Cultivation and preparation of crude drugs
3- Preservation of plant material (Drying, stabilization and fermentation)
6- Grinding of crude drugs
7- crude drug extraction
Cultivation and preparation of crude drugs
3- Preservation of plant material (Drying, stabilization and
6- Grinding of crude drugs
7- crude drug extraction
3. Medicinal plants class. acc. to
Wild Plants or Cultivated Plants.
Medicinal plants class. acc. to native
Indigenous plants grown in native land e.g.
Aconitum napellus in the mountains of
Naturalized plants grow in a foreign land
e.g. Datura stramonium introduced from
Europe to U.S.A.
4. Disadvantages of Collection of Drugs from Wild
1- Distributed over wide areas so there are
difficulties in collection and transportation because
they are mostly growing in deserts, or forests far
from any means of transport.
2- Collection by unskilled collectors may lead to
adulteration by collection of:
a- The desired plant with unwanted plants
b- Undesirable organ of the desired plant
c- The desired plant at improper time.
5. 3- Market Supply:
Continuous extensive collection may lead to
extinction or a serious deficiency of the plant and
insufficient for the market needs and may lead to
6. Advantage of cultivation of medicinal
1- Concentration of a large number in a small
area and therefore simplifying collection.
2- Control of the purity of the product (i.e. gives
drugs with maximum purity).
3- Cultivation assures a regular and constant
market supply and helps to break down
7. 4- Improvement of the drug by controlling
certain factors in cultivation as:
I- Treatment of seeds before sowing to ensure
germination, e.g., soaking hyoscymus seeds in
sulphuric acids fasten germination.
II- The use of fertilizers which increase the
active constituents of the plant, by providing the
essential elements for plants nutrition such as N, P
III- Controlling insect's infestations.
5- It is essential in the case of plants subjected to
governmental control e.g. opium
8. Disadvantage of cultivation of medicinal plants:
1- High cost of production; high cost of labour and
2- Adverse weather conditions such as floods,
drought, pests, insects and diseases.
3- Some medicinal plants require imitation to
particular habitat, e.g.
- Cannabis requires tropical climate production of
- Cinchona requires damp hot weather.
- Aloes require a heavy rain fall.
9. PROPAGATION OF MEDICINAL PLANTS
Vegetative propagation (Cutting, Division, Layering,
Budding and Grafting).
Cell and organ cultures and clonal propagation of
medicinal plants as sources of drugs
10. 2- COLECTION OF MEDICINAL PLANTS:
Suitable time for collection(why?)
- The qualitative and quantitative active constituent composition of
plants may change greatly (not constant) during the course of
1- Growing season (Time of the year).
2- Time of the day.
3- Stage of maturity.
- To ensure maximum quality of a medicinal plant, It must be
collected at a proper timing and stage of development.
- The active constituents may be distributed in
1- All parts of the plant or
2- concentrated in certain organs or in specific tissues of these
11. Factors affecting collection of
I- Growing season (Time of the year):
Rhubarb contains anthranols in winter
and anthraquinones in summer.
note: anthranol and anthrones are
stronger laxative than anthraquinone.
Colchicum corms have no alkaloids in
autumn but rich in alkaloid in spring.
12. II- Time of the day:
Digitalis leaves collected in the
afternoon contain more glycosides
than those collected in the morning.
Solanaceous leaves have higher
alkaloidal content in the morning
than those collected in the afternoon.
Salep tubers are collected in the
morning due to higher mucilage
13. III- Stage of maturity:
The unexpanded flower-heads of
santonica contains 3% of
anthelmintic principle called
"santonin". When the flower heads
start to open, the santonin
percentage start to decrease.
Clove is collected as flower buds
with the highest percentage of
All solanaceous leaves contain
higher alkaloid content when the
plant is in the flowering stage
14. Rules for collection
Leaves and herbs
Are collected at the beginning of the flowering stage when
they contain the optimum percentage of their active
Collection should be done in dry weather, as wet weather
may cause deterioration and discoloration during drying. e.g.:
1- Senna leaves: The whole plant is cut and the leaves are
picked off after drying in the sun.
2- Digitalis leaves: They are gathered directly from the plants.
3- Coca leaves: they are gathered directly from the plants
when nearly ready to fall from the stem.
4- Tea leaves: The best quality is collected when still in the
- Are usually gathered when fully developed, just at the time
of pollination and before the formation of fruits.
1- Cloves and Santonica are collected while in bud stage.
2- Chamomile flower are collected just after full expansion.
Fruits فاكهة وليست ثمرة
Near the ripening season, when they are fully mature but
not completely ripened, (i.e. before ripening)
Collected when fully ripe (i.e. separated
from the pericarp)
Is collected in the spring or in early
summer when the cambium is active and the
bark can be easily stripped off from the trunk
Roots and rhizomes
Are collected at the end of the vegetation
period, i.e. usually in the autumn. In most
cases they must be washed free of adhering
soil and sand.
17. Preparation and curing of drugs before
After collection of crude drugs, they need
some sort of preparation before drying.
5-Curing of drugs.
the outer layers (cork and cortex) of Cinnamon is
a- Lack or low percentage of active principles.
b- Presence of unrequired constituents in the
Bleaching (color removal)
a- Bleaching by exposure to sunlight, such as:
The red algae "Carrageen" appears in commerce
as a pale cream colored.
b- Bleaching by coating with a layer of inert
substance such as CaCO3 or CaSO4 for ginger
19. Curing of drugs
It is a process of inducing some desirable
changes in the drug after collection and before
drying by enzymatic action, example:
Tea leaves: To set free soluble caffeine and to
oxidize tannin into insoluble products.
Vanilla pods: To set free vanillin.
Gentian root: To yield less bitter drugs.
21. Preservation (why?)
The plant material must first be preserved so that the active
compounds will remain unchanged during transport and
The cells of living plants contain not only low molecular-
weight compounds and enzymes, but they also have many
kinds of barriers that keep these constituents apart.
When the plant dies, the barriers are quickly broken down
and the enzymes then get the opportunity to promote
various chemical changes in the other cell constituents, e.g.
by oxidation or hydrolysis.
22. A- Drying of Crude Drugs
Moisture must be removed in order to:-
1- Stop the enzymatic action that might change the active constituent.
2- Avoid deterioration upon storage by preventing the growth of
microorganisms (bacteria and fungi).
3- Facilitate packing and storage.
4- Lower the transportation cost as the weight of the drug is greatly reduced.
5- Comply the pharmacopeial requirements for maximum moisture contents.
In a dried drug the enzymes are not destroyed but only rendered inactive
due to the low water content, As soon as water is added, they become active
again. Hence, dried drugs must be protected from moisture during
23. Methods of drying:
a) Direct fire.
a) Sun drying
b) Shade drying
c) Drying champers.
d) Vacuum drying.
e) Freeze drying lyophilization.
When the crude drug has been collected under primitive conditions, without
access to a drier, it must be dried in the open.
Even then, the material should be spread out in shallow layers with good
ventilation to facilitate the drying.
The choice of sunshine or shade is determined by the sensitivity to light of the
24. Tunnel drier (drying chamber):
The most efficient drying is achieved in large
driers of the tunnel type.
The plant material is spread out on shallow
trays, which are placed on mobile racks and
passed into a tunnel where they meet a stream
of warm air. The air temperature is kept at 20-40
°C for thin materials such as leaves, but is often
raised to 60-70 °C for plant parts that are harder
to dry, e.g. roots and barks.
25. Precaution 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.
Digitalis leaves must be dried rapidly in vacuum ovens at about
2- Flowers must be dried rapidly at low temperature in shade or
in, drying chambers to retain their color.
3- Fruits and seeds are spread on trays and dried in sun or shade.
4- Barks, large roots and rhizomes are dried in sun and rhizome
are generally sliced transversely or longitudinally to facilitate
26. Freeze-drying (lyophilization) is a very mild
method.Frozen material is placed in an evacuated apparatus
which has a cold surface maintained at -60 to -80 °C. Water
vapor from the frozen material then passes rapidly to the
cold surface.The method requires a relatively complicated
apparatus and is much more expensive than hot-air drying.
For this reason, it is not used as a routine method, but it is
very important for drying heat-sensitive substances, e.g.
antibiotics and proteins.
Advantage of lyophilization:-
1- Prevents chemical and enzymatic changes in the chemical
2- Prevents oxidative changes of substances that are usually
oxidized if dried by other means.
27. B- Stabilization of Crude Drugs
On long storage, enzymatic reactions will slowly destroy the constituents,
because the last traces of water can never be removed.
In order to avoid this degradation, the enzymes should be destroyed before
drying, a process usually called stabilization.
The most common method being brief exposure (a few minutes only) of the
plant material to ethanol vapor under pressure (0.5 atm).
Stabilization may be of value for the isolation of compounds that are very
susceptible to enzymatic degradation.
28. C- Fermentation of Crude Drugs
- Enzymatic transformation of the original plant constituents is
- The fresh material is then placed in thick layers, sometimes covered and
often exposed to raised temperatures (30-40 °C) and humidity, so as to
accelerate the enzymatic processes. (This treatment is usually called
- The fermented product must, of course, be dried afterwards to prevent
attack by microorganisms, e.g. moulds.
- Fermentation is mostly used to remove bitter or unpleasant tasting
substances or to promote the formation of aromatic compounds with a
pleasant smell or taste.
- It is mainly applied to drugs used as spices or stimulants, e.g. vanilla, tea
29. 4- PACKING OF THE CRUDE DRUGS
Packing of the drugs should be done in such a way that:
1- Helps in saving space during transportation and storage
2- Provides sufficient protection to the drugs.
5- STORAGE OF CRUDE DRUGS
There are great differences in the stability of crude drugs because of slow
enzymatic changes in the constituents.
- Drugs containing glycosides and esters are usually less stable than those
6-GRINDING OF CRUDE DRUGS
- Regardless of whether the crude drug is to be used for isolation of a pure
compound or for manufacture of a simple preparation, the first operation that
must be performed is grinding of the plant material to a powder of suitable
30. 7. Extraction of Crude Drugs
Types of extracts
- Dry extracts for solid pharmaceutical dosage form e.g. capsules and tablets
- Tinctures and fluid extracts for liquid pharmaceutical dosage form e.g.
There are many procedures for obtaining extracts like:
1- Maceration. 2- Percolation. 3- Infusion. 4- Decoction.
5- Digestion. 6- Continuous hot extraction, 7- Solvent-solvent precipitation.
8- liquid-liquid extraction.
10- Specific procedures.