ESSENTIAL OILSVOLATILE OILS

Volatile oils Are volatile in steam Differ entirely from fixed oils in both

chemical and physical properties. Frequently associated with other

substances such as gums and resins. Tend to resinify on exposure to air. They are secreted in:A. oil cells.B. secretion ducts or cavities.C. glandular hairs.

USES OF ESSENTIAL OILS

Essential oils are consumed in numerous uses; they are used :

• For their therapeutic actions. • For flavoring, e.g. oil of lemon.• In perfumery, e.g. oil of rose• As starting materials for the synthesis

of other compounds, e.g. oil of trupentine

Therapeutic Purposes Of Volatile Oils

They are used :

• As inhalations, e.g. eucalyptus oil.• Orally, e.g. peppermint oil.• As gargles & mouthwashes, e.g. thymol.• Transdermally• In aromatherapy, e.g. lavender, rosemary &

bergamot

Oils with a high phenol content, e.g. clove and thyme have antiseptic properties.Oils showing antispasmodic activity. e.g. fennel, mentha,chamomile, anise, rosemary. Whereas others are used as carminatives. Used in food preservation & cosmetic preparations.

NOTEcarminatives means: either prevents formation of gas in the GIT or facilitates the expulsion of gas.

Composition of Volatile Oils

Volatile oils are generally mixtures of hydrocarbons and oxygenated compounds derived from these hydrocarbons.

The odor and taste of volatile oils is mainly determined by these oxygenated constituents, which are to some extent soluble in water but more soluble in alcohol.

NOTERose water & tinctures of lemon

CH3

OH

H3C CH3

Menthol

(peppermint oil)

CH3

O

H3C CH2

Carvone

(caraway oil)

CH3

H3C CH3

OH

Thymol

(thyme oil)

OH

OCH3

Eugenol

(clove oil)

OCH3

CH3

Anethole

(anise oils)

CHO

Cinnamaldehyde

(cinnamon oil)

CH2

Physical Properties

1. They possess characteristic odors.2. They are characterized by high refractive

indices.3. Most of them are optically active.4. Their density is generally lower than that of

water (except for sassafras, clove & cinnamon oils).

5. May darken in color when exposed to light. 6. They are immiscible with water, but they are

sufficiently soluble to impart their odor to water. The aromaticity of water depend on this slight solubility.

Although volatile oils have different chemical properties, they have a number of physical properties in

common:

Essential oils are prepared by:A. Distillation.B. Scarification and expression.C. Extraction.D. Enzymatic hydrolysis.E. Enfleurage.

Preparation of volatile oils

A- Distillation

There are three basic types of essential oil distillation:1. water or "hydro-distillation"2. water and steam or "wet steam"3. steam or "dry steam“

1- Hydro-distillation in this method the plant material is immersed totally in boiling water. The disadvantages are that the heat is difficult to control and hence the rate of distillation is variable. Also there is a possibility for overheating and "burning" which lead to a poorer quality oil.

2- Water/steam distillation the plant material is placed on a grid which keeps the plant material above the water level. The water is boiled below the grid and "wet" steam passes through the plant material. Over packing of the still can cause the steam to leave parts of the plant un-extracted.

3- Steam Distillation by direct steam provided from a separate boiler. The still contains a grid plate under which an open steam pipe is fitted. The advantages of "dry" steam distillation are that it is rapid, therefore it is less likely to damage those oils. Most advanced type of distillation

B-Scarification and expression

These are mechanical techniques carried at room temperature.Used in preparation of heat sensitive oils. Process:Squeezing of the plant material under water stream which yield a mixture of essential oil, water, cellulose, wax and other substance.Removal of water an cellulose by centrifugation.Removal of wax by chilling followed by feltration.

C- Extraction

For preparation of delicate flowers oils which contain either small amounts of oils or heat sensitive oils

Classified into:I. Non-volatile solvent extraction.II. Volatile solvent extraction.III. Extraction with supercritical gases.

D- Enzymatic hydrolysis

For glycosidic volatile oils e.g. mustard oil.

Principle:1. Subjecting the plant material to enzymatic

hydrolysis to liberate the volatile constituents.2. Separation of the volatile constituents by

distillation or extraction.3. Purification of the products.

Used to extract oils utilized in perfumery.

Process:• A glass plate is covered with a thin

coating of especially prepared and odourless fat.

• The freshly cut flowers are individually laid on to the fat which in time becomes saturated with their essential oils.

• The flowers are renewed with fresh material.

E- ENFLEURAGE

Difference between Volatile & Fixed Oils

Carrier oils AKA fixed or base oils; are the oily non volatile part of the plant, typically obtained from the seed or nut. They are called ‘fixed’ as they have large molecules that do not evaporate like the essential oils.

Several points differ 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 alkalis.

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

1- Clove (Caryophylli)) مسمار ) قرنفل

Origin:Clove consists of the whole flower buds of Syzygium aromaticum . F. Myrtaceae.dried until they become reddish-brown.

MorphologyThe flower bud is reddish-brown and consists of a quadrangular stalked portion, the hypanthium, 10 mm to 17.5 mm long, surmounted by four divergent lobes of sepals which surround a globular head .The head is globular and dome-shaped, composed of four imbricated petals

The powder is dark brown and has strong aromatic spicy agreeable odour and warm spicy agreeable taste Examine under a microscope The powder shows

epidermis and underlying parenchyma Large oil glands short fibers occurring singly or in small groups with thickened, lignified walls . abundant of parenchyma containing cluster crystals of calcium oxalate numerous triangular pollen grains Xylem vessels and fibres.

Note : prisms of calcium and Starch granules are absent.

Uses relieve pain and to promote healing flavouring industries (spice)anaesthetic properties (for toothache)Antispasmodic and carminativeIn manufacture of vanillin.

Active constituents volatile oil (15 -20%) ,which contain eugenol (85%).Pyrogallol tannin.

Chemical test sudan III → red colour.FeCl3 → blue colour.KOH: needle crystals of K eugenate.

Adulteration of clove:

Clove StalksExternally, they are brownish and rough .internally presence of prisms of calcium oxalate and pseudo crystal sheath. Mother Cloves This can be detected by the presence of much starch in the seeds. Brown Cloves ( Expanded flowers) Exhausted Cloveslighter than water

2- German chamomile البابونج

Origin: German chamomile is the dried flower heads of Matricaria chamomilla, family Compositae

Morphology The flower head is almost hemispherical, with hollow receptacle carrying two types of small sessile flowers called florets: ray florets and central or disc florets.

Active constituents:flavonoid glycosides.volatile oil contains matricarin which converted to chamazulene by heating.

Usescalm frayed nerves (tranquilizer).carminative, antispasmodic.local anti-inflammatory for sun burns

Chemical test: sudan III : red colour

3- Anise Fruit (Fructus Anisi, Aniseed) يانسون

Origin:Is dried ripe fruits of Pimpinella anisum F. Umbelliferae

Morphology Anise fruits are greyish brown, about 2-12mm. long, ovoid,They are broad near the base, and taper gradually towards the apex, which is crowned with a stylopod. Cremocarp separated into its meri-carps which usually remain united and attached to a pedicel longer than the fruit. Each mericap possesses five ridges, rough to touch due to presence of short, stout hairs

The powder is greenish-yellow or brownish-green. The powder have strong aromatic agreeable

characteristic taste and sweet strongly aromatic taste shows the following

characters:

fragments of branched vitta usually crossed by the cells of the endocarp

aleurone grains micro-rosettes of calcium oxalatenon-glandular, unicellular warty hairsFew fibres and pitted parenchyma

Active constituents1. Volatile oil (2 to 6%) contain anethole 2. fixed oil and protein.

Uses:Carminativeflavoring agentStimulant

Chemical test: Sudan III

4- Cinnamon Bark(Cortex Cinnamomi)

Origin: Cinnamon is the dried bark of cinnamomum zeylanicum, Family Lauraceae, deprived of most of its cortex known as Ceylon Cinnamon.

Morphology Cinnamon occurs as quills (single or double compound quills ).1 meter in length.

powder: a reddish brown powder with acharacteristic pleasant and aromatic odour and taste, showing fragments of:

fibres, they are thick-walled and lignified with lumen and few slit-shaped pits.

thin-walled oil cells Sclereids, isodiametric, thick wall,

lignified, the outer wall is less thickened than the others.

Starch granules and needle crystals of calcium oxalate.

Cork cells are rare

Constituents:1) volatile oil (0.5 -1 % ) (contains cinnamicaldehyde, eugenol)2) tannin and mucilage Uses:- Carminative- Antispasmodic- Mild astingent- Flavoring agent.The oil is also a powerful germicide Chemical test: Sudan III, Rhuthenium red, FeCl3

and KOH for eugenol

5- Cassia Bark(Chinese Cinnamon)

Origin: It is the dried bark of Cinnamomum cassia,Family Lauraceae.

Morphology:Chanelled pieces or Single quill up to 40 cm long, earthy brown colour with patches of the thin grayish cork.

Powder: differs than cinnamon in:

1. Odour is less delicate, taste as cinnamon but slightly mucilaginous.

2. Numerous fragments of cork cells, polygonal with slightly thick wall, contains reddish brown content.

3. Fibres are shorter and thicker.

Active constituents: Volatile oil consisting of Cinnamicaldehyde,no

eugenol is found

Use The same uses as cinnamon bark

Chemical test all as cinnamon but negative test for eugenol

7- Mentha Herb (Peppermint)(Herba Mentha Piperitae)نعناع

Origin: they dried from the leaves and flowering tops

of Mentha piperita F. Labiatae

Powder the powder is brownish-green. with an aromatic characteristic odour and an aromatic taste followed by a sensation of cold in the mouth. It is characterized microscopically by the presence of fragments of:

cells of the epidermis having wavy walls and diacytic stomata  Glandular labiaceous hair, unicellular base with multicellular head composed of 8-16 radiating cells Non-glandular hairs. Different types of xylem vessels, fibres and wood parenchyma. Calcium oxalate crystals are absent

Active constituents 1. Volatile oil : chief components are menthol 2. Tannin

Uses:1. car minative and flavoring agent.2. inflammation of the mouth and pharynx (oral

preparations) 3. Menthol is used in pharmaceutical preparations as local

antipruritic, counter irritant and antiseptic.4. Recently the oil is used for treatment of colitis.

5. Chemical test: Sudan III

THE END