Essentials of Botanical Extraction - Anup Kumar Das, Subhash C. Mandal, Vivekananda Mandal

Essentials of Botanical Extraction (eBook)

Principles and Applications

Anup Kumar Das, Subhash C. Mandal, Vivekananda Mandal (Autoren)

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2015 | 1. Auflage
220 Seiten
Elsevier Science (Verlag)
978-0-12-802563-5 (ISBN)

Essentials of Botanical Extraction: Principles and Applications provides a unique, single source of valuable information on the various botanical extraction methods available, from conventional to the use of green and modern extraction technologies including ultrasounds, microwaves, pressurized liquids, and supercritical fluids. Most extracts obtained from botanicals are often poorly characterized with unidentified active or inactive constituents. A wise selection of an extraction strategy is vital to drug discovery from medicinal plants as extraction forms the basic first step in medicinal plant research. This book also explores the mathematical hypotheses and innovations in botanical extractions and analyzes different post extraction operations so that dependency on serendipity is reduced and the same be converted into programmed drug discovery. - Reviews the history and current state of natural product drug discovery and development, highlighting successes and current issues - Explains the application of chemometric tools in extraction process design and method development - Introduces process intensification as applied to the processing of medicinal plant extracts for rapid and cost-effective extraction

Dr. Subhash C. Mandal, PhD is Professor at Division of Pharmacognosy, Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India. Professor Mandal is the recipient of prestigious awards including Endeavour Research Award, Government of Australia; Distinguished Education & Research Award, AAiPS, USA; Talented Scientist Award, University of Colombo, Sri Lanka; SAARC Fellowship Award, University Grants Commission (UGC), Bangladesh; Fast Track Young Scientist Award, Department of Science and Technology , UGC Research Award, India and Outstanding University Teachers' Award , Department of higher education , Government of West Bengal , India. He has supervised more than 30 doctoral and 25 M. Pharm scholars and has more than 300 research publications, several patents, books and book chapters to his credit. Professor Mandal has delivered more than 50 research presentations around the globe, has chaired many international conferences, and successfully completed more than 10 government-funded research projects. He is reviewer and board member of several high-impact journals and is a recognized host scientist for many international research programs with developing countries sponsored by the Indian Government. He has visited more than 30 countries for various scientific deliberations, collaborations and exchange programmes.

Front Cover 1
Contents 6
Foreword by Sarker 12
Foreword by Verpoorte 14
Preface 16
Chapter 1 - Introduction 18
Introduction 18
1.1 OLDER STRATEGIES 19
1.2 CONTEMPORARY STRATEGIES 19
1.3 ADVANTAGES 20
1.4 CHALLENGES 21
Chapter 2 - History and Background on the Use of Natural Products Obtained from Plants as Therapeutic Agents 24
2.1 A GENERAL OVERVIEW 24
2.2 DRUG USAGE DURING THE PREHISTORIC PERIOD 25
2.3 DEVELOPMENTS AND DRUG USAGE DURING ANCIENT TIMES/PRE-HELLENIC CIVILIZATIONS 26
2.4 DRUG DISCOVERY AND DEVELOPMENT DURING THE MIDDLE AGES 31
2.5 DEVELOPMENTS AND DRUG USAGE DURING THE LAST PHASES OF THE MIDDLE AGES 32
FURTHER READING 34
Chapter 3 - Botanicals as a Screening Source of New Drugs: Past Success Stories and Present-Day Concerns 36
3.1 HISTORIC ROLE OF BOTANICALS 36
3.2 BOTANICALS AS SOURCES OF NEW LEADS DURING 1984–2014 48
FURTHER READING 50
Chapter 4 - What All Should Know about Plant Drugs 52
4.1 ROLE OF PLANTS IN DRUG DEVELOPMENT 53
4.2 FACTORS THOUGHT TO BE THE REASON FOR DECLINING INTEREST IN BOTANICALS 65
4.3 APPROACHES AND STRATEGIES TO IMPROVE THE STATUS OF DRUG DISCOVERY FROM BOTANICALS 68
4.4 APPROACHES IN MEDICINAL.PLANT SELECTION PRIOR TO.EXTRACTION 70
4.5 AN OVERVIEW ON PRE-EXTRACTION TECHNIQUES 74
FURTHER READING 78
Chapter 5 - Extraction of Botanicals 80
5.1 INTRODUCTION 80
5.2 UNDERSTANDING THE LINK BETWEEN BOTANICAL EXTRACTION AND THEIR STANDARDIZATION 84
5.3 GENERAL EXTRACTION APPROACHES AND THEORIES 85
5.4 FACTORS AFFECTING EXTRACTION OF BOTANICALS 95
FURTHER READING 99
Chapter 6 - Classification of Extraction Methods 100
6.1 CLASSIFICATION OF VARIOUS NONCONVENTIONAL EXTRACTION TECHNIQUES 101
6.2 REMOVAL OF UNWANTED AND INTERFERING COMPONENTS AFTER EXTRACTION 151
FURTHER READING 153
Chapter 7 - Innovative Extraction Process Design and Optimization Using Design of Experimental Approach 154
7.1 INTRODUCTION 154
7.2 TERMINOLOGIES WE NEED.TO KNOW 156
7.3 ISSUES ADDRESSED THROUGH EXPERIMENTAL DESIGN 161
7.4 RSM AS A TOOL FOR.OPTIMIZATION IN MAE 168
7.5 RSM AS A TOOL FOR.OPTIMIZATION IN SUPERCRITICAL FLUID EXTRACTION 175
7.6 RSM AS A TOOL FOR.OPTIMIZATION IN PRESSURIZED LIQUID EXTRACTION/ACCELERATED SOLVENT EXTRACTION 175
FURTHER READING 179
Chapter 8 - Identification Strategies of Phytocompounds 182
8.1 IDENTIFICATION STRATEGY FOR.VOLATILE COMPOUNDS 182
8.2 IDENTIFICATION STRATEGY OF NONVOLATILE COMPOUNDS 183
8.3 IDENTIFICATION OF KNOWN COMPOUNDS USING REFERENCE STANDARDS 183
8.4 IDENTIFICATION OF KNOWN COMPOUNDS WITHOUT.REFERENCE STANDARDS 185
8.5 IDENTIFICATION OF COMPOUNDS.WITH UNKNOWN STRUCTURES 185
8.6 THE STAGES IN STRUCTURAL ELUCIDATION 186
FURTHER READING 188
Chapter 9 - Qualitative Phytochemical Screening 190
9.1 DETECTION OF ALKALOIDS 190
9.2 DETECTION OF GLYCOSIDES 193
9.3 DETECTION OF FLAVONOIDS 194
9.4 DETECTION OF COUMARIN.DRUGS 194
9.5 DETECTION OF.ESSENTIAL OILS 195
9.6 DETECTION OF.CARBOHYDRATES 196
9.7 DETECTION OF PROTEINS.AND AMINO ACIDS 196
9.8 DETECTION OF.TRITERPENOIDS 197
9.9 DETECTION OF STEROIDS 197
9.10 DETECTION OF TANNINS.AND PHENOLIC.COMPOUNDS 197
9.11 SPRAY REAGENTS 198
FURTHER READING 202
Chapter 10 - Profiling Crude Extracts for Rapid Identification of Bioactive Compounds 204
10.1 INTRODUCTION 205
10.2 TECHNIQUES ROUTINELY EMPLOYED IN DEREPLICATION STUDY 205
10.3 STAGES WHERE DEREPLICATION IS APPLIED DURING TRADITIONAL AND MODERN APPROACHES OF DRUG DISCOVERY 211
10.4 CONSTRUCTION AND CHARACTERIZATION OF EXTRACT LIBRARIES 215
FURTHER READING 218
Index 220

Chapter 1

Introduction

Abstract

There has been a remarkable increase in interest on herbals and their products over the last decade or so. With the outstanding developments in the areas of separation technology and bioassay methodology, botanical research is enjoying renewed attention for providing novel and interesting chemical entities. Advancements and upgradation in the field of hyphenated techniques have assisted in carrying out preisolation analysis and fractionation of crude extracts, isolation and simultaneous online detection of bioactives, chemical fingerprinting and profiling, apart from dereplication studies.

While different chapters of this book are devoted to a number of specific issues related to botanical extraction, this introductory chapter presents a general overview with respect to several strategies involved in botanical extraction and its related domain.

Keywords

Bioactives; Bioassay; Crude extracts; Dereplication; Herbals; Hyphenated techniques

Chapter Outline

1.1 Older Strategies 2

1.2 Contemporary Strategies 2

1.3 Advantages 3

1.4 Challenges 4

The subjects “Pharmacognosy” and “Natural Product Chemistry” have developed concomitantly, and both have coevolved as a single distinct discipline and are closely related as well. Both encompass enormous varieties of naturally occurring entities that are synthesized and accumulated by plants or living organisms and mainly deal with chemical structures of these organic entities, their natural distribution, their biosynthesis, rate of turnover and metabolism, and their biological functions or bioactivity.

Pharmacognosy provides the tool to identify, select, and process natural products destined for medicinal and other uses. Although most pharmacognostic and phytochemistry studies focus on plant and phytomolecules derived from them, other sections of organisms are also regarded as pharmacognostically interesting as shown in Figure 1.1.

Crude or an untreated extract from any one of these sources may typically contain known, novel, structurally similar, or diverse chemical(s) with or without some form of biological activity. Generally, bioactive compounds of natural origin from the above-cited sources are popularly known as Secondary metabolites. In order to understand the term secondary metabolites, it is mandatory to understand what is meant by primary and secondary metabolism.

The process of synthesizing essential components in plants such as proteins, carbohydrates, fats, and nucleic acids that are all vital for their sustainability is generally termed primary metabolism, and the essential components thus produced are called primary metabolites. An interesting fact about a plant’s defense system against some natural, synthetic factors or unnatural factors (virus attack, radiation exposure) is that plants start producing compounds that are generally not essential for their growth, development, or reproduction but are produced either as a result of the organism adapting to its surrounding environment or as a defense mechanism against predators to help in the sustainability of the organism. Such compounds are called secondary metabolites, and the process through which they are formed is known as secondary metabolism.

Figure 1.1 Various sources of natural products.

The study of Pharmacognosy can be divided into the following fields:

1. Medical ethnobotany—this deals with the understanding and study of the traditional uses of plants for medicinal purposes.

2. Ethnopharmacology—the study of efficiency and efficacy qualities of traditionally used plants and medicinal substances derived from them.

3. Phytotherapy—a part of pharmacognosy focusing on the use of crude or semipure mixtures of extracts for medicinal use. It is sometimes considered as an alternative medicine.

4. Zoopharmacognosy—deals with self-medication of nonhuman animals by selecting and using plant parts, soils, and insects to treat and prevent diseases.

5. Marine pharmacognosy—study of chemicals derived from marine organisms.

Strategies for research in the area of natural product chemistry and pharmacognosy have evolved quite significantly over the last 20 years. These can be classified into two main categories:

1.1. Older Strategies

1. A straightforward chemotaxonomic study.

2. Selection of potent sources simply relying on ethnobotany and ethnopharmacology reports.

3. Simple adoption of phytochemical surveillance and in the process overlooking their bioactivity.

4. Simple isolation and identification of compounds from natural sources followed by in vitro and in vivo biological action investigation.

1.2. Contemporary Strategies

1. Modern advances in extraction and separation techniques actually have helped phytochemists to venture and adopt bioassay-guided isolation of secondary metabolites.

2. Strategies to access the metagenome of the botanical source by constructing and screening DNA libraries. Such genome-mining strategies appear to be a promising tool for the discovery of bioactive compounds.

3. Introduction of the concepts of system biology, reverse pharmacology, dereplication, chemogenomics, chemically engineered extract, gene microarray analysis, metabolomic fingerprinting, and chemical fingerprinting actually have shifted the focus more towards bioactivity oriented drug discovery.

4. Introduction of “omic” technologies as high-throughput methods has actually opened the methodological possibilities to investigate extensively into the pharmacological mode of action, synergy effects, multitarget synergy effects, and multitarget property of complex crude extracts.

5. Introduction and advancement of sophisticated hyphenated techniques (high-performance liquid chromatography mass spectrometry (HPLC–MS), HPLC-nuclear magnetic resonance (NMR), HPLC–MS–NMR, HPLC–diode array detector–MS–NMR, etc.) in the field of separation techniques with high-sensitivity detectors have allowed better detection of small molecular compounds present in biological systems.

The advantages and challenges of botanical drug discovery as compared to its synthetic counterpart are summarized below:

1.3. Advantages

• Botanicals offer an unmatched chemical diversity coupled with immense biological potency.

• Bioactive molecules obtained from nature have evolved to bind to proteins and do possess drug-like properties.

• Bioactive molecules obtained from botanicals can provide various chemical “building blocks” that can be used to synthesize more complex molecules. A popular example has been diosgenin from Dioscorea floribunda for the synthesis of oral contraceptives. Similar was the case with camptothecin from Camptotheca species, which led the development of novel anticancer molecules such as topotecan and irinotecan.

• Selection and usage of botanical sources are mainly done on the basis of its long-term use by humans and is popularly known as ethnomedicine. This approach is thought to be safer than selecting plant species with no history of human use. Discovery of drugs from Rauwolfia serpentine, Digitalis purpurea, etc. in the past actually comes under this class of approach of drug discovery.

• Pure bioactives can be administered in a reproducible, accurate dose with apparent therapeutic benefits.

• They can also lead to the improvement of analytical assays for particular compounds or for compound classes. This helps in the screening of plants for potential toxicity and for quality control of therapeutic formulations for human or animal intake.

• Bioactive compounds assist in structural elucidation, which may enable the production of synthetic compounds, incorporation of structure-related modifications, and finally help in the validation of mechanisms of action.

1.4. Challenges

Utilization of the whole plant or their crude preparations for therapeutic or experimental reasons can have several drawbacks including

• Disparity in the amount of the bioactives with different geographic areas, seasons, with different plant parts and morphology, and with different climatic and environmental conditions.

• Co-occurrence of unwanted compounds causing synergistic, antagonistic, or undesirable responses; modifications of the pharmacological activity cannot be disregarded.

• Changes or losses of bioactivity occur due to variability in collection, storage, and preparation of the raw material.

• Lack of an appropriate dereplication strategy has resulted in reoccurrence of species and phytocompounds within many extract libraries. Redundancy from an economical point of view is totally undesirable in natural product drug discovery.

• Production of an adequate amount of the potent bioactive compound is needed for drug discovery and drug profiling, which may require an extensive optimization and scale-up steps.

• The...

Erscheint lt. Verlag	2.2.2015
Sprache	englisch
Themenwelt	Naturwissenschaften ► Chemie ► Analytische Chemie
	Naturwissenschaften ► Chemie ► Organische Chemie
	Technik ► Umwelttechnik / Biotechnologie
ISBN-10	0-12-802563-8 / 0128025638
ISBN-13	978-0-12-802563-5 / 9780128025635

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