DEFINITION:
Extration may be defined as the
process in which animal or plant tissue are treated with specific solvents by
using extraction process medically active constituents are dissolved out.
METHOD OF EXTRATION:
For extraction process there
are various method which include the following.
Extraction
with organic solvents:
*Percolation
*Maceration
*Extraction
using soxhlet apparatus
Extraction
with water
*Infusion
*Decoction
*Digestion
*Steam distillation
Other
methods include
*Super critical fluid extraction and
phytonocs
*Spouted extraction
*Vertical or turbo extraction
*Ultra sound extraction
*Counter current extraction
*Successive solvent extraction
EXTRATION WITH ORGANIC
SOLVENTS:
PERCOLATION:
Exhaustive extraction or percolation
is defined as complete removal of desired extractive substances from the drug
substances (material)
GENERAL METHOD FOR EXTRACTING
BOTANICALS:
Moisten 1000gms of powdered botanical
with sufficient quantity of prescribed menstrum to render it evenly and
distinctly damp
Macerate
for 6hrs in light covered containers(this will enable the plant cells to absorb
the menstrum)
Then
pack in cylindrical percolator
Add
enough menstrum to saturate powder and leave stratum above it.
When
the liquid begins to drop from percolator close. The lower surface cover the
percolator and macerate for prescribed time(48hrs)
Then
open (hofmann clamp) valve and allow the percolation to proceed slowly.
Collect
the preserve first 850ml
Continue
percolation by gradually adding more menstrum over the herb until botanical is
exhausted.
Recover
the alchol from the reminder of percolate and concentrate to soft extract in a
vaccum apparatus at a temperature exceed 450 c
Dissolve
this residue in the reserved portion of percolate,mix thoroughly add a
sufficient quantity of menstrum to make fluid extract measure 1000ml (k)and
filter.
MACERATION:
Maceration is defined as soaking in
botanical in suitable solvent for a specified period of time any where from
several hours to 3 weeks until solute portions are dissolved in menstrum or
maceration is a process of extraction of drug with a solvent with several daily
shaking or stirrings at room temperature.
PROCEDURE:
Solid ingredients+750ml of perscrised
solvent.
Allow
to stand for a period of atleast one week in warm place with free quent
agitation for proper dissolution.
Filter the mixture.
Residue wash with sufficient quantity
of solvent.
Combine filtrates make upto 1000ml.
ADVANTAGES:
*Small
samples are prepared in exactly the same way as technical and production
holders.
*highly
versatile.
*Drugs
passing through smelling(strong)properly or high mucous content can be
processed.
HOT
CONTINOUS EXTRATION SOXELATION:
Convinent way to thimble in central
plant extract eith pure solvent.
+
PROCEDURE:
Material is placed in thimble in
central compartment with sulphoning device and side arm connected to lower
compartment.
Solvent placed in central compartment
Solvent is heated to boiling
Vapour passing through side arm into
reflux condenser
Vapour gets condensed and liquefied
and drops into thimble containing the material to be extracted
Warm solvent percolates through the
material and wall of thimble
The extract is gradually collected in
central compartment
On reaching the top of siphon the
entire liquid in central compartment flows through this and back into lower
solvent container
Process in thus repeated.
APPLICATIONS:
Useful for exhaustive extraction of
plant with a particular solvent
Eg: defalting or where 100%
yield of a particular component is desired.
Also useful for exhaustive sequential
extraction with series of solvents of increased
polarity
is desired.
Eg:Hexane,chloroform,and
water.
DISADVANTAGES:
Due
to continous recycling the extract that collects in lower container is
continously being heated that may suffer thermal degradation reaction.
If
the operation is carried out on a large scale it may not be suitable for use
with solvents with relatively high boiling points such as methanol or
water,since the whole apparatus below the condenser needs to be at this
temperature for effective movement of solvent vapour.this method is limited for
pure solvents or azeotropic mixture.
EXTRATION
WITH WATER
INFUSION:
It is a dilute solution of readily
soluble constituents of crude drugs.
PROCEDURE:
Moisten 60gms of herb cut coarsely
ground in 1lit distilled water.
Allow to stand for 15min and then add
the balance of litre of boiling water.
Cover the vessel tightly and allow
standing approximately for 30minutes.
Strain the mixture and pass water to
make infusion mixture 1 litre.
Filter refrigerate or preserve.
DISADVANTAGES:
Difficult to standardize and are
unstable and particularly susceptible to attack by various drugs and bacteria.
2.DECOCTION:
This process extracts vegetable
substances or substances that contain water soluble constituents from crude
drugs by boiling in water for 15min.coating straining and passing sufficient
cold water through drug to produce required volume.
PROCEDURE:
Cut the powdered herb(60gms) and place
in suitable vessel.
1lit of cold water preferably
distilled is placed over it.
Cover the vessel well and boil the
mixture for 15min.
Allow to cool and then strain through
muslin cloth and pass enough cold water through strainer to make the product
measure it.
Filter,refrigerate or preserve.
3.DIGESTION:
This is form of maceratin in which
gentle heat is used during process of extraction.
ADVANTAGE:
It is used when moderately elevated
temperature is not objectionable and the solvent efficiency of menstrum
increased there by.
4.STEAM
DISTILLATION,EXPRESSION.EXTRATION AND ENZYMATIC HYDROLYSIS:
METHOD
FOR VOLATILE OILS:
METHOD
FOR STEAM DISTILLATION AS FOLLOWS:
*Water distillation
*water
and steam distillation
*Direct steam distillation
WATER
DISTILLATION:
It is mostly applicable to such
material which is dried initially in air and the constituents are not degraded
by boiling upto 100Oc
Eg:Turpentine oil
WATER
AND STEAM DISTILLATION:
It is often suitable for such plant
material,whether fresh or dried the constituents of which degradation by direct
boiling.
Eg:clove oil,cinnamon oil
DIRECT
STEAM DISTILLATION:
It is invariably applicable to fresh
drug that is loaded with sufficient natural moisture and hence no maceration is
required.
Eg:pipperment oil,spearmint oil.
ADVANTAGES:
*Relatively
simple equipment.
*No
separate filtration step is required to separate,extrated oil from plant
material.
DISADVANTAGES:
Cannot be used where the oil contains
hydrolysable substances such as Esters (or) those that are easily oxidized (or)
decomposed by heat.
EXPRESSION:
Expression may be accomplished by four
following methods.They are as follows.
1. Spooge method.
2. Scarification method.
3. Rasping process.
4. Mechanical process.
EXTRACTION
OF VOLATILE OIL: It involves
*Extraction with volatile solvents.
*Extration with non-volatile solvents.
EXTRATION
WITH VOLATILE SOLVENTS:
Eg:Hexane,benzene
ADVANTAGES:
Maintaining an uniform temperature
during extraction process ensures retention of more intenses and natural
fragnance.
Flueal concretes-represent an
admixture of natural odoriferous components of flowers ,plant waxes,colour
pigments and certain albuminous material.
EXTRATION
WITH NON-VOLATILE SOLVENTS:
Three methods adopted for extraction
they are as follows
*Enfleuraga method
*Pnematic method
*Maceration method
OTHER
METHODS
1)SUPER
CRITICAL FLUID EXTRACTION:
It is process of separating one component
from another using super critical fluids as extracting solvent.
ADVANTAGES:
*Environmental improvement and reduce
product contamination.
*Selectively
*Speed
DISADVANTAGES:
*Use of high sophisticated equipment
*High pressure and high temperature is
required.
2)SPOUTED
BED EXTRATION:
This is a process meant for physical
removal of pigment layer which gives a better product than thah obtained by
solvent extraction.
Eg:production of annatto powder from
seeds of Bixaorellana
3.VORTICO
OR TURBO EXTRACTOR:
A method adopted to reduce the length of time involved is simple
maceratin process.
Eg: cinchona bark.
DISADVANTAGES:
*Temperature may rise due to high
speed stirring.
*Equilibrium separation of drug
residues from miscelles is difficult.
4.ULTRA
SOUND EXTRACTION:
It is defined as frequencies above
20,000 HZ waves used to accelerate extraction.
Eg:play a major role in decomposition
of alkaloid’s in Jaborandi observed after 30s ultra sound treatment on
laboratory scale at 20 HZ.
EXTRATION
BY ELECTRICAL ENERGY:
Eg:Extration of scopolamine from seeds
and throns of thorn apple.
5.COUNTER-CURRENT
METHOD(EXTRACTION):
It is a process in which plant
material is in a contact with charged solvent at same time as fresh solvent is
being brought contact in with pre extracted drug.
APPLICATION:
Alkaloids,Amino
acids,Antibiotics,Phenolic including anthroquinone derivates,cardiac
glycosides.PGS.Steriods,F.A,essential oils and vitamins.
6.SUCCESSIVE
SOLVENT EXTRACTION:
*This is meant for air dried material.
*Based on increasing order of
polarity.