinery may be better than suppression of all inflammation for the treatment of inflammatory conditions [1,2].

An emerging approach to the alleviation of neuroinflammation involves the use of medicinal plants and herbs. Epidemiological studies have indicated that the incidence of neurological disorders among people living in Asia is lower than that in the Western world. This may be due to the regular consumption of phytochemicals in the form of spices. Extensive research over the last 10 years has indicated that phytochemicals derived from various spices e.g., turmeric, red pepper, black pepper, licorice, clove, ginger, garlic, coriander, cinnamon, target inflammatory and oxidative stress pathways and retard or delay the onset of neurological diseases. More than 7000 phytochemicals, which possess antiproliferative, anti‐inflammatory, antiviral, and hypocholesterolemic properties, have been identified (Figure 1.1). Unlike vitamins and minerals, phytochemicals are not required for the maintenance of cell viability, but play a vital role in protecting neural cells from neuroinflammation and oxidative stress associated with aging and brain disea...

Table of contents

• Cover
• Title Page
• Table of Contents
• Contributors
• Preface
• Acknowledgments
• 1 Use of Phytochemicals against Neuroinflammation
• 2 Flavonoids in Transgenic Alzheimer’s Disease Mouse Models
• 3 Neuroprotective Effects of Polyphenols in Aging and Age‐Related Neurological Disorders
• 4 Indian Herbs and their Therapeutic Potential against Alzheimer’s Disease and Other Neurological Disorders
• 5 Garlic and its Effects in Neurological Disorders
• 6 Effects of Extra‐Virgin Olive Oil in Neurological Disorders
• 7 Ginger Components as Anti‐Alzheimer Drugs: Focus on Drug Design
• 8 Phytomedicine
• 9 Effects of Phytochemicals on Diabetic Retino‐neuropathy
• 10 Herbal Drugs
• 11 Neuroprotective Properties of Dietary Polyphenols in Parkinson’s Disease
• 12 Potential of Polyphenols in the Treatment of Major Depression
• 13 Effect of Phytochemicals on Diabetes‐Related Neurological Disorders
• 14 Neuroprotective Effects of Extra‐Virgin Olive Oil and its Components in Alzheimer’s Disease
• 15 Protective Role of Black‐Tea Extract in a Transgenic Drosophila Model of Parkinson’s Disease
• 16 Apitherapy
• 17 Molecular Mechanisms behind the Beneficial Activity of Polyunsaturated Fatty Acids in Alzheimer’s Disease and Related Conditions
• 18 Prevention of Neuroinflammation by Resveratrol
• 19 Modulation of the Estradiol and Neprilysin Pathways by Resveratrol in a Lipopolysaccharide Model of Cognitive Impairment
• 20 Neuroprotective Effect of Resveratrol in Cerebral Ischemia
• 21 Effects of Nobiletin in Animal Models of Cognitive Impairment
• 22 Potential Neuroprotective Effects of Curcumin against Dementia
• 23 Neuroprotective Activity of Curcumin and Emblica officinalis Extract against Carbofuran‐Induced Neurotoxicity in Wistar Rats
• 24 Potential Use of Curcuminoids for the Treatment of Alzheimer’s Disease
• 25 Prevention by Curcumin of Neuroinflammation in Intracerebral Hemorrhage
• 26 Effect of Polyphenols on Protein Misfolding
• 27 Molecular Mechanisms Involved in the Neuroprotective Action of Phytochemicals
• 28 Nutraceuticals and Cognitive Dysfunction
• 29 Summary and Perspective
• Index
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