History Definition and Scope of Pharmacognosy

Chapter 1

History, Definition and Scope of Pharmacognosy

MEANING OF 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, recent historical research has found an earlier usage of this term. 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 pharmacognosy 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 collection are subjected only to drying or making them into transverse or longitudinal 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 pharmacists, 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 cantharides; 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.

ORIGIN OF PHARMACOGNOSY

Views on the beginning of life on planet Earth have forever remained controversial and an unending subject of debate. Nevertheless, we can say with certainty that the vegetable kingdom was already there when man made his appearance on Earth. As man began to acquire closure acquaintance with his environment, he began to know more about plants, as these were the only curative agents he had. As he progressed and evolved, he was not only able to sort on as to which plant served for eating and which did not, but he went beyond and began to associate curative characteristics with certain plants, classifying them as painkillers, febrifuge, antiphlogistics, soporific and so on. This must have involved no doubt, a good deal of trial and error, and possibly some deaths in the beginning also, but as it happened antidotes against poisons were also discovered. As we shall see later, drug substitutes were also forthcoming. All these states of affairs indicate that the origin of pharmacognosy, i.e. the study of natural curative agents points towards the accent of human beings on mother earth, and its historical account makes it clear that pharmacognosy in its totality is not the work of just one or two continental areas but the overall outcome of the steadfast work of many of the bygone civilizations like the Chinese, Egyptian, Indian, Persian, Babylonian, Assyrian and many more. Many of today’s wonderful modern drugs find their roots in the medicines developed by the tribal traditions in the various parts of the world.

HISTORY OF PHARMACOGNOSY

In the early period, primitive man went in search of food and ate at random, plants or their parts like tubers, fruits, leaves, etc. As no harmful effects were observed he considered them as edible materials and used them as food. If he observed other effects by their eating they were considered inedible, and according to the actions he used them in treating symptoms or diseases. If it caused diarrhoea it was used as purgative, if vomitting it was used as memtic and if it was found poisonous and death was caused, he used it as arrow poison. The knowledge was empirical and was obtained by trial and error. He used drugs as such or as their infusions and decoctions. The results were passed on from one generation to the other, and new knowledge was added in the same way.

Ancient China

Chinese pharmacy, according to legend, stems from Shen Nung (about 2700 B.C.), emperor who sought out and investigated the medicinal value of several hundred herbs. He reputed to have tested many of them on himself, and to have written the first Pen T-Sao, or Native Herbal, recording 365 drugs. These were subdivided as follows: 120 emperor herbs of high, food grade quality which are non-toxic and can be taken in large quantities to maintain health over a long period of time, 120 minister herbs, some mildly toxic and some not, having stronger therapeutic action to heal diseases and finally 125 servant herbs that having specific action to treat disease and eliminate stagnation. Most of those in the last group, being toxic, are not intended to be used daily over a prolonged period of weeks and months. Shen Nung conceivably examined many herbs, barks and roots brought in from the fields, swamps and woods that are still recognized in pharmacy (podophyllum, rhubarb, gin seng, stramonium, cinnamon bark and ephedra). Inscriptions on oracle bones from the Shang Dynasty (1766–1122 B.C.), discovered in Honan Province, have provided a record of illness, medicines and medical treatment. Furthermore, a number of medical treatises on silk banners and bamboo slips were excavated from the tomb number three at Ma-Huang-Tui in Changsha, Hunan Province. These were copied from books some time between the Chin and Han periods (300 B.C.–A.D. 3) and constitute the earliest medical treatises existing in China.

The most important clinical manual of traditional Chinese medicine is the Shang Hang Lun (Treatise on the Treatment of Acute Diseases Caused by Cold) written by Chang Chung-Ching (142–220). The fame and reputation of the Shang Han Lun as well as its companion book, Chin Kuei Yao Lueh (Prescriptions from the Golden Chamber), is the historical origin of the most important classical herbal formulas that have become the basis of Chinese and Japanese-Chinese herbalism (called ‘Kampo’).

With the interest in alchemy came the development of pharmaceutical science and the creation of a number of books including Tao Hong Jing’s (456–536) compilation of the Pen T’sao Jing Ji Zhu (Commentaries on the Herbal Classic) based on the Shen Nong Pen T’sao Jing, in 492. In that book 730 herbs were described and classified in six categories: (1) stone (minerals), (2) grasses and trees, (3) insects and animals, (4) fruits and vegetables, (5) grains and (6) named but unused. During the Sui dynasty (589–618) the study of herbal medicine blossomed with the creation of specialized books on plants and herbal medicine. Some of these set forth the method for the gathering of herbs in the wild as well as their cultivation. Over 20 herbals were chronicled in the Sui Shu JingJi Zhi (Bibliography of the History of Sui). These include the books Zhong Zhi Yue Fa (How to Cultivate Herbs) and the Ru Lin Cat Yue Fa (How to Collect Herbs in the Forest).

From the Sung Dynasty (960–1276) the establishment of pharmaceutical system has been a standard practice throughout the country. Before the ingredients of Chinese medicine can be used to produce pharmaceuticals, they must undergo a preparation process, e.g. baking, simmering or roasting. The preparation differs according to the needs for the treatment of the disease. Preparation methods, production methods and technology have constantly been improved over time.

In 1552, during the later Ming Dynasty, Li Shi Zhen (1518–1593) began work on the monumental Pen T’sao Kan Mu (Herbal with Commentary). After 27 years and three revisions, the Pen T’sao Kan Mu was completed in 1578. The book lists 1892 drugs, 376 described for the first time with 1160 drawings. It also lists more than 11,000 prescriptions.

Ancient Egypt

The most complete medical documents existing are the Ebers Papyrus (1550 B.C.), a collection of 800 prescriptions, mentioning 700 drugs and the Edwin Smith Papyrus (1600 B.C.), which contains surgical instructions and formulas for cosmetics. The Kahun Medical Papyrus is the oldest—it comes from 1900 B.C. and deals with the health of women, including birthing instructions.

However, it is believed that the Smith Papyrus was copied by a scribe from an older document that may have dated back as far as 3000 B.C. Commonly used herbs included: senna, honey, thyme, juniper, cumin, (all for digestion); pomegranate root, henbane (for worms) as well as flax, oakgall, pinetar, manna, bayberry, ammi, alkanet, aloe, caraway, cedar, coriander, cyperus, elderberry, fennel, garlic, wild lettuce, nasturtium, onion, peppermint, papyrus, poppy-plant, saffron, watermelon, wheat and zizyphus-lotus. Myrrh, turpentine and acacia gum were also used.

Ancient India

In India knowledge of medicinal plants is very old, and medicinal properties of plants are described in Rigveda and in Atharvaveda (3500–1500 B.C.) from which Ayurveda has developed. The basic medicinal texts in this world region— The Ayurvedic writings—can be divided in three main ones (Charaka Samhita, Susruta Samhita, Astanga Hrdayam Samhita) and three minor ones (Sarngadhara Samhita, Bhava Prakasa Samhita, Madhava Nidanam Samhita). Ayurveda is the term for the traditional medicine of ancient India. Ayur means life and veda means the study of which is the origin of the term. The oldest writing—Charaka Samhita—is believed to date back six to seven centuries before Christ. It is assumed to be the most important ancient authoritative writing on Ayurveda. The Susruta Samhita is thought to have arisen about the same time period as the Charaka Samhita, but slightly after it Astanga Hrdayam and the Astanga Sangraha have been dated about the same time and are thought to date after the Charaka and Susruta Samhitas. Most of mentioned medicines origin from plants and animals, e.g. ricinus, pepper, lilly, valerian, etc.

Ancient Greece and Rome

Greek scientists contributed much to the knowledge of natural history. Hippocrates (460–370 B.C.) is referred to as father of medicine and is remembered for his famous oath which is even now administered to doctors. Aristotle (384–322 B.C.), a student of Plato was a philosopher and is known for his writing on animal kingdom which is considered authoritative even in twentieth century. Theophrastus (370–287 B.C.), a student of Aristotle, wrote about plant kingdom. Dioscorides, a physician who lived in the first century A.D., described medicinal plants, some of which like belladonna, ergot, opium, colchicum are used even today. Pliny wrote 37 volumes of natural history and Galen (131–A.D. 200) devised methods of preparations of plant and animal drugs, known as ‘galenicals’ in his honour.

Pharmacy separated from medicine and materia medica, the science of material medicines, describing collection, preparation and compounding, emerged.

Even upto the beginning of twentieth century, pharmacognosy was more of a descriptive subject akin mainly to botanical science, and it consisted of identification of drugs both in entire and powdered conditions and concerned with their history, commerce, collection, preparation and storage.

The development of modern pharmacognosy took place later during the period 1934–1960 by simultaneous application of disciplines like organic chemistry, biochemistry, biosynthesis, pharmacology and modern methods and techniques of analytic chemistry, including paper, thin layer, and gas chromatography and spectophotometry.

The substances from the plants were isolated, their structures elucidated and pharmacological active constituents studied. The development was mainly due to the following four events:

Isolation of penicillin in 1928 by William Fleming and large-scale production in 1941 by Florey and Chain.

Isolation of resperpine from rauwolfia roots and confirming its hypotensive and tranquilizing properties.

Isolation of vinca alkaloids, especially vincristine and vinblasting. Vincristine was found useful in the treatment of leukaemia. These alkaloids also have anticancer properties.

Steroid hormones like progesterone were isolated by partial synthesis from diosgenin and other steroid saponins by Marker’s method. Cortisone and hydrocortisone are obtained from progesterone by chemical and microbial reaction.

This period can also be termed antibiotic age, as besides pencillin, active antibiotics like streptomycin, chloramphenicol, tetracycline and several hundred antibiotics have been isolated and studied extensively.

Some of the important aspects of the natural products that led to the modern development of drugs and pharmaceuticals are as follows:

Isolation of phytochemicals

Strong acting substances such as glycosides of digitalis and scilla, alkaloids of hyoscyamus and belladonna, ergot, rauwolfia, morphine and other alkaloids of opium were isolated and their clinical uses studied.

Structure activity relationship

Tubocurarine and toxiferine from curare have muscle relaxant properties because of quaternary ammonium groups. The hypotensive and tranquillizing actions of reserpine are attributed to the trimethoxy benzoic acid moiety which is considered essential. Mescaline and psilocybine have psychocative properties. Presence of a lactone ring is essential for the action of cardiac glycosides. Likewise anthraquinone glycosides cannot have their action without satisfying the positions at C3, C1, C8, C9 and C10.

Drugs obtained by partial synthesis of natural products

Oxytocic activity of methyl ergometrine is more than that of ergometrine. In ergotamine, by 9:10 hydrogenation, oxytocic activity is suppressed and spasmolytic activity increases. We have already referred to the preparation of steroid hormones from diosgenin by acetolysis and oxidation and further preparation of cortisone by microbial reactions.

Steroid hormones and their semisynthetic analogues represent a multimillion dollar industry in the United States.

Natural products as models for synthesis of new drugs

Morphine is the model of a large group of potent analgesics, cocaine for local anaesthetics, atropine for certain spasmolytics, dicoumarol for anticoagulants and salicin for salicylic acid derivatives. Without model substances from plants a large number of synthetics would have been missed.

Drugs of direct therapeutic uses

Among the natural constituents, which even now cannot be replaced, are important groups of antibiotics, steroids, ergot alkaloids and certain antitumour substances. Further, drugs as digitoxin, strophanthus glycosides, morphine, atropine and several others are known since long and have survived their later day synthetic analogues.

Biosynthetic pathways

Biosynthetic pathways are of primary and secondary metabolites. Some of the important pathways are Calvin’s cycle of photosynthesis, shikimic acid pathway of aromatic compounds, acetate hypothesis for anthracene glycosides and isoprenoid hypothesis for terpenes and steroids via acetatemevalonic acid-isopentyl pyrophosphate and squalene.

Progress from 1960 onwards

During this period only a few active constituents mainly antibiotics, hormones and antitumour drugs were isolated or new possibilities for their production were found. From 6-amino penicillanic acid, which has very little antibiotic action of its own, important broad-spectrum semisynthetic penicillins like ampenicillin and amoxicillin were developed.

From ergocryptine, an alkaloid of ergot, bromocryptine has been synthesized. Bromocryptine is a prolactin inhibitor and also has activity in Parkinson’s disease and in cancer. By applications of several disciplines, pharmacognosy from a descriptive subject has again developed into an integral and important disciplines of pharmaceutical sciences.

Technical products

Natural products, besides being used as drugs and therapeutic aids, are used in a number of other industries as beverages, condiments, spices, in confectioneries and as technical products.

The coffee beans and tea leaves besides being the source of caffein are used as popular beverages. Ginger and wintergreen oil are used less pharmaceutically but are more used in preparation of soft drinks. Mustard seed and clove are used in spice and in condiment industry. Cinnamon oil and peppermint oil besides being used as carminatives are used as flavouring agents in candies and chewing gum. Colophony resin, turpentine oil, linseed oil, acacia, pectin, and numerous other natural products are used widely in other industries and are called technical products.

Pharmaceuticals aids

Some of the natural products obtained from plants and animals are used as pharmaceutical aids. Thus gums like acacia and tragacanth are used as binding, suspending and emulsifying agents. Guar gum is used as a thickening agent and as a binder and a disintegrating agent in the manufacturing of tablets. Sterculia and tragacanth because of their swelling property are used as bulk laxative drugs. Mucilage-containing drugs like ishabgul and linseed are used as demulcents or as soothing agents and as bulk laxatives. Starch is used as a disintegrating agent in the manufacture of tablets and because of its demulcent and absorbent properties it’s used in dusting powders. Sodium alginate is used as an establishing, thickening, emulsifying deflocculating, gelling and filming agent. Carbohydrate containing drugs like glucose, sucrose and honey are used as sweetening agents and as laxative by osmosis.

Agar, in addition to being used as a laxative by osmosis, is also used as an emulsifying agent and in culture media in microbiology. Saponins and sponin-containing drugs are used as detergents, emulsifying and frothing agents and as fire extinguishers. Tincture quillaia is used in preparation of coal tar emulsions. Saponins are toxic and their internal use requires great care, and in some countries their internal use as frothing agents is restricted. Glycyrrhiza is used as sweetening agent for masking the taste of bitter and salty preparations.

Fixed oils and fats are used as emollients and as ointment bases and vehicles for other drugs. Volatile oils are used as flavouring agents.

Gelatin is used in coating of pills and tablets and in preparation of suppositories, as culture media in microbiology and in preparation of artificial blood plasma. Animal fats like lard and suet are used as ointment bases. Beeswax is used as ointment base and thickening agent in ointments. Wool fat and wool alcohols are used as absorbable ointment bases.

Thus, from the above description it can be seen that many of the natural products have applications as pharmaceutical aids.

Discovery of new medicines from plants— nutraceutical use versus drug development

Little work was carried out by the pharmaceutical industry during 1950–1980s; however, during the 1980–1990s, massive growth has occurred. This has resulted in new developments in the area of combinatorial chemistry, new advances in the analysis and assaying of plant materials and a heightened awareness of the potential plant materials as drug leads by conservationists. New plant drug development programmes are traditionally undertaken by either random screening or an ethnobotanical approach, a method based on the historical medicinal/food use of the plant. One reason why there has been resurgence in this area is that conservationists especially in the United States have argued that by finding new drug leads from the rainforest, the value of the rainforests to society is proven, and that this would prevent these areas being cut down for unsustainable timber use. However, tropical forests have produced only 47 major pharmaceutical drugs of worldwide importance. It is estimated that a lot more, say about 300 potential drugs of major importance may need to be discovered. These new drugs would be worth $147 billion. It is thought that 125,000 flowering plant species are of pharmacological relevance in the tropical forests. It takes 50,000 to 100,000 screening tests to discover one profitable drug. Even in developed countries there is a huge potential for the development of nutraceuticals and pharmaceuticals from herbal materials. For example the UK herbal materia medica contains around 300 species, whereas the Chinese herbal materia medica contains around 7,000 species. One can imagine what lies in store in the flora-rich India!

SCOPE OF PHARMACOGNOSY

Crude drugs of natural origin that is obtained from plants, animals and mineral sources and their active chemical constituents are the core subject matter of pharmacognosy. These are also used for the treatment of various diseases besides being used in cosmetic, textile and food industries. During the first half of the nineteenth century apothecaries stocked the crude drugs for the preparation of herbal tea mixtures, all kinds of tinctures, extracts and juices which in turn were employed in preparing medicinal drops, syrups, infusions, ointments and liniments.

The second half of the nineteenth century brought with it a number of important discoveries in the newly developing fields of chemistry and witnessed the rapid progress of this science. Medicinal plants became one of its major objects of interest and in time, phytochemists succeeded in isolating the pure active constituents. These active constituents replaced the crude drugs, with the development of semisynthetic and synthetic medicine, they became predominant and gradually pushed the herbal drugs, which had formerly been used, into the background. It was a belief that the medicinal plants are of no importance and can be replaced by man-made synthetic drugs, which in today’s scenario is no longer tenable. The drug plants, which were rapidly falling into disuse a century ago, are regaining their rightful place in medicine. Today applied science of pharmacognosy has a far better knowledge of the active constituents and their prominent therapeutic activity on the 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 biotechnology have already been successful for the production of genetically engineered molecules and biotransformed natural products, respectively.

Lastly, crude drugs and their products are of economic 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 Administration, 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.

FUTURE OF PHARMACOGNOSY

Medicinal plants are of great value in the field of treatment and cure of disease. Over the years, scientific research has expanded our knowledge of the chemical effects and composition of the active constituents, which determine the medicinal properties of the plants. It has now been universally accepted fact that the plant drugs and remedies are far safer than that of synthetic medicines for curing the complex diseases like cancer and AIDS. Enormous number of alkaloids, glycosides and antibiotics have been isolated, identified and used as curative agents. The modern developments in the instrumental techniques of analysis and chromatographical methodologies have added numerous complex and rare natural products to the armoury of phytomedicine. To mention a few, artemissinin as antimalarial, taxol as anticancer, forskolin as antihypertensive, rutin as vitamin P and capillary permeability factor and piperine as bioavailability enhancer are the recent developments. Natural products have also been used as drug substitutes for the semisynthesis of many potent drugs. Ergotamine for dihydroergotamine in the treatment of migraine, podophyllotoxin for etoposide, a potent antineoplastic drug or solasodine and diosgenin that serve for the synthetic steroidal hormones are the first-line examples of the recent days.

In the Western world, as the people are becoming aware of the potency and side effects of synthetic drugs, there is an increasing interest in the plant-based remedies with a basic approach towards the nature. The future developments of pharmacognosy as well as herbal drug industry would be largely dependent upon the reliable methodologies for identification of marker compounds of the extracts and also upon the standardization and quality control of these extracts. Mother earth has given vast resources of medicinal flora and fauna both terrestrial and marine, and it largely depends upon the forthcoming generations of pharmacognosists and phytochemists to explore the wonder drug molecules from this unexploited wealth.

Little more needs to be said about the present-day importance of medicinal plants, for it will be apparent from the foregoing that the plant themselves either in the form of crude drugs or even more important, for the medicinally active materials isolated from them, have been, are and always will be an important aid to the physician in the treatment of disease.

PHARMACOGNOSTICAL SCHEME

To describe drugs in a systematic manner is known as pharmacognostical scheme, which includes the following headings:

Biological Source

This includes the biological names of plants or animals yielding the drug and family to which it belongs. Botanical name includes genus and species. Often some abbreviations are written after the botanical names, of the biologist responsible for the classification, for example, Acacia arabica Willd. Here Willd indicates the botanist responsible for the classification or nomenclature. According to the biennial theory, the botanical name of any plant or animal is always written in italic form, and the first letter of a genus always appears in a capital later.

Biological source also includes the family and the part of the drug used. For example, biological source of senna is, Senna consists of dried leaflets of Cassia angustifolia Delite, belonging to family Leguminosae.

Geographical Source

It includes the areas of cultivation, collection and route of transport of a drug.

Cultivation, Collection and Preparation

These are important to mention as these are responsible for quality of a drug.

Morphological Characters

In case of organized drugs, the length, breadth, thickness, surface, colour, odour, taste, shape, etc. are covered under the heading morphological characters, whereas organoleptic properties (colour, odour, taste and surface) should be mentioned, if the drug is unorganized.

Microscopical Characters

This is one of the important aspects of pharmacognosy as it helps in establishing the correct identity of a drug. Under this heading all the detailed microscopical characters of a drug is described.

Chemical Constituents

The most important aspect which determines the intrinsic value of a drug to which it is used is generally described under this heading. It includes the chemical constituents present in the drug. These kinds of drugs are physiologically active.

Uses

It includes the pharmaceutical, pharmacological and biological activity of drugs or the diseases in which it is effective.

Substituents

The drug which is used during non-availability of original drug is known as substituent. It has the same type of physiological active constituents; however, the percentage quantity of the drug available may be different.

Adulterants

With the knowledge of the diagnostic characters of drugs, the adulterants can be detected. One should have the critical knowledge of substances known to be potential adulterants. Most of the times the adulterants are completely devoid of physiologically active constituents, which leads in the deterioration of the quality. For example, mixing of buffalo milk with goat milk is substitution, whereas mixing of water in the milk is adulteration. In the first case, goat milk is substitute and in the second case water is adulterant.

Chemical Tests

The knowledge of chemical tests becomes more important in case of unorganized drugs whose morphology is not well defined.