This document discusses various methods for extracting active compounds from plants, including maceration, decoction, percolation, soxhlet extraction, microwave-assisted extraction, ultrasound-assisted extraction, and supercritical fluid extraction. It also covers techniques for isolating and purifying compounds from crude extracts, such as fractional crystallization, distillation, chromatography, and HPLC. The goal of extraction is to separate soluble plant metabolites from insoluble plant matter using selective solvents and standard procedures.

1. BASICS OF PHOTOCHEMISTRY
BY
Snehal S. Manekar
Dr. Rajendra Gode Institute of Pharmacy,
Amravati

2. Drug discovery from these natural plant sources based on the
active constituents, its nature and properties which can be
used for the ailment of any specific diseases.
Selection of appropriate extraction methods involves the
acquisition of the knowledge related to ethno use which finally
helps the scientists to work on those methods.
Isolation of active drug substance from the complex
framework of plant materials, utilizes the concepts of
Chemistry and other scientific investigation which play a
central role in drug discovery.

3. EXTRACTION METHODS
Extraction is the separation of medicinally
active phytoconstituents of plant using
selective solvents by applying some standard
procedures.
The purpose of all extraction is to separate
the soluble plant metabolites, leaving
behind the insoluble cellular marc
commonly called as residue.

4. By means of extraction, the initial crude extracts which are
obtained contain complex mixture of many plant metabolites, like
alkaloids, glycosides, phenolics, terpenoids and flavonoids etc.

5. Tea Powder
Decoction—Crude extract
Caffeine
Hot water
Isolation
Extraction
Fractionation
(Pure substance)

7. Maceration, infusion,
percolation and decoction
Maceration is one of the widely
adopted and used techniques that can
be applied in wine making.
Maceration involved soaking plant
materials (coarse or powdered form)
in a stoppered container along with a
suitable solvent and let it be stand at
room temperature for a period of
minimum 3 days with frequent
agitation or shaking.

10. Infusion and decoction uses the
same principle as that of maceration;
in which the course or powdered drug
material are soaked in cold or boiled
water. However, the maceration
period for infusion is shorter and
the sample is boiled in specified
volume of water (eg. 1:4 or 1:16) for
a defined time for decoction.
Decoction method is applied for the
extraction of heat-stable compounds,
hard plants materials (e.g. roots and
barks) and also more oil-soluble
compounds compared to maceration
and infusion.

11. Another method which is used is Percolation technique
that takes the help of specific equipment called
percolator.
Percolation technique is having similar fundamental
principle as that of maceration.
In percolation technique, dried powdered samples of
plant are packed in the percolator, boiling water is then
added and the whole is macerated for 2 hours. The
percolation process is usually done at moderate rate (e.g.
6 drops /min) until the extraction is completed before
evaporation to get a concentrated extracts.

13. Soxhlet extraction or hot
continuous extraction

15. Continuous Hot Extraction
In soxhlet extraction method, finely ground
sample is placed inside a porous bag which
is referred as “Thimble”. This thimble is
made from a strong filter paper or cellulose,
which is placed inside a thimble chamber of
soxhlet apparatus.
In extraction process, a suitable solvent is
heated in bottom flask, which is then
vaporizes into the sample thimble. After
reaching the sample thimble, this solvent
condenses in the condensor and drip back.
When the liquid content reaches the siphon
arm, the liquid contents emptied into the
bottom flask and the process is continued.

16. Microwave extraction allows organic compounds
to be extracted more rapidly, with similar or
better yield as compared to conventional
extraction methods.
The advantages that MAE has over Soxhlet are:
– Reduction in extraction time
– Improved yield
– Better accuracy
– Suitable for thermolabile substances.
Modern methods
Microwave assisted extraction

17. Microwave assisted extraction
(MAE)

18. Microwave theory
Microwaves are non-ionizing electromagnetic
waves of frequency between 300MHz to 300
GHz and positioned between the X-ray and
radio rays in the electromagnetic spectrum.
Microwaves are made up of two oscillating
perpendicular field’s i.e.
– Electric field
– Magnetic field.
MW-They come
from applying a large
voltage to a thing called
a cavity magnetron,
which involves the
interactions of electrons
with a magnetic field.
2.The microwaves cre
ate an oscillating
electric field.

19. INSTRUMENTS
There are two types of MAE systems:
– Closed extraction vessels
– Focused microwave ovens
Both comprises of following four components:
– Microwave generator: Magnetron which
generates microwave energy
– Wave guide: Propagate microwave to
microwave cavity
– The applicator: Where the sample is placed
– Circulator : Allow microwave to move in
forward direction

20. EXTRACTION PRINCIPLE
• Dried plants contain a minute microscopic trace
of moisture which serves as target for microwave
heating.
• High temperature and pressure is generated
inside the oven.
• High temperature causes dehydration of cell
which accounts for its reduction of mechanical
strength.
The MAE process is as follows:
– Microwave radiation generates
– Moisture get heated up and evaporates
– Generation of tremendous pressure on cell wall
– Swelling of plant cell
– Rupture of the cell
– Leaching out of phyto-constituents.

21. Advantages
 Low cost of equipment.
 Rapid process.
 Less solvent required.
Disadvantages
 High pressure used increase safety risks.
 Increase in temperature destruct
phytoconstituents.

22. Ultrasound-assisted extraction (UAE) or Sonication
extraction

23. UAE involves the use of ultrasound ranging from 20 kHz to 2000 kHz.
With the action of ultrasound a mechanistic effect is produced which
increases the surface contact between solvents and samples and thus
enhances the permeability of cell walls.
When the plant materials are subjected to ultrasound, physical and
chemical properties of the materials are altered and also disruption the
plant cell wall takes place. This helps to enhance the release of
compounds and enhancing mass transport of the solvents into the plant
cells.

24. SUPERCRITICAL FLUID EXTRACTION
At a certain temperature and pressure condition,
liquid and vapour phases of a substance become
indistinguishable known as CRITICAL
CONDITION
Substances above critical point- “SUPERCRITICAL
FLUIDS” (SCF).
Supercritical fluid extraction is the process of
separating one component from another (the
matrix) using supercritical fluids as the extracting
solvent

25. 1. Fluid reservoir (gas cylinder in case of CO2)
2. Pump
3. Extraction cell/column (stationary phase)
– Usually stainless steel Chamber or vessel in compartment
– Capable of withstanding high pressure
– Open tubular capillary columns or packed columns
4. Restrictor
5. Collector (trapping system)
INSTRUMENTATION

26. WHY CO2 ???
 Chemically inert,
 Non-toxic,
 Non-flammable
 Low costs and
 Readily available
Many pressurized
gases are actually
supercritical fluids.
Ex. NITROGEN

27. SC–CO2
Critical
temperature
(31.3°C) and
pressure
(72.9 atm.)
Loading material into extraction cell
Mobile phase: Solutes mixed with supercritical fluid
Exposure of mobile phase to pressure (72.9 atm.)
and temperature (31.3 C)
Beyond critical point mobile phase have high
penetration power so phytoconstituents
Dissolved in solvent
Isolation of phytoconstituents by precipitation

29. Advantages
1.Selectivity is one of
the important benefit
of SFE technique.
2.Extraction time is
reduced.
3.Solvent can be
reused.
Disadvantages
1.Initial cost of
equipment is very
high.
2.SF CO2 is commonly
used for non polar
compounds so
modifiers are
required.
3.Experts required for
processing.

30. ISOLATION AND PURIFICATION
OF CONSTITUENTS
i) Fractional Crystallization
ii) Fractional Distillation
iii) Fractional Liberation
iv) Paper Chromatography
v) Thin Layer Chromatography
vi) Column Chromatography
vii) High Performance Thin Layer
Chromatography (HPTLC)
viii) High Performance Liquid
Chromatography (HPLC)