Extraction, Distillation & Other processes involved in the Purification & Preparation of Active Constituents from Medicinal Plants

1. EXTRACTION, DISTILLATION, EVAPORATION &
OTHER PROCESSES USED IN PURIFICATION &
PREPARATION OF ACTIVE CONSTITUENTS
FROM MEDICINAL PLANTS
Dr ARYA MOHAN
MVSc SCHOLAR
DEPT OF VPT
CV&AS MANNUTHY

2. • Asia- abundant medicinal and aromatic plant species, well
documented traditional knowledge, a long-standing practice of
traditional medicine, and the potential for social and economic
development of medicinal and aromatic plants (MAPs)
• One of the largest biodiversity regions in the world, containing
some of the richest countries in plant resources
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3. • The use of herbal medicines in Asia represents a long history of human
interactions with the environment
• Plants used for traditional medicine contain a wide range of substances
that can be used to treat chronic as well as infectious diseases
• Due to the development of adverse effects and microbial resistance to the
chemically synthesized drugs, men turned to ethnopharmacognosy
• They found thousands of phytochemicals from plants as safe and broadly
effective alternatives with less adverse effect- anticancer, antimicrobial,
antioxidant, antidiarrheal, analgesic and wound healing
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4. Medicinal Plants
• Constitute an effective source of both traditional and modern
medicine
• Food supplements
• Nutraceuticals
• Pharmaceutical intermediates
• Chemical entities for synthetic drugsPURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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5. EXTRACTION
Separation of medicinally active portions of plant or animal
tissues from inactive or inert components by using selective
solvents in standard extraction procedures
Products- impure liquids, semi solids, or
powders
Solvent used- Menstruum
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6. galenicals
Decoctions
Infusions
Fluid extracts
Tinctures
Pilular (semisolid) extracts
Powdered extracts
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7. PURPOSE
The standardized extraction procedures for crude drugs
to attain therapeutically desired portion
 to eliminate inert material by treatment with a selective solvent
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8. Extract thus obtained may be used as
medicinal agent
 Tinctures and fluid extracts
 Incorporated to any dosage form such as tablets or capsules
 Fractionated to isolate individual chemical entities
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9. Choice of solvents
• Successful determination of biologically active compounds
depends on the type of solvent used in the extraction procedure
• Influenced by what is intended with
the extract
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10. Properties of Good Solvent
• Low toxicity
• Ease of evaporation at low heat
• Promotion of rapid absorption of extract
• Preservative action
• Inability to cause the extract to dissociate
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11. Solvents used for extraction
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12. Steps Involved
Size reduction
Extraction
Filtration
Concentration
Drying
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13. Size Reduction
• Objective for powdering the plant material is to rupture its
organ, tissue and cell structures so that its medicinal ingredients
are exposed to the extraction solvent
• Size reduction maximizes the surface area, which in turn
enhances the mass transfer of active principle from plant
material to the solvent
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14. EXTRACTION METHODS

15. Factors Affecting Extraction Methods
Length of extraction period
Solvent used
Solvent pH
Temperature
Particle size of plant tissue
Solvent to sample ratio
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16. General techniques
Maceration
Infusion
Digestion
Percolation
Decoction
Soxhlet extraction
Aqueous alcoholic extraction by fermentation
Counter- current extraction
Ultrasound extraction
Supercritical Fluid Extraction
Phytonic process
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17. Maceration
• The whole or coarsely powdered crude drug is placed in a
stoppered container with the solvent
• Allowed to stand at room temperature for a period of at least 3
days with frequent agitation until the soluble matter has
dissolved
• The mixture then is strained, the marc (the damp solid material)
is pressed
• The combined liquids are clarified by filtration or decantation
after standing PURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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18. Infusion
• Fresh infusions are prepared by macerating the crude drug for a
short period of time with cold or boiling water
• These are dilute solutions of the readily soluble constituents of
crude drugs.
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19. Decoction
• The crude drug is boiled in a specified volume of water
for a defined time
• It is then cooled and strained or filtered
• This procedure is suitable for extracting water-soluble, heat-
stable constituents
• The volume is then brought down to one-fourth its original
volume by boiling during the extraction procedure
• Process is typically used in preparation of Ayurvedic extracts -
“quath” or “kawath”.
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20. Digestion
• This is a form of maceration in which gentle heat is used during
the process of extraction
• It is used when moderately elevated temperature is not
objectionable
• Solvent efficiency of the menstruum is thereby increased
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21. Percolation
• This is the procedure used most frequently to extract active
ingredients in the preparation of tinctures and fluid extracts
• Solid ingredients are moistened with an appropriate amount of
the specified menstruum
• Allowed to stand for approximately 4 h in a well closed
container
• The mass is packed and the top of the percolator is closed
• Additional menstruum is added to form a shallow layer above
the mass
• Mixture is allowed to macerate in the closed percolator for 24 h
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22. • 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
• 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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23. PURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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24. Hot extraction process
• Finely ground crude drug is placed in a porous bag or
“thimble” made of strong filter paper
• Extracting solvent in flask is heated
• Its vapours condense in condenser
• Condensed extractant drips into the thimble containing the
crude drug, and extracts it by contact
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25. • 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 residuePURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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26. Advantages
• Large amounts of drug can be extracted with a much smaller
quantity of solvent
• This effects tremendous economy in terms of time, energy and
consequently financial inputs.
• At small scale, it is employed as a batch process
• More economical and viable when converted into a continuous
extraction procedure on medium or large scale
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27. Aqueous Alcoholic Extraction by Fermentation
• Soaking the crude drug - powder or a decoction (kasaya) - for a
specified period of time
• It undergoes fermentation and generates alcohol in situ
• This facilitates the extraction of the active constituents contained in
the plant material
• Alcohol thus generated also serves as a preservative
• karpurasava, kanakasava, dasmularista
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28. PURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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29. Counter-current Extraction
• Wet raw material is pulverized using toothed disc disintegrators to produce a
fine slurry
• In this process, the material to be extracted is moved in one direction within a
cylindrical extractor where it comes in contact with extraction solvent
• The further the starting material moves, the more concentrated the extract
becomes
• Complete extraction is thus possible when the quantities of solvent and material
and their flow rates are optimized
• Finally, sufficiently concentrated extract comes out at one end of the extractor
while the marc (practically free of visible solvent) falls out from the other end
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30. Advantages
A unit quantity of the plant material can be extracted with much
smaller volume of solvent
Commonly done at room temperature, which spares the
thermolabile constituents from exposure to heat
As the pulverization of the drug is done under wet conditions, the
heat generated during comminution is neutralized by water - again
spares the thermolabile constituents from exposure to heat
 More efficient and effective than continuous hot extraction.
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31. Ultrasound Extraction
• Involves the use of ultrasound with frequencies ranging from 20
kHz to 2000 kHz
• This increases the permeability of cell walls and produces
cavitation
• Eg :- extraction of rauwolfia root
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32. Disadvantage
Higher costs
Deleterious effect of ultrasound energy (more than 20 kHz) on
the active constituents of medicinal plants through formation of
free radicals and consequently undesirable changes in the drug
molecules.
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33. Supercritical Fluid Extraction
• Super critical fluid is any substance at a temperature and pressure
above its critical point, where distinct liquid and gas phase do not
exist (304.1K & 7.38 atm for CO2)
• Can effuse through solids like a gas and dissolve material like a
liquid
• CO2 is the most commonly used SF
• Once absorbed it can easily dissolved into substance contained
within the solid similar to a liquid, provides ideal condition for
extraction with a high degree of recovery in a short period of time.PURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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34. • Dissolved substance are recovered by depressurizing.
• SFE is carried out in a cylindrical extraction vessels at a
relatively low temperature, avoids the decomposition of
thermolabile components
• CO2 being non polar organic solvents are added to alleviate the
polarity limitations
• Instead of carbon dioxide, argon is being used because it is
inexpensive and inert
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35. Why CO2 ???
At supercritical fluid state ,CO2 is neither a gas nor a liquid,
which have reduced viscosity
Inexpensive
safe
abundant
Inert
non inflammable
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36. Advantages
The extraction of constituents at low temperature, which
strictly avoids damage from heat and some organic solvent
 No solvent residues
Environmentally friendly extraction procedure
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37. Phytonics Process
• A new technology for the production of high quality natural
fragrant oils, flavours and biological extracts
• Advanced Phytonics Limited (Manchester, UK) has developed
this patented technology termed “phytonics process”
• The products mostly extracted are fragrant components of
essential oils and biological or phytopharmacological extracts -
used directly without further physical or chemical treatment.
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38. • The core of the solvent is 1,1,2,2-tetrafluoroethane, better known
as hydrofluorocarbon-134a (HFC-134a).
• This product was developed as a replacement for
chlorofluorocarbons.
• The boiling point of this solvent is -25° C.
• It is not flammable or toxic.
• Unlike chlorofluorocarbons, it does not deplete
the ozone layer
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39. • The process can be made highly selective in extracting a specific
class of phytoconstituents
• Biological products made by this process have extremely low
residual solvent.
• These solvents are neither acidic nor alkaline and, therefore, have
only minimal potential reaction effects on the botanical materials.
• The processing plant is totally sealed so that the solvents are
continually recycled and fully recovered at the end of each
production cycle
• Only utility needed to operate these systems is electricity and, even
then, they do no consume much energy
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40. • There is no scope for the escape of the solvents.
• If some solvents do escape, they contain no chlorine and
therefore pose no threat to the ozone layer
• Waste biomass from these plants is dry and “ecofriendly” to
handle
APPLICATIONS
pharmaceutical-grade extracts
pharmacologically active intermediates
antibiotic extracts
phytopharmaceuticals
herbal drug industry, in the food, essential oil and flavor
industries etc.
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41. Advantages
Unlike other processes that employ high temperatures, the
phytonics process is cool and gentle and its products are never
damaged by exposure to temperatures in excess of ambient
No vacuum stripping is needed which, in other processes, leads
to the loss of precious volatiles
The process is carried out entirely at neutral pH and, in the
absence of oxygen, the products never suffer acid hydrolysis
damage or oxidation
 The technique is highly selective, offering a choice of operating
conditions and hence a choice of end products
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42. It is less threatening to the environment
It requires a minimum amount of electrical energy
It releases no harmful emissions into the atmosphere and the
resultant waste products (spent biomass) are innocuous and
pose no effluent disposal problems
The solvents used in the technique are not flammable, toxic or
ozone depleting
The solvents are completely recycled within the system.
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43. Factors Affecting Choice of Extraction
Process
 Nature of crude drug
 Stability of crude drug
 Cost of crude drug
 Solvent
 Concentration of product
 Recovery of solvent
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44. Parameters for Selecting an Appropriate
Extraction Method
Authentication of plant material should be done before performing extraction.
Use the right plant part
Conditions used for drying the plant material largely depend on the nature of its
chemical constituents. Hot or cold blowing air fl ow for drying is generally
preferred.
Grinding methods should be specified and techniques that generate heat should
be avoided as much as possible.
Powdered plant material should be passed through suitable sieves to get the
required particles of uniform size.
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45. Nature of constituents:
a) If the therapeutic value lies in non-polar constituents, a non-polar
solvent may be used.
i)For example, lupeol is the active constituent of Crataeva nurvala and, for its
extraction, hexane is generally used.
ii)For plants like Bacopa monnieri and Centella asiatica, the active constituents
are glycosides and hence a polar solvent like aqueous methanol may be used.
b) If the constituents are thermolabile, extraction methods like cold
maceration, percolation and CCE are preferred.
i)For thermostable constituents, Soxhlet extraction (if non aqueous solvents are
used) and decoction (if water is the menstruum) are useful.
c)Suitable precautions should be taken when dealing with constituents that
degrade while being kept in organic solvents, e.g. flavonoids and phenyl
propanoids. PURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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46. d) In case of hot extraction, higher than required temperature
should be avoided.
e) Standardization of time of extraction is important, as:
i) Insufficient time means incomplete extraction.
ii) If the extraction time is longer, unwanted constituents
may also be extracted. For example, if tea is boiled for too long,
tannins are extracted which impart astringency to the final
preparation.
f) The number of extractions required for complete extraction is
as important as the duration of each extraction.
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47. The quality of water or menstruum used should be specified
and controlled.
Concentration and drying procedures should ensure the safety
and stability of the active constituents
The design and material of fabrication of the extractor are also
to be taken into consideration.
Analytical parameters of the final extract, such as TLC and
HPLC fingerprints, should be documented to monitor the
quality of different batches of the extracts.
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48. FILTRATION
• Extract obtained is separated from marc
• By allowing it to trickle into a holding tank
• Marc retained at false bottom
• Extract received in holding tank
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49. CONCENTRATION
• Enriched extract – MISCELLA – fed into wiped evaporator
• Concentrated under vacuum concentrated extract
vacuum chamber
dryer
pulverized solid mass free from
solvent
• Solvent recovered is recycled for next batch
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50. DRYING
• Filtered extract is subjected to spray drying with a high
pressure pump
• Drying powder is mixed with suitable diluents or excipients
and blended to obtain a homogenous powder
• Straight away used for making tablets, for filling capsules
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51. Distillation
• Process of separating the component substances from a liquid
mixture by selective condensation and evaporation
• Aromatic compounds ,essential oils from plants such as
almonds, orange blooms and roses
• Raw material is heated and fragrant compounds are recollected
through condensation of distilled vapour
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52. Types of distillation
• Dry or destructive distillation
• Fractionation distillation
• Hydrodistillation
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53. DESTRUCTIVE DISTILLATION
• Distilling volatile oil in the absence of air
• Raw materials are heated directly without a carrier solvent
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54. Fractionation distillation
 Separation of components from volatile mixtures using
fractional column
 Hydrocarbons from oxygenated volatile oil
oEg. Citral, eucalyptol
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55. hydrodistillation
• Traditional method widely used for the extraction of the active components and
essential oils from plant samples.
• Good for the extraction of volatile active compounds
• Since high extraction temperature is required it cannot be used for thermolabile
compounds.
• A technique that does not involve organic solvents
• Can be applied both for dried and for wet plant
samples
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56. 4 basic categories include
a) water distillation
b) water and steam distillation
c) direct steam distillation
d) distillation with cohobation
The choice between the four modifications depends on the
boiling point of the essential oil and the nature of the medicinal
or aromatic plant.
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57. Water distillation
• The medicinal or aromatic plant sample is placed in a flask and water is
added in an appropriate amount
• The flask is then connected to a condenser
• It is heated and brought to boil
• Distillate is collected in a tube
• It comes out as a mixture of oils
• The steam that is formed from the water, which is then collected
separately
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58. Disadvantages
The plant material near the bottom of the flask, which is in direct contact
with the fire, may char
If the water is not enough to last for the whole process and the plant is
overheated and charred
The long contact with hot water can cause hydrolysis of some active
compounds
The time required in this procedure is high
 Heat control is not easy
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59. Water and steam distillation
• An alternative version of hydrodistillation
• The plant is supported and not in direct contact with the hot
furnace bottom.
• Distillation is occurred by the rising steam from the boiling
water.
• With this technique, the overheating and the charring of the
plant material could be avoided.
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60. Direct steam distillation
• Extraction occurs with the use of steam generated outside the
tank in a steam generator or in a boiler.
• The plant is supported above the steam inlet
• The extraction time can be significantly reduced
• Recommended for distillation of high-boiling oils and hard
materials such as roots and woods
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61. Distillation with cohobation
• Process of returning the condensate water from the separator
back to the flask of the extraction unit so that it can be boiled
again
• Higher extraction yields can be obtained because of the
decreased water quantity
• Quality of the essential oil can be affected by the prolonged
treatment, which can cause decomposition of the product
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63. EVAPORATION
• Removing a volatile solvent from non volatile sample
Microwave assisted
Rotary vacuum evaporator assisted
• Increases rate of evaporation by
a) Reducing the pressure to lower the boiling point of solvent
b) Rotating the sample to increase the effective surface area
c) Heating the solution
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64. OTHER PROCESSES INVOLVED

65. SUBLIMATION
• Process by which compound in solid state changes to vapour
state without passing through liquid state
• Deposited as crystal or cake
 Separation of camphor from chips of
Cinnamomum camphora
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66. CHROMATOGRApHY
• Laboratory technique for the separation of mixtures
• Identification and separation of active constituents of plant
extract
• Mobile phase
• Stationary phase
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67. Types of chromatography
Paper chromatography
Column chromatography (CC)
Gas chromatography (GC)
Thin layer chromatography (TLC)
High performance thin layer chromatography (HPTLC)
High performance liquid chromatography (HPLC)
Optimum performance laminar chromatography (OPLC)PURIFICATION & PREPARATION OF ACTIVE CONTITUENTS IN
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68. Paper chromatography
• Principle:- partition
• Stationary phase – moisture in cellulose fibres
• Mobile phase – vary
• Component separation may depend on the solubility in the
stationary phase
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69. Column chromatography
• Most effective technique
• Stationary phase (silica gel) is packed in a column
• Mobile phase is passed through the column after loading the
extract on top of stationary phase
• Mobile phase carry the natural products
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70. Gas chromatography
• Separates compounds based on their volatilities
• While passing through the column the compounds get heated
and vaporised into a gaseous state or normally present as
gases.
• Used in quality control-contamination with herbicides,
pesticides and another materials can be found out
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71. Thin layer chromatography
• Most commonly used
• Easiest and cheapest technique
• Stationary phase – silica or alumina
• Mobile phase – vary
• Principle – adsorption
• Plant mixture to be separated applied as spot near the base of
the plate which placed in a closed glass tank containing a layer
of developing solvent.
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72. High performance thin layer chromatography
• Separation of natural compounds is achieved on high performance
layers with detection and data acquisition
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73. High performance liquid chromatography
• Useful for compounds that cannot be vaporized or that decompose
under high temperature
• Principle-partition
• Powerful pump is used to force eluents through the column filled
with extremely fine particles(3-10 µm) of packing material
• High speed and performance due to the forceful pumping of the
mobile phase
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74. • Qualitative and quantitative analysis
• Stationary phase-solid, gel or solid –liquid combination
• Mobile phase-liquid or gas
• Separation based on interaction and differential partition of
sample between mobile phase and stationary phase.
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75. Optimum performance laminar chromatography
• Planar and liquid chromatographic techniques
• Hybrid technique between TLC and HPLC
• Enables high performance separation of single sample or of
several samples in parallel
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