EXTRACTION PROTOCO

LS
 Extraction

• Is the separation of medicinally active porti

ons of plant (and animal) tissues using selec
tive solvents through standard procedures.

• The products so obtained from plants are r

elatively complex mixtures of metabolites, i
n liquid or semisolid state or in dry powder
form (after removing the solvent), & are int
ended for oral or external use.
 Medicinal plants
• The Medicinal plants constitute an effectiv
e source of both traditional and modern m
edicines, herbal medicine has been shown
to have genuine utility and about 80% of r
ural population depends on it as primary h
ealth care. [WHO, (2005)]
Medicinal plants are the richest bi
o-resource
 drugs of traditional systems of medicine,
 modern medicines,
 nutraceuticals,
 food supplements,
 folk medicines,
 pharmaceutical intermediates,
 chemical entities for synthetic drugs.
 Choice of solvents
• Successful determination of biologically activ
e compounds depends on the type of solvent
used in the extraction procedure.

• The choice of solvent is influenced by what is

intended with the extract.
Properties of a good solvent in pl
ant extractions
 low toxicity,
 ease of evaporation at low heat,
 promotion of rapid physiologic absorption of
the extract,
 preservative action,
 inability to cause the extract to complex or di
ssociate.
Solvents used for active component extraction
 Water
• Water is universal solvent.
• used to extract plant products with antimicrobial a
ctivity.
• Traditional healers use primarily water & consisten
t antimicrobial activity is obtained.
Plant extracts: organic solvents >>> water extract.
• Water soluble flavonoids (mostly anthocyanins) ha
ve no antimicrobial significance.
• only water soluble phenolics are important as
antioxidant compound.
 Acetone
• Dissolves many hydrophilic and lipophilic compo
nents.
• a very useful extractant, especially for antimicrobi
al studies (phenolic group extract).
• extraction of tannins + phenolics:
aqueous acetone >>> aqueous methanol
• Both acetone and methanol were found to extract
saponins  antimicrobial activity.
 Alcohol
• The identified components from plants (antimicrobia
l) = aromatic or saturated organic compounds  most
often obtained through initial ethanol or methanol ext
raction.
• Ethanol, found easier to penetrate the cellular membr
ane to extract the intracellular ingredients(polypheno
ls) from the plant material.
• Methanol is more polar than ethanol but due to its cyt
otoxic nature.
• The higher concentrations of more bioactive flavonoi
d compounds were detected with ethanol
70% due to its higher polarity than pure ethanol.
 Chloroform
• Used to obtain tannins and terpenoids.

• Terpenoid lactones successive extracti

ons of dried barks with chloroform.
 Ether

• Commonly used selectively for the extra

ction of coumarins and fatty acids.
 Dichloromethanol
• Specially used for the selective extraction of
only terpenoids.
Steps Involved in the Extra
ction of Medicinal Plants

1. Size reduction
2. Extraction
3. Filtration
4. Concentration
5. Drying
 Extraction

Medicinal plants Aromatic plants

1. Cold aqueous percolation 1. Essential oils
2. Hot aqueous extraction 2. Concretes
(decoction) 3. Bsolutes
3. Solvent extraction 4. Pomades
(cold / hot) 5. Esinoids
 Selection of plant
• Plant based natural constituents can be derived f
rom any part of the plant like bark, leaves, flowe
rs, roots, fruits, seeds, etc.
• Plants are usually air dried to a constant weight
before extraction.
• oven drying: every part were cut into pieces d
ried in an oven @ 60°C for 9 hrs. & pulverized.
• Other method for drying the plants is the oven d
rying at about 40°C for 72 h.
The general techniques of medicinal
plant extraction
 maceration,
 infusion,
 percolation,
 digestion,
 decoction,
 hot continuous extraction (Soxhlet),
 aqueous-alcoholic extraction by fermentation,
 counter-current extraction,
 microwave-assisted extraction,
 ultrasound extraction (sonication),
 supercritical fluid extraction,
 phytonic extraction (with hydrofluorocarbon solvent
s).
 Maceration
• The whole / coarsely powdered crude drug is place
d in a stoppered container with the solvent.
• Allow to stand @ room temperature for a period of
at least 3 days with frequent agitation until the sol
uble matter gets dissolved.
• The mixture then is strained, the marc (the damp s
olid material) is pressed,
• The combined liquids are clarified by filtration or d
ecantation after standing.
• This method is best suitable
for use in case of the
thermolabile drugs.
 Infusion
• Fresh infusions are prepared by macerating t
he crude drug for a short period of time with
cold or boiling water.
• These are dilute solutions of the readily solub
le constituents of crude drugs.
 Digestion
• This is a form of maceration in which gentle
heat is used during the process of extraction.
• It is used when moderately elevated temperat
ure is not objectionable.
• The solvent efficiency of the menstruum is th
ereby increased.
Image=microwave
Digestion system
 Decoction
• In this process, the crude drug is boiled in a specifie
d volume of water (1;4) for a defined time,
• Volume is reduced to 1/4th the original,
• It is then cooled and strained / filtered.
• This procedure is suitable for extracting  water-s
oluble, heat-stable constituents.
• Typically used in preparation of Ayurvedic extracts
= “quath” / “kawath”
 Percolation
• Used most frequently to extract active ingredients in th
e preparation of tinctures and fluid extracts.
• The solid ingredients are moistened with an appropria
te amount of the specified menstruum,
• Allowed to stand for approximately 4 hours in a well c
losed container, After stand time, the mass is packed &
the top of the percolator is closed.
• the mixture is allowed
• to macerate in the closed
percolator for 24 h.
Hot Continuous Extraction (So
xhlet)
• The finely ground crude drug is placed in a por
ous bag or “thimble” made of strong filter pape
r, which is placed in chamber of the Soxhlet ap
paratus.
• The extracting solvent in flask is heated, and its
vapors condense in condenser.
• The condensed extractant drips into the thimbl
e containing the crude drug & extracts it by co
ntact.
 Soxhlet apparatus
• When the level of liquid in chamber rises to the to
p of siphon tube, the liquid contents of chamber si
phon into flask
• This process is continuous and is carried out until
a drop of solvent from the siphon tube does not le
ave residue when evaporated.