Definitions “volatile oils”, “Ethereal oils” or Essential oils” Volatile oils: Complex liquid mixtures of odoriferous compounds of varying chemical composition, which easily evaporate when exposed to air at room temperature, and which are used for either their specific therapeutic activity or their aroma.  Aromatherapy is a branch of complementary medicine, which depends on the use of aromatic plants, their extracts, mainly their essential oils to promote health, beauty and vitality.

2. VOLATILE OILS
INTRODUCTION
MOSTAFA MAHMOUD HEGAZY PH.D

3. Objectives
 1- Definition, biological activities and applications
 2- Challenges and Economic Importance
 3- Characters, storage
 4- challenges encountered potential properties of EOs
 5- Applications in Pharmaceutical industry
 I- therapeutic agent
 II- excipient

4. Definitions “volatile oils”, “Ethereal oils” or Essential oils”
Volatile oils: Complex liquid mixtures of odoriferous
compounds of varying chemical composition, which easily
evaporate when exposed to air at room temperature, and which are
used for either their specific therapeutic activity or their aroma.
Aromatherapy is a branch of complementary medicine, which
depends on the use of aromatic plants, their extracts, mainly their
essential oils to promote health, beauty and vitality.

5. Biological activities
antimicrobial
Anti-inflammatory
antioxidant
immunostimulant
counter irritant
spasmolytic
diuretic
wound Healing

6.  Generally, gram-positive more
susceptible to a variety of EOs than
gram-negative because of lipoproteins
presence and hydrophilic
lipopolysaccharide outer membrane,
respectively which creates a barrier
against hydrophobic molecules.
 Interestingly, both the hydrophilic
and hydrophobic parts of the
phenolic compounds facilitate
antibacterial activity for both.
Antibacterial activity

7.  Essential oils applications
 Medically: Pharmaceuticals, Nutraceuticals
and clinical Aromatherapy.
 Spa and health clubs for Relaxation as a
Massage Oil.
 Cosmetics for Hair Care, Skin Care, Sun Care
and Makeup.
 Animal feed
 Toiletries as in Soaps, Shampoos, Oral Care
and Baby Care.

8.  Essential oils applications (cont.)
 Fragrances as in Perfumes, Body
Sprays and Air fresheners.
 Food & Beverages: Bakery,
Confectionery, Dairy, MRE's - Meals
Ready to Eat Meals and Meat.
 Home Cleaning as a Kitchen
Cleaners, Floor Cleaners and
Bathroom Cleaners.

9. Pharmaceutical
industry cosmetics
food industry
agricultural
pesticides

10.  1- Volatility.
 2- Rapidly absorbed as they good penetrants
(hydrophobic nature and low molecular weight)
 3-Fast metabbolism ??? Is it good or bad?
 4- Instability in the presence of light, oxygen, moisture
and heat.
 5- Highly concentrated essence mixtures vary in
component nature and concentration even in the same
plant in different seasons and chemotypes
Challenges encountered potential properties of EOs

11.  Economic Importance of essential
oils
 Around 30,000 species of aromatic
plant around the world.
 About 250 to 300 EOs are available
in the global market.
 About 150 considered to be
commercially important oils based
on their price and/or quantity traded.

12.  Accoding to Essential Oils Market
Size, Share, Analysis Report, 2020-
2027.
 The global essential oils market
demand was estimated at 247.08
kilotons in 2020.
 Essential Oils Market Report Scope
 Market size value in 2020 = USD 18.62
Billion
 Revenue forecast in 2027 = USD 33.26
Billion

15. Physical Characters of Volatile Oils
1- Strongly refractive liquids. 2- Many of them are optically active.
3- Readily volatile in steam or at ordinary temperatures.
4- They are characterized by a pleasant smell. 5- Insoluble in water.
Storage of Volatile Oils
• Deterioration of volatile oils during storage is attributed to reactions such as
oxidation, polymerization, hydrolysis and interaction of functional groups.
• Temperature, light, oxygen, moisture and traces of metals, must be taken
into account during storage.

16. Precautions before and during storage
 1- Oils should be free from metallic impurities (
iron containers ).
 2- Oils are dried over anhydrous Sodium sulphate
to get rid of any traces of moisture.
 3- Containers (stainless steel lined, aluminium alloy
and glass) used for storage should be dark colored
and tightly closed sometimes under CO2 or N2 (inert
gases).
 4- The oils are kept away from light and at low
temperature.

17. Fixed Oil
Volatile Oil
Non volatile at R.T. (grease on filter
paper)… (non distillable)
Volatile at room temperature ….
(distillable)
Mixture of fatty acid esters (Soap
formation)
Mixture of oxygenated and non-oxygenated
terpene hydrocarbons and ????
Rancidify in light and air
Resinify in light and air
secondary metabolite primary metabolite

18. Occurrence
I- Mostly in plants in specific structures
Glandular hairs e.g. Labiatae, Oil cells e.g. Lauraceae
Oil ducts or vittae e.g. Umbelliferae, oil glands (cavities)
e.g.Rutaceae
I- Plant physiological Significance
1- Detoxification products.
2- Solvents for wound healing resins
3- insects Attractants for pollination of the flowers.
4- Protectants: repelling of insects and herbivorous.

19. II- Animal sources: e.g. musk and Ambergris
Physiological Significance
Attractants and Protectants
II- Uses :
1- Therapeutic uses: local stimulants, local
analgesic, diuretic, Carminatives, Mild antiseptics,
Local irritants and Anthelmintic.
2- Perfumery.
3- Spices and condiments.
4- Flavoring agents: for food, pharmaceuticals,
cosmetics, and tobacco.

20. The method depends on:
 1- The condition of the plant material i.e. intact, crushed or powdered.
 2- The location of the oil in the plant (superficial or deep).
 3- The amount of the oil.
 4- The nature of the constituents.
Principle of Distillation Methods
 The boiling point of most volatile oil constituents range between 150oC-300oC.
 Distillation at such high temperatures may cause either decomposition or
polymerisation. The presence of water during distillation allows the process
to be carried out at a temperature below 100oC.
 This is explained by Dalton’s law of partial pressure which states that:
“When two immiscible liquids are heated together, they will boil at a
temperature below the boiling point of either one”

21. PREPARATION OF VOLATILE OILS
The following methods are commonly used for preparation of volatile oils:
Expression method Extraction method Enzymatic hydrolysis
Distillation method
Water Distillation
Water and Steam
Distillation
Direct Steam
Distillation
Extraction with Volatile
Solvents
Extraction with Non-Volatile
Solvents
The Enfleurage Method
The Pneumatic Method
The Maceration Method
Sponge Method
Scarification Process
Expression of Rasping Process
Machine Processes

22. Distillation apparatus
1- The body of the still (distillation flask on laboratory scale) :
usually made of copper lined with stainless steel (not iron)
2- The condensing system (condenser).
3- The receiver (collecting flask) (e.g. Florentine receivers).
Cohobation is the return of the aromatic water (water
saturated with volatile oil) to the body of the still to be
redistilled in order to improve the yield of oil.
Rectification of hydrodistilled oils (Purification): Removal of
bad smelling, irritating and / or colored impurities is carried
by Redistillation.
Removal of water and moisture is done by filtration over
anhydrous sodium sulfate.

23. Water
Distillation
Water and Steam
Distillation
Direct Steam Distillation
process material is boiled
with water.
steam is passed
through the
macerated mixture.
The steam is
generated
elsewhere and is
piped into the
mixture.
Steam is forced through
the fresh material. (contain
considerable amount of
moisture, no maceration).
Plant
Material
1- Dried e.g.
powders of
Barks and wood
2- Petals which
may lump with
steam.
Dried and fresh
especially herbs
and leaves that
their volatile oils
may be affected by
boiling.
Fresh materials
containing sufficient
moisture
leaf, stem and flowers

24. Water Distillation Water and Steam Distillation Direct Steam Distillation
Mode of charging Material
completely covered
with H2O
H2O is present in the still but
steam alone is in contact with the
plant.
N. B.: Dried material should be
wet.
H2O is completely absent.
Steam is forced through the
material which is placed on
perforated trays.
Hydrodiffusion Better when
material moves
freely in H2O
Better when charging is even Better when charging is even
Steam Pressure About atmospheric About atmospheric Can be modified according to
plant condition and nature of oil
Temperature About 100 oC About 100 oC Can be modified according to
plant condition and nature of oil

25. Water Distillation Water and Steam
Distillation
Direct Steam Distillation
Rate of
Distillation
Low Good High
Yield of Oil Relatively Low, since:
1- Esters may be
hydrolyzed.
2- Water soluble and
high boiling point
constituents remain in
the still.
Better since hydrolysis
is diminished
The best if no lumping
or channeling
Commercial
preparations
1- Oils of terpentin
stable oil
2- Oil of rose
* Oils of Cloves and
Cinnamon
* Oil of Citronella
* Oils of Peppermint

26. Water Distillation Water and Steam
Distillation
Direct Steam Distillation
Advantages 1- Low priced.
2- portable still ..Could be
carried near production
area.
Hydrolysis is prevented
since no excessive wetting
of material.
1- Stills are more durable and
suitable for large scale
production.
2- Suitable for oils rich in esters
and high boiling point
constituents.
Disadvantages 1- Burning of plant.
2- Cohobation must be
carried.
3- Not used for oils rich in
saponifiable, water soluble or
high boiling point
constituents.
Hydrodiffusion could be
hindered by
1-fine comminution,
2- uneven charging or
3-excessive wetting
resulting in low yield.
1- Powders could not be used
since easy channeling.
2- Superheated steam is not
used since it results in plant
drying therefore wet steam is
preferred

27. Scarification and Expression Methods
Principle
Mechanical procedures, carried at room temperature and
based on puncturing and or squeezing of the plant material
to liberate the oil.
The classical process includes:
1- Squeezing of the peel (zest) under a stream of water
yielding an emulsion formed of essential oil, water, pectin,
cellulose, pigments and traces of waxes.
2- Removal of water, pectin and cellulose by centrifugation.
3- Removal of waxes by strong cooling (chilling) followed
by filtration or decantation.

28. Applications:
This method is used for the preparation of oil of lemon, oil of orange, and oil of
bergamot which present in large amounts in outer peels of fruits e.g. epicarps
which differ than oil prepared by steam distillation in composition, activity
and uses ???????
The two principal methods of scarification are:
1- The “Sponge Method"
2- Ecuelle-à-piquer Method (Scarification).
3- Expression of rasping
4- Machine processes

29. Sponge Method
1- Fruits (e.g. Citrus fruits) are washed, cut
into halves and peels collected.
2) Pericarp are soaked in water, turned
inside out “squeezed”, by means of
sponge
3) The saturated sponge with exuded
aqueous and oily mixture is squeezed in a
vessel and the emulsion obtained
centrifuged and cooled and then the
upper oily layer is separated.

30. Ecuelle-à-piquer method (Scarification):
It is based on puncturing (Scarifying) the surface
of whole fruits and thus allowing exudation of
the oil from the outer colored zone of their peels.
This is formed in funnel made of copper and
tinned inside. The upper part bears on its inside
surface numerous strong long metal pins, which
penetrate the epidermis. The oil is then collected
and leaves to separate from water.

31. Expression of rasping: the outer layer of
the peel with a grater, collecting the
rasping in special bags (horsehair bags)
followed by strong pressing.
Machine processes: whole fruits are
charged into machines in which the peels
are removed, sprayed with water,
squeezed or pressed and the oil collected
through wool filters.

33. Extraction Methods
Applications:
For delicate flowers e.g. Jasmine which contain either:
1- Small amounts of oils. 2- Oils which decompose by the action of heat (stem).
I- Extraction by Volatile Solvent
Extraction by Volatile Solvent of low boiling points e.g. benzene, or hexane in a
continuous extraction apparatus “Soxhlet”. The volatile oil solution obtained is then
evaporated under reduced pressure, where the volatile solvent will evaporate, leaving
the volatile oil behind. The solvent should be:
1- Dissolves the oil with the least amount of impurities.
2- Dose not react with any of the oil constituents.
3- Has a low boiling point. 4- Leaves no residue on evaporation.

34. II- Extraction by Non-Volatile Solvent
This processes are used for preparation of natural flower
oils producing perfumes.
Solvent used are:
1- Fats e.g. Lard and tallow.
2- Fixed oils (carrier oil) e.g. Olive oil.
the following procedures are used:
1- Enfleurage Method (French = to impregnate with scent
of flowers
2- Pneumatic Method 3- Maceration Method
4- Super critical fluid extraction

35. Enfleurage Process
Flower Petals
Add fat mixture
[Lard & tallow (2 : 1)]
1) Enfleurage Product
[Fat saturated with oil]
* Add absolute alcohol
* Successive extraction
* Cooling to remove most of fat
2) Triple extract
[alc. solution of vol. oil + pigments + traces of fats]
Evaporation of alcohol
or fractional distillation
Dilution with
H2O + NaCl
3) Absolute of Enfleurage
[Semi-solid, alcohol-free product]
4) Volatile oil

36. 2- The Pneumatic Method: Similar to the Enfleurage principle , and involves the
passage of a current of warm air through the flowers. The air laden with suspended
volatile oil is then passed through a spray of melted fat in which the volatile oil is
absorbed.
3- The Maceration Method: The flowers are gently heated and rotated with melted fat
“lard or fixed oil” until complete exhaustion. They are then stained out, squeezed and
the process is repeated until a special concentration is reached. The oil-containing fat is
allowed to cool and the oil can be obtained from the mixture by successive extraction
with alcohol.
4- Super critical fluid extraction [Extraction by supercritical gases]: The oil components
are not subjected to hydrolysis or deterioration.

37. Methods of Preparation of Volatile oils
Disadvantages
Advantages
Applications
Process
The use of high
temperature and water
may affect constituents.
Cheapest commercial
technique (as regards
apparatus, solvents and
source of heat).
Suitable for dried and fresh
plant material rich in
volatile oils with
constituents mostly
unaffected by heat.
Distillation
High cost due to need of
high number of workers.
1) Carried at room
temperature heat
sensitive oils .
2) Yields oils with
more natural
odors.
Suitable for preparation of
oils present in large
amounts in outer peels of
fruits and rich in heat-
sensitive constituents.
Scarification
and Expression
High cost due to use of
solvents and or/ great
number of workers.
1) Carried at room
temperature.
2) Yields oils with
more natural odors.
Usually for fresh materials
with heat-sensitive oils
present in small amounts.
Extraction

38. Plant name Non-volatile Glycoside Volatile aglycone Other hydrolytic products Hydrolytic enzyme
Gaultheria procumbens
(Ericaceae)&
Gaultherin
& / or
Monotropin
Methyl salicylate
Methyl salicylate
Primeverose
(Xylose+glucose)
Glucose
Gaultherase
Gaultherase
Geum urbanum
(Rosaceae)
Gein Eugenol Glucose -Glucosidase
Brassica nigra
(Brassicaceae)
Sinigrin Allyl isothiocyanate Glucose +Potassium acid
sulfate
Myrosin
Vanilla planifolia
(Orchidaceae)
Glucovanillin Vanillin Glucose -Glucosidase
Amygdala amara
(Rosaceae)
Amygdalin Benzaldehyde Gentiobiose (2
glucose units) +HCN
Emulsin
Preparation of Volatile Oil After Enzymatic Hydrolysis
• Occasionally the volatile oil is found in the plant in a glycosidal form.
• The odoriferous substance is set free only by hydrolysis of certain odorless glycosides present in the plant.
• The following are examples of such oils:

39. 1- Therapeutic agent
2- excipient
I- Flavoring agent
II- Permeation enhancers
Applications in Pharmaceutical industry

40. Quality control of drugs containing essential oils
1- Morphological and microscopic examinations in order to
determine the genuinely and detect adulteration of the plant
material. Microscopically, the presence of volatile oils could be
detected by using lipophilic dyes (Sudan III).
2- Determination of the percentage of the essential oil
(Quantitation).
3- Preliminary analysis of the oil by HPTLC (Finger-print
chromatogram)

41. Quality control of essential oils
A- Label of commercial products of essential oils and concretes should
specifically include the following: the source organ, the geographical
origin, and the Latin binomial name of the plant in order to avoid any
confusion.
It should be noticed that the common name of the plant is not sufficient to
precisely identify the oil in most cases, e.g. oregano oils are obtained from
different species according to localities; thus Greek oregano (Origanum
vulgare), Turkish oregano from Origanum onites, Spanish oregano from
Corydothymus capitatus and Mexican oregano from Lippia graveolens.

42. B- In addition, Pharmacopoeias require different tests including:
1- Evaluation of the miscibility with alcohol.
2- Measurement of physical constants such as refractive index,
optical rotation, relative density (specific gravity) and solidification
temperature.
3- Determination of various indices such as the acid, ester, carbonyl
and iodine values.
4- Chromatographic analysis.

43. Determination of the Percentage of a volatile oils in a plant
materials (Quantitation, Clevenger’s apparatus)
Description It consists of a round bottom Pyrex distillation flask
attached to a special graduated trap designed for collection of oils
lighter or heavier than water.
Procedure:
1- Introduce a known weight of the entire or powdered drug with 3-6
times of water or water + glycerin why…? in the distillation flask.
2- Allow the process to be carried over a period of 5-6 hours. till ?

44. 3- The distillate, received in the graduated trap, is allowed to cool till
a constant volume of oil could be recorded.
4- The percentage v/w is calculated (on dry weight) from the
following formula: % v/w (i.e. mL of oil / 100 gm dry plant
material) = (V x 100)/ W Where V = volume of oil W = weight
of plant material. If the apparatus available to be used for oils heavier
than water, Xylene should be added…? in the measuring side tube
and % of oil calculated as follows:
% v/w = (V2 - V1) x 100
W

45. Pharmacopoeial requirements for essential oils
1- Miscibility with alcohol
1- Most volatile oils are completely miscible with absolute alcohol.
2- with diluted alcohol
a- The higher miscibility, the higher the % of oxygenated constituents.
b- The miscibility decreased on adulteration with non-polar solvents such as
petroleum ether (turbidity).
3- Water immiscible and mostly lighter than water except clove, cinnamon and
wintergreen oils

46. 2- Physical Examination
For evaluation of the sample or detection of adulterants.
I- Odor
The detection of any abnormal odor by smelling 1 or 2 drops of the oil applied on a filter paper
indicates either adulteration or deterioration during storage (e.g. orange oil acquires a
caraway odor on bad storage since limonene is autoxidized to carvone and carveol).
II- Solubility
The solubility in non-polar solvents such as benzene, carbon disulfide
and light petroleum is tested. Any turbidity indicates the presence of moisture.
III- Relative density (specific gravity)
The apparatus used for determination is a pycnometer.
The specific gravity of a volatile oil may give an indication on its composition e.g.
Oils with specific gravity < 0.9 are usually rich in hydrocarbons.
Oils with specific gravity > 1.0 are mostly rich in aromatic compounds such as???.

47. III- Optical rotation
Determination of optical rotation is carried out by using a polarimeter and is helpful
in detection of adulteration and identification of the variety of the sample.
1- For oils
a- French oil of turpentine is levorotatory [l (-)] since l- pinene is present in the oil
in high concentration.
b- American oil of turpentine is dextrorotatory [d (+)] because d- pinene is its
major constituent.
2- For oil isolate (pure compound): The optical rotation gives also an indication on
the method of preparation of the volatile :
I- All synthetic compounds are racemic (dl).
II- Natural compounds are generally optically active. They may occur in (l) or (d)
forms. Example: natural camphor is (l) or (d) while synthetic camphor is (dl).

48. 4- Chromatographic analysis:
TLC is used routinely for quality control
purposes.
GLC is the most suitable method due to
the volatility of the constituents. It can be
used for qualitative and quantitative
purposes.
"The chromatographic profile is a list of
constituents selected among those that are
representative and characteristic of an
essential oil."

49. Removal of terpenoid hydrocarbons
(Terpeneless oils of dill, lemone and orange)
Oils rich in terpenoid hydrocarbons are liable to rapid deterioration on storage through
oxidation and polymerization to yield bad smelling (generally with turpentine-like odor) and
resinified products.
The process of elimination of terpenoid hydrocarbons could be considered as a specific
procedure for rectification. Thus a considerable amount of the terpenoid hydrocarbons could be
removed by any of the following methods to produce "terpeneless-oils":
1- Fractional distillation under reduced pressure; hydrocarbons have lower boiling points
than oxygenated compounds and therefore, distill first and are discarded.
2- Column chromatography on silica gel, by eluting hydrocarbons with n-hexane then
oxygenated compounds with absolute alcohol.
3- Selective extraction of the oxygenated components with dilute alcohol followed by
distillation.

50.  Terpeneless oils are more expensive than natural
oils, and
are characterized by being:
1- Richer in oxygenated compounds.
2- More soluble in low-strength alcohols.
3- Employed in smaller quantities to give the same
strength of odor.
4- More stable being less liable to deterioration

51. Chemistry of Volatile Oils
• volatile oils are complex mixture of hydrocarbon and related oxygenated compounds.
• The hydrocarbons mentioned here are collectively known as “terpenes”.
The formula “C10H16” is called now true terpenes.
• In practice the term “terpene” is applied to all the C10 isoprenoid compounds, including
those containing oxygen. They were collectively called "terpenes", however, the suffix –oid is
more logical, the –ene suffix should be restricted to the unsaturated hydrocarbons of the class.
CH3 CH3
OPP
Isoprene Unit (C5) "Active Isoprene"
Isopentyldiphosphate
1
2
3
4
1
2
3
4
5 5
Head
Tail
Myrcene

52. Determination the Structure of Terpenes and the Isoprene Rule:
• The molecule structure of terpenes, are built theoretically from “isoprene”
unit.
• Each molecule is made up of the union of two or more isoprene units.
• These units are usually united in a “head to tail manner”.
• They yield isoprene as final product of destructive distillation (i.e. pyrolysis).
CH3 CH3
OPP
Isoprene Unit (C5) "Active Isoprene"
Isopentyldiphosphate
1
2
3
4
1
2
3
4
5 5
Head
Tail
Myrcene

53. The union of two or more of isoprene units gives different
classes of compounds

54. The union of two or more of isoprene units gives different
classes of compounds

55. CLASSIFICATIONOF CONSTITUENTS
OF VOLATILE OILS
(1) Terpene Hydrocarbons
(A) Terpene Alcohols
(B) Terpene Phenols & Ethers.
(C) Terpene Aldehydes.
(E) Esters.
(F) Terpene Oxides.
(G) Terpene Peroxides.
(3) Sulfur-containing compounds.
(4) Nitrogen-containing compounds.
(2) Oxygenated Terpene Compounds (D) Terpene Ketones

56. Rubalgin cream (camphor,
capsicum oleoresin, methyl salicylate,
menthol, peppermint oil, turpentine oil)
Vicksacid oint (camphor,
eucalyptus oil, methyl salicylate,
thymol)
Moov cream (camphor, capsicum oleoresin,
methyl salicylate, menthol)

57. OROVEX-H M. W. (SODIUM
HYALURONATE + THYMOL + MENTHOL +
GLYCERIN + CHLORHEXIDINE + ALOE +
CALENDULA + CHAMOMILE +
EUCALYPTUS)
KENARA M. W. (THYMOL +
MENTHOL CRYSTALS +
CHLORHEXIDINE DIGLUCONATE +
GLYCERIN)
Listerine (Thymol, Eucalyptol, methyl
salicylate, menthol)

58. FOLLOWCEASE SYRUP (
THYME + EUCALYPTUS +
PEPPRMINT + LEMON)
THYMY SYRUP (ANISE +
HONEY + THYME)
vapozol sol. for inh. (benzoin tr,
camphor, eucalyptus oil, peppermint oil)

59. KLENVA VAG.DOUCHE
(ALUM + CHAMOMILE EXTRACT +
THYMOL + MENTHOL + METHYL
PARABEN + CITRIC ACID)
GOLD CLEANSING GEL
(ALOE VERA + PANTHENOL +
GLYCERIN + MENTHOL + TEA TREE
OIL + THYMOL + CHAMOMILE)
MALVA VAG.DOUCHE (MALVA EXTRACT +
TEGOBTAIN + CHLORHEXIDINE GLUCONATE +
CHLOROCRESOL + THYMOL + MENTHOL +
CHAMAZULENE)

60. GRIPE baby WATER SYRUP
(TERPENELESS DILL SEED OIL)
COLOMINT CAPS. (0.2 ml
PEPPERMINT OIL)
Rowachol cap. (α-pinene, β -pinene,
menthol, menthone, camphene, borneol,
cineole)

61. WATER PILL WITH
POTASSIUM CAPLETS
(ILLEGAL IMPORT) (POTASSIUM +
JUNIPER + PARSLEY + UVA URSI EXT.
+ BUCHU EXT.)
URINEX CAPS.
(ALPHA PINENE + ANETHOL +
BETA PINENE + BORNEOL +
CAMPHENE + CINEOL +
FENCHONE)
Rowatinex Cap. (α-pinene, β-pinene,
camphene, borneol, anethol, fenchone,
cineole)

63.  EOs are good penetrants
increasing their own
bioavailability and that of co-
administered products,
making them good synergists.
Essential Oils as a promising permeation enhancers for
transdermal drug delivery