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Pharmacognosy & Phytochemistry - I

INTRODUCTION TO PHARMACOGNOSY

Pharmacognosy, known initially as materia medica, may be defined as the study of crude drugs obtained from plants, animals and mineral kingdom and their constituents. There is a historical misinformation about who created the term pharmacognosy. According to some sources, it was C. A. Seydler, a medical student at Halle, Germany, in 1815; he wrote his doctoral thesis titled Analectica Pharmacognostica. However, The physician J. A. Schmidt (Vienna) used that one in his Lehrbuch der materia medica in 1811, to describe the study of medicinal plants and their properties. The word pharmacog-nosy is derived from two Latin words pharmakon, ‘a drug,’ and gignoso, ‘to acquire knowledge of’. It means ‘knowledge or science of drugs’.

Crude drugs are plants or animals, or their parts which after collec-tion are subjected only to drying or making them into transverse or lon-gitudinal slices or peeling them in some cases. Most of the crude drugs used in medicine are obtained from plants, and only a small number comes from animal and mineral kingdoms.

Drugs obtained from plants consist of entire plants, whereas senna leaves and pods, nux vomica seeds, ginger rhizome and cinchona bark are parts of plants. Though in a few cases, as in lemon and orange peels and in colchicum corm, drugs are used in fresh condition, and most of the drugs are dried after collections. Crude drugs may also be obtained by simple physical processes like drying or extraction with water. Therefore, aloe is the dried juice of leaves of Aloe species, opium is the dried latex from poppy capsules and black catechu is the dried aqueous extract from the wood of Acacia catechu. Plant exudates such as gums, resins and balsams, volatile oils and fixed oils are also considered as crude drugs.

Further drugs used by physicians and surgeons or phar-macists, directly or indirectly, like cotton, silk, jute and nylon in surgical dressing or kaolin; diatomite used in filtration of turbid liquid or gums; wax, gelatin, agar used as pharmaceutical auxiliaries of flavouring or sweetening agents or drugs used as vehicles or insecticides are used in pharmacognosy.

Drugs obtained from animals are entire animals, as can-tharides; glandular products, like thyroid organ or extracts like liver extracts. Similarly, fish liver oils, musk, bees wax, certain hormones, enzymes and antitoxins are products obtained from animal sources.

Drugs are organized or unorganized. Organized drugs are direct parts of plants and consist of cellular tissues. Unorganized drugs, even though prepared from plants are not the direct parts of plants and are prepared by some intermediary physical processes, such as incision, drying or extraction with water and do not contain cellular tissue. Thus aloe, opium, catechu, gums, resins and other plant exudates are unorganized drugs.

Drugs from mineral sources are kaolin, chalk, diatomite and other bhasmas of Ayurveda.

human beings. Researchers are exploiting not only the classical plants but also related species all over the world that may contain similar types of constituents. Just like terrestrial germplasm, investigators had also diverted their attention to marine flora and fauna, and wonderful marine natural products and their activities have been studied. Genetic engineering and tissue culture biotech-nology have already been successful for the production of genetically engineered molecules and biotransformed natural products, respectively.

Lastly, crude drugs and their products are of economi-cal importance and profitable commercial products. When these were collected from wild sources, the amount collected could only be small, and the price commanded was exorbitantly high. All this has now changed. Many of the industrially important species which produced equally large economic profits are cultivated for large-scale crop production. Drug plants, standardized extracts and the therapeutically active pure constituents have become a significant market commodity in the international trade. In the light of these glorious facts, scope of pharmacognosy seems to be enormous in the field of medicine, bulk drugs, food supplements, pharmaceutical necessities, pesticides, dyes, tissue culture biotechnology, engineering and so on.

Scope for doctoral graduates in pharmacognosy is going to increase in the coming years. The pharmacognosist would serve in various aspects as follows:

Academics: Teaching in colleges, universities, museums and botanical gardens.

Private industry: Pharmaceutical companies, consumer products testing laboratories and private commercial testing laboratories, the herbal product industries, the cosmetic and perfume industries, etc.

Government: Placement in federal agencies, such as the Drug Enforcement Agency, the Food and Drug Admin-istration, the U.S. Department of Agriculture, Medicinal plant research laboratories, state agencies like forensic laboratories, environmental laboratories, etc.

Undoubtedly, the plant kingdom still holds large number of species with medicinal value which have yet to be discovered. Lots of plants were screened for their pharmacological values like, hypoglycaemic, hepatoprotective, hypotensive, antiinflammatory, antifertility, etc. pharmacognosists with a multidisciplinary background are able to make valuable contributions in the field of phytomedicines.

Sources of Natural Drugs

The following are the natural sources of Drugs:

• Biological sources (i.e. from Terrestrial and Marine living things)

o Plants o Animals o Microorganisms: Fungi, Algae, Bacteria

• Mineral sources
• Biotechnology: Tissue culture/ Recombinant DNA Technology

Plant Sources

Plant source is the oldest source of drugs. Most of the drugs in ancient times were derived from plants. Almost all parts of the plants are used i.e. leaves, stem, bark, fruits and roots.

The number of species of flowering plants is estimated to be 2 to 2.5 lakhs falling in about 300 families and 10000 genera. Only a small percentage of the total species have been studied scientifically for the presence of any therapeutic activity and isolation of the responsible bioactive compound isolated.

Investigators face numerous hurdles and problems in the systematic investigation of all the species and as a result thousands of species are still not investigated thoroughly.

In many areas of the world, plants used in folklore medicine have been recorded. In other regions of the world such information has not been recorded or lost. Ethno botanists across the world have been trying to gather and record such valuable information before it is completely lost or forgotten.

The search for new drug needs a team work of experts from various domains such as botany, pharmacognosy, pharmacology, phytochemistry, medicine etc.

Majority of the natural drugs from plant sources are derived from Spermatophytes (seed bearing plants). Thy phyla Angiosperme is the dominant one while the phyla Gymnospermae yields few useful drugs such as Turpentine oil, Colophony, ephedrine etc. Male Fern from Pteridophyta provides Taenicidal (tape worm killing) agents

In Angiospermae, Dicotyledon plants provide more drugs than the Monocotyledon plants which yield limited drugs such as Squill, Lemon grass oil, Aloes etc.

Examples of drugs obtained from plants include Quinine, Atropine, Cocaine, Morphine, Codeine, Ergotamine, Reserpine, Caffeine, Sennosides, Glycyrrhizin, volatile oils, fixed oils etc.

Animal Sources:

Gelatin is obtained from ox and sheep, Wool fat from sheep, Beeswax from honeycomb, Cochineal from insects are some examples of drugs obtained from land animals.

Classification of Drugs of Natural Origin

INTRODUCTION

The flora and fauna of mother earth has a great diversity. The number of plant species divided in about 300 families and 10,500 genera are supposed to be about 2–2.5 lacs. At least 100– species of medicinal plants are currently cultivated and about 30–40 of them are the large-scale field corps. Drugs of the animal and mineral origin have also been used since the beginning and even today many such crude drugs are important, commercial products. All these drugs of natural origin have been used as the curative agents and even in this age of scientific discoveries and invention, natural drug have been the primary choice as a source of drug. Human inquisitiveness has gone beyond the terrestrial regions and exploited the seas and oceans which contain about 5 lacs species of marine organisms. Therapeutically active constituents found in these organ-isms open yet another great natural source of drugs of unending search.

Crude drugs can be regarded as the substances either used directly or indirectly as a drug which have not been changed or modified in its chemical composition.

The crude drugs of natural origin can be divided into two main categories as organized crude drugs and unorganized crude drugs.

Organized Drugs

Organized drugs consist of the cellular organization in the form of anatomical features. These are mostly the crude drugs from plant sources. Almost all of the morphological plant parts or the entire plant itself can be called as an organized drugs. A long list can be made of such crude drugs. To mention few of them, like, Cinchona bark, Sandalwood, Quassia wood, Senna, Digitalis leaves, Nux vomica seeds, Rauwolfia roots and many other examples of above-mentioned groups or crude drugs exemplified by some other morphological organs can be quoted as the example of organized crude drugs

Microscopical and anatomical studies are preeminent for such crude drugs. These can be used directly in medicine or can be used by modifying or by extracting the active ingredient from it. The simple medicines prepared from these drugs are herbal teas, extracts, tinctures, etc., and it may be extensively processed for the isolation and purification of pure therapeutically active constituent which is ultimately responsible for the action of the drug.

Unorganized Drugs

The unorganized drugs do not have the morphological or anatomical organization as such. These are the products which come directly in the market but their ultimate source remains the plants, animals or minerals. Microscopical studies are not required for such crude drugs. These includes products like plant exudates as gums, oleogums, oleogumresins, plant lattices like that of opium, aloetic juices like aloes or dried extracts of black and pale catechu, agar, alginic acid, etc., are products coming under this group. Other products like essential oils, fixed oils, fats and waxes obtained from vegetable or animal sources, although hydro-distilled or extracted from plant, become the direct commodity for use. Unorganized crude drugs may be miscellaneous mineral products like shilajit. These products may be solid, semisolid or liquid and the physical, chemical and analytical standards may be applied for testing their quality and purity.

CLASSIFICATION OF CRUDE DRUGS

The most important natural sources of drugs are higher plant, microbes and animals and marine organisms. Some useful products are obtained from minerals that are both organic and inorganic in nature. In order to pursue (or to follow) the study of the individual drugs, one must adopt some particular sequence of arrangement, and this is referred to a system of classification of drugs. A method of classification should be:

a) simple,

b) easy to use, and

c) free from confusion and ambiguities.

Because of their wide distribution, each arrangement of classification has its own merits and demerits, but for the purpose of study the drugs are classified in the following different ways:

1.Alphabetical classification 2.Taxonomical classification 3.Morphological classification 4.Pharmacological classification 5.Chemical classification 6.Chemotaxonomical classification

Alphabetical Classification

Alphabetical classification is the simplest way of classifica-tion of any disconnected items. Crude drugs are arranged in alphabetical order of their Latin and English names (common names) or sometimes local language names (ver-nacular names). Some of the pharmacopoeias, dictionaries and reference books which classify crude drugs according to this system are as follows:

1.Indian Pharmacopoeia 2.British Pharmacopoeia 3.British Herbal Pharmacopoeia 4.United States Pharmacopoeia and National Formu-lary 5.British Pharmaceutical Codex 6.European Pharmacopoeia

In European Pharmacopoeia these are arranged according to their names in Latin where in United States Pharmaco-poeia (U.S.P.) and British Pharmaceutical Codex (B.P.C.), these are arranged in English.

Merits

·It is easy and quick to use. ·There is no repetition of entries and is devoid of con-fusion.

Genus: This is the part of the plant name that is most famil plant—Papaver (Poppy), Aquilegia (Columbine), and so on. The plants in a genus are often easily recognizable as belonging to the same group. Species: This is the level that defines an individual plant.Often, the name will describe some aspect of the plant— the colour of the flowers, size or shape of the leaves, or it may be named after the place where it was found. Together, the genus and species name refer to only one plant, and they are used to identify that particular plant. Sometimes, the species is further divided into subspecies that contain plants not quite so distinct that they are classified as variet species should be written after the genus name, in small letters, with no capital letter. Variety: A variety is a plant that is only slightly differentfrom the species plant, but the differences are not so insig-nificant as the difference abbreviated to var. The name follows the genus and species name, with var. before the individual variety name. Form: A form is a plant within a species that has minorbotanical differences, such as the co flower or shape of the leaves. The name follows the genus and species name, with form (or f.) before the individual variety name. Cultivar: A cultivar is a cultivated variety through deliberate hybridization, and can be reproduced (vegetatively or by seed) to produce more of the same plant. The name follows the genus and species name. It is written in the language of the person who described it, and should not be translated. It is either written written in front of the name.

Merits Taxonomical classification is helpful for studying evolution Demerits This system also does not correlate in between the chemical constituents and biological acti the drugs.

Morphological Classification

This is the part of the plant name that is most famil-iar; the normal name that you give a Papaver (Poppy), Aquilegia (Columbine), and so on. The plants in a genus are often easily s belonging to the same group. This is the level that defines an individual plant.Often, the name will describe some aspect the colour of the flowers, size or shape of the leaves, or it may be named after the

. Together, the genus and species name refer to only one plant, and they are used to identify that particular plant. Sometimes, the species is further divided into subspecies that contain plants not quite so distinct that they are classified as variet-ies. The name, of the species should be written after the genus name, in small letters, with no capital letter. A variety is a plant that is only slightly differentfrom the species plant, but the differences nificant as the differences in a form. The Latin is varietas, which is usually abbreviated to var. The name follows the genus and species name, with var. before the individual

A form is a plant within a species that has minorbotanical differences, such as the co flower or shape of the leaves. The name follows the genus and species name, with form (or f.)

A cultivar is a cultivated variety—a particularplant that has arisen either naturally or hybridization, and can be reproduced (vegetatively or by seed) to produce more

The name follows the genus and species name. It is written in the language of the person who described it, and should not be translated. It is either written in single quotation marks or has cv.

Taxonomical classification is helpful for studying evolution-ary developments.

This system also does not correlate in between the chemical constituents and biological acti

iar; the normal name that you give a Papaver (Poppy), Aquilegia (Columbine), and so on. The plants in a genus are often easily

This is the level that defines an individual plant.Often, the name will describe some aspect the colour of the flowers, size or shape of the leaves, or it may be named after the

. Together, the genus and species name refer to only one plant, and they are used to identify that particular plant. Sometimes, the species is further divided into subspecies The name, of the species should be written after the genus name, in small letters, with no capital letter.

A variety is a plant that is only slightly differentfrom the species plant, but the differences , which is usually abbreviated to var. The name follows the genus and species name, with var. before the individual

A form is a plant within a species that has minorbotanical differences, such as the colour of flower or shape of the leaves. The name follows the genus and species name, with form (or f.)

a particularplant that has arisen either naturally or hybridization, and can be reproduced (vegetatively or by seed) to produce more

The name follows the genus and species name. It is written in the language of the person who in single quotation marks or has cv.

This system also does not correlate in between the chemical constituents and biological activity of

In this system, the drugs are arranged according to the morphological or external characters of the plant parts or animal parts, i.e. which part of the plant is used as a drug, e.g. leaves, roots, stem, etc. The drugs obtained from the direct parts of the plants and containing cellular tissues are called as organized drugs, e.g. rhizomes, barks, leaves, fruits, entire plants, hairs and fibres. The drugs which are pre-pared from plants by some intermediate physical processes such as incision, drying or extraction with a solvent and not containing any cellular plant tissues are called unorga-nized drugs. Aloe juice, opium latex, agar, gambir, gelatin, tragacanth, benzoin, honey, beeswax, lemon grass oil, etc., are examples of unorganized drugs.

Organized drugs

Woods: Quassia, Sandalwood and Red Sandalwood.

Leaves: Digitalis, Eucalyptus, Gymnema, Mint, Senna,Spearmint, Squill, Tulsi, Vasaka, Coca, Buchu, Hamamelis, Hyoscyamus, Belladonna, Tea.

Barks: Arjuna, Ashoka, Cascara, Cassia, Cinchona, Cinnamon, Kurchi, Quillia, Wild cherry.

Flowering parts: Clove, Pyrethrum, Saffron, Santonica, Chamomile.

Fruits: Amla, Anise, Bael, Bahera, Bitter Orange peel,Capsicum, Caraway, Cardamom, Colocynth, Coriander, Cumin, Dill, Fennel, Gokhru, Hirda, Lemon peel, Senna pod, Star anise, Tamarind, Vidang.

Seeds: Bitter almond, Black Mustard, Cardamom, Colchi-cum, Ispaghula, Kaladana, Linseed, Nutmeg, Nux vomica,

Physostigma, Psyllium, Strophanthus, White mustard. Roots and Rhizomes: Aconite, Ashwagandha, Calamus, Calumba, Colchicum corm, Dioscorea, Galanga, Garlic, Gention, Ginger, Ginseng, Glycyrrhiza, Podophyllum, Ipecac, Ipomoea, Jalap, Jatamansi, Rauwolfia, Rhubarb, Sassurea, Senega, Shatavari, Turmeric, Valerian, Squill.

Plants and Herbs: Ergot, Ephedra, Bacopa, Andrographis,

Kalmegh, Yeast, Vinca, Datura, Centella.

Hair and Fibres: Cotton, Hemp, Jute, Silk, Flax.

Unorganized drugs

Dried latex: Opium, Papain

Dried Juice: Aloe, Kino

Dried extracts: Agar, Alginate, Black catechu, Pale catechu,Pectin

Waxes: Beeswax, Spermaceti, Carnauba wax

Gums: Acacia, Guar Gum, Indian Gum, Sterculia, Tra-gacenth

Resins: Asafoetida, Benzoin, Colophony, copaiba Gua-iacum, Guggul, Mastic, Coal tar, Tar, Tolu balsam, Storax, Sandarac.

Volatile oil: Turpentine, Anise, Coriander, Peppermint,Rosemary, Sandalwood, Cinnamon, Lemon, Caraway, Dill, Clove, Eucalyptus, Nutmeg, Camphor.

Demerits Drugs having different action on the body get classified separately in more than one group that causes ambiguity and confusion. Cinchona is antimalarial drug because of presence of quinine but can be put under the group of drug affecting heart because of antiarrhythmic action of quinidine. Chemical Classification Depending upon the active constituents, the crude drugs are classified. The plants contain various constituents in them like alkaloids, glycosides, tannins, carbohydrates, saponins, etc. Irrespective of the morphological or taxonomical char grouped into the same group. The examples are shown in this table.

characterize certain classes of plants. This gives birth to entirely a new concept of chemotaxonomy that utilizes chemical facts/characters for understanding the taxonomical status, relationships and the evolution of the plants. For example, tropane alkaloids generally occur among the members of Solanaceae, thereby, serving as a chemot-axonomic marker. Simi of classification of crude drugs. The berberine alkaloid in Berberis and Argemone, Rutin in Rutaceae members, Ranunculaceae alkaloids among its members, etc., are other examples. It is the latest system of classification that gives more scope for understanding the relationship between chemical constituents, their biosynthesis and their possible action.

Drugs having different action on the body get classified separately in more than one group that causes ambiguity and confusion. Cinchona is antimalarial drug because of presence of quinine but nder the group of drug affecting heart because of antiarrhythmic action of quinidine.

Depending upon the active constituents, the crude drugs are classified. The plants contain various glycosides, tannins, carbohydrates, saponins, etc. Irrespective of the morphological or taxonomical char-acters, the drugs with similar chemical constituents are grouped into the same group. The examples are shown in this table. Merits It is a popular approach for phytochemical studies. Demerits Ambiguities arise when particular drugs possess a number of compounds belonging to different groups of compounds. Chemotaxonomical Classification This system of classification relies on the chemical similarity of a taxon, i.e. it is based on the existence of relationship between constituents in various plants. There are certain types of chemical constituents that characterize certain classes of plants. This gives birth to entirely a new concept of chemotaxonomy t utilizes chemical facts/characters for understanding the taxonomical status, relationships and

For example, tropane alkaloids generally occur among the members of Solanaceae, thereby, serving axonomic marker. Similarly, other secondary plant metabo-lites can serve as the basis of classification of crude drugs. The berberine alkaloid in Berberis and Argemone, Rutin in Rutaceae members, Ranunculaceae alkaloids among its members, etc., are other examples. test system of classification that gives more scope for understanding the relationship between chemical constituents, their biosynthesis and their possible action.

Drugs having different action on the body get classified separately in more than one group that causes ambiguity and confusion. Cinchona is antimalarial drug because of presence of quinine but nder the group of drug affecting heart because of antiarrhythmic action of quinidine.

Depending upon the active constituents, the crude drugs are classified. The plants contain various glycosides, tannins, carbohydrates, saponins, etc. Irrespective of acters, the drugs with similar chemical constituents are

proach for phytochemical

Ambiguities arise when particular drugs possess a number of compounds belonging to different groups of compounds. Chemotaxonomical Classification This system of classification relies on the a taxon, i.e. it is based on the existence of relationship between constituents in various plants. There are certain types of chemical constituents that characterize certain classes of plants. This gives birth to entirely a new concept of chemotaxonomy t utilizes chemical facts/characters for understanding the taxonomical status, relationships and

For example, tropane alkaloids generally occur among the members of Solanaceae, thereby, serving lites can serve as the basis of classification of crude drugs. The berberine alkaloid in Berberis and Argemone, Rutin in Rutaceae

test system of classification that gives more scope for understanding the relationship

Adulteration of Drugs of Natural Origin

INTRODUCTION

Medicinal plants constitute an effective source of traditional (e.g. ayurvedic, chinese, homeopathy and unani) and modern medicine. Herbal medicine has been shown to have genuine utility. Germany and France, together represent 39% of the $14 billion global retail market. In India, about 80% of the rural population depends on medicinal herbs and/or indigenous systems of medicine. In fact today, approximately 70% of ‘synthetic’ medicines are derived from plants. Popularity among the common people increased the usage of medicinal plants/herbal drugs. Herbal adulteration is one of the common malpractices in herbal raw- material trade. Adulteration is described as intentional substitution with another plant species or intentional addition of a foreign substance to increase the weight or potency of the product or to decrease its cost. In general, adulteration is considered as an intentional practice. However, unintentional adulterations also exist in herbal raw-material trade due to various reasons, and many of them are unknown even to the scientific community. The present chapter deals with different intentional and unintentional adulterations, reasons behind them and methods for easy identification of the spurious plant and authentication of the authentic plant.

ADULTERATION

A treatise published two centuries ago (in 1820) on adulterations in food and culinary materials is a proof for this practice as an age-old one. Due to adulteration, faith in herbal drugs has declined. Adulteration in market samples is one of the greatest drawbacks in promotion of herbal products. Many researchers have contributed in checking adulterations and authenticating them. It is invariably found that the adverse event reports are not due to the intended herb, but rather due to the presence of an unintended herb. Medicinal plant dealers have discovered the ‘scientific’ methods in creating adulteration of such a high quality that without microscopic and chemical analysis, it is very difficult to trace these adulterations.

Definition: The term adulteration is defined as substituting original crude drug partially or wholly with other similar-looking substances. The substance, which is mixed, is free from or inferior in chemical and therapeutic property.

Types of Adulterants

Adulteration in simple terms is debasement of an article. The motives for intentional adulteration are normally commercial and are originated mainly with the intension of enhancement of profits. Some of the reasons that can be cited here are scarcity of drug and its high price prevailing in market. The adulteration is done deliberately, but it may occur accidentally in some cases. Adulteration involves different conditions such as deterioration, admixture, sophistication, substitution, inferiority and spoilage. Deterioration is impairment in the quality of drug, whereas admixture is addition of one article to another due to ignorance or carelessness or by accident. Sophistication is the intentional or deliberate type of adulteration. Substitution occurs when a totally different substance is added in place of original drug. Inferiority refers to any substandard drug, and spoilage is due to the attack of microorganisms.

Unintentional Adulteration

Unintentional adulteration may be due to the following reasons:

1. confusion in vernacular names between indigenous systems of medicine and local dialects
2. lack of knowledge about the authentic plant
3. nonavailability of the authentic plant

Careless collections

Some of the herbal adulterations are due to the carelessness of herbal collectors and suppliers. Parmelia perlata is used in ayurveda, unani and siddha. It is also used as grocery. Market samples showed it to be admixed with other species (P. perforata and P. cirrhata). Sometimes, Usnea sp. is also mixed with them. Authentic plants can be identified by their thallus nature.

Unknown reasons ‘Vidari’ is another example of unknown authentic plant. It is an important ayurvedic plant used extensively. Its authentic source is Pueraria tuberosa, and its substitute is Ipomoea digitata. However, market samples are not derived from these two. It is interesting to know that an endangered gymnosperm Cycas circinalis is sold in plenty as Vidari. The adulterated materials originated from Kerala, India. Although both the authentic plant and its substitute are available in plenty throughout India, how C. circinalis became a major source for this drug is unknown. P. tuberosa can be easily identified by the presence of papery flake-like tubers, I. digitata by the presence of its concentric rings of vascular bundles and their adulterant C. circinalis by its leaf scars and absence of vessel elements.

Intentional Adulteration Intentional adulteration may be due to the following reasons:

1. adulteration using manufactured substances
2. substitution using inferior commercial varieties
3. substitution using exhausted drugs
4. substitution of superficially similar inferior natural substances
5. adulteration using the vegetative part of the same plant
6. addition of toxic materials
7. adulteration of powders
8. addition of synthetic principles Adulteration using manufactured substances In this type of adulteration the original substances are adulterated by the materials that are artificially manufactured. The materials are prepared in a way that their general form and appearance resemble with various drugs. Few examples are cargo of ergot from Portugal was adulterated with small masses of flour dough moulded to the correct size and shape and coloured, first using red ink, and then into writing ink. Bass-wood is cut exactly the required shape of nutmegs and used to adulterate nutmegs. Compressed chicory is used in place of coffee berries. Paraffin wax is coloured yellow and is been substituted for beeswax, and artificial invert sugar is used in place of honey.

Substitution using inferior commercial varieties In this type, the original drugs are substituted using inferior quality drugs that may be similar in morphological characters, chemical constituents or therapeutic activity. For example hog gum or hog tragacanth for tragacanth gum, mangosteen fruits for bael fruits, Arabian senna, obovate senna and Provence senna are used to adulterate senna, ginger being adulterated with Cochin, African and Japanese ginger. Capsicum annuum fruits and Japanese chillies are used for fruits of C. minimum.

Substitution using exhausted drugs In this type of substitution the active medicaments of the main drugs are extracted out and are used again. This could be done for the commodities that would retain its shape and appearance even after extraction, or the appearance and taste could be made to the required state by adding colouring or flavouring agents. This technique is frequently adopted for the drugs containing volatile oils, such as: clove, fennel etc. After extraction, saffron and red rose petals are recoloured by artificial dyes. Another example is balsam of tolu that does not contain cinnamic acid. The bitterness of exhausted gentian is restored by adding aloes.

Substitution of superficially similar inferior natural substances The substituents used may be morphologically similar but will not be having any relation to the genuine article in their constituents or therapeutic activity. Ailanthus leaves are substituted for belladona, senna, etc. saffron admixed with saff flower; peach kernels and apricot kernels for almonds; clove stalks and mother cloves with cloves; peach kernel oil used for olive oil; chestnut leaves for hamamelis leaves and Japan wax for beeswax are few examples for this type of adulteration.

Adulteration using the vegetative part of the same plant The presence of vegetative parts of the same plant with the drug in excessive amount is also an adulteration. For example, epiphytes, such as mosses, liverworts and lichens that grow over the barks also may occur in unusual amounts with the drugs, e.g. cascara or cinchona. Excessive amount of stems in drugs like lobelia, stramonium, hamamelis leaves, etc. are few example for this type of adulteration.

Addition of toxic materials In this type of adulteration the materials used for adulteration would be toxic in nature. A big mass of stone was found in the centre of a bale of liquorice root. Limestone pieces with asafetida, lead shot in opium, amber-coloured glass pieces in colophony, barium sulphate to silvergrain cochineal and manganese dioxide to blackgrain cochineal, are few examples in this adulteration.

Addition of synthetic principles Synthetic pharmaceutical principles are used for market and therapeutic value. Citral is added to lemon oil, whereas benzyl benzoate is added to balsam of Peru. Apart from these, the herbal products labelled to improve sexual performance in men, when analysed, contained sildenafil. Brand names included Actra-Rx, Yilishen, Hua Fo, Vinarol and Vasx, Sleeping Buddha containing estazolam, Diabetes Angel containing glyburide and phenformin are few examples under this category.

Adulteration of powders Powdered drugs are found to be adulterated very frequently. Adulterants used are generally powdered waste products of a suitable colour and density. Powdered olive stones for powdered gentian, liquorice or pepper; brick powder for barks; red sanders wood to chillies; dextrin for powdered ipecacuanha, are few adulterants.

absence of calcium oxalate and presence of uniseriate medullary rays, crystal fibres, and wavy medullary rays of cascara bark, lignified trichomes, and plasmodesma in nux vomica. Stone cells are absent in the frangula bark, whereas they are present in cascara. Presence of pith in rhizomes and absence in roots, warty trichomes of senna, and presence or absence of crystals of aloin indicates different varieties of aloes, glandular trichomes of mint, etc. The powder of clove stalks contains sclereids and calcium oxalate crystals, but cloves do not contain these two. Rauwolfia micrantho, R. densiflora, and R. perokensis are found to serve as an adulterant for R. serpentine. The roots of these species can bedifferentiated from R. serpentine by the presence of sclerenchyma in the above species which is absent in R. serpentine.

CHEMICAL EVALUATION

The chemical evaluation includes qualitative chemical tests, quantitative chemical tests, chemical assays, and instrumental analysis. The isolation, purification, and identification of active constituents are chemical methods of evaluation. Qualitative chemical tests include identification tests for various phytoconstituents like alkaloids, glycosides, tannins, etc. The procedures for the identification tests of various phytoconstituents are given under their respective chapters in the text, where it could be referred. Examples of identification of constituents are: copper acetate used in the detection of colophony present as an adulterant for resins, balsams, and waxes; Holphen’s test for cottonseed oil and Baudouin’s test for sesame oil in olive oil; the test with acetic and nitric acids for Gurjun balsam in copaiba; Van Urk’s reagent for ergot; Vitali’s morins reaction for tropane alkaloids; iodine for starch; murexide test for purine bases, etc. are examples of this evaluation.

Quantitative chemical tests such as acid value (resins, balsams), saponification value (balsams), ester value (balsams, volatile oils), acetyl value (volatile oils), etc. are also useful in evaluation of a drug by means of chemical treatment.

Chemical assays include assays for alkaloid, resin, volatile oil, glycoside, vitamins, or other constituent. Few examples are the assay of total alkaloid in belladonna herb, the total alkaloid and nonphenolic alkaloid in ipecacuanha, the alkaloid strychnine in nux vomica, the resin in jalap, and the vitamins in codliver oil. The results obtained can conclude the presence of inferior or exhausted drug and, by proving absence of the assayed constituent, it will suggest complete substitution of a worthless article.

Instrumental analyses are used to analyse the chemical groups of phytoconstituents using chromatographic and spectroscopic methods. Chromatographic methods include paper chromatography, thinlayer chromatography, gas chromatography, highperformance liquid chromatography, and highperformance thinlayer chromatography. Spectroscopic methods include ultraviolet and visible spectroscopy, infrared spectroscopy, mass spectroscopy, and nuclear magnetic spectroscopy.

PHYSICAL EVALUATION

In crude plant evaluation, physical methods are often used to determine the solubility, specific gravity, optical rotation, viscosity, refractive index, melting point, water content, degree of fibre elasticity, and other physical characteristics of the herb material.

Solubility

Drugs specific behaviours towards solvents are taken into consideration. This is useful for the examination of many oils, oleoresins, etc. Few examples are the solubility of colophony in light petroleum, the solubility of balsam of Peru in solution of chloral hydrate, the solubility of castor oil in half its volume of light petroleum and the turbidity produced with two volumes of the solvent; the solubility of balsam of Peru in an equal volume of alcohol, 90%, and the production of a turbidity with a larger volume; castor oil is soluble only in three volumes of 90% alcohol, while the adulterated form it shows good solubility in alcohol. Alkaloidal bases are soluble in organic solvents and alkaloidal salts are soluble in polar solvents.

Optical Rotation

Anisotropic crystalline solids and samples containing an excess of one enantiomer of a chiral molecule can rotate the orientation of planepolarized light. Such substances are said to be optically active, and this property is known as optical rotation. The enantiomer that rotates light to the right, or clockwise when viewing in the direction of light propagation, is called the dextrorotatory (d) or (+) enantiomer, and the enantiomer that rotates light to the left, or counterclockwise, is called the levorotatory (l) or ({) enantiomer. Few examples of drugs with this property are eucalyptus oil (0° to +10°), honey (+3° to {15°), Chenopodium oil ({30° to {80°), etc.

Refractive Index

Refractive index is defined as the property of a material that changes the speed of light, computed as the ratio of the speed of light in a vacuum to the speed of light through the material. When light travels at an angle between two different materials, their refractive indices determine the angle of transmission refraction of the light beam. In general, the refractive index varies based on the frequency of the light as well; thus, different colours of light travel at different speeds. High intensities can also change the refractive index. This could be used as a parameter in evaluating the herbal drugs; for example castor oil 1.4758 to 1.527, clove oil 1.527 to 1.535, etc.

Specific Gravity

It is also known as relative density. The ratio of the mass of a solid or liquid to the mass of an equal volume of distilled water at 4°C (39°F) or of a gas to an equal volume of air or hydrogen under prescribed conditions of temperature and pressure. Some examples of specific gravity of drugs are cottonseed oil 0.88–0.93, coconut oil 0.925, castor oil 0.95, etc.

Viscosity

Viscosity is the resistance of a fluid to flow. This resistance acts against the motion of any solid object through the fluid and also against motion of the fluid itself past stationary obstacles. Viscosity of a liquid is constant at a given temperature and is an index of its composition. Viscosity also acts internally on the fluid between slower and fastermoving adjacent layers. Since it is constant at a given temperature, it is used as an evaluation parameter; for example, pyroxylin kinematic viscosity, 1100–2450 centistokes.

Melting Point

The melting point of a solid is the temperature at which it changes state from solid to liquid. Plant constituents have very sharp and constant melting points. As far as crude drugs are concerned,