• The term Pharmacognosy has been derived from the 2
• i) pharmakon, which means a drug &
• ii) gnosis, which means knowledge of or gignosco, which means
to acquire knowledge of.
• Thus the full meaning of the term Pharmacognosy is `knowledge
of drugs’ or `to acquire knowledge of drugs’.
•This term was introduced by C.A. Seydler, a German
medical student in 1815.
•gignosis- to acquire knowledge
•Pharmacognosy therefore means knowledge of drugs.
5. Introduction to pharmacognosy
• Pharmacognosy is an applied science which is concerned with acquiring
knowledge of crude drugs by the application of various scientific disciplines
• Pharmacognosy deals with NATURAL products and is described as:
• the study of medicinal or therapeutic agents of natural origin, i.e.
• Mineral sources
• It also includes the study of their history, distribution, cultivation, collection,
preparation, identification, evaluation, preservation & commerce
6. Introduction to Pharmacognosy
•A brief history of natural products in medicine
•Value of natural drug products
•Production of natural drug products
•The role of natural products in drug discovery
7. PHARMACOGNOSY , HISTORY AND SCOPE
Pharmacognosy is the study of crude drugs obtained from plants, animals and mineral
kingdoms and constituents obtained therefrom. Even though the science of pharmacognosy
has been practiced since the advent of mankind, the term Pharmacognosy was first used by
C.A. Seydler, a German scientist, in 1815 in his book Analecta Pharmacognostica. It is
derived from two Latin words pharmakon, 'a drug', and gignosco, 'to acquire knowledge
of'. It means knowledge or science of drugs.
Drugs used in medicine today are either obtained from nature or are of synthetic origin.
Natural drugs are obtained from plants, animals or mineral kingdom. Drugs from
microorganisms like antibiotics were not known in the earlier times.
Synthetic drugs or syntheticals like aspirin, sulpha drugs, some vitamins and some
antibiotics are synthesized in laboratories from simple chemicals through various chemical
8. • Natural drugs obtained from plants and animals are called drugs
of biological origin and the active principles, because of which
they have their therapeutic use, are produced in the living cells of
plants and animals.
• 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
Drugs obtained from plants consist of entire plants, while Senna
leaves and pods, nuxvomica seeds, ginger rhizome
9. and cinchona bark are parts of the plants. Though in a few cases, as in lemon
and orange peels and in colchicum corm, drugs are used in fresh condition, most
of the drugs are dried after collection.
Crude drugs may also be obtained by simple physical processes like drying or
extraction with water. Thus 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
Further drugs used by physicians and surgeons or pharmacists, directly drugs 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 flavoring or sweetening agents or drugs used as
vehicles or insecticides are treated in Pharmacognosy.
10. • Drugs obtained from animals are entire animals, as cantharides,
glandular products, like thyroid organ or extracts like liver extract.
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 the plants and consist of cellular
• Unorganized drugs, even though prepared from plants, are not the
direct parts of the plants and are prepared by some intermediary
physical processes like 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, the well-known Makardhwaj and other bhasmas of
11. • HISTORY OF PHARMACOGNOSY
Diseases are born with man and drugs came into existence since a very
early time to remove the pain of diseases and to cure them. Thus, the
story and the history of drugs is as old as the mankind.
• In the early period, primitive man went in search of food and ate at
random plants or parts like tubers, fruits, leaves, etc.
• If he found that no harmful effects were observed, he considered them
as edible materials and used them as food.
• If he found that by their eating other actions were found, 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 vomiting it was used as an emetic and
• if it was found poisonous and death was caused, he used it as an
• 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 from one generation to another generation
and new knowledge was added in the same way.
12. In India knowledge of medicinal plants is very old and medicinal properties of
plants are described in Rigveda and in Atharvaveda (3500- 1500 BC) from which
Ayurveda has developed.
In the ancient well-known treatises are Charka Samhita dealing mostly with plants
and Sushrut Samhita in which surgery is also mentioned.
In Egypt, people were familiar with medicinal properties of plants and animals.
They were familiar with human anatomy and knew of embalming the dead and
preserving their bodies as described in Papyrus Ebers (1550 BC), an ancient book
found in one of the mummies.
Greek scientists contributed much to the knowledge of natural history. Hippocrates
(460—370 BC) is referred to as father of medicine and is remembered for his
famous oath which is even now administered to doctors.
Aristotle (384—322 BC), a student of Plato was a philosopher and is known for his
writing on animal kingdom which is considered authoritative even in twentieth
20. The era of European exploration
21. Theophrastus (370—287 BC) a student of Aristotle, wrote about plant
Dioscorides, a physician who lived in the first century AD, described medicinal
plants, some of which like belladonna, ergot, opium, colchicum are used even
Pliny wrote 37 volumes of natural history and Galen (131—200 AD) devised
methods of preparation of plant and animal drugs, known as 'galenicals' in his
Pharmacy separated from medicine and materia medica, the science of material
medicines describing, collection, preparation and compounding, emerged. As
mentioned earlier in 1815 Seydler introduced the name pharmacognosy.
Even up to the beginning of 20th century pharmacognosy was more 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.
22. Period 1934-1960
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 modem methods and
techniques of analytical chemistry, including paper, thin layer and gas
chromatography and spectrophotometry.
The substances from the plants were isolated, their sfructures elucidated and
pharmacological active constituents studied. The development was mainly due
to the following four events:
l. Isolation of penicillin in 1928 by William Fleming and large scale
production in 1941 by Florey and Chain.
2. Isolation of reserpine from Rauwolfia roots and confirming its hypo-
tensive and tranquilizing properties
27. Dried extract
•Dried extract is a solid drug preparation that can be incorporated into
tablets, coated tablets and capsules. In production, the drug is most
exhaustively extracted with a solvent. Thereafter, the solvent used for
extraction evaporates again and the solid residue is fed to a drying
process. Dried extracts have a moisture content of max. 5%, however,
they tend to attract moisture and thus clump together. Therefore, the
dried extracts often contain additives such as maltodextrin, syrup,
33. Classification of crude drugs
• Crude drug i.e Simple drug
• Crude drugs are plant, animal or their parts which
after collection are subjected only to drying or
making them into transverse/ longitudinal slices
pieces or peeling them in some cases. They exist in
• Crude drugs may be derived from various natural
sources like plants, animals, minerals and micro-
34. • Because of their wide distribution the arrangement of
classification in a definite sequence is necessary to
understand easily. Although each system of
classification has its own merits and demerits, but for
the purpose of study the drugs are classified in the
following different ways:
35. Alphabetical Classification
• The crude drugs are arranged according to the alphabetical order/form of
their Latin and English names. Some of the Pharmacopoeias and reference
books which classify crude drugs according to this system are as follows.
The time-tested alphabetical classification is now-a-days considered to be
the least disputed way of classification in all walks of life.
• Pharmacopoeias have always been written on this basic mode of
classification. For drugs either Latin names or common vernacular names
can be used.
36. 1) Indian Pharmacopoeia (IP) 1955 (Latin)
2)Indian Pharmacopoeia (IP) 1966 (English)
3)British Pharmacopoeia (BP) (English)
4)British Pharmacopoeia Codex (BPC) (English)
5)United States of Pharmacopoeia (USP) (English)
6)European Pharmacopoeia (Latin)
37. • Advantages:
• It is simple method, in this system location,
tracing and addition of the drug is easy,
• No technical person is required for handling the system.
• Scientific nature of the drug cannot be identified
by this method, whether they are organised or
• This system does not help in distinguishing the drugs of plant,
animal and mineral source. (Original source is not clear)
39. 2. Morphological classification:
• Here the crude
according to the
are arranged (Grouped)
of the plant or animal
represented into organised (Cellular) drugs and
unorganised ( Acellular ) drugs.
•Drugs are the direct parts of the plant and are
divided into leaves, barks wood, root, rhizome, seed,
fruit, flower, stem, hair and fibers.
40. • Unorganised ( Acellular):
• Drugs are the products of plant, animal and mineral
source and they are divided into dried latex, dried
juice, dried extracts, gums, resins, fixed oils and fats,
waxes, volatile oil, animal products, minerals (Solids,
liquids, semi solids etc).
43. • Advantages:
• This system of classification is more convenient for
practical study especially when the chemical nature of
the drug is not clearly understood.
• This type of classification is very useful in identifying the
• It does not give an idea about biological source,
chemical constituents and uses.
•When different parts of the plant
contain different chemical constituents, it is difficult
to classify them.
44. 3. Chemical classifications of crude drugs
•Here, the crude drugs are divided into different
groups according to the chemical nature of their
most important constituent present in the drug to
which the pharmacological/therapeutic activity of
drug is attributed.
46. • Advantages :
• Chemical constituents are known,
• Medicinal uses are known
• Disadvantages :
• Drugs of different origin are grouped under similar chemical
• This type of classification makes no proper
placement of drugs containing two different types of
• Eg: Certain drugs are found to contain alkaloids and
glycosides (Cinchona), Fixed oil and volatile oil (Nutmeg) of
equal importance together and hence it is difficult to
categorize them properly
47. 4. Taxonomical classification of crude
•In this system the drug are arranged according
taxonomical studies. The drugs are arranged
according to their phylum, order, family, genus and
species. It is purely a type of botanical
classification or biological classification and
restricted mainly to crude drugs from plant source.
49. • Advantages:
• Easy for the classification of crude drugs
• The system is criticized for its failure to recognize the
organised / unorganised nature of crude drugs in their
• The system fails to face into an account chemical nature of
active constituent and therapeutic significance of crude
• The drugs obtained from plants having alternate leaves,
flowers, seeds, capsules (Hyocyamus, Datura, Bellodonna,
Stromonium) are considered with other members of
50. 6. Pharmacological classification of crude
Here, the crude drugs are grouped according to
pharmacological action (Therapeutic action) of
their chief active constituent (most important) or
53. • Advantages
• The special advantage is that if even chemical constituents of
the crude drugs are not known they can be classified
properly on the basis of therapeutic or pharmacological uses.
• Regardless of morphology, taxonomical status or chemical
nature, the drugs are grouped together, provided they
exhibit similar pharmacological uses.
• Eg: Senna, Castor oil, Jalap, Colocynth are grouped together
as purgatives/laxatives because of their common
54. 6. Chemo- taxonomical classification of crude
• In this system of classification, the equal importance
is given for taxonomical status and chemical
constituents. There are certain types of chemical
constituents which are characteristics of certain
classes of plants.
•Eg:Tropane alkaloids generally occur in most of
the members of Solanaceae
•Eg: Volatile oils occur in the members of
Umbelliferae and Rutaceae.
In the last class, we have discussed about
• Alphabetical classification
• Taxonomical Classification
• Morphological classification
• Chemical classification
• Pharmacological classification of Crude Drugs
On completion of this lesson, you would be
able to know:
• Methods of adulteration of Crude Drugs
• Commonly used substitutes in adulteration
• Evaluation for determining adulterants
60. Adulteration and Evaluation
• Adulteration involves incorporation of impurities.
• Includes spoilage deterioration admixture.
• Genuine drugs are intentionally substituted.
• With spurious, inferior, defective or harmful substances.
61. • Adulteration is a practice of substituting original crude drug partially or
wholly with other spurious substances but the later is either free from or
inferior in chemical and therapeutic properties.
• The motives for intentional adulteration are normally commercial one
and originate mainly with the intention 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. It is also very common with the contraband drugs.
• Adulteration means deterioration, admixture, sophistication,
substitution, inferiority and spoilage
67. • The ovoid tears of gum acacia, ribbon shaped characteristic of
tragacanth, disc-shaped structure of nux vomica, conical shape
of aconite, quills of cinnamon etc. are important diagnostic
• The general appearance of the lot of a crude drug often indicates
whether it is likely to comply with prescribed standards, such as
percentage of seed in colocynth, stalk in clove, etc.
• Over drying, makes leaf drugs and flowers brittle and cause
them to break in transit making the task of morphological
• The wavy shape of Rauwolfia, pungent taste of capsicum and
ginger, brown colour of cinnamon, odour and taste of spice-
drugs like, asafoetida, black pepper, nutmeg, caraway, cummin,
etc. are important diagnostic organoleptic characteristics.
69. • Microscopic evaluation also covers study of the constituents by
application of chemical methods to small quantities of drugs in powdered
form or to histological sections of the drug (Microchemistry or
• A drop of phoroglucinol and concentrated hydrochloric acid give red
stain with lignin.
• Mucilage is stained pink with ruthenium red and also, when treated with
corallin soda and few drops of sodium carbonate solution, cellulose
swells and dissolves in cuoxam,
• while N/50 iodine solution stains blue starch and hemicelluloses.
• Histological studies are made from very thin sections of drugs.
• The characteristics of cell walls, cell contents, starch grains, calcium
oxalate crystals, trichomes, fibres, vessels, etc. can be studied in detail
• e.g. lignified trichomes in nux vomica, warty trichomes of senna, wavy
medullary rays of cascara bark, glandular trichomes of mint etc. Some
important types of Trichomes are shown below.
70. • Microscopic linear measurements and quantitative microscopy are also covered
under this technique of evaluation.
• The powdered cloves do not contain sclereid or calcium oxalate crystals, but both
of them are present in powdered clove stalks.
• Powdered clove fruits show presence of starch while it is absent in cloves.
• Presence of non-lignified vessels in powders of rhubarb and ginger indicate
• Other important histological aspect is the quantitative microscopy and linear
measurements. The various parameters studied here are stomata number and
index, palisade ratio, vein-islet number, size of starch grains, length of fibres, ete.
• Senna varieties are distinguished by differing stomata number and palisade ratio.
The diameter of starch grains in Cinnamomum cassia is 10 microns; hence, useful
for detecting adulterants. The number of sclerenchymatous cells per square mm
of cardamom is useful for detecting different varieties of cardamom seed.
78. There are six forms of calcium oxalate crystals in plants as follows:
(I) Cubical (Prisms): As the name indicates, these crystals are cubical' in shape (i.e. th .
width and length is equal) and also have three equal axes, all at right angles to one
(2) Rhombic (Diamond Shaped): Here crystals have three axes, which axes are at right
to each other and unequal in length.
(3) Tetragonal: This is characterized by presence of three axes, at right angles to one
vertical or principal axis.
(4) Monoclinic: This form has three axes and all the three are unequal. The lateral two at
right angles to each other, while the third. i.e. Principal is at right angles to lateral The
monoclinic crystals shine more than the tetragonal system.
80. (5) Acicular: These are excessively long slender forms, with pointed ends and normally
(6) Rosettes (Clusters): These are also aggregate crystals. This type has shape similar
to full expanded rose flower and hence the name rosettes
Apart from above six types many times, very minute deltoid or arrow-shaped crystals
occupying the full cells in which they occur, are also reported. They are known as
Microsphenoidal or sandy crystals of calcium oxalate.
82. M = weight in mg of the sample, calculated on basis of sample dried at 1050
P = 2,86,000 in case of ginger starch grains powder
Lycopodium spore method can be used for evaluation of powdered clove, ginger,
cardamom,nutmeg,umbelliferous fruits, etc.
86. Water immiscible solvent, such as light petroleum is used for the extraction of fixed
and essential oils, steroids and aglycones.
Chloroform and ether are used for the separation of alkaloids and quinines.
The extraction of organic bases like alkaloids usually necessitates basification of
plant material if a water immiscible solvent is to be used while for aromatic acids
and phenols, acidification may be required.
The glycosides are soluble in water and alcohol, but insoluble in non-polar
Tannins are phenolic matter soluble in water, alcohol and ethyl acetate. Extraction
itself may be performed by repeated maceration with agitation, percolation or by
continuous extraction using Soxhlet extractor.
88. • Each extract is concentrated by distilling off the solvent and then
evaporating to dryness on water-bath.
• The extract obtained with each solvent is weighed. Its percentage is
calculated in terms of air-dried weight of plant material. The colour and
consistency of the extract are noted.
• The extracts with different solvents can also be prepared by successively
macerating (co extraction) the powdered drug in order of increasing
• The general approach for extraction of different constituents from fresh
plant may be briefly described in the following chart