Filetype PDF | Posted on 14 Sep 2022 | 3 years ago
Authentication
digital resources
163x Filetype PDF File size 0.26 MB Source: www.oleumdietetica.es
[Downloaded free from http://www.jpbsonline.org on Tuesday, December 14, 2021, IP: 80.32.132.150]
Review Article
Preparation of Medicinal Plants: Basic Extraction and Fractionation
Procedures for Experimental Purposes
1 2
Abdullahi R. Abubakar , Mainul Haque
1Department of ctPreparation of medicinal plants for experimental purposes is an initial step and key
Pharmacology and Ain achieving quality research outcome. It involves extraction and determination
Therapeutics, Faculty of of quality and quantity of bioactive constituents before proceeding with the
Pharmaceutical Sciences, bstrintended biological testing. The primary objective of this study was to evaluate
Bayero University, A
2 various methods used in the preparation and screening of medicinal plants in our
Kano, Nigeria, Unit of daily research. Although the extracts, bioactive fractions, or compounds obtained
Pharmacology, Faculty
of Medicine and Defence from medicinal plants are used for different purposes, the techniques involved in
Health, National Defence producing them are generally the same irrespective of the intended biological
University of Malaysia, testing. The major stages included in acquiring quality bioactive molecule are the
Kuala Lumpur, Malaysia selection of an appropriate solvent, extraction methods, phytochemical screening
procedures, fractionation methods, and identification techniques. The nitty-gritty
of these methods and the exact road map followed solely depends on the research
design. Solvents commonly used in extraction of medicinal plants are polar
solvent (e.g., water, alcohols), intermediate polar (e.g., acetone, dichloromethane),
and nonpolar (e.g., n-hexane, ether, chloroform). In general, extraction
procedures include maceration, digestion, decoction, infusion, percolation,
Soxhlet extraction, superficial extraction, ultrasound-assisted, and microwave-
assisted extractions. Fractionation and purification of phytochemical substances
are achieved through application of various chromatographic techniques such
as paper chromatography, thin-layer chromatography, gas chromatography, and
high-performance liquid chromatography. Finally, compounds obtained are
characterized using diverse identification techniques such as mass spectroscopy,
infrared spectroscopy, ultraviolet spectroscopy, and nuclear magnetic resonance
spectroscopy. Subsequently, different methods described above can be grouped
Received : 14-07-2019. and discussed according to the intended biological testing to guide young
Revised : 10-09-2019. researchers and make them more focused.
Accepted : 14-10-2019. Keywords: Chromatography, extraction, fractionation, isolation, medicinal plants
Published : 29-01-2020.
IntroductIon by extraction, fractionation, and isolation of the
edicinal plants are extracted and processed for bioactive compound where applicable. In addition, it
Mdirect consumption as herbal or traditional comprises determination of quantity and quality of
bioactive compounds.[1-5]
medicine or prepared for experimental purposes. Recently, plant as a source of
The concept of preparation of medicinal plant for Address for correspondence: Prof. Mainul Haque,
experimental purposes involves the proper and timely Unit of Pharmacology, Faculty of Medicine and Defence Health,
collection of the plant, authentication by an expert, National Defence University Malaysia, Kem Sungai Besi, 57000
adequate drying, and grinding. This is followed Kuala Lumpur, Malaysia.
E-mail: runurono@gmail.com
Access this article online This is an open access journal, and articles are distributed under the terms of the
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows
Quick Response Code: others to remix, tweak, and build upon the work non-commercially, as long as
Website: www.jpbsonline.org appropriate credit is given and the new creations are licensed under the identical terms.
For reprints contact: reprints@medknow.com
DOI: 10.4103/jpbs.JPBS_175_19 How to cite this article: Abubakar AR, Haque M. Preparation of medicinal
plants: Basic extraction and fractionation procedures for experimental
purposes. J Pharm Bioall Sci 2020;12:1-10.
© 2020 Journal of Pharmacy and Bioallied Sciences | Published by Wolters Kluwer - Medknow 1
[Downloaded free from http://www.jpbsonline.org on Tuesday, December 14, 2021, IP: 80.32.132.150]
Abubakar and Haque: Preparation of medicinal plants
[6,7]
medicine is gaining international popularity because medicinal properties. Secondary plant constituents.
of its natural origin, availability in local communities, These are also known as secondary metabolites such as
cheaper to purchase, ease of administration, and alkaloids, terpenoids, saponins, phenolic compounds,
perhaps less troublesome. Also, herbal medicine may flavonoids, and tannins. These are responsible for many
be useful alternative treatment in case of numerous side [6,7]
biological or pharmacological activities. Bioassay-
[1-5]
effects and drug resistance. Extraction of medicinal guided fractionation. It involves extraction of plant
plants is a process of separating active plant materials material followed by testing for biological activity.
or secondary metabolites such as alkaloids, flavonoids, Once the extract tested is found to be biologically
terpenes, saponins, steroids, and glycosides from inert active, the next step is to proceed with fractionation.
or inactive material using an appropriate solvent and Subsequently, various fractions obtained are tested for
standard extraction procedure. Plant materials with biological activity. Also, the most productive portion
high content of phenolic compounds and flavonoids is then taken for compound isolation. Finally, the
were found to possess antioxidant properties, and compound isolated is identified and tested for biological
hence are used to treat age-related diseases such activity.[1,5,8]
Bioautography. It is a process that uses both
as Alzheimer’s disease, Parkinsonism, anxiety, and TLC and antimicrobial testing to establish the identity
[2,5]
depression. Several methods were used in the of a compound extracted as well as its antimicrobial
extraction of medicinal plants such as maceration, [5,9]
activity. Finger printing in medicinal plants. It involves
infusion, decoction, percolation, digestion and Soxhlet the use of chromatographic techniques, identification
extraction, superficial extraction, ultrasound-assisted, techniques, and chemical analysis to characterize a
and microwave-assisted extraction. In addition, thin- pharmacologically active compound from a medicinal
layer chromatography (TLC), high-performance liquid [4,5]
plant. Immunoassay. It is a process of identification
chromatography (HPLC), paper chromatography (PC), of bioactive molecule as well as its biological activity
and gas chromatography (GC) were used in separation via immune reaction, receptor binding, and enzyme-
[1-5]
and purification of the secondary metabolites. mediated reactions. The extract and low-molecular-
The choice of an appropriate extraction method weight secondary metabolites first interact with
depends on the nature of the plant material, solvent monoclonal antibody to detect drug–receptor binding.
used, pH of the solvent, temperature, and solvent to This is followed by application of enzyme-linked
sample ration. It also depends on the intended use immunoassay (ELISA) to determine its enzymatic
[1-5] [5]
of the final products. This study aimed to assess activities.
various solvents of extractions, methods of extraction,
fractionation, purification, phytochemical screening, solvents of extrActIon
and identification of bioactive compounds in medicinal The solvent used for the extraction of medicinal plants
plants. is also known as the menstruum. The choice of solvent
Definition of terms depends on the type of plant, part of plant to be
Medicinal plant. It refers to a plant comprising active extracted, nature of the bioactive compounds, and the
ingredients or secondary metabolites that possess availability of solvent. In general, polar solvents such
biological activity. A whole plant may be medicinally as water, methanol, and ethanol are used in extraction
[4,6,7] of polar compound, whereas nonpolar solvents such
active or plant parts. Herbal medicine. These are
medicinal preparations comprising active ingredients as hexane and dichloromethane are used in extraction
of nonpolar compounds.[3,5,10]
obtained from the herbal plant. The product can be During liquid–liquid
made from the whole plant or any part. Preparations extraction, the conventional way is to select two miscible
from by-product herbal plants such as oils, gums, solvents such as water–dichloromethane, water–ether,
and other secretions are also considered as herbal and water–hexane. In all the combinations, water is
[4,6,7] present because of its high polarity and miscibility
medicine. Menstruum. It is a liquid or a suitable
[2,3] with organic solvent. The compound to be extracted
solvent chosen for an effective extraction process.
Marc. It is an insoluble or inert drug material that using liquid–liquid extraction should be soluble in
[2,3] organic solvent but not in water to ease separation.[11]
is left behind at the end of the extraction process.
Micelle. It is the mixture of both the extracted drug Furthermore, solvent used in extraction is classified
[2,3] according to their polarity, from n-hexane which is the
material and the solvent of extraction. Primary
[3,5,10]
plant constituents. These are mainly nutritional least polar to water the most polar. The following
components of plants such as common sugars, amino are 11 various solvents of extractions arranged
according to the order of increasing polarity[3,9]
acid, proteins, and chlorophyll. These have little or no :
2 Journal of Pharmacy and Bioallied Sciences ¦ Volume 12 ¦ Issue 1 ¦ January-March 2020
[Downloaded free from http://www.jpbsonline.org on Tuesday, December 14, 2021, IP: 80.32.132.150]
Abubakar and Haque: Preparation of medicinal plants
Solvents Polarity (v) Ionic liquid (green solvent). This is a unique solvent
1. n-Hexane 0.009 of extraction and is highly polar and extremely heat
2. Petroleum ether 0.117 o
stable. It can remain in a liquid state even at 3,000 C
3. Diethyl ether 0.117 and usable where high temperature is applicable. It
4. Ethyl acetate 0.228 has extreme miscibility with water and other solvent
5. Chloroform 0.259 and is very suitable in the extraction of polar
6. Dichloromethane 0.309 [14]
7. Acetone 0.355 compounds. Advantages. It has excellent solvent
8. n-Butanol 0.586 that attracts and transmit microwave, and hence
9. Ethanol 0.654 it is suitable for microwave-assisted extraction. It
10. Methanol 0.762 is nonflammable and is useful for liquid–liquid
[14]
11. Water 1.000 extraction and highly polar. Disadvantage. It is
not ideal for preparation of tinctures.[14]
During fractionation, the selected solvent is added Factors to be considered in selecting solvents of
according to the order of increasing polarity, starting extraction
from n-hexane, the least polar to water with the highest Various factors enumerated below should be taken
polarity.[3,9]
If a researcher wishes to select five solvents into consideration when choosing a solvent of
during fractionation, the usual practice is to choose two extraction.[3,9,15]
solvents with low polarity (n-hexane, chloroform), two (i) Selectivity. The ability of a chosen
with medium polarity (dichloromethane, n-butanol), solvent to extract the active constituent and leave the
and one with the highest polarity (water). inert material. (ii) Safety. Ideal solvent of extraction
should be nontoxic and nonflammable. (iii) Cost. It
ProPertIes of solvent of extrActIons should be as cheap as possible. (iv) Reactivity. Suitable
solvent of extraction should not react with the extract.
(i) Water. It is the most polar solvent and is used in the (v) Recovery. The solvent of extraction should be
[9,12]
extraction of a wide range of polar compounds. quickly recovered and separated from the extract. (vi)
Advantages. It dissolves a wide range of substances; Viscosity. Should be of low viscosity to allow ease of
it is cheap, nontoxic, nonflammable, and highly penetration. (vii) Boiling temperature. Solvent boiling
polar.[9,12]
Disadvantages. It promotes bacterial temperature should be as low as possible to prevent
and mold growth; it may cause hydrolysis, and a degradation by heat.[3,9,15]
large amount of heat is required to concentrate the
extract.[9,12] Methods used In extrActIon of MedIcInAl
(ii) Alcohol. It is also polar in nature, miscible lAnts
P
with water, and could extract polar secondary Quite numbers of procedures were technically used
metabolites.[9,12] Advantages. It is self-preservative in the extraction of medicinal plants. Some newer
at a concentration above 20%. It is nontoxic at methods are still evolving, whereas the existing ones
low concentration, and as small amount of heat are undergoing modifications.[2,5]
is required for concentrating the extract.[9,12] The choice of an
appropriate way of extraction is very vital, which in
Disadvantages. It does not dissolve fats, gums, some cases depends on the intended use of an extract.
and wax; it is flammable and volatile.[9,12]
(iii) Chloroform. It is a nonpolar solvent and is useful Factors to be considered in choosing
in the extraction of compounds such as terpenoids, extraction method
[3,12,13] (a) Stability to heat. Heat-stable plant material is
flavonoids, fats, and oils. Advantages. It
is colorless, has a sweet smell, and is soluble in extracted using Soxhlet extraction or microwave-
alcohols. It is also well absorbed and metabolized assisted extraction, whereas plant materials that are
[3,12,13] not heat stable are extracted using maceration or
in the body. Disadvantages. It has sedative and
[3,12,13] [2,11]
carcinogenic property. percolation. (b) Nature of solvent. If the solvent of
(iv) Ether. It is a nonpolar solvent and is useful in extraction is water, maceration is a suitable method but
the extraction of compounds such as alkaloids, for volatile solvent percolation and Soxhlet extraction
[3,12,13] [2,11]
terpenoids, coumarins, and fatty acids. are more appropriate. (c) Cost of the drug. Cheap
Advantages. It is miscible with water, has low drugs are extracted using maceration, whereas costly
drugs are preferably extracted using percolation.[2,11]
boiling point, and is tasteless in nature. It is also
a very stable compound and does not react with (d) Duration of extraction. Maceration is suitable
[3,12,13] for plant material requiring long exposure to the
acids, bases, and metals. Disadvantages. It is
[3,12,13] menstruum, whereas techniques such as microwave- or
highly volatile and flammable in nature.
Journal of Pharmacy and Bioallied Sciences ¦ Volume 12 ¦ Issue 1 ¦ January-March 2020 3
[Downloaded free from http://www.jpbsonline.org on Tuesday, December 14, 2021, IP: 80.32.132.150]
Abubakar and Haque: Preparation of medicinal plants
ultrasound-assisted extraction are used for a shorter container. Water is then poured and stirred. Heat
[2,11] is then applied throughout the process to hasten
duration. (e) Final volume required. Large volume
products such as tinctures are prepared by maceration, the extraction.[1-3,11]
The process is lasted for a
whereas concentrated products are produced by short duration usually about 15 min. The ratio
[2,11]
percolation or Soxhlet extraction. (f) Intended use. of solvent to crude drug is usually 4:1 or 16:1. It
Extracts intended for consumption by human are is used for extraction of water soluble and heat
usually prepared by maceration, whereas products stable plant material.[1-3,11]
intended for experimental testing are prepared using (v) Percolation. The apparatus used in this process is
[2,11]
other methods in addition to maceration. called percolator. It is a narrow-cone-shaped glass
Commonly used methods in the extraction of vessel with opening at both ends. A dried, grinded,
medicinal plants and finely powdered plant material is moistened
with the solvent of extraction in a clean container.
(i) Maceration. This is an extraction procedure in More quantity of solvent is added, and the
which coarsely powdered drug material, either mixture is kept for a period of 4 h. Subsequently,
leaves or stem bark or root bark, is placed inside the content is then transferred into percolator
a container; the menstruum is poured on top with the lower end closed and allow to stand for
until completely covered the drug material. The a period of 24 h.[2,3,11]
The solvent of extraction is
container is then closed and kept for at least three then poured from the top until the drug material
days.[1-4,11,16]
The content is stirred periodically, and is completely saturated. The lower part of the
if placed inside bottle it should be shaken time to percolator is then opened, and the liquid allowed
time to ensure complete extraction. At the end to drip slowly. Some quantity of solvent was added
of extraction, the micelle is separated from marc continuously, and the extraction taken place by
by filtration or decantation. Subsequently, the gravitational force, pushing the solvent through
micelle is then separated from the menstruum the drug material downward.[2,3,11]
The addition
by evaporation in an oven or on top of water of solvent stopped when the volume of solvent
[1-4,11,16]
bath. This method is convenient and very added reached 75% of the intended quantity of
suitable for thermolabile plant material. the entire preparations. The extract is separated
(ii) Infusion. This is an extraction process such as by filtration followed by decantation. The marc is
maceration. The drug material is grinded into fine then expressed and final amount of solvent added
powder, and then placed inside a clean container. to get required volume.[2,3,11]
The extraction solvent hot or cold is then poured (vi) Soxhlet extraction. This process is otherwise known
on top of the drug material, soaked, and kept as continuous hot extraction. The apparatus is called
for a short period of time.[1-3,11]
This method is Soxhlet extractor made up of glass. It consists of
suitable for extraction bioactive constituents that a round bottom flask, extraction chamber, siphon
are readily soluble. In addition, it is an appropriate tube, and condenser at the top. A dried, grinded,
method for preparation of fresh extract before use. and finely powdered plant material is placed inside
The solvent to sample ratio is usually 4:1 or 16:1 porous bag (thimble) made up of a clean cloth
[1-3,11] [1-4,11,17,18]
depending on the intended use. or strong filter paper and tightly closed.
(iii) Digestion. This is an extraction method that The extraction solvent is poured into the bottom
involves the use of moderate heat during extraction flask, followed by the thimble into the extraction
process. The solvent of extraction is poured into chamber. The solvent is then heated from the
a clean container followed by powdered drug bottom flask, evaporates, and passes through the
material. The mixture is placed over water bath or condenser where it condenses and flow down to
in an oven at a temperature about 50o [1,3,11]
C. Heat the extraction chamber and extracts the drug by
was applied throughout the extraction process to coming in contact. Consequently, when the level
decrease the viscosity of extraction solvent and of solvent in the extraction chamber reaches the
enhance the removal of secondary metabolites. top of the siphon, the solvent and the extracted
This method is suitable for plant materials that are plant material flow back to the flask.[1-4,11,17,18]
The
[1,3,11]
readily soluble. entire process continues repeatedly until the drug
(iv) Decoction. This is a process that involves is completely extracted, a point when a solvent
continuous hot extraction using specified volume flowing from extraction chamber does not leave
of water as a solvent. A dried, grinded, and any residue behind. This method is suitable for
powdered plant material is placed into a clean plant material that is partially soluble in the chosen
4 Journal of Pharmacy and Bioallied Sciences ¦ Volume 12 ¦ Issue 1 ¦ January-March 2020
no reviews yet
Please Login to review.
