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IJCBS, 12(2017):75-85
International Journal of Chemical and Biochemical Sciences
(ISSN 2226-9614)
Journal Home page: www.iscientific.org/Journal.html
© International Scientific Organization
Isolation of bioactive compounds from essential oils – A comprehensive
review
Farwa Nadeem٭1, Muhammad Waqar Azeem1 and Muhammad Idrees Jilani1
1
Department of Chemistry, University of Agriculture, Faisalabad-38040-Pakistan
Abstract
Essential oils are rapidly gaining global attention due to number of fruitful applications in cosmetic products, food
industries, sanitary articles and pharmaceutical medicines because of anti-viral, immuno-modulatory, analgesic, anti-diuretic, anti-
inflammatory, anti-parasitic, anti-biotic, anti-ulcer, anti-tubercular, anti-allergic, anthelmintic, anesthetic, anti-insecticidal, anti-
urolithiatic, anti-cancer, anti-diabetic, anti-fungal, anti-bacterial, anti-oxidant, anti-pyretic, cardio-vascular, hepato-protective and
anti-fertility potentials. This review article is designed to compile recent extraction methods and latest fractionation techniques for
isolation of bioactive compounds of essential oils obtained from oleoresin exudations, gums, rhizomes, fruits, roots, seeds, barks,
flowers and leaves. Solvent free microwave extraction, supercritical fluid extraction, direct steam distillation, hydro distillation
and simple steam distillation are commonly used methods for extraction of scents that can further be fractionated using fractional
distillation or vacuum distillation and high speed counter current chromatography. Chemical derivatization of scented oils is an
advanced approach to convert simpler chemicals into complex compounds that possesses better physiochemical characteristics
and higher market value. Ketones, esters, hydrocarbons, aldehydes and alcohols are the major group of chemicals commonly
found in essential oils however concentration and relative abundance of each class of compound depends on nature of feedstock,
type of plant material, conditions of environment and time of harvesting. Both volatile and non-volatile chemicals are found in
essential oils but scents are mainly attributed to highly volatile and thermally unstable chemical constituents.
Key words: Essential oil, Isolation, Extraction, Fractionation, Chemical constituents, Traditional uses and Modern applications
Full length article *Corresponding Author, e-mail: farwa668@gmail.com
1. Introduction herbs and higher plants including fruits, flowers, bark, roots,
For centuries, different plant varieties have leaves and seeds [5]. Active plant components or bioactive
extensively been used for fulfillment of human requirements chemical constituents can be abundantly found in some
specific parts or portions of plant. Different types of
and as medicinal remedy against several pathogenic diseases medicinal components extracted from plants which proved
because plants are known to have strong antibiotic chemical to be helpful for mankind are mostly secondary metabolites
constituents since ancient times [1]. Numerous important which are naturally produced in the plants [6]. However,
chemical compounds have been extracted and isolated by therapeutic activities of different plant verities are specific
research scholars and scientists from different plant sources and mainly depend on nature and type of plant, soil
that are widely used in industries and factories [2]. Large conditions, pH, climate, temperature and numerous other
number of bioactive compounds from plants are also ecological factors [7].
attempted to synthesize in biochemical laboratories using
various synthetic routes [3]. Ironic asset of information on Therapeutic potentials and their corresponding
healing and defensive medicines already existed in several actions are mainly dependent on secondary metabolites and
previous researches of Indian scholars that were also several other naturally occuring chemical constituents.
included in Indian religious book named "Atharvaveda" [4]. Highly effective bioactive components can be thoroughly
According to an estimate, almost 1300 different plant studied after extraction and isolation by organized plant
species are commonly used for preparation of medicines and selection at different research institutes that resultantly
drugs along with several other purposes. Natural plant found fruitful applications in various natural products [8].
components can be obtained from different parts of smaller After isolation, bioactive compounds are tested for
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medicinal potentials and therapeutic activities on animals Various types of the aromatic or scented oils have
and human beings which clued towards invention and lead traditionally been used in many cultures of different
towards discovery of best quality medicines [9]. Sodium countries all over the world. Wide spread usage of essential
cromolyn and Sodium cromoglycate are best known oils usually range from healing purposes to religious
naturally occuring antiseptic compounds which can also be applications. It was introduced by Egyptians who first time
prepared through "furanochromone khelline". Utilization of used aromatic herbs and essential oils in 4500 B.C.E [30].
chemical constituents of plants has provided foundation for They prepared herbal medicinal product named "Kyphi"
number of lifesaving medicines [10]. Essential oil of the containing sixteen active ingredients that was also used in
plants is natural product that constitutes several chemical perfumes. Egyptians used balsams, scented barks, spices,
compounds. Depending on the nature of feedstock used, perfumed oils, resins and aromatic vinegar in daily routine
essential oil can be extracted through various processes [31]. Essential oils and various other plant extracts were also
using hydro-distillation [11], steam-distillation [12], used in preparation of medicinal cakes, suppositories,
supercritical fluid extraction [13] and cold press methods ointments, pills and powders. These scented aromatic oils
[14]. Essential oil possesses numerous unique characteristic also found fruitful applications in several higher authorities.
features that make it useful for wide range of applications Aromatic gums such as cedar and myrrh were extensively
including food industry [15], cosmetic products [16], used in embalming but their essential oil was never
aromatherapy [17] and pharmaceutical medicines [18]. extracted. First time Chinese applications of essential oils
Essential oil extracted from various scented plants having were recorded during 2697 to 2597 B.C.E in reign of Huang
different botanic species is highly unstable due to high rate Ti who was a legendry Yellow Emperor in his famous book
of volatility. Previously, it was believed that essential oil is named "The Yellow Emperor’s Book of Internal Medicine".
derived from name of medicine called "Quinta essential" In Indian culture, Ayur Veda medicines have been used
given by "Paracelsus von Hohenheim" who was the Swiss since approximately 3000 years that are actually made of
therapeutics recognizer [19]. essential oil. In some regions of India, essential oils are not
Essential oil obtained from different extraction only used for medicinal purposes but also as essential part of
prayers. In between 400 B.C.E to 500 B.C.E, Greeks got
techniques or isolation processes by different botanic comprehensive knowledge about essential oil through
species is known to have different anti-microbial activities Egyptians and used them in medicines thus also known as
[20] and anti-fungal potentials [21]. Essential oils are "Father of Medicine". Essential oils were commonly used in
usually accountable for aroma, fragrance and therapeutics bathing soaps and massage oils for maintenance of general
which show tremendous biological activities. body health. In short, they worked very hard in finding
Microorganisms are very harmful for all living organisms as therapeutic applications of essential oils to prepare highly
they are responsible for different diseases related to skin and valuable medicines for mankind. Romans used essential oils
teeth along with severe problems in the animals and plants. in perfumes and cosmetics to prepare massage oils and
Among all microorganisms, gram negative and gram soaps. Ali-ibn sena wrote a comprehensive book on
positive also cause spoilage of food and decomposition of importance of essential oils and their uses along with
several commercially important edible materials [22]. extraction methods. Recently, lots of researchers have
Scented oil can be extracted and isolated through different worked in Europe related to aromatic oils and written
plants by adopting various procedures and techniques. Some number of books on aromatherapy [32].
important methods for extraction of oil are ultrasonic wave
extraction [23], microwave extraction [24], solvent 3. Sources of Essential Oils
extraction [25], super critical fluid extraction [13], cold Aromatic or essential oils can be extracted or
press [26], steam distillation [27] and hydro distillation [28].
Scented oil of citrus fruits can also be extracted through isolated from more than one parts of plants including
mechanical methods and even by direct squeezing. flowers or leaves and rose, carnation, mimosa, lavender,
Distillation process requires dried or fresh plant material jasmine, clove and rosemary are its common examples.
depending on nature and type of feedstock. Hydro Essential oil can be extracted through leaves of different
distillation involves direct input of herbal material in water types of plants such as mint, lemongrass, ocimum spp. and
while in case of steam distillation plant material does not jamrosa and from leaves and stems of the patchouli,
come in direct contact with aqueous media instead heated verbena, geranium, petitgrain and cinnamon [33]. Barks of
through steam. By using steam distillation and hydro some plants are also used for extraction of essential oil such
distillation, only volatile components can be extracted and as cassia, cinnamon and canella from sandal, cedar and pine
heavy aromatic components are unable to be separated [29]. wood etc. [34]. Some seeds including coriander, dill, fennel,
caraway and nutmeg are also known to be the excellent
2. History of Essences and Essential Oil source of essential oil [35]. Roots of sassafras, saussurea,
angelica, vetiver and valerian also contains significant
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amount of scent or aromatic oil [36]. Furthermore, some Villanova who was a Catalan practitioner. Since 13th
fruits like bergamot, lemon, orange and juniper and few century, essential or aromatic oil was extensively used by
rhizomes such as ginger, curcuma, calamus and orris also drugstores and their pharmaceutical effects were properly
constitute highly valuable essential oil [37]. Numerous gums studied however their applications were not very common
or oleoresin exudations of Myroxylon balsamum, myrrh, till 16th century in Europe. Just after that, essential oil was
Peru, storax and benzoin also contains significant amount of merchandized to the city of London. Two scientists
essential oil [38]. Brunschwig and Reiff extensively discussed the process of
distillation along with uses of essential oil but essential oils
4. Characteristics of Essential Oils were quite less in number at that time. Some major sources
Essential oil is the low density liquid having high of essential oils at that time were anise, cinnamon, mace,
volatility, specific characteristics odour and strongly clove, nutmeg, spike, turpentine and juniper wood. Du
hydrophobic nature. The word "essential" is basically used Chesne, a French practitioner stated that essential oil
for chemical constituents having distinctive scent, specific preparation was well recognized in 17th century and almost
aroma and unique essence. Essential oil is also known as fifteen to twenty different essential oils were stored in
"volatile oil" or "ethereal oil" and it differs from cooking oil, drugstores. The tea tree essential oil has been used since the
rock oil and fixed oil. Essential oil extracted by various end of 18th century when Australian colonization started
sources contains different chemical constituents and however it probably had already been used by innate
possesses variable physiochemical properties. Some Australians. De la Croix performed first experiment in 1881
important chemical constituents of scented oils are which showed strong anti-bacterial properties of several
aldehyde, phenols, ketones, esters, alcohols and terpenes essential oils against different strains of bacteria.
along with hydrocarbons. Essential oils are mostly used in Nevertheless, during 19th and 20th century, medicinal
treatment of various diseases related to skin infections and applications of essential oils progressively became less
severe cancers. There are several other applications where important due to their excess usage in cosmetic industries
essential oils prove to be highly promising and have number and perfumed products [40].
of useful applications. Essential oils can be removed from 5. Advanced Extraction Techniques
non-woody portions of plants as they are also found in
secretory cells, glandular trichomes, canals, cavities and High quality and quantity of essential oil can be
different types of epidermal cells. Essential oils can easily ensured by improving methods of extraction and isolation of
be absorbed due to lighter weight and according to an compounds from natural feedstock. Numerous classical
estimate almost 3000 different types of essential oils have techniques have commonly been used for extraction of
been recognized among which 300 are relatively more scented oil that is of great economic importance all over the
significant on larger scale. Most essential oils are only used world. Water and steam distillation, maceration, enfleurage,
for smells, fragrances, aromas or essences while some are cohobation, steam distillation and hydro distillation are
used as flavoring agent and also for preservation of food. some traditional methods for oil extraction. Process of
Some essential oils has been documented to show maceration is adjustable and mainly used when distillated
antimicrobial activities while others are known to have essential oil is of poor quality and low yield. Distillation is
strong anti-oxidant, anti-depression, anti-bacterial, anti- best known method for extraction of aromatic oils from
fungal, anti-parasitic, anti-mycotic, anti-insecticidal, anti- powdered almonds, rose blossoms and rose petals whereas
toxigenic and anti-viral potentials. Highly variable activities solvent extraction is more suitable for very delicate,
of essential oils obtained from different feedstocks are expensive and thermally unstable materials constituting
mainly due to unique chemical composition that also jasmine, hyacinth and tuberose. Water or hydro distillation
determines physiochemical properties of oils [39]. is more appropriate method when scented oil is to be
extracted from citronella oil and it has recently been
Although numerous plant species are used for investigated that minor constituents of essential oils when
various purposes such as fragrances, perfumes, flavors and isolated from different natural sources plays significant role
other properties but antiquity activity of identical essential as anti-bacterial agent and exhibit combined effect when
oil of terpentines was declared by Roman and Greek found in combination with other chemical constituents. Pure
historians. The extraction of essential oil was first time organic and herbal materials are precious natural resources
attempted through simple distillation approximately 2000 that are very beneficial in daily routine as pharmaceutical
years ago in Eastern countries including India, Egypt and products, drugs, medicines, fragrances, food additives,
Persia. Furthermore, improvements in extraction and flavors, direct food articles and as coloring agents.
isolation techniques were made by Arab scientists in 09th Applications of plants are known to have extensive history
century. First most realistic approach or written explanation all over the world since many centuries therefore human
for distillation method of essential oil is mainly attributed to beings are still trying to improve extraction methods [23].
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Essential oils are very complex mixtures of 5.1 Effleurage
millions of volatile compounds generally found in low
concentration. Following methods are mostly used for Volatile scented constituents of essential oils
extraction of essential oil from all type of materials (A) obtained from fresh parts of plants including leaves and
distillation (i) direct distillation (ii) hydro distillation (iii) flower petals are extremely small in quantity that cannot be
steam distillation, (B) percolation/solvent extraction (i) commercially used thus need to be stored by effleurage
enfleurage (extraction with cold fat) (ii) infusion (boiling method. In some cases, odorless and bland fixed oil or fat is
with hot water) (iii) Soxlet extraction (C) cold compression feast in reedy layer on glass dishes. In effleurage, flower
(D) solvent free microwave extraction (E) non- petals constituting highly volatile essential oil are placed on
conventional/recent extraction techniques (i) ultrasonically fat or any other adsorbent material for some hours and petals
assisted extraction (ii) extraction through electrical energy are continuously replaced after regular interval of time to
(iii) supercritical fluid extraction. Four different extraction ensure complete extraction. When layers of fats have
methods are commonly used for different feedstocks (a) adsorbed maximum aroma or fragrance, essential oil is
steam distillation can be used for both fresh and dried plant separated by chemical treatment with alcohol that is
material (b) hydro distillation is applicable when plant specifically known as "enfleurage" and widely used for
material can directly be contacted with water (c) cold production of perfumes and pomades. In several perfume
pressing or screw pressing can be used for oil extraction industries, essential oil is mostly obtained by fat adsorption
from citrus peels, pericarps of fruits, wood materials and and then extraction is accompanied by petroleum ether or
also from bark of pyrogenation. By the steam sweeping hexane [43].
extraction or hydro distillation only volatile compounds can 5.2 Distillation
be extracted leaving behind all heavy aromatic chemical
constituents. Superheated steam can also be used for Simplest and widely used method for extraction of
extraction of aromatic compounds and is produced at much essential oil is "distillation" that is usually achieved at
elevated temperatures under highly pressurized conditions constant temperature of about 50°C to ensure the isolation
[41]. of scented oil with additional natural smells. However,
Superheated steam is used for drying of plant heating at much higher temperature generally alters
materials that is to be used for baking purposes but is less chemical nature of the aromatic oil. This characteristic
known sphere in production of essential oils. However nature of essential oil is of great importance in the scent,
extraction of essential oil is quite difficult as temperature aroma and perfume industry as distillation is the most
greater than 230°C causes burning and temperature ranging economical method on commercial scale for extraction of
from 205°C to 220°C results in limited biomass pyrolysis oil. The process of destructive distillation for volatile
for distillation of flashy volatile aromatic oil. In order to essential oil is not an appreciable approach as it significantly
differentiate basic types of aqueous based distillation enhances chances of decomposition of unstable aromatic
processes they have been named as (i) water and steam molecules. Decomposition is mostly observed when woody
distillation (ii) simple distillation (iii) steam distillation (iv) materials and resins of Cupressaceae or Pinaceae are heated
water distillation (v) direct steam distillation. These in the absence of air that ultimately results in the loss of
technical terms were first time familiarized by the scientist essential volatile components. Charcoal is the final product
Von Rechenberg and are now recognized in essential oil obtained after simple distillation that can further be used for
productiveness. All these processes focus on similar various purposes. Separated volatile material which is
theoretic reflections in which double phased system is deled condensed usually separates in two layers (i) aqueous layer
of distillation. Major difference actually arises in which contains crude acetic acid, methyl alcohol and wood
management of different procedure materials. Some volatile naphtha and (ii) remaining liquid in form of simple tar, pine
essential oils like lemon oil and orange oil undergo tar and juniper tar depending on type of wood being used.
decomposition prior to distillation and thus preferably Dry distillation can also be used for extraction of oil but if
extracted through mechanical or cold press method. In some wood is coarsely grounded or chipped and heat is quickly
cases, epidermis constitutes oil glands that are situated in provided then only 10 percent of total wood weight can be
external parts of peel. In "ecuelle method", fruits are directly recovered [44].
pressed to separate oil from epidermal glands and then 5.3 Supercritical Fluids Extraction
smashed peels are washed with water to extract essential oil
whereas juice of fruits is isolated through middle tube that Most recent and highly efficient method for
centers the fruit. Resulting solution is the emulsion of water isolation of essential oil is "supercritical fluid extraction"
and oil from which oil is separated by a well-known process that mostly uses carbon dioxide in super critical form to
called "centrifugation". Peels of the fruits have to be extract volatile scented oil from natural plant material due to
removed before extraction of oils [42]. economic favorability. This technique has tremendously
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