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Extraction
 Extraction, as the term is used pharmaceutically, involves
the separation of medicinally active portions of plant or
animal tissues from the inactive or inert components by
using selective solvents in standard extraction procedures.
Extraction may be defined as the treatment of the plant or
animal tissues with solvent, whereby the medicinally
active constituents are dissolved, and most of the inert
matter remains undissolved.
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 The products so obtained from plants are relatively impure
liquids, semisolids or powders intended only for oral or
external use.

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Purpose
The purposes of standardized extraction procedures for
crude drugs are to attain the therapeutically desired
portion and to eliminate the inert material by treatment
with a selective solvent known as menstruum.
The extract thus obtained may be ready for use as a
medicinal agent in the form of tinctures and fluid extracts,
it may be further processed to be incorporated in any
dosage form such as tablets or capsules.

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  It may be fractionated to isolate individual chemical
entities such as ajmalicine, hyoscine and vincristine, which
are modern drugs.
 Thus, standardization of extraction procedures contributes
significantly to the final quality of the herbal drug.

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 General Terms Used
• Menstrum: Solvent used for extraction is known as menstrum. Eg;
Water, Alcohol, Ether.
• Marc: The inert fibrous and other insoluble materials remaining after
extraction.
• Extracts: Preparations of liquid (Tinctures), Semisolid (soft extracts),or
Solid (dry extract)
• Tinctures: alcoholic or hydro-alcoholic solutions prepared from
vegetable material or from chemical substances. E.g. belladonna tincture
• Expression is the physical act of applying pressure to squeeze out
oils or juices from plants. This was normally achieved with a
tincture press.
General Method of
Extraction
1. Communition (reducing substances to small size)
2. Penetration of the crude drug by menstrum
3. Dissolution of the active principles by menstrum
4. Diffusion of the dissolved active principles
5. Separation of the dissolved active principles from the
marc by filtration or expression.

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Grinding
1. Large particles take a longer time for complete extraction than
small ones and large differences in particle size thus slow
down the extraction process.
2. Several types of machines are available for grinding crude
drugs:
3. Hammer mill; a common type for grinding crude drugs.
4. Knife mill; is useful for production of low-dust powders of
leaves, barks and roots for subsequent percolation or
maceration.
5. Tooth mill; is used for production of very fine powders.

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Grinding Cont…..
1. Grinding produces a certain amount of heat which must be
observed when grinding crude drugs containing heat-
sensitive compounds.
2. Mills cooled with liquid nitrogen are available for such
purposes.
3. Cold grinding is also preferable for crude drugs containing
volatile oils.
4. Following grinding, the material must be sifted to ensure the
proper particle size.

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Choice of
Menstrum
Highly selective for the compound to be
extracted
Not
 High capacity for extraction
react with the extracted or with other
compound compounds in the plant
material
Have low price
Harmless to the man and to the
environment
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Completely volatile.
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Generally used
Solvents
Water
Aliphatic alcohols with up to three Carbon
atoms
Ether
Chloroform
Glycerin

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Difference Between Water and
Alcohol WATER ALCOHOL
Advantages: Advantages:
•Cheap •Selective
•Non toxic •No additional preservatives
•Non Inflammable required
•Non toxic

Disadvantages: Disadvantages:
•Non-Selective •Costly
•Promote Hydrolysis
•Promote enzymatic
degradation
•Good media for microbial
growth
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 Solvents for
Extraction
Aliphatic alcohols with up to three carbon atoms, or
mixtures of the alcohols with water, are the solvents with
the greatest extractive power for almost all natural
substances of low molecular weight like alkaloids,.
According to the pharmacopoeias, ethyl alcohol is the
solvent of choice for obtaining classic extracts such as
tinctures and fluid, soft and dry extracts

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 Solvents for
Extraction
 The ethanol is usually mixed with water to induce
swelling of the plant particles and to increase the
porosity of the cell walls which facilitates the diffusion of
extracted substances from inside the cells to the
surrounding solvent.
For extraction of barks, roots, woody parts and seeds the
ideal alcohol/water ratio is about 7:3 or 8:2.
For leaves or aerial green parts the ratio 1:1 is usually
preferred in order to avoid extraction of chlorophyll.
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 Various Methods of
Extraction
Maceration
Percolation
Infusion
Decoction(for water soluble/thermostable constitutes)
Digestion (similar to maceration)

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Maceration
The term maceration comes from the Latin macerare,
meaning to soak.
This simple widely used procedure involves leaving the
pulverized plant to soak in a suitable solvent in a closed
container.

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Definition
It is a process in which the properly comminuted drug is
permitted to soak in the menstruum until the cellular
structure is softened and penetrated by the menstruum and
the soluble constituents are dissolved.

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Purpose of
maceration
The main purpose of maceration is the extraction of drugs
from the plants.
With the maceration extraction method, the flowers are
soaked in a hot oil to have their cell membrane ruptured
and hot oil than absorb the essence.

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Process
In the maceration process, the drug to be extracted is
generally placed in a wide-mouth container with the
prescribed menstruum (drug solvent ratio: 1:5 or 1:10), the
vessel is stoppered tightly, and the contents are agitated
repeatedly over a period usually ranging from 2 to 14 days
(Minimum 3 days).
Plant material (crushed or cut small or moderately coarse
powder) if necessary.
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 The agitation permits the repeated flow
of fresh solvent over the entire surface
area of the comminuted drug.
An alternative to repeated shaking is to
place the drug in a porous cloth bag that
is tied and suspended in the upper
portion of the menstruum, much the
same as a tea bag is suspended in water
to make a cup of tea.
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  As the soluble constituents dissolve in the menstruum,
they tend to settle to the bottom because of an increase in
the specific gravity of the liquid due to its added weight.
Occasional dipping of the drug bag may facilitate the speed
of the extraction.

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 The extractive is separated from the marc by expressing the
bag of drug and washing it with additional fresh
menstrum, the washings being added to the extractive.
The process is repeated for once or twice with fresh solvent.
They are also known as galenic formulations
(galenicls), in honor to Claudius Galen the precursor of
preparing drugs from plants.

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Application of maceration
 The method is suitable for both initial and bulk
extraction.

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Multiple Maceration
Multiple maceration is aimed at achieving maximum extraction
by using portions of total volume of men strum for successive
maceration.
The drug: menstruum ratio is low.
Double Maceration = Volume divided into 2 equal portions
Triple Maceration = Volume divided into 3 equal portions

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Percolation
 Percolation is derived from the Latin word
“per” meaning through and “colare” meaning to strain.

 Percolation is a process in which comminuted drug is

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Percolation Introduction
During percolation the drug is
packed in special suitable
apparatus termed as “Percolator”
The collected extractive is called
as “Percolate”
Most of the drug extractions are
performed by Percolation.
Ex. Preparation of Coffee
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Percolators
Percolators vary in their size, shape, capacities,
composition and utility.
For industrial scale (Large scale extraction) mainly stainless
steel and glass-lined metal percolators are used having
different size and operation.
Percolators used for extraction of leaves have 6-8 feet in
diameter and 12-18 feet in height.

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 Percolator

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Percolators
Sometimes percolators are also equipped with pressure that
is used to force the menstruum through the drug column.
On small scale, glass percolators (capacity up-to
1,000g) may be used
The shape of such percolators are different including;
Cylindrical (use less amount of menstruum)
Roundish
Conical or funnel shaped

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Advantages
More complete extraction of constituents
Shorter processing time
Increased flexibility in processing.

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Disadvantages
fine powders and materials such as resins and plants that
swell excessively (e.g., those containing mucilages) can clog
the percolator.
if the material is not distributed homogenously in the
container, the solvent may not reach all areas and the
extraction will be incomplete.
Incompatibility of percolation with certain herbs
Additional complexity in processing
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Percolation Process
It mainly consist of following
steps;
1. Size reduction
2. Imbibition
3. Packing
4. Maceration
5. Percolation

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Size Reduction
The drug to be extracted is subjected to suitable degree of
size reduction, usually from coarse powder to fine powder;
 To increase the surface area of the drug exposed to
the menstruum,
 For uniform packing of the percolator,
 To ensure complete exhaustion of the drug.

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Imbibition
During imbibition the powdered drug is moistened with a
suitable amount of menstruum and allowed to stand for four
hours in a well closed container.
During this period the drug swells up as the menstruum
penetrates the cell walls. The preliminary moistening of the drug
is necessary because:
 The dried tissue swells when it comes in contact with the
menstruum but if packed in the dry condition subsequent
swelling will reduce the porosity of the material and choke the
percolator,
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Imbibition Cont….
 The air present in the interstices (in between particles) is
removed by menstruum, which will otherwise disturb the
packing of the percolator due to which the menstruum
will run through the channels results in inefficient
extraction,

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Packing
After imbibition the moistened drug is evenly packed into
the percolator.
The packing should not be too tight, it will lead to slow
extraction rate. Similarly, loose packing will allow the
menstruum to pass through quickly resulting in
incomplete contact with the drug.
The drug should occupy 2/3rd capacity of the percolator.

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Maceration
After packing sufficient menstruum is added to saturate the
material. When the liquid begins to drip from the bottom
of the percolator, the tap fitted at its bottom is closed.
 More menstruum is added if required
The percolator is allowed to stand for 24 hours to macerate
the drug.

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Percolation
After 24 hours maceration, the lower tap is opened and
liquid collected therein is allowed to drip slowly at a
controlled rate until 3/4th volume of the finished product is
obtained.
Sufficient amount of menstruum is simultaneously added
over the drug because at no time packed material should
be allowed to become dry.
After collecting 3/4th volume, the percolate is tested for
complete exhaustion of the drug by various tests.
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Percolation Process
The outlet of the percolator then is opened and the liquid
contained therein is allowed to drip slowly.
 Additional menstruum is added as required, until the
percolate measures about three-quarters of the required
volume of the finished product.
The marc is then pressed and the expressed liquid is added to
the percolate.
Sufficient menstruum is added to produce the required volume,
and the mixed liquid is clarified by filtration or by standing
followed by decanting.

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Complete Extraction
Test
Tests to check complete exhaustion of the drug:
Take a few ml of the last percolate and evaporate to dryness,
it no residue remains - it shows that the drug is
completely exhausted.
Specific chemical tests may be performed on the percolate
for the drugs containing alkaloids, glycosides, tannins,
resins or bitter constituents.

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Examples
Tincture of belladonna
Compound tincture of cardamom
Strong tincture of ginger etc.

Application of Percolation
 The method is suitable for both initial and bulk
extraction.
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Continuous Extraction
This procedure is considered as the most common method
used for the extraction of organic constituents from dried
plant tissue.
Soxhlet extraction Apparatus is commonly used for
continuous extraction.
It can be used both on laboratory and industrial scales.

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Soxhlet Apparatus
A piece of laboratory apparatus invented in 1879 by Franz
von Soxhlet.
Originally designed for the extraction of a lipid from a
solid material.
However, a Soxhlet extractor is not limited to the extraction
of lipids.
 Typically, a Soxhlet extraction is only required where the
desired compound has a limited solubility in a solvent, and
the impurity is insoluble in that solvent.
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Parts
The apparatus consists of three parts-
 A flask: For boiling of solvent.
 ASoxhlet extractor: Having drug in
thimble,
the a side tube & siphon tube
 A reflux condenser: For condensation
of vapors
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SOXHLET APPARATUS
Thimble

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Different Parts

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Labelled Diagramme

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Workin
gIn this method, the finely ground crude drug is placed in a
porous bag or “thimble” made of strong filter paper, of the
Soxhlet apparatus.
The extracting solvent in is heated, and its vapors
flask condense in condenser .
The condensed extractant drips into the thimble containing
the crude drug, and extracts it by contact.

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Workin
g When the level of liquid in chamber rises to the top of
siphon tube , the liquid contents of chamber siphon into
flask.
This process is continuous and is carried out until a drop
of solvent from the siphon tube does not leave residue
when evaporated.
The advantage of this method, compared to previously
described methods, is that large amounts of drug can be
extracted with a much smaller quantity of solvent.
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Video Demonstration

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Advantages
 The advantage of this method, compared to previously
described methods, is that large amounts of drug can be
extracted with a much smaller quantity of solvent.

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References
Remington’s Pharmaceutical Sciences.
Cooper & Guns Dispensing
Cooper & Gun’s Tutorial.
Bentley’s Text Book of Pharmaceutics.
 http://www.fkog.uu.se/course/a/biolakt/biolakt-archive/BiolAkt%202010-
2/StudentpresentationerHT2010%20%28kopia%29/BiolAktHT2010_Extraktion
NatProd_Yassir_Suzan/Extraction%20of%20natural%20products_files/Page470.
htm
 https://www.inkling.com/read/ansel-pharmaceutical-dosage-form-drug-

delivery-9th/chapter-13/extraction-methods-for.
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