Useful for pharmacy students

1. Volatile oils
Dr.U.Srinivasa, Professor and Head,
Department of Pharmacognosy,
Srinivas College of Pharmacognosy, Mangalore
Email – drsrinivaspharmacy@rediffmail.com

2. VOLATILE OILS
• Definition :
• The odorous, volatile principles of plant and animal
sources are known as volatile oils. They are liquid,
volatile oils will evaporate or volatize when exposure
at an ordinary temperature and so they are called
ethereal oils. They are also called as essential oils as
they are essences or concentrated constituents of the
plants.

3. General properties of volatile oils
1.They are soluble in alcohol, ether and other
lipid solvents and practically insoluble in
water.
2. They are usually lighter than water.
3. They possess characteristic odours and they
have high refractive index

4. • 4. Most of them are optically active.
• 5. They are secreted in special structuree
such as duct, cell, schzogenous or lysigenous
gland, trichomes.
• 6. They are commonly found in the species
of Labiatate, Rutaceae, Piperaceae,
Zingeberaceae, Umbellifereae, Myrtaceae
and Lauraceae.

5. • 7. They are present in entire plant or in any
part of the plant.

6. • CHEMICAL NATURE:
• Chemically , they are derived from terpenes
and their oxygenated compounds. They are
made up of isoprene units ( C5H8) and are
usually mono-, sesqui-, and diterpenes with
empirical formulae as C10H16,C15H24, and
C20H32 respectively.

7. • Classification of volatile oils:
• 1. Alcohol volatile oils –Eg Cardamom, Coriander
• 2. Aldehyde volatile oils – Eg Cinnamon, Lemon peel
• 3. Ester volatile olis – Eg Lavender, Mustard
• 4. Hydrocarbon volatile oils – Eg Turpentine, Black
pepper
• 5. Ketone volatile olis – Eg Caraway, Camphor

8. • 6. Oxide volatile oils – Eg Eucalyptus, Chenapodium
• 7. Phenolic ether volatile oils – Eg Fennel, Nutmeg
• 8. Phenol volatile oils – Eg Clove

9. Preparation of volatile oils
 The principal methods used in the preparation
of volatile oils from plants depend on:
1. Distillation in water or steam.
2. Mechanical methods.
a) Enfleurage (extraction of oils used in
perfumery).
b) Ecuelle method

10. 3. Extraction with solvents.
4. Enzymatic hydrolysis (for glycosidic volatile
oils e.g. mustard oil).
5. Supercritical fluid extraction

11. Production and uses of volatile oils
• The total annual production of volatile oils is
estimated to be in the region of 45,000 tones,
worth approximately US$700 million.
There are about 100 commercially valuable
volatile oils directly derived from plants.

12. Biosynthesis and chemical composition
• Chemical constituents of volatile oils may be
divided into 2 broad classes, based on their
biosynthetic origin:
1. Terpene derivatives formed via the acetate-
mevalonic acid pathway.
2. Aromatic compounds formed via the shikimic
acid-phenylpropanoid route.

13. Aromatic compounds
OH
OCH3
Eugenol
(clove oil)
OCH3
CH3
Anethole
(anise oils)
CHO
Cinnamaldehyde
(cinnamon oil)
CH2

14. Physical properties
• Although volatile oils differ greatly in their chemical
constitution, they have a number of physical
properties in common:
1. They possess characteristic odors.
2. They are characterized by high refractive indices.
3. Most of them are optically active.

15. 4. Their density is generally lower than that of
water (the essential oils of sassafras, clove, or
cinnamon are the exceptions).
• As a rule, volatile oils are immiscible with
water, but they are sufficiently soluble to
impart their odor to water. The aromatic
waters are dependent on this slight solubility.

16. Volatile oils × Fixed oils
• Several points of differentiation exist between
volatile oils and fixed oils.
1. Volatile oils can be distilled from their natural
sources.
2. Volatile oils do not consist of glyceryl esters of
fatty acids. Hence, they do not leave a
permanent grease spot on paper and cannot
be saponified with alkalies.

17. • 3. Volatile oils do not become rancid as do
the fixed oils, but instead, on exposure to light
and air, they oxidize and resinify.

18. Uses of drugs containing essential oils
Pharmacy
Perfumery
Food technology
Miscellaneous industries (as starting materials
for the synthesis of the active principles of
medicines, vitamins, and fragrances).

19. Preparation of volatile oils
 The principal methods used in the
preparation of volatile oils from plants
depend on:
1. Distillation in water or steam.
2. Mechanical methods
3. Extraction with solvents.
4. Enzymatic hydrolysis
5. Supercritical fluid extraction

20. 1. Distillation method
• This is the most widely used method for the
extraction of volatile oil
• PROCEDURE – The plant material is
macerated and then steam distilled, when
the essential oils go into distillate from which
they are extracted by pure organic volatile
solvents.

22. • Like Light Petroleum ether.
• However , the method should be used with a
great care , since some essential oils are
decomposed during distillation and some are
hydrolyzed to none or less fragrant
compounds

23. 2. Mechanical methods
• A) Enfleurage method
• B) Eculle method
• Enfleurage method
• It is also known as cold fat extraction

24. Enfleurage method
• It is also known as cold fat extraction
• Used for the extraction of delicate perfumes
from Flower petals

25. Method -
• The fresh flower petals are mechanically
spread on a layer of fatty material, ( A glass
plate is covered with a thin coating of
especially prepared and odourless fat)
allowed to imbibe and the exhausted petals
are replaced by fresh material.

27. • The process is continued till the fatty layer is
saturated with volatile principles, which are
then extracted with lipid solvent like ethyl
alcohol.
• The extract having ethyl alcohol and essential
oils is distilled under reduced pressure to
remove the solvent.

28. • Advantages –
• In case of distillation method , volatile oil
may undergoes hydrolysis, polymerization or
resinification or delicate oils becomes lost in
large volumes of water or where the flowers
continue to produce fragrance after the
harvest effleurage is usually practiced

29. Ecuelle method ( Expression method)
• It is also known as expression method
• Used for the extraction of citrus oils from
citrus fruits.

30. Method –
• Here oil cells in rind are ruptured
mechanically using pointed projections by
twisting the raw material over them in
Clockwise direction either mechanically or
manually.

31. • The oil is then separated from the juice by
centrifugation.
• The other half of the oil is generally not
extracted and such residue is used for the
isolation of inferior quality of oil by
distillation.

32. • Eg citrus, lemon and grass oils are extracted
by this method

34. 3. Extraction with solvents.
•
• Here they are using volatile solvents to
extract the volatile oil. i.e Petroleum ether,
benzene

35. Method –
• Fresh flowers are transferred into specially
constructed extractors at room temperature
and carefully treated with purified solvent ,
usually petroleum ether.

36. • The solvent penetrates the flowers and
dissolves the natural perfume together with
some waxes and other albuminous and
coloring matter
• This solution is pumped into an evaporator
and concentrated at low temperature. After
complete evaporation of solvent the flower
oil is obtained.

37. • Application –
• This method is used in perfume industry for
the production of volatile oils using lipid
solvents like petroleum ether or benzene
• Advantages-
• It is quick
• Quality assured and economical method

38. • The decomposition of volatile oil is less as
compared to hydro distillation method
• The solvent distilled off may be reused for
extraction

39. 4. Enzymatic extraction
• Here , the volatile oil is normally found in
plants substances in the form of odourless
glycosidal combination. However , the
odoriferous compounds are liberated free
only by hydrolysis.
• Volatile oil of bitter almond
( Benzaldehyde)

40. Preparation and analysis of oils

41. CLOVE OIL
• Method of production :
• It is prepared from the well developed clove
flower buds by steam distillation
• Method of analysis :
• Specific gravity of oil – 1.038- 1.060
• Refractive index – 1.527 -1.535

42. CINNAMON OIL
• Method of production :
• Cinnamon oil is obtained from steam
distillation of leaves and twigs of the plant
cinnamomum cassia . It contains not less than
1% of volatile oil.

43. • Method of analysis :
• Optical rotation – 0 to – 2
• Specific gravity – 1.000 to 1.030
• Refractive index – 1.562 to 1.582

44. EUCALYPTUS OIL
• Method of Production :
• The leaves are subjected to steam distillation
• Method of analysis :
• Optical rotation – 0 to 10
• Specific gravity – 0.897 to 0.915
• Refractive index – 1.457 to 1.469

45. MENTHA OIL
• Method of preparation:
• The flowering tops of mentha are collected
and air dried . The dried flowering tops are
introduced into a mild-steel still, where steam
distillation is carried out for 3-4 hrs under
reduced pressure .

46. • In the first 2hrs , upto 85% of the oil gets
distilled out.
• The density of the mentha oil is less than
water, because of which it floats on the
surface of water.
• The distillate consisting of mentha oil and
water is introduced in a separating vessel ,
where oil is separated by decantation

47. • Method of analysis :
• Neural to Litmus
• Optical rotation – 16 to – 30 at 25o
• Specific gravity – 0.900 to 0.912
• Refractive index – 1.4590 to 1.4650

48. SANDAL WOOD OIL
• Method of production :
• It is obtained by the process of steam distillation
from the heartwood of plant Santhalum album
• Method of analysis :
• Optical rotation – -15 to – 20 at 25o
• Specific gravity – 0.973 to 0.985
• Refractive index – 1.500 to 1.510

49. Lemon gross oil
• Method of production :
• It is obtained by the process of steam distillation
from the fresh herb of the plant Cymbopogan
citrates
• Method of analysis :
• Optical rotation – -3 to +1o
• Weight per ml – 0.892 to 0.909
• Refractive index – 1.4808 to 1.4868

50. CLOVE
• Biological source : It consists of the dried flower
buds of Eugenia caryophyllus
• Family : Myrtaceae
• Chemical constituents :
• 1. Volatile oil ( 16-21%)- Phenol chiefly Eugenol
( 80-88), Acetyl eugenol (10-15) and α and β
Caryophyllene

51. • 2. Tannins (10 – 13%) – Pyrogallol tannins
• 3. Others substances are Methyl furfural and
dimethyl furfural.

52. Medicinal uses
• Used as an antiseptic
• Used as a stimulant
• Used as a carminative
• Used as flavouring agent
• Used as Local anaesthetic ( eugenol)

53. • Used as spice
• Used in tooth ache
• Used in dental preparations, mouth washes,
oil used in perfumery
• Clove oil and zinc oxide are used in
temporary filling of dental cavities

54. Diagnostic characters
• Odour : Aromatic
• Pollen grains : Small, biconvex with rounded
or triangular
• Oil glands : Fragments of parenchyma with
entire or portion of oil glands
• Aerenchyma : Portion of loose parenchyma

55. • Fibres : Sclerenchymatous fibres associated
with parenchymatous cells
• Sclerieds : Oval to sub rectangular, thickened
walls having numerous simple or branched
pits
• Calcium oxalate : In the form of cluster crystals
• When starch is present then it is from
Anthophylli (Mother clove)

56. CINNAMON
• Biological source:
• It consists of dried inner bark of the plant
cinnamomum zeylanicum .
• Family : Lauraceae
• It contains not less than 1% of volatile oil.

57. Chemical constituents :
• It contains about 0.5 to 1.0% of volatile oil.
• 1.2% of tannins (Phlobatannins)
• Mucilage
• Calcium oxalate
• Starch
• Sweet substance known as mannitol
• Cinnamon oil contains 60-70% of cinnamic
aldehyde, 5-10% of eugenol, and benzaldehyde,
cumminaldehyde and other terpines.

58. Uses :
• Carminative
• Stomachic
• Mild astringent
• Flavouring agent
• Aromatic
• Used as a spice and condiment
• Preparation of candy, dentrifies and perfumes
• Oil is powerful germicide

59. Diagnostic characters :
• 1. Organoleptic characters:
▫ Colour - reddish brown powder
▫ Odour - characteristic, pleasant and aromatic
▫ Taste - characteristic, pleasant and aromatic
2. Phloem fibres : Isolated bast fibres , strongly
lignified, slender , measures 250- 600 microns in
length and 15- 30 microns in breadth

60. • 3. Stone cells :
• Almost U shaped as one wall is thinner than the
other three, strongly lignified
• 4.Starch grains :
• Abundant starch grains which does not measure
more than 10 microns
• 5.Calcium oxalate crystals:
• Presence of small acicular raphides in the
parenchyma
• 6. Oil cells :
• Big and isolated

61. FENNEL
• Biological source :
• Drug consists of dried ripe fruits of Foeniculum
vulgare
• Family : Umbelliferae

62. Chemical constituents :
• Fennel contains volatile oil (1-4%), fixed oil (9-
12%)and proteins (20%)
• The chief constituents of volatile oil are a phenolic
ether anethole (50-60%) and ketone fenchone (18-
20%)
• Volatile oil also contains anisic aldehyde, alpha , ß –
pinene, ascorbic acid, niacin etc

63. Uses:
• Carminative
• Stomachic
• Expectorant
• Flavouring agent
• Aromatic
• Stimulant
• Anthelmintic
• Useful in dental and mouth wash preparation
• Fennel water is useful in colic and flatulence in
children

64. Diagnostic characters :
• Mesocarp :
• Lignified and reticulate nature of the parenchyma
• Endocarp :
• Cells showing parquetry arrangement
• Endosperm:
• Polyhedral, thick walled cells containing aleurone
grains, minute calcium oxalate crystals and oil
globules
• Vittae :
• Many in the form f yellowish brown fragments

65. CORIANDER
• Biological source :
• Drug consists of dried ripe fruits of Coriandrum
sativum
• Family : Umbelliferae

66. Chemical constituents :
• It contains volatile oil (1-4%), fixed oil (9-12%)and
proteins (20%)
• The chief constituents of volatile oil are limonene, p-
cymene, camphor, coriandrol etc
• Malic acid,
• Tannin,
• Vitamin A

67. USES :
• Carminative
• Stomachic
• Expectorant
• Flavouring agent
• Aromatic
• Stimulant
• Diuretic
• Anthelmintic
• Aphrodisiac

68. Diagnostic characters :
• Sclerenchymatous layer :
• Group of fusiform fibres of sclerenchyma running
way and at times crossing with each other .
• Endocarp :
• Cells showing parquetry arrangement
• Endosperm:
• Polyhedral, thick walled cells containing aleurone
grains, minute calcium oxalate crystals and oil
globules
• Vittae :
• Many in the form f yellowish brown fragments

69. CARAWAY
• Biological source :
• Drug consists of dried ripe fruits of Carum carvi
• Family : Umbelliferae

70. Chemical constituents :
• It contains volatile oil (1-4%), fixed oil (8-20%)and
proteins
• The chief constituents of volatile oil are caravone,
caravol, pinene, coriandrol etc
• Resin,

71. Uses :
• Carminative
• Flavouring agent
• Spice
• Stimulant
• Stomachic
• Preparation of mouth washes, tooth paste, chewing
gums, soap and cosmotics

72. Diagnostic characters :
• Sclereids :
• Group of sclereids in the mesocarp .
• Endosperm:
• Large portion of endosperm containing aleurone
grains and oil globules with microsphenoidal crystals
calcium oxalate.
• Vittae :
• Many in the form of yellowish fragments composed
of thin walled cells.

73. Eucalyptus
• Biological source :
• Drug consists of from fresh leaves of plant
Eucalyptus globules.
• It contains not less than 65% of cineole
• Family : Myrtaceae

74. Chemical constituents :
• It contains volatile oils. The chief constituent of
volatile oil is cineole, also known as eucalyptol, also
contains pinene, camphene and traces of
phellandrene, citronellal.
• It also contains Gallo tannins, methyl ester of p-
couramic acid

75. Uses :
• Antiseptic
• Expectorant
• Counter - irritant
• Antibacterial and antituberculosis
• Used to relieve cough and in chronic bronchitis in the
form of inhalation
• Solution of eucalyptus oil is used as nasal drops

76. Diagnostic characters :
1. Organoleptic characters:
▫ Odour - characteristic and aromatic
▫ Taste - characteristic and aromatic
2. Epidermis cells :
Polygonal epidermal cells with numerous, well
developed , prominent sunken stomata
( Anamocytic stomata)

77. • 3. Oil glands :
• Large secretary oil glands either entire or fragments
• 4. Calcium oxalate crystals :
• Both prism and cluster crystals
• 5. Fibres :
• Well developed sclerenchymatous fibres from the
vascular bundle region

78. MENTHA
• Synonym: Peperimint
• Biological source: It consists of fresh flowering
tops or aerial parts of the plants known as
Mentha piperita
• Family : Labiatate

79. • Chemical constituents:
• The chief constituent of peppermint is volatile
oil (0.7-1.5%) and 6-12% of Tannin.
• The chief constituent of volatile oil are
menthol (50-60%), menthyl acetate,
menthone ,cineole and small amounts of
terpenes

80. • Diagnostic characters :
• Covering trichomes : Thick, coarse, uniseriate
with many cells
• Glandular trichomes: Unicellular stalk and a
head with 1-8 cells (yellow colour)
• Stomata : Diacytic

81. • Epidermis:
• Cells with wavy walls
• Negative characters:
• Absence of calcium oxalate crystals in the
mesophyll tissue
• Uses: carminative, stimulant, spasmolytic and
antiseptic

82. NUTMEG
• Synonym: Myristica
• Biological source: It consists of dried kernals of the
seeds of the plant known as Myristica fragrans
• Family : Myristicaceae

83. Chemical constituents:
• Nutmeg contains 5 to 16% of volatile oil and about
30% of fat.
• The volatile oil contains about 4% to 8% myristicin,
elemicine and safrole.
• The fatty acid constituents of the fixed oil are
myristic acid, palmatic acid, oleic acid, lauric acid
etc
• The fat of the nutmeg is also known as nutmeg
butter. It also contains protein and starch.

84. Uses
• Aromatic
• Stimulant
• Carminative
• Flavouring agent
• Used in soap industry
• The fat and volatile oil are used in rheumatism

85. Diagnostic characters :
• Odour : Characteristic aroma
• Oil cells : Big oil cells in brown fragments
• Fat- crystals :
• Crystalline groups of fat in the form of bunches of
small needles
• Starch grains : Abundant , simple (spherical) and
compound

86. LEMON GROSS OIL
• Biological source :
• It is the oil distilled from the fresh herb of the plant
Cymbopogan citrates
• Family : Graminae

87. Chemical constituents
• Mainly contains citral and citronellol
• Geraniol
• Linalool
• Methyl heptenol
• Limonene

88. Uses :
• Flavouring agent
• Perfuming agent
• Used as a mosquito repellent
• Used as a source of citrol

89. QUESTIONS
• Define volatile oils and add a note on various
methods of extraction of volatile oils. (10)
• Define and classify essential oils with examples.
Write the pharmacognosy of Clove. (10)
• Explain in detail the method of manufacture
and analysis of Cinnamon. (10)

90. • Define and describe volatile oils by physical
and chemical properties. (10)
• Give the source, diagnostic characters, active
constituents and uses of Cinnamon and
Fennel. (10)

91. • Give the powdered microscopical characters of
Coriander and Clove. (5)
• Write a note on Supercritical fluid extraction
method (SCFE) and its significances. (5)
• Write a note on method of preparation and
analysis of Clove. (5)

92. • Differentiate microscopically the Fennel and
Coriander. (5)
• Give the source, active constituents and uses of
Eucalyptus and Sandal wood. (5)
• Define and classify with examples volatile oils. (5)
• Enfleurage method of extraction of volatile oils
and its significances. (5)

93. • Write a note on general properties and
chemical nature of essential oils. (5)
• Give the source, active constituents and uses
of Mentha and Coriander. (5)
• Write the chemical structures for the
following (a) Eugenol (b) Menthol
• (c) Limonene (d) Cinnamic aldehyde. (5)

94. • Advantages of Supercritical fluid extraction. (2)
• Diagnostic characters of Mentha piperita. (2)
• Write a note on Eculle method and its
applications. (2)
• Chemical tests for volatile oils. (2)
• Analysis of Eucalyptus oil. (2)