Preface

Essential oils have been used by global communities for centuries, for different purposes such as medicinal, flavoring, preservatives, perfumery, aromatherapy, dentistry, cosmetics, insecticide, fungicide, bactericide, among others. Essential oils are natural and biodegradable substances, usually non-toxic or with low toxicity to humans. Essential oils are botanical products with having volatile nature and are known for their special odor and are found effective in the treatment of oxidative stress, cancer, epilepsy, skin allergies, indigestion, headache, insomnia, muscular pain, and respiratory problems, etc. Essential oils principally enhance resistance to abiotic stress and protection against aquatic herbivores. They possess antimicrobial, antifungal, antitumor, and antioxidant activities. However, essential oils are easily lost or degraded under ambient conditions (temperature, air, light, and humidity), resulting in limited applications. So, their encapsulation is one of the proven techniques to successfully protect essential oils and enable various applications. The purpose of this book is to offer current knowledge on essential oils' chemical structure, therapeutic, and biological activities, to describe their functional uses, and to assess the benefits and drawbacks of their usage in many fields.

Essential Oils: Extraction Methods and Applications addresses the topics related to methods of extracting essential oils, biological and therapeutic applications, their uses in different sectors of the industry, and will also address methods and applications of encapsulated essential oils. In addition, we cover issues such as the latest biological applications of essential oils, as well as traditional and modern methods for extracting essential oils. This book should be useful for different industries like pharma, perfumery, flavoring, perfumery, aromatherapy, cosmetics, others and also useful for faculty, researchers, students from academics, and laboratories which are linked to essential oils and their useful properties, applications of the different paradigms. The summaries of the work reported in the following 43 chapters are as follows:

Chapter 1 discusses the plant essential oils and their isolated bioactive components for their potential antiviral activities in detail. The fundamental knowledge of antiviral properties of essential oil along with their mechanisms of actions, efficacy, and safety is needed for their targeted drug delivery systems, which are consequential to their further research, new drug design, and further applications.

Chapter 2 covers the use of essential oils derived from aromatic plants as a safer and more nutritious alternative to artificial preservatives. Essential oils' natural properties, extraction procedures, and activity against pathogenic and deteriorating microorganisms, as well as their uses in food preservation, are discussed.

Chapter 3 reviews the sources and composition of various essential oils and the variety of extraction methods. Primarily, it focuses on applying essential oils in different industrial sectors like chemicals, food preservation, pharmaceutical, and pesticides, etc.

Chapter 4 focuses on the effect of various abiotic and biotic factors (drought, temperature, salt, heavy metals, UV light, living organisms, etc.) on essential oils production and composition. The importance of these factors to adequate agricultural practices for aromatic plants cultivation and to obtain high-quality essential oils is also discussed.

Chapter 5 emphasizes the potential antiviral effect of essential oils by reviewing some recent literature. It illustrates the different methods implemented to investigate the in vitro antiviral activity of EOs and their components along with their mechanisms of action. Furthermore, the effectiveness of EOs against several viral illnesses that impact human body systems, as well as some plants and animals, are also highlighted.

Chapter 6 discusses Mentha species and their chemical compositions on account of their biological activity as reported by the scientists, with a focus on microbiological activity. Mentha piperita L. is judged to be the most promising of the species offered to be used as an herbal medication.

Chapter 7 describes the plant secondary metabolites that play a significant role as anti-oxidants, anti-cancerous, anti-microbial, and have medicinal properties. The influence of microbes on plants is elaborated in the context of the enhanced production of these secondary metabolites in various stress conditions, with mechanisms of contact briefly elaborated.

Chapter 8 details the valorization of limonene (an essential oil) into compounds with high commercial value by different reactions, such as alkoxylation, hydration, and acetalization over heterogeneous catalysts. Also, the conversion of limonene into p-cymene is studied. Different solid materials, like clays, zeolites, heteropolyacids, and silica with sulfonic groups towards the valorization of limonene are discussed.

Chapter 9 discusses the role of essential oils in various industrial applications, focusing on pharmaceutical, cosmetic manufacturing, food processing, and preservation industry. The major focus dealt with volatile bioactive compounds in essential oils that are responsible for altering synthetic additives with natural composites in food, cosmetics, and medicines.

Chapter 10 discusses the most common uses of essential oils in various sectors. It focuses on the increased use of essential oils in the food, beverage, packaging, cosmetics, perfumery, medical, agriculture, textile, and cleaning industries in line with the increasing awareness and demand of consumers for natural ingredients.

Chapter 11 deals with various pharmacological activities of essential oils and their major chemical components. The mechanism of action and pharmacological targets of various essential oils particularly anti-inflammatory, anticancer, antiviral, antifungal, larvicidal, antidiabetic, and antibacterial activities are discussed in the present chapter. Additionally, the potential efficacy of terpenoids and phenylpropanoids in the treatment of cancer, inflammation, and viral infections are illustrated in this chapter.

Chapter 12 reveals the stability and efficacy associated challenges that are often encountered by essential oils that led to compromised efficiency. Further, the chapter gives insight to overcome these challenges through various encapsulation techniques, their formulation aspect, and the advantages as per the reported literature.

Chapter 13 discusses the antimicrobial effect of essential oils and their food application. Additionally, the biotechnological strategies for extracting essential oils for food application and the methods for evaluating the essential oil's inhibitory activity are discussed. Moreover, the influence of extraction methods on the antimicrobial compounds in essential oils is also presented.

Chapter 14 epitomizes the application of essential oils in food packaging and food products. Essential oils sources such as plants, fruit, and flowers and their chemical composition are presented in this chapter. The main focus of this chapter is to highlight the potential application of essential oils as an antimicrobial, antifungal, and antioxidant agent in different food packaging and products.

Chapter 15 discusses the use of essential oils against biofilm-forming bacteria. The formation and organization of biofilms and their role in acquiring antibiotic resistance are presented. The main focus is given to provide information on the nature of essential oils, their antimicrobial and antibiofilm activities, and their mechanism of action.

Chapter 16 discusses the biological applications of essential oils such as antibacterial, antifungal, antiviral, antioxidant, and anti-inflammatory activities and their usage in the treatment of various ailments such as cancer, respiratory tract diseases, cardiovascular diseases, obesity, and diabetes. Additionally, the sources and extraction process of essential oil are also discussed.

Chapter 17 details the various essential oils used as biopesticides in agriculture, food storage, and the household. The delivery and the pesticidal modes of action of biopesticides are discussed in detail. The target pest and the active ingredients responsible for the pesticidal action are also presented.

Chapter 18 explicitly describes the larvicidal and ovicidal potential of essential oils with special reference to potent larvicidal activity against mosquito vectors including Aedes aegypti, Anopheles stephensi, A. Albopictus, and the ovicidal activity against human head lice (Pediculus humanus), domestic animal gastrointestinal nematode (Haemonchus contortus) and American bollworm (Armigera Helicoverpa Hubner).

Chapter 19 discusses the primary applications of essential oils as pesticides and their biological activity with a different class of organisms and discusses potential directions for the use of essential oils as pesticides of the future. Additionally, the role of essential oils synergistic compositions and toxic effects of essential oils on non-target organisms are also studied. The main aim of this chapter is to explain the present state of knowledge and recent advances in the phytochemistry of plant essential oils, their biological activity in a variety of species, and their potential as...