Preface

Oxidative stress, a state that reflects an imbalance between the production of reactive oxygen species (free radicals) and antioxidant defenses, is known to play a pivotal role in the development and progression of several chronic human diseases. To prevent damage to important cellular components (such as DNA, proteins, and lipids) biological systems present enzymatic and nonenzymatic defenses to counteract high levels of free radicals besides the antioxidants obtained from the diet. Important lines of defense against the harmful effects caused by reactive chemical species include: superoxide dismutase, catalase, enzymes of the glutathione system (such as glutathione peroxidase) and also glutathione, the most abundant thiol in animal cells.

The goal of this book is to present and discuss in more detail some topics especially related to, but not limited to, the glutathione antioxidant system in health and disease. Hopefully, this book will be a handbook for researchers and students providing basic and advanced knowledge and encouraging future research in related fields. The book consists of seven chapters, covering some important aspects of glutathione and glutathione antioxidant enzymes, but also including information about the role of oxidative stress and other important antioxidant enzymes, and the function of the immune and purinergic systems in the modulation of the glutathione system. In this sense, this book provides interdisciplinary information and within each chapter, the reader will be given an overview of the subject to be covered.

A brief outline of the book chapters is as follows. Chapter 1 (*Modulation of glutathione antioxidant enzymes in health and disease: Role of the purinergic and immune systems – Charles Elias Assmann*) discusses the interplay between the purinergic and immune systems in the modulation of the glutathione system in health and disease. Chapter 2 (*Subcellular localization of glutathione peroxidase, change in glutathione system during ageing and effects on cardiometabolic risks and associated diseases - Théophile Mbemba Fundu*) addresses the localization of glutathione peroxidase in cellular compartments, the alterations in its activity in the process of cellular aging, and the impact on cardiometabolic risk and associated diseases. Chapter 3 (*GPx activity and diseases - Eren Sarıkaya*) provides an overview of the role of glutathione peroxidase in diseases. Chapter 4 (*Neurodegenerative diseases: Potential effect of glutathione - Aoula Moustapha*) presents some insights into the role of glutathione in neural cells and discusses some consequences of glutathione disturbances in neurodegenerative pathologies, such as Alzheimer's and Parkinson's disease, in which oxidative stress plays a major role. Chapter 5 (*Periodontal health and disease in glutathione - Figen Öngöz*) presents information on glutathione peroxidase in periodontal health and disease, including aspects related to systemic disease, smoking, wound healing, and medication. Chapter 6 (*Effect of oxidative stress on sperm cells - Alejando Córdova Izquierdo*) examines some general aspects of oxidative stress in cells and its effects in sperm cells, also reviewing the effects on male and female fertility. And finally Chapter 7 (*Typical catalases: Function and structure - Yonca Yuzugullu Karakus*) focuses on the function and structure of mono-functional heme-catalases, emphasizing the information obtained in the last few years mainly in relation to the secondary activity of these enzymes.

In conclusion, based on the broad range of issues covered in this book, we hope that both academic researchers and students can learn and share the knowledge presented here. This book is the result of several collaborating parties. We gratefully acknowledge all the authors and reviewers for their precious contribution to this book, the valuable assistance of Ms. Lada Bozic, and all the support of the book publisher throughout the publication process.

#### **Margarete Dulce Bagatini**

**1**

Section 1

Glutathione System in

Health and Disease

Federal University of the Fronteira Sul, Academic Coordination, Chapecó Campus, Chapecó, SC, Brazil Section 1
