Naturally Occurring Bioactive Compounds

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• Publisher: Elsevier Science
• Year: 2006
• eBook ISBN: 9780080464923
• Topic: Technology & Engineering
• Subtopic: Organic Chemistry
• Index: Technology & Engineering

This timely book provides an overview of natural products/botanicals used for the management of insect-pest and diseases. It will help readers to update and widen their knowledge about natural products and their bio-activities against plant pathogens. The volume explores activity, chemistry, toxicity and geographic distribution of plants. Discussions concerning the methodology used for the detection of active principles, their mode of action and commercial prospects are of utmost importance and worthy of note.- Focuses on recent achievements in natural bio-actives- Global coverage of natural products / plants- Targets the most important issues of natural botanicals/ biocides- Includes innovative ideas with lucid explanations- Contains specialized chapters, such as, natural control of multi-drug resistant organisms, anti-salmonella agents, natural house-dust-mite control agents, and naturally occurring anti-insect proteins, etc.- Covers research on bioactives: From Lab to Field and Field to Market- Includes eco-friendly and economically viable herbal technology

Chapter 1 Natural compounds as antioxidant and molting inhibitors can play a role as a model for search of new botanical pesticides

Cespedes A Carlos L. Céspedes A, J Guillermo Avila, J Camilo Marin, Dominguez L Mariana Domínguez L, Patricio Torres, Eduardo Aranda

Introduction

Nowadays, pesticides of synthetic origin have been widely used, producing a strong impact on the environment with the emergence of resistant strains of microbes and insects to these types of compounds. New plant protection chemicals are needed for modern pest management due to insect resistance and ecological disorders associated with numerous currently used pesticides (Castillo et al., 1998). One area of investigation that is not so much an innovation as it is a return to an old approach with new technology is the characterization of secondary plant products (Berenbaum, 1989, 2002), and this can help in plant defense through new biotechnological approaches like metabolomic, genomic, and proteomic (Berenbaum, 1995, 2002; Kessler and Baldwin, 2002; Sumner et al., 2003). Most of them have potent effects on insect pests, low mammalian toxicity, lack of neurotoxic activity, low persistence in the environment, and biodegradability (Jacobson, 1989; Singh et al., 1997). Thus, organic molecules of botanical origin may offer a safe source of compounds for pest management, being environmentally friendly, and an excellent alternative to persistent synthetic insecticides (Berenbaum, 1989; Miyazawa et al., 1997; Castillo et al., 1998; Crowley et al., 1998).

Plants in general produce a great variety of secondary metabolites that do not have apparent function in physiological or biochemical processes; these compounds (or allelochemicals) are important in mediating interactions between plants and their biotic environment (Berenbaum, 1989, 1991, 1995, 2002; Kessler and Baldwin, 2002).

There is a widespread effort to find new pesticides, and currently it is focused on natural compounds such as flavonoids, coumarins, terpenoids, and phenolics from diverse botanical families from arid and semi-arid lands of Mexico and Americas.

Additional experimental work has been carried out with natural products, which are potential models for defensive substances against insect and fungal predators (Kubo et al., 1994, 1995; Crombie, 1999; Kubo et al., 2000) and as enzyme inhibitors, tyrosinase or acetylcholinesterase (AChE) for instance (Kubo, 1997; Keane and Ryan, 1999; Ortego et al., 1999; Kubo et al., 2000; Céspedes et al., 2001a, 2001b; Kubo et al., 2003a, 2003b). The increasing interest in the possible application of secondary metabolites for pest management has directed the investigation towards search for new sources of biologically active natural products, with new mode, sites, and mechanisms of action, selectivity, and specific action (Jacobson, 1989; González-Coloma et al., 1997; Singh et al., 1997; Conner et al., 2000; Eisner et al., 2000; Eisner and Meinwald, 1995); these characteristics may enhance their value as commercial pesticides (González et al., 1992; Isman et al., 1995, 1996; Valladares et al., 1997; González and Estévez-Braun, 1998; González et al., 2000).

Recent studies have demonstrated that many plant species produce and accumulate a large variety of secondary metabolites that provide defense against insect predators (Berenbaum, 1989; Guella et al., 1996; Marvier, 1996; Berenbaum, 2002). Among several efforts to find new pesticides, current research is focused on limonoids from the Meliaceae family due to their potent effects on insect pests and their low toxicity to non-target organisms (Koul and Isman, 1992; Kumar and Parmar, 1996; Singh et al., 1997). Some examples are Azadirachta indica (Meliaceae) and Derris elliptica (Fabaceae), which produce very well known insecticides azadirachtin and rotenone, respectively (Gomes et al., 1981; Kraus et al., 1993, 1995). The main characteristics that account for the successful use of these secondary metabolites as natural insecticides are mentioned above, which make them lesser aggressive to the environment than the synthetic ones (Camps, 1988; Berenbaum, 1989; Castillo et al., 1998).

Although the members of the family Meliaceae are widely distributed in the world, only Melia, Toona, Cedrela, and Swietenia have been studied (Arnason et al., 1987; Champagne et al., 1992; Kubo, 1992; Arnason et al., 1993; Kraus et al., 1993; Kubo, 1993; Govindachari et al., 1995; Chan and Taylor, 1966; Céspedes et al., 2000), and have afforded some limonoids such as azadirachtin, gedunin, toosendanin, cedrelanolide, mexicanolide, odoratol, anthothecol, nomilin, bussein, entandrophragmin, among others. Azadirachtin is the best known example of these limonoids (Champagne et al., 1989; Ramji et al., 1996). This compound and their analogues are potent insect antifeedant and ecdysis inhibitors (Govindachari et al., 1995; Kraus, 1995). However, the structural complexity of this compound precludes its synthesis on a commercial scale (Isman et al., 1996). These facts have led us to search for new simple secondary metabolites with insecticidal activity from other families including plants of Agavaceae, Asteraceae, and Meliaceae, such as Yucca spp., Parthenium spp., Roldana spp., Tagetes spp., and Cedrela spp., respectively, specially from tropical and subtropical lands of Mexico.

As mentioned earlier, tyrosinase also known as polyphenol oxidase (PPO) (Meyer, 1987) is a copper containing enzyme widely distributed in microorganisms, animals, and plants. It catalyzes two distinct reactions of melanin synthesis (Robb, 1984), the hydroxylation of a monophenol (monophenolase activity) and the conversion of an o-diphenol to the corresponding o-quinone (diphenolase activity). Tyrosinase is responsible for browning in plants and is considered to be deleterious to the color quality of plant-derived foods and beverages. In addition, sclerotization and molting regulation processes in insects show that tyrosinase is one of the key enzymes in the insect metamorphoses process (Andersen, 1990).

AChE, which is the enzyme contained in nerve tissues, plays an exceedingly important role in the transmission of a nerve impulse. The free acetylcholine in the inactive form bound to proteins accumulates in the ending of a nerve in vesicles. The consumed acetylcholine is constantly replenished by its synthesis (by the acetylation of choline). All these processes are occurring when an impulse is transmitted through a cholinergic synapse. Thus, the process of synaptic transmission is an involved biochemical cycle of acetylcholine exchange. AChE has a key role in this cycle because the inhibition of activity leads to the accumulation of free acetylcholine in the synaptic cleft, producing the disruption of nerve impulses, then convulsive activity of the muscles can be transformed into paralysis, and other features of self-poisoning by surplus acetylcholine appear. It occurs when AChE is inhibited by some terpenoids (Ryan and Byrne, 1988; Miyazawa et al., 1997). On other hand, modifications to AChE can confer resistance to insecticides (Fournier et al., 1992).

In addition to many chemicals (flavonoids, stilbenoids, phenylpropanoids, and phenolics, among o...

Table of contents

• Cover image
• Title page
• Table of Contents
• Preface to the Series
• Preface
• Chapter 1 Natural compounds as antioxidant and molting inhibitors can play a role as a model for search of new botanical pesticides
• Chapter 2 Pesticides based on plant essential oils: from traditional practice to commercialization
• Chapter 3 Natural substrates and inhibitors of multidrug resistant pumps (MDRs) redefine the plant antimicrobials
• Chapter 4 New concept to search for alternate insect control agents from plants
• Chapter 5 Role of Melia azedarach L. (Meliaceae) for the control of insects and acari: present status and future prospects
• Chapter 6 Bioactivity of fabaceous plants against food-borne and plant pathogens: potentials and limitations
• Chapter 7 Screening of plants against fungi affecting crops and stored foods
• Chapter 8 Opportunities and potentials of botanical extracts and products for management of insect pests in cruciferous vegetables
• Chapter 9 The potential for using neem (Azadirachta indica A. Juss) extracts for pine weevil management in temperate forestry
• Chapter 10 Plant allelochemicals in thrips control strategies
• Chapter 11 Importance of plant secondary metabolites for protection against insects and microbial infections
• Chapter 12 Naturally occurring house dust mites control agents: development and commercialization
• Chapter 13 The search for plant-derived compounds with antifeedant activity
• Chapter 14 An overview of the antimicrobial properties of Mexican medicinal plants
• Chapter 15 Promissory botanical repellents/deterrents for managing two key tropical insect pests, the whitefly Bemisia tabaci and the mahogany shootborer Hypsipyla grandella
• Chapter 16 Naturally occurring anti-insect proteins: current status and future aspects
• Chapter 17 Antifungal natural products: assays and applications
• Contributors
• Subject Index