An Introduction to pharmacognosy

Pharmacognosy deals with:
• The plants and animals that yield drug
substances.
• 2-The chemical, physical and biological properties
of the substances.
• 3- The methods employed in harvesting the
crude drugs.
• 4- The methods employed in processing and
storing crude drugs.
• 5- The methods used for extraction and
preparation of their active constituents.
• 6- The knowledge of the medicinal uses of the
crude drugs.
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For detailed description of drugs, the following
parameters should be fulfilled:
• the biological and geographical sources,
• a short note on the history
• and the name of the drug.
• cultivation of the plant,
• collection of the part used,
• drying,
• packing
• and other treatments of the drugs during its
course from the biological source to market.
1- Origin:
2- Cultivation and preparation:

• Including the macro- and microscopical
characters.
•
• The chemical identification of the drug.
3- Characters:
4- Constituents
5- Chemical tests
6- Adulteration and/or substitution
7- Isolation and purification of the active constituents
8- Uses of the drug in folk medicine and therapy

Crude drug = Raw Drug
• It is the harvested and usually the dried plant
or animal sources of pharmaceutically or
medicinally useful products before they have
undergone extensive processing or
modification.
• It is a part of plant or animal, which has been,
or still, used in medicine or such products of
these vegetable parts which have been
extracted but not used by it.
Crude Drugs

• Entire plants or animals i.e Lobelia, Mentha,
Cantharidis, Cochineal.
• Entire members of plants or animals i.e Clove
and thyroid gland.
• Minerals i.e. Chalk, Kaolin and Talc.
• Substances derived from plants or animals i.e.
Opium, Aloes, Tragacanth, Resins, Musk, Beeswax
and Gelatin.
Examples of Crude Drugs:

• Fibres and Fabrics used for making surgical
dressings
• i.e Materials used as strainers for filteration or
for clarifying cloudy liquids, “Filteration
Material” e.g. Diatomite and Asbestos, also
substances as Agar, Gelatin and Wax.
• Materials used for destruction of insect pests
“Insecticides and Pesticides” i.e Derris and
Pyrethrum.

• 1- Identification of the source of the materials
forming a drug.
• 2- Determination of its morphological characters.
• 3- Investigation of the potency of the drug, purity
and freedom from admixture.
• 4- Planning the proper methods of cultivation of
the medicinal plants yielding these drugs.
• 5- Prescription of details of processes of collection
and preparation.
• 6- Detailed knowledge of the constituents of drugs
and investigation of their chemical nature and
various reactions.
Functions of a pharmacognosist

Classification of Crude drugs
Vegetable drugs are usually arranged for study in
one or other of the following ways:
1- Alphabetical:
using either Latin or English names; the drugs are
arranged in an alphabetical order.
2- Taxonomic:
using one of the accepted systems of botanical
classification; the drugs are according to the plants
from which they are obtained in phyla, orders,
families. Genera and species.

• 3- Morphological:
• dividing the drugs into groups e.g. leaves,
flowers, fruits, seeds,..... which are referred to as
“Organized drugs", and groups as dried lattices,
extracts, gums, resins, oils, fats and waxes which
are known as “Unorganized drugs".
• 4- Chemical:
• the drugs are divided into groups according to
their most important constituents.
• e.g. drugs containing volatile oils, glycosides,
alkaloids, bitter principles, tannins, saponins,......

5- Pharmacological and therapeutic effects:
• grouping of drugs according to the
pharmacological action of their most important
constituents or their therapeutic use.
• e.g. astringent, irritant, drugs affecting the
gastrointestinal tract, drugs promoting systemic
effects on the muscle and nervous system, drugs
affecting the circulatory system, drugs used
chemotherapeutically for the treatment of
infectious diseases, etc....

• Drugs are either official or unofficial.
• An official drug is one which is listed and
described in a book recognized by the
government as the legal authority for
standards “Pharmacopoeia’’.
• The 1st Egyptian Pharmacopeia appeared in
English in 1953 and in Arabic in 1961.
Official and unofficial drugs

• There are two origins for each drug; the
natural or biological, as well as, the
geographical origin.
• The commercial origin is also of interest
in case of certain drugs.
Origin of drugs

• It is the plant or animal yielding it, if a plant,
botanical origin or botanical source and if an
animal, zoological origin or source.
• The knowledge of the biological source
enables one to indicate with certainty the
proper right material and the precise article
one wishes to obtain.
1-The natural or biological
origin (source(

• e.g. Strophanthus is used as a heart tonic and
includes about 30 species, all species from the
same district in central Africa.
• One year, the drug is active, even poisonous and
in other cases it is inactive. This is due to the fact
that the drug is gathered from any species, which
collectors amy find.
• If the drug is obtained from one and the same
species the supply of the drug will be always of
the same potency.
• So the identification of the exact origin of the
drug needs comparison with authentic or
genuine samples or identification by comparison
with herbarium or referring to gardens or
museums.

The binomial system for nomenclature of
drugs
• Is due to Swedish biologist Linnaeus, in this system the
first name, which is always spelt with Capital letter,
denotes the genus.
• whilst the second name denotes the species. It is
however, still equally correct to use capital where the
species is named after a person.
• Thus the species of Cinchona named after Charles Ledger,
who brought its seed from Brazil 1865, is known as
Cinchona Ledgeriana.
• It is noted that the pharmacopoeias and research papers,
botanical names are followed by names of persons which
refer to the botanist who first described the species or
variety.

• The specific name is usually chosen to indicate:
1- Some striking characteristics of the plant:
• a- Glycyrrhiza glabra
(glabrous = smooth).
Refers to the fruit of this species which is a smooth pod.
• b- Atropa belladonna
(bella = beautiful, donna = lady)
the juice of the berry placed in the eyes causes
dilatation of the pupils, thus giving a striking
appearance).
• c- Hyoscyamus muticus
(muticus = short).
The plant being short.

2- A characteristic colour:
a- Piper nigrum (nigrum = black)
b- Veratrum viride (viride = green)
c- Citrus aurantium (aurantium = golden yellow)
d- Digitalis purpurea (purpurea = purple)
e- Digitalis lutea (lutea = yellow)
3- An aromatic plant or certain aroma:
a- Myritaceae fragrans (having a fragrant, nice
aroma)
b- Caryophyllus aromaticus (refers to the aroma)

4- Geographical source or history of a drug:
• Cannabis indica (growing in India)
5- Pharmaceutical activity or an active
constituents:
a- Papaver somniferum (sleep inducing)
b- Quillaia saponaria (containing saponins)
6- General meaning or a special indication
a- Allium sativum (= cultivated)
b- Triticum vulgaire (= wild)

• It is the region in which the plant or animal
yielding the drug grows.
• Knowledge of the geographical source also
assists in identification of the biological origin,
because it is generally known that plants of
certain type come from particular districts and
one may often exclude from consideration
entire families of plants, as well as, individual
species or one may deduce the possibility that
the drug may be derived from a plant
belonging to one of some few families
characteristic of the region.
2- Geographical sources of drugs

• Every climatic region of the earth is the native
habitat of some species of animals and plants.
• Drugs are collected in all parts of the world, the
Mediterranean region yields more drugs than any
region of the world however India, East Indies,
Europe, South and Central America yield
numerous valuable drugs.
• It is important to note that the habitat affects not
only the constituents but also the medicinal value
of the natural drug.

• The commercial origin drugs refer to the
countries included in their production and/or
their channels of trade so such drugs frequently
bear a geographical name indicating:
• 1- The country in which they are collected
i.e. English Hyoscyamus
• 2- The city from which they are shipped
i.e Alexandrian Senna
• 3- Indicate a certain veriety
i.e Spanish Liquorice
3- Commercial origin

• Production of crude drugs from their
medicinal plants involves the following steps:
• I. Cultivation
• II. Collection
• III. Drying
• IV. Packing
• V. Preservation and protection
Production of Crude Drugs

• Crude medicinal drugs may be collected from:
- Wild growing medicinal plants
- Cultivated medicinal plants.
• Plants growing in their native countries are said
to be indigenous to these regions,
• e.g. Aconitum napellus of the mountainous
regions of Europe,
• Hyoscyamus muticus of Egypt, Cannabis sativa of
India.
• Plants are said to be naturalized when they grow
in a foreign land or in locality other than their
native home.
Cultivation of medicinal plants

Collection of Crude drugs from wild
growing medicinal plants has the
following disadvantages
• 1- Wild medicinal plants found spread in wide
distribution “unlimited areas”.
• 2- There is significant difficulty in collection and
transportation because they are mostly growing
in deserts and forests far from any means of
transport.
• 3- Continuous extensive collection of wild
medicinal plants can lead to extinction or serious
deficiency of the plant.
• 4- the collected amount of wild medicinal plants
may be insufficient for the market needs.

• 5- Adulteration; collection of crude medicinal
drugs from wild sources may lead to
adulteration that can be attributed to
ignorance of collectors who may collect:
• a- The desired plant with others.
• b- Undesirable organ of the desired plant.
• c- The desired plant at improper time.

Collection of Crude drugs from
cultivated growing medicinal plants
has the following advantages
• 1- Concentration of a large quantity of the plant
of choice in relatively small areas simplifies
collection.
• 2- Cultivation provides an excellent mean for
control of the purity of the crude drug.
• 3- Cultivation assures regular and constant
supply can be sufficient to market needs.

• 4- Cultivation allows producers to apply different
methods for improvement of the gained crude drug by
controlling certain factors:
• a- Treatment of seeds before sowing to ensure
germination and exclusion of defective seeds i.e. soaking
Hyoscyamus seeds in dilute sulphuric acid fasten
germination.
• b- The use of fertilizers which can provide cultivated
plants with certain essential elements as N, K and P
which can increase the produced active constituents.
• c- The use of certain insecticides and pesticides help
control of insect’s infestations.

The disadvantages of collection of crude
drugs from cultivated medicinal plants
are:
• 1- The high cost of production when applied
on small scale while economic only when
carried on large scale.
• 2- Some medicinal plants require particular
habitat for their growth and the procedures
of their cultivation usually gain failure.
• i.e. Cannabis requires tropical climate
production of narcotic resin while Aloes
require a heavy rainfall.

• For successive cultivation of medicinal plants
and production of crude drugs with quality, it
is necessary to study the conditions under
which medicinal plants flourish in their wild
state and trying to reproduce these conditions
or improve them.

Factors affecting plant growth and
production of crude drugs
• Classified into:
1- Environmental factors:
• Including water, light, temperature, altitude, etc.
2- Soil and soil contents:
• Including plant nutrients, macro-elements and
micro-elements, active elements, inactive
elements, organic matter and living organisms.
• 3- Growth Regulators.
• 4- Genetics and plant tissue culture.

1- Environmental Factors:
• a- Water:
• Importance of water:
• 1- It is an important component of the cell
which is the building unit for every living
creature.
• 2- It is a vital factor in all biological reactions
and transformations in living beings, it can act
as medium, catalyst, part of the biological
reaction or even end product of it.

• b- Temperature:
• Temperature divides the world into various zones and
plant growth is greatly affected by temperature.
• The effect of temperature on the reaction of the plant
which is finally expressed in its effect on the plant
growth as a whole.
• It has a great effect on on seeding
i.e as temperature is increased, the rate of growth is
increases until an optimum value is reached, above
which further increase in temperature leads to a
decrease in growth rate.
• This is due to the fact that chemical reactions, in
general, increase in rate as temperature is increased,
but as it is still further increased, other reactions, such
as heat denaturation and protein inactivation
predominates.

• For each plant, growth is designated by three
temperatures:
- The minimum temperature
- The optimum temperature
- The maximum temperature
c- Altitude:
• It affects the growth of medicinal plants.
• In general, the highest temperature are
experienced near the equator, and temperature
falls with elevation
• i.e Jamaica to have a tropical climate on the coast
and a temperat one in the mountains so sugar
can be cultivated at the coast as it is a lowland
plant while Tea can be cultivated at elevations.

• d- Light:
• Plants vary in the amount and intensity of the
light which they rquire.
• The effects of light intensities on the growth
of plants are related mainly to the role of light
in “Photosynthesis”.
• ‘Photoperiodism’:
• defined as the response of plants to the length
of day, or correctly, to the relative length of
day and night.

Plants classified into three broad
photoperiodic classes with respect to
their flowering behavior:
• 1- Short-day plants:
• These plants flower only when the daily period of
illumination is shorter than a particular critical length
i.e. Tobacco.
• 2- Long-day plants:
• These plants flower only when the daily period of
illumination exceeds some critical duration i.e. Dill.
• 3- Day-neutral plants:
• These plants flower under any of a wide range of day
lengths i.e. Capsicum.

• “Plant nutrients and/or Plant Manures”
• Soil is a mosaic of rock particles, plant roots,
micro-organisms, decaying organic matter
(humus), aqueous soil solution and
interconnecting air passages.
• Soil is a store house of water and minerals
required for growth of plants.
• Soil differs from one another both in physical and
chemical properties.
2- Soil and soil contents

• “Absolute water capacity”
• The amount of water which remains in a soil
after any excess has drained away.
• The air capacity of a soil is inversely
proportional to water capacity.
• i.e. Sandy soil are very permeable while clays
possess a high power of absorbing water.

Organic Manures
• Manure is a mixture of organic matter, which is
composed mainly of plant remains put under
animals in the stable and ultimately mixed with
the animal urine and other animal excretions and
some of the stable soil.
• Importance of manures:
• 1- Manures are used as fertilizers.
• 2- They block the soil particles together and
improve conditions of growth i.e. organic matter
in soil takes up and holds water in the same ways
as a sponge holds water.
• 3- Manure is of value as a source of nutrient
elements, especially nitrogen.

Essential elements commonly supplied by
the soil are divided into 4 groups:
• 1- Main nutrients or Macro-elements:
• Involving nitrogen (N), phosphorus (P) and potassium (K).
• Commercial fertilizer containing one of these elements is
called a simple fertilizer and if containing all of them, a
complete.
• N.B.:
• - Deficiency of (N) produces stunted yellow colour
(chlorosis).
• Deficiency of (P) reduction of plant size and deep green
colour.
• Deficiency of (K) reduction of carbohydrate synthesis.

• 2- Active elements:
• Involving calcium, magnesium and sulphur.
• The little amount of which increases plant
growth, but more than adequate amount has
no effect on plant growth.
• 3- Inactive elements:
• Involving sodium, aluminum, silicon and
iodine.
• They have negligible effect on plant growth.

• 4- Micro-elements:
• Involving iron, boron, copper, manganese,
zinc, cobalt, lead and molybdenum.
• These are needed within very minute amounts
for plant growth while any rise in this amount
has poisonous effect on plants.

3- Plant growth regulators
• Growth and development of plants is regulated by a
number of chemical substances, which together exert a
complex interaction to meet the needs of the plant.
• Five groups of plant hormones are well established
they are:
-Auxins
- Gibberellins (GA)
-Cytokinins
- Abscisic acid and its derivatives
- Ethylene

• They are: - specific in their action,
- active in very low concentrations
• Regulate: - cell enlargement,
- cell division,
- cell differentiation,
- organogenesis,
- senescence and dormancy
• Some are classified as growth regulators while
others as growth inhibitors.
• Growth stimulators: i.e. auxins, gibberellins (GA)
and cytokinins
• Growth inhibitors: i.e. abscisic acid and its
derivatives and ethylene

Growth stimulators
• a- Auxins:
• The most important natural one is 3- or β-indole
acetic acid (IAA).
• Typical effects of auxins are:
• 1- Stimulates the growth (cell elongation).
• 2- Ovary growth: IAA alone is not always
sufficient to promote fruit growth but GA may be
needed.
• 3- Cambial activity: the ratio of IAA and GA is
important in determining whether phloem or
xylem tissues were formed by the cambium.

• 4- Effects on the formation of secondary
metabolites
• i.e. seedlings and young plant of Mentha piperita
when treated with IAA, gave in the mature plants
an increased yield (30-50%) of oil which itself
contained more menthol.
• 5- The main practical uses of auxins are:
- Low concentrations accelerate rooting of woody
and herbaceous plants.
- Higher concentrations act as selective herbicides
or weed killers.

• b- Gibberellins:
• About 40 gibberellins are now known, in higher
plants they are synthesized in leaves and
accumulated in immature seeds and fruits.
• They have the following effects:
• 1- Induce flowering at earlier stages.
• 2- Increase the length of the dwarf varieties of many
plants.
• 3- effects on secondary metabolites
- Volatile oils in case of Citrus, Mentha and many
umbelliferous fruits, the amounts of volatile oils
variably increased

- Alkaloids: Belladonna, Hyoscyamus and
Nicotiana produced more alkaloids.
- Glycosides: The total glycosides in Digitalis
were increased.
• c- Cytokinins:
• It is the cell division hormone.
• Their effects are:
• 1- Cell division.
• 2- Cell differentiation and morphogenesis (ratio
of cytokinin/auxin).
• 3- They have inhibitory effect on senescence.

Growth Inhibitors
• a- Abscisic acid:
• It is widely distributed in plants.
• It acts by antagonizing GA, blocking synthesis of
DNA and enzymes.
• It induces seed dormancy and inhibits shoot
growth and helps to withstand draft conditions.
• b- Ethylene:
• It was demonstrated that ethylene evolved by
stored apples inhibited the growth of potato
shoots enclosed with them.

II- Collection of Crude Drugs
• Qualitative and quantitative composition of
plants may change greatly during the course
of growing season, time of the day and stage
of maturity.
• To ensure maximum quality of a crude drug, it
must be collected at a proper stage of
development.
• The active constituents may be distributed in:
• All parts of the plant or
• Concentrated in certain organs or
• In specific tissues of these organs.

Factors affecting collection of medicinal plants:
• 1- Time of the year:
• The active constituents of medicinal plants
vary quantitatively and qualitatively througout
the year.
• Examples:
• a- Rhubarb contains no anthraquinones in
winter but contains anthranoles, which on
arrival of warm weather converted by
oxidation to anthraquinones.

• b- Colchicum corms is almost free of
bitterness and almost devoid of colchicine in
autumn and is full of starch, so it is collected
at the end of the autumn and used by the
farmers of Austria as food instead of potatoes,
but in spring and early summer it is bitter due
to high colchicine content and hence should
be collected for medicinal use.

• 2- Time of the day:
• Affects both the therapeutic value and activity of
medicinal drugs.
• It is an important factor in determining the
concentration of active constituents in medicinal
drugs.
• Examples:
• a- Digitalis leaves collected in the afternoon
contain more glycosides than those collected in
the morning.
• i.e the active glycosides undergo hydrolysis to
physiologically less active aglycones during the
night and recombine with sugars during day-time.

• b- Solanaceous leaves have higher alkaloid
content when collected in the morning than
those collected in the afternoon.
• 3- Stage of maturity and age of the
plant:
• The quality and quantity of the active
constituents depend on the stage of maturity
and age of the medicinal plants collected.

• Examples:
• a- Santonica flowers are most rich in santonin,
when they are unexpanded and when they
start to open, the santonin content starts to
decrease due to light oxidation to yield
inactive photo-santonin.
• b- Solanaceous leaves contain higher alkaloid
content when the plant is in the flowering
stage.

• Certain Pharmacopeias specify the time and
stage of collection of certain important drugs
as they should be collected when they are
containing the highest amount of active
principles and they will have better
appearance when dried.
• Example E.P. 1984 specified that: Lobelia herb
must be collected towards the end of the
flowering stage.

General rules for collecting crude drugs
are as follows:
Leaves
• They are collected at the beginning of the
flowering stage when they contain the
optimum percentage of their active
constituents.
• Collection must be done in dry weather as wet
weather causes deterioration and
discoloration during drying.

• Methods of collection varies according to the
medicinal plant:
• Senna leaves: the whole plant is cut and the
leaves are picked off after drying in the sun.
• Digitalis leaves: are gathered directly from the
plants.
• Coca leaves are gathered directly from the
plants when nearly ready to fall from the
stem.

Flowers
• Collection of flowers must be carried out in
fine dry weather in order to fix the colour of
the product.
• Generally flowers are gathered just at the time
of pollination and before the formation of
fruits.
• Exceptions are:
• Cloves and Santonica are collected in bud
stage.
• Chamomile flower are collected just after full
expansion.

Barks
• It is usually done in the spring or in early
summer when the cambium is active and the
bark can be easily stripped off from the trunk
and branches.
• Longitudinal incisions are made at intervals,
round incisions are made of the stem and the
bark is stripped off in long pieces.

Fruits
• Fruits are collected near the ripening stage
• i.e. when they are fully grown but not
completely ripened.
• Seeds are collected when mature
• i.e. they are separated from the pericarp.
Seeds

• Include: Roots, Rhizome, Bulbs and Corms.
• Generally they should be collected in autumn
or winter after removal of aerial parts and
before the vegetative process starts.
Underground organs

• Include: Resins, Gums, Latex,….etc.
• They are usually collected in dry weather.
• Unorganized drugs are usually natural
secretions such as beeswax and myrrh or
derived from parts of plants or animals by
some process as:
• 1- Incision, e.g. Opium and Gum Tragacanth.
• 2- Decoction, e.g. Agar and Gum Arabia.
• 3- Expression, e.g. Olive oil.
Unorganized drugs

Different methods used for preparation of
crude drugs before drying
• After collection of crude drugs, many of them
need distinct procedures for preparation before
drying.
• i.e. cleaning, grabling, decortication, bleaching
and sometimes curing.
• Examples:
• De-cortication of Cinnamon bark
• Cinnamon bark present as a very thin bark in
small quills, compound quills showing
longitudinal yellow lines marking the pericycle
fibers on the outer surface due to removal of the
outer layers (cork and cortex).

• The official appearance gained by
decortication process, which is done for the
following reasons:
• 1- lack or existence of low percentage of
active constituents in the outer parts.
• 2- Present of unrequired constituents in the
outer tissues
• i.e. bitter substance which alter its sweet
taste.

Bleaching of Ginger and Nutmeg:
• Bleacjhing alters the appearance of certain
drugs when they are being prepared for the
market, i.e. Ginger and Nutmeg.
• Coating with a layer of inert substance such as
CaCO3 or CaSO4 for preservation purposes.
• Curing of certain drugs:
• It is a process of inducing some desirable
changes in the drug after collection and
before drying by enzymatic action.

• Examples:
• Tea Leaves: curing is done to set free soluble
caffeine and oxidize tannin into insoluble
products.
• Vanilla pods: curing is done to set vanillin
free.

III- Drying of Crude Drugs
• Fresh plants usually contain high percentage of
moisture (up to 80 or 90 %).
• The duration of drying process varies from few
hours to many weeks.
• Importance of drying of crude drugs:
• 1- drying stop the enzymatic action that might
change the active constituents, i.e. to fix the
active constituents.
• 2- Drying help in avoidance of deterioration of
crude drugs upon storage by preventing the
growth of micro-organisms (bacteria and fungi).

• 3- Drying of crude drugs facilitate packing and
storage and decreases transportation cost as
the weight of the drug is greatly reduced.
• 4- Careful drying is also essential to obtain
drugs which:
- Retain their physical characters.
- Retain their chemical constituents.
- Fulfill the Pharmacopoeial requirements for
maximum moisture content.

Factors affecting drying process
Temperature Time
• The duration of drying varies from few hours to
several weeks depending on the structure and
water content of the drug.
• Drying process should reduce moisture content
of the drug below its critical threshold level.

Methods of drying
Natural drying Artificial drying
Sun Drying Shade Drying
Direct fire
Stove
Drying champers
Vacuum drying
Freeze drying
" Lypophilization"

1- Natural Drying:
• It is the use of climatic heat.
• i.e. -the drug is dried by exposure to direct sun
- spreading in the shade by putting on the
floor or mats or trays in a single layer and as
drying proceeds drugs are turned over
• Whether the drug is dried in the sun or shade
it is protected from moisture and so it is
covered at night or in periods of rain.

• Sun drying
• Used for those items which are not
affected by direct action sunlight.
• Shade drying
• Used when it is desirable to retain the
natural color of the drug and preserve its
sensitive active constituents.

• Physical Drying
- carried out by the use of elevated
temperature and/or decreased pressure
(vacuum) or the use of radiation of infrared or
radiofrequency wavelength.
• Chemical Drying
- carried out by the use desiccants.
2 - Artificial Drying:

• Drying with artificial heat is generally the most
acceptable method when skillfully operated
• The heat should be such as to maintain an
efficient temperature for vaporizing the moisture
but not high to affect the constituents of the
drug.
• And the ventilation such as to efficiently utilize
the heat units in the air and then remove the
moisture-laden air at the time of saturation.
• When heat and ventilation are properly
controlled, the plant material is thoroughly dried
and produces a drug of maximum quality both in
the constituents and appearance.

Advantages of artificial drying:
• 1- immediately stops enzymatic action
• i.e. in Digitalis leaves the natural moisture
content of the leaf is sufficient to cause an
enzymatic hydrolysis of the cardiac glycosides
as soon as the leaf is harvested, if the leaves
are allowed to dry naturally, a very rapid
hydrolysis if these glycosides occur.

• 2- is a rapid method, usually done at a well
controlled temperature.
• i.e. rapid drying, not only prevents the
decomposition of active principles but also
retains the color of the drug.

Artificial heat may be applied by:
• 1- Direct fire.
• 2- Use of heated stones.
• 3- Use of stoves, these must be done carefully
to prevent the damage produced to drugs
when dried i.e. burning.
• 4- Drying sheds or chambers.
• 5- Drying ovens.

• 6- Pneumatic high speed drying is applied for
sensitive drugs.
• i.e. Digitalis. The drug is dried by exposure to high
temperature (800°C) for a fraction of a second
under reduced pressure.
• 7- Freeze Drying (Lypophilization)
• It is an extreme form of vacuum drying, in which
the water is frozen and drying takes place by
subliming the solidified ice-phase where very low
temperature and high vacuum are used.

Precautions for drying different plant
organs:
• 1- Leaves:
• must be dried as quickly as possible to retain
their fresh green color and prevent decomposing
of their active constituents.
• i.e. Digitalis leaves must be dried rapidly in
vacuum ovens at 60°C.
• 2- Flowers:
• must be dried rapidly at low temperature in
shade or in drying chambers to retain their
colour.

• 3- Fruits and seeds
• are spread on trays and dried in sun or shade.
• 4- Barks, large roots and rhizomes
• Dried in the sun and rhizomes are generally
sliced transversely or longitudinally to
facilitate drying.

Changes encountered in crude drugs
during drying:
• 1- Size and weight
• due to loss of water where drugs get smaller in
size and lose 80 – 90 % of their original weight.
• 2- Shape and appearance
• Some drugs shrivel and shrink when dried and
the surface get wrinkled or reticulated.
• i.e. Black pepper on drying shows polygonal
reticulations.

• 3- Texture:
• Fresh organs are generally firm on drying, drug
become harder.
• i.e. leaves brittle and horny for drugs containing
starch “gelatinization”.
• 4- Color:
• On drying the drug becomes darker in color but in
certain cases a total change may occur.
• i.e. Tea leaves change from green to dark brown
almost black.

• The green color of certain drugs changes to
brown on drying due to decomposition of
chlorophyll either by the influence of the
acidic sap or of heat and oxygen.
• 5- Odour:
• In certain drugs drying changes the natural
odour.
• i.e. Digitalis and Hyoscyamus loose their bad
odours when dried while vanilla pods are
odourless when fresh and on drying acquire a
fragrant, pleasant, aromatic odor due to the
liberation of vanillin which has a nice aroma.

• 6- Taste:
• The taste of the drug may be altered.
• Gentian is very bitter when fresh and becomes
pleasant on drying.
• 7- Constituents:
• Constituents of some drugs may change due
to drying.
• i.e. fresh vanilla pods contain the glycosides
gluco-vanillin and gluco-vanillic alcohol on
drying hydrolysis of both glycosides and
oxidation of acid to vanillin occurs.

IV- Packing of Crude drugs
• Importance of packing of crude drugs:
• 1- Packing provides protection against dust,
micro-organism and insects attack.
• 2- Packing is economic as it reduces the space
required during storage and shipment.

• Effect of packing on appearance:
• The various ways of packing usually affect the
appearance of the drug.
• i.e. Indian Senna leaves are packed into large bales,
using hyraulic pressure resulting in the leaves being
flatter and showing faint oblique or transverse
markings where the midribs and margins of their
leaves have been impressed.
• Packing also may give indication to the geographical
source and port of transport of the drug.
• i.e. Opium, which is the dried latex from the unripe
capsules of Papaver somniferum L. Opium is collected
principally in Turkey, Yugoslavia, India and China by
incising the capsules in various ways and using various
instruments.

• Turkish opium occurs in sub-cylindrical cakes
about 9 cm high and 14 cm in diameter coated
with coarsely powdered poppy leaves, giving
them a greenish motted appearance.
• Indian opium is imported in 5 kg blocks wrapped
in 2 sheets of thin grease proof paper and tied
with tape and placed in polyethylene bags.
• Persian Opium occurs in brick shaped cakes, each
wrapped in red paper sometimes in form conical
masses and short sticks.

V- Preservation and protection of
crude drugs
• Crude drugs are subjected to many hazards at all
stages in their path from the living plant or
animal to their ultimate use in pharmacy.
• Storage represents the last stage in in the
handling of crude drugs before being used and it
is a most important stage.
• Drugs usually deteriorate either slowly or rapidly
in the time of storage with few exceptions such as
Cascara and Frangula barks which shouldn’t be
used except after a certain period of time.

• Certain Pharmacopoeias give well, clear
instructions concerning time of storage, after
which drugs shouldn’t be used.
• i.e. Digitalis, Ergot and Cannabis for their
active constituents decompose and they get
less active.

• The general undesirable changes which may
occur on storage are:
• a- Aromatic drugs usually lose their aroma.
• b- Drugs containing fixed oils may be rancid.
• c- Volatile oils may be thickened and
resinified.
• d- Examples:
- Digitalis leaves may lose their activity.
- Ergot may acquire a dis-agreable odor.

For these reasons, Pharmacopoeias clear
instruction for storage of crude drugs,
they must be stored:
• 1- In well closed containers.
• 2- Protected from light, moisture and dust.
• 3- At low temperature.
• 4- Protected from insect infestation.

The principle factors responsible for
deterioration of crude drugs may be
Physico-chemical Factors Biological Factors
a- Moisture
b- Light
c- Temperature
d- Air
a- Bacteria & fungi
b- Mites and Nematodes
c- Insects
d- Rodents

1- Physicochemical factors
a- Moisture
• Dried drugs stored in the usual containers
reabsorb about 10 % or more of moisture and
are termed air dried.
• Moisture may cause:
• 1- Hydrolysis of active constituents by
enzymes.
• 2- Growth and nourishment of bacteria and
fungi.

To overcome the effect of hydrolysis
stabilization of the drug may be carried:
• a- Temporary stabilization:
• Can be done by enclosing dehydrating agent
as lime or calcium chloride in the container of
the stored drug.
• b- Complete stabilization:
• Can be done by destroying enzymes.
• Subjecting the fresh drug to alcohol vapors or
immersing them in alcohol.

b- Light:
• Any reaction needs a certain energy level which
may be provided by light radiation leading to
photochemical reactions.
• Light may affect delicate drugs having color.
i.e. - Rose petals are red when fresh and changing
to brown on exposure to light.
- Digitalis leaves lose its activity more rapidly in sun
light.
- To avoid the these effects of light, stored in the
dark or by the use of opaque or amber colored
glass containers.

c- Temperature:
• The rates of biological processes are
accelerated by raising the temperature.
• A slight raise in temperature above the normal
will activate the enzymatic action or include
molecular rearrangements.
• Drugs directly affected with the rise in
temperature are those containing volatile oil
such as clove and chamomile.

d- Air:
• Oxygen of air has a definite oxidation effect
on the active constituents of some drugs
leading to lowering the quality of the product.
• In some cases oxidative changes are required
to produce the required active constituents,
i.e. Frangula bark.

2- Biological Factors:
a- Bacteria and fungi
• Sufficient moisture content is essential for
bacterial or fungal infestation.
• Fungi usually attack drugs rich in nutritive
substances such as roots and rhizomes if they
are not stored properly.
• Bacterial and fungal infestation may change
the physical properties of the drug such as
color and texture.
• The presence of fungi is indicated by their
hyphae.

b- Mites and Nematodes:
• Mites belong to the spider group.
• recognized under the microscope by having
four pairs of legs and oval body.
• They are visible by the naked eye.
• Nematodes belong to the group of round
worms.
• Mite sand Nematodes may attack the wheat
flour and belladonna stems.

c- Insects:
• The dried drugs and their powder form are
susceptible to attack by insects which render
them unstable for preparation of standard
extracts.
• Insects should be destroyed before storage of
drugs by one of the following methods:
• 1- Heat treatment
• 2-Fumigation
• 3- Liming
• 4- Freezing

• 1- Heat treatment:
• is done by exposing crude drugs to
temperature 60-65 °C which can kill the
insects as well as their eggs.
• Disadvantages:
• - not suitable for thermo-labile constituents.
• i.e. if heating affects the active constituents of
the drug.

• 2- Fumigation:
• Includes use of volatile insecticides in closed
areas such as carbon disulphide.
• Disadvantages:
• Has to be repeated at intervals is its dose isn’t
sufficient to kill eggs.

• 3- Liming:
• Done by dipping the crude drug in freshly
slacked lime or sprinkled with quick lime
which will block the respiratory system of
insects and larvae.
• Liming is used with few drugs as Ginger and
Nutmeg.
• 4- Freezing:
• By subjecting the drug in refrigerator.

d- Rodents:
• Rodents are rats and mice can attack crude
drugs during storage if they are stored in
paper, cloth, card-board or wooden
containers.
• Rodents attack can be prevented by storing in
glass, plastic or metal containers and/or the
use of rodenticides (e.g. alpha-naphthyl-
thiourea).

Chemistry of Crude Drugs
Food Storage Products
(Primary Metabolites)
By-Products of Metabolism
(Secondary Metabolites)
a- starch
b- Amino acids &
Proteins
c- Fixed oils & Fats
a- Crystals
b- Gums, Mucilages & Pectins
c- Tannins & tannin containing
drugs
d- Volatile Oils
e- Alkaloids
f- Glycosides

1- Primary Metabolites:
a- Starch:
• Starch is the most important carbohydrate
present in the plant cell.
• It is formed by accumulation of glucose
molecules formed during photosynthesis.
• It is a polysaccharide of glucose units with the
general formula (C6H10O5)n.
• Starch consists of two molecules:
• 1- Amylopectin (80%): is a branched sugar
insoluble in water.
• 2- Amylose (20%): is a linear chain of glucose
units soluble in water

• Special chemical test for Starch:
Starch suspension + dilute iodine solution
Blue color
• Uses of Starch:
• 1- Dusting powder due to its absorbent
properties.
• 2- Skin emollient (in mucilage forms).
• 3- Antidote for Iodine poisoning.
• 4- Suspending agent and tablet disintegrants.

b- Proteins:
• are complex nitrogenous compounds of high
molecular weight.
• Chemically: polypeptides of amino acids.
• i.e. mixtures of amino acid units joined
together by peptide linkages through
elimination of water.
• Stored by the plants usually in the form of
amorphous masses or small paricles called
Aleurone grains.

• Microscopical chemical tests for proteins:
• 1- Millon’s reagent
stains proteins red on warming
• 2- Picric acid
stains proteins yellow
• 3- Iodine solution
satins proteins yellowish brown

c- Fixed oils and Fats
• Esters of long chain fatty acids of high
molecular weight.
• i.e. Stearic and Oleic acids and glycerol.
• Being either solids or liquids depends on the
proportion of esters of saturated (solid
i.e.Stearic acid) or unsaturated (liquid i.e Oleic
acid) fatty acids.
• In plants they are abundant in fruits and seeds

Characters of fixed oils and Fats
• 1- lighter than water,
- greasy in touch
- leave permanent stains on paper.
• 2- Insoluble in water and alcohols except
castor oil (soluble in alcohol).
• 3- Soluble in ether, chloroform and petroleum
ether.
• 4- Stain red with Sudan III.

• 5- Easily saponified by aqueous solution of
KOH yielding glycerol and salt of acids (soaps).
• 6- Fixed oils are liquids at normal temperature
(glycerides of unsaturated fatty acid).
• 7- Fats are solids or semisolid glycerides of
saturated fatty acids.

• Uses of Fixed oils and Fats:
• 1- Nutritive use.
• 2- Pharmaceutically as solvents in
intramuscular injections.
• 3- Preparation of soaps, Liniments, Plasters.
• 4- Laxatives, Demulcents and emolients.

2- Secondary Metabolites:
a- Crystals
• i- Calcium oxalate:
- produced in plant tissues as detoxifying
products for the toxic by product oxalic acid.
- exhibit certain diagnostic shapes which can be
considered as key elements for the natural
drugs containing them.

Forms of Calcium oxalate Crystals
a- Prisms: - Quillaia bark,
- Hyoscyamus leaf,
- Liquorice

• b- Cluster: - Rhubarb
- Stramonium
- Clove
• c- Rosette: - Aleurone grains of Umbelliferae.
• d- Acicular or Needle-shaped crystals (raphides)
- Squill
• e- Micro-crystals or sandy crystals
- Belladonna leaf (microsphenoidal)
- Cinchona bark (microprismatic)

• Special Arrangement of Calcium oxalate:
• Crystal sheath:
- Group of fibers ensheathed with parenchyma
membrane, each cell containing one calcium
oxalate prism. i.e. Liquorice.
• Crystal layer:
• Group of parenchyma cells, each cell
containing calcium oxalate cluster.
• i.e. Stramonium

ii- Calcium carbonate:
- embedded in or incrusted in the cell wall in
the form of concentrations found on
outgrowths of the cell wall and termed
cystoliths.
- i.e. Cannabis
- Special chemical tests:
- CaCO3 dissolves with effervescence in dilute
acids.
- i.e. dil. HCl

iii- Hisperidin and Diosmin:
• Crystalline masses of diosmin are present in the
epidermal cells of buchu leaves.
• These crystals are insoluble in organic solvents
but soluble in KOH.
• iv- Silica:
• Occurs as incrustation on cell walls or masses in
the interior of cells.
• i.e. Silica nodules can be found in the
sclerenchyma layer of cardamom seeds.

b- Tannins:
• Phenolic substances present in the plants.
• Able to combine with protein of the animal hides,
prevent their putrification and convert them to
leather.
• Are high molecular weight compounds.
• Many of them are glycosides
• Have astringent effect

• Tannins are classified into two main groups:
• a- Hydrolysable tannins (Pyrogallol tannins)
• i.e. tannins in galls, Cloves, Pomegranate.
• b- Condensed tannins (Catechol tannins)
• i.e. tannins in Cinnamon, Cinchona, Tea.
• Special chemical test:
• Hydrolysable tannins bluish black
• Condensed tannins greenish black
FeCl3
FeCl3

c- Volatile Oils:
• constitutes the most important odorous
principles in various parts of the plant.
• They are secreted with several secretory
structures, i.e. Cells , glands, ducts, hairs
which give red color with Sudan III.
• Insoluble in water.
• Soluble in alcohol.
• Can be stem distilled without decomposition.
• Chemically they are mixtures of hydrocarbons
and oxygenated compounds.

• Volatile oils are mostly used as flavoring
agents, in perfumery and carminative while
some volatile oils have therapeutic uses as:
a- Volatile oil of Buchu (urinary tract antiseptic).
b- Volatile oil in Chenopodium (anthelmintic).
c- Volatile oil in Eucalyptus (anti-rheumatic).

d- Alkaloids:
• are organic nitrogenous substances basic
compounds.
• Derived from natural origin.
• Have marked physiological activities.
• Are bitter crystalline substances, but some are
liquids.
i.e. Nicotine in tobacco
Coniine in Hemlock
• Have different structural formulae according
to the nature of the basic chemical structures
(i.e. non-heterocyclic structure).

• Chemical classification of alkaloids:
• 1- Phenyl ethylamine
i.e. Ephedrine (Sympathomimetic).
• 2- Tropane
i.e. Atropine (Para-sympathomimetic).
• 3- Phenantherine
i.e. Morphine (narcotic analgesic).
• 4- Quinoline
i.e. Quinine (anti-malarial).
• 5- Indole
i.e. Ergotamine
• 6- Purine
i.e. Caffeine (CNS stimulant).

• Chemical tests for Alkaloids:
• Most alkaloids are precipitated by the
following reagents:
• 1- Mayer’s reagent (potassium mercuric
iodide).
• 2- Wagner’s reagent (iodine/potassium iodide)
• 3- Dragendorf’s reagent

e- Glycosides:
• are non-reducing substances.
• Bitter tasted solids.
• Soluble in water and alcohol.
Hydrolysis
By acids or enzymes
Aglycone
(non-reducing character)
Glycone (sugar)
(reducing character)
Glycosides

• Classification of Glycosides:
1- Phenolic Glycosides:
i.e.
a- Hydroquinone glycosides
b- Flavonoids (flavus means yellow colored)
c- Anthraquinone glycosides
d- Coumarin glycosides
hydrolysis
Phenolic aglycone + different sugars

2- Cardiac glycosides
• Chemically:
steroidal aglycones
+ unsaturated lactone ring + 2-deoxy sugars
O
R1
OH
R2
O
O
3
19
12
14
23
17
16
18
OO
OO
OO
O
H3C
H3C
H3C
OH
HO
HO
OH O
OH OH
CH3
O
1
4
1
4
3
4

• Uses:
- heart tonics (cardiotonics).
- treatment of auricular fibrillation
- treatment of cardiac arrhythmia.
• Cardiac glycosides are two types:
• a- Cardienolides (contain 5-membered
lactone ring).
• b- Bufadienolides (contain 6-membered
lactone ring).

• Chemical tests of cardiac glycosides:
1- Baljet’s test
2- Kedde’s test
for lactone ring
3- Liberman’s-
Burchard test
for steroidal
ring
4- Keller-
Killiani test
for Deoxy-
sugar

3- Saponin Glycosides
• produce permanent froth in aqueous solutions.
• have hemolytic properties (i.e. cause blood
hemolysis).
• Classified according to the sapogenin obtained:
• a. Steroidal Saponins (C27) i.e. Dioscorea, Digitalis
• b. Triterpenoid Saponins (C30) i.e. Quillaia, Ginseng
Sapogenin + suagrs
(aglycone)
Saponins
hydrolysis

4- Cyanogentic Glycosides
• yield HCN (hydrogen cyanide) as one of the
products of hydrolysis.
• can be detected in plants by the HCN reaction
with sodium picrate paper (yellow)
red color due to the formation of sodium iso-
purpurate
i.e. Linamarin in Linseed.

5- Thioglycosides or Sulphated or
Thiocyanate Glycosides
• yield allyl isothiocyanate as one of the
hydrolytic products.
• used as condiments and counter irritant
• i.e. Sinirgin in Black mustard.
Sinalbin in White mustard.

Adulteration of Natural Products
• Adulteration occurs when the drug is:
- scarce
- expensive
Types of adulteration:
1- Sophistication (True adulteration).
2- Substitution 3- Admixture
4- Inferiority 5- Deterioration or spoilage
6- Addition of worthless heavy materials.
7- the presence of adventitious materials within the
drug.
8- Addition of waste products of suitable color or
density to the powdered drug.

1- Sophistication or True adulteration:
• The addition of spurious or an inferior
material to any article with intends to defraud.
• Examples:
• Addition of wheat flour to powdered ginger
with enough capsicum to restore or enhance
the pungency and enough curcuma to
maintain the color.
• Small masses of flour dough molded to the
correct size and shape of ergot, and colored by
dipping first in red ink and then writing ink.

• Nutmeg has been imitated by cutting pieces of
basswood to the required shape or by molding
a mixture of clay and leguminous meal.
• Coffee has been imitated by compressing
powdered chicory to the shape of coffee
beans.
• Pieces of string dipped in red ink have been
substituted for Saffron or addition of safflower
(American saffron).

2- Substitution:
• Replacement of the original drug by the
adulterant, i.e. an entirely different article used.
• Different ways of substitution:
a- Substitution by inferior commercial varieties
Examples:
- Capsicum minimum fruits and chilies C.annum
fruits.
- Safflower for safron.

• b- Substitution by exhausted drugs
• Examples:
• Preparation of volatile oils from cloves or from
umbelliferous fruits such as fennel and
caraway, the ungrounded drug is used and the
dried exhausted material closely resembles
the genuine drug.
• Coloring matter of saffron and red rose petals
when removed during exhaustion, the residue
is colored by artificial dyes as is done with.

• c- Substitution by superficially similar but
cheaper natural substances which usually
having no relation to genuine drugs.
• Examples:
• Peach Kernels and Apricot kernels for
Almonds.
• Clove stalks and mother cloves are mixed with
cloves.

3- Admixture
• It is the addition of one article to another
through accident, ignorance or carelessness but if
that addition has been done intentionally to
defraud, it is sophistication.
• Admixture may occur through faulty collection
i.e. collecting the drug not at the proper time,
collection of other parts of the same plant,
collection from other plans by mistake or
ignorance of collectors (Argel instead of Senna).

4- Deterioration
• It is the impairment of the quality of the drug by
the abstraction or destruction of valuable
constituents by distillation, extraction, aging,
moisture, heat, fungi and/or insects.
• Examples:
• Powdered Squill hardened through absorption of
moisture.
• Coffee which lost its caffiene through over
roasting.
• Ergot which is moldy.
• Rhubarb that has become wormy.

5- Spoilage
• It is a form of deterioration in which the
quality or value or usefulness of an article is
impaired or destroyed by the action of fungi
as to render the drug unfit for human
consumption.

6- Inferiority
• Can be defined as any substandard condition for
any cause.
• Examples:
• The dried seeds of Nux vomica, containing less
than 1.15 % strychnine would be inferior or
substandard drug.
• Addition of synthetic material to fortify inferior
products such as adding citral to lemon.
• Addition of benzyl benzoate to balsam of Peru is
considered an adulteration.

7- Addition of worthless heavy
material
• Addition of large masses of stones in liquorice
bales.
• Addition of lead shots in pieces of Opium.
• Addition of mineral, vegetable oils, glycerin or
ammonium nitrate to saffron.
• 8- the presence of adventitious matter
naturally with the drug.

9- Addition of waste products of suitable
color or density to powdered drugs
• Examples:
• It is generally powdered waste products of a suitable
color and density that are used.
• Addition of powdered olive stones to drugs like
powdered liquorice and Gentian, powdered Guaiacum
wood to Nux vomica.
• Addition of hazel nut shells to cinnamon, exhausted
ginger to Ginger, bran.
• Addition of saw dust to powdered Ipeca.
• Addition of red sanders wood to chillies.
• N.B. if the color of the adulterant needs adjustment, it
is sometimes done by roasting it till the tint is matched.

Evaluation of Crude Drugs
• It includes:
• 1- Identification of crude drugs.
• 2- Determination of its quality and purity.
• For each official crude drug, there are limits
for its quality and purity listed in its
monograph (the specified pages of the
Pharmacopoeia describing the drug).

• The identity is established by:
Collecting it from a plant that is positively
identified.
Comparing it with a preserved sample
(herbarium) that is previously identified.
Comparing the unknown drug with a
published description of authentic drug
sample.

• The quality of crude drugs refer to its active
constituents as:
- Carbohydrates
- Volatile oils
- Glycosides
- Alkaloids

• High quality crude drugs is gained through
collecting it keeping in mind the following
considerations:
1- Correct authenticated natural source.
2- Correction at the proper time, stage of
development using proper manner.
3- Proper cleaning and drying processes.
4- Proper protection of it and of its samples
against insects, fungi, dirt and moisture.

• Targets for crude drugs evaluation:
Investigation of biochemical variation in the
drug.
Detection of and deterioration due to
treatment and storage.
Determination of purity of the drug i.e.
substituted or adulteration.

• Steps of evaluation of crude drugs :
a- Morphological or organoleptic evaluation.
b- Microscopical investigation.
c- Chemical evaluation.
d- Biologic evaluation.
e- Physical evaluation.

a- Morphological or organoleptic evaluation:
• The term organoleptic evaluation refers to the
sensory evaluation.
• The characteristics which are evaluated with
the help of sense organs such as color, odor,
taste, texture…….etc.
• The sensory characters of organized as well as
unorganized drugs give the idea about the
quality of the drug.

• b- Microscopic evaluation:
• Microscopical investigation of unorganized
drugs in an important parameter for the
evaluation.
• For the faster and finer transverse sections
microtome is used which gives very high
degree of thinness with the reproducible
results.
• Very fine sections are selectively subjected to
staining reactions with various staining
reagents for study of chemical nature of the
cellular organization.

• Important staining reagents as:
Phloroglucinol and hydrochloric acid for
lignified tissues.
Chloro-zinc iodide reagent for cellulosic
tissues.
Tincture of alkannol for subrised or
cuticularized walls.
Ruthenium red for gums and mucilage
containing cells.

• Another important aspect of microscopical
evaluation is the study of surface constants.
• The leaf constants like stomatal number,
stomatal index, palisade ratio, vein islet and
vein termination number are studied by using
camera lucida.
• These constants are used for the detection of
their adulteration.

• c- Chemical evaluation:
It comprises of different chemical tests &
chemical assays.
Preliminary phyto-chemical screening is a part
of chemical evaluation for establishing
chemical profile of drugs.
Isolation, purification and identification of
active constituents are chemical methods of
evaluation.

• d- Biological evaluation:
• Includes the quantitative assay of the drugs using
biological models of intact animals, animal
preparations, isolated living tissues or micro-
organisms.
Bioassy: is the assay of pharmacologically active
substances by using biological means yields
valuable information about the potency of the
drug.
- When the intact animal is used for the bioassy,
the specific strains of experimental animals may
be used.
- i.e. rats, mice, guinea pigs, rabbits, cats, dogs,
pigeon….etc., are commonly used experimental
animals.

 Micro bioassay:
- is a type of biological assay specially
preformed with micro-organisms, i.e. bacteria
and fungi.
- In a typical microbiological assay, evaluation is
performed on the various cultures of micro-
organisms and the activity is represented on
the basis of average response of a large
population of micro-organisms.
- The micro bioassay procedures are used for
vitamins like Niacinamide, Calcium
pantothenate and Vitamin B12…..etc., for the
evaluation of potency of antibiotics.

Chemical examination of plant
constituents
Alkaloids
Mayer’s test Dragendorff’s reagent
Hager’s reagent Wagner’s reagent

Carbohydrates
Molisch’s test
Fehling’s test
Benedict’s test
Aniline acetate test
Bial’s test
Tannic acid test
Cobalt chloride test
Barfoed’s test
Seliwinoff’s test
Iodine test
Tollen’s test

Glycosides
(i)
Anthraquinone
Glycosides
(ii)
Cardiac
Glycosides
(iii)
Cyanogenetic
Glycosides
(iv)
Flavonoid
Glycosides
(v)
Saponin
Glycosides
Grignard’s test

(i)
Anthraquinone
Glycosides
Micro-sublimation test.
Borntrager’s test.
Modified Borntrager’s test.

(ii) Cardiac
Glycosides
(a)
Cardenolides
(b)
Bufedanolide
(c)
Deoxy sugar
in cardiac
glycosides
1-Baljet’s test.
2-Legal’s test.
3-Kedde’s test.
Liebermann’s
test.
Killer-Killani’s test.

(iv) Saponin
Glycosides
Foam test. Haemolytic test.
Liebermann’s test.

(v) Flavonoid
Glycosides
(vi) Coumarin
Glycosides
a-Shinoda test.
b- Lead acetate test.
Fluorescence test.

Phytosterols Fixed oils and
Fats
Liebermann Burchard’s
test.
a- Spot test.
b- Saponification
test.

Phenolic
compounds
and tannins
a- Ferric chloride test.
b- Gelatin test.
c- Lead acetate solution.
Proteins and
amino acids
a- Millon’s test.
b- Biuret test.
c- Ninhydrin test.

Gums and
Mucilage
Volatile oil
Hydro-distillation method
for essential oil
a- Alcoholic precipitation.
b-Molisch’s test

Plant tissues
Meristimatic Tissues Permanent Tissues
Apical
Meri-stem
Lateral
Meri-stem
Photoderm
Pro-cambium
Ground meristem
Vascular Cambium
Cork Cambium
Cell wall chemical
impregnations

Permanent Tissues
Simple Complex
Ground
tissues
Epidermis
Vascular tissues
Xylem Phloem Periderm
Parenchyma Collenchyma
Periderm

Cell Wall Chemical Impregnations
Cutin
Lignin
Suberin
Hemi-cellulose
Chitin

• These tissues change into other tissues on
development, examples:
 Meristimatic tissue:
is characterized by the following:
- Small, thin walled cuboidal closely arranged
cells.
- Multiply by the process of cell division.
- The cells without intercellular spaces.
- Newly formed cells may become
differentiated into mature permanent tissues.
I-Temporary tissues

• Located:
- near tips of roots
- in buds at tips of stems (apical meristems)
- between wood and bark of trees.
- model joints of such plants as grasses.
- and wherever extensive growth occurs.
• Apical Meristem:
- involved in primary plant body.
i.e.: - protoderm develop to give epidermis.
- procambium give xylem and phloem.
- ground meristem develop to give cortex,
pitch which give rise to primary plant tissues.

• Lateral Meristem (Secondary Tissue):
• Vascular cambium develops into xylem and
phloem
• Cork cambium develops into phellogen,
periderm, cork and cork parenchyma.

• usually don’t change into other kind of tissues
• In most cases retain their structure and
functional characteristics throughout life.
• Simple tissues:
• formed of one kind of cells mainly constructed
similarly and performing one kind of function.
II-Permanent tissues

• 1- Epidermis (epi- : upon, derma: skin):
- usually one cell thickness where cells are
usually colourless.
- Guard cells which control gas movement
through epidermal pores called (Gr. Stoma
opening).
- Possess chlorophyll in bodies called
chloroplasts.
- Outer cell walls often coated by a waterproof,
waxy cutin (cuticle).

• Exceptions:
• a- Epidermal cells of roots have extensions
called root hairs.
• b- Some epidermal cells are modified i.e.
exhibit secretory function.
• c- Some epidermal cells of the plant parts
have epidermal hairs above ground form
outgrowths of one or several cells.

• 2- Ground tissue:
• a- Parenchyma; (Greek, para-: besides, en- in,
chin: pour):
• consists of thin walled cells that are
approximately isodiametric
• e.g. not much longer than they are wide.
• The individual cells may be spherical, cubical,
many sided or irregular in shape, they contain
living protoplasm and retain their property of
cell division even tough division may never
occur after the cells are mature.

• The presence of living protoplasm also means
they can function in the storage of water and
food, or in photosynthesis and even secretion,
in wound healing
• They are found abundantly in higher plants in
roots, stems, leaves, fruits and flowers.
• Green chlorophyll bearing parenchyma cells of
leaves and green stems are called
chlorenchyma.

An Introduction to pharmacognosy

An Introduction to pharmacognosy

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An Introduction to pharmacognosy