SECONDARY METABOLITIES .pdf

Secondary
Metabolites
UNIT-IV
Mr. Vishal S. Bagul
Assistant Professor
Department of Pharmacognosy
H. R. Patel Institute of Pharmaceutical
Education and Research, Shirpur
(Maharashtra)
Mr. Vishal S Bagul, Assistant Professor., HRPIPER

Content
Definition and classification
properties and test for identification of
Alkaloids
Glycosides
Flavonoids, Tannins,
Volatile oil and Resins

Introduction
• Metabolism is the collection of chemical
processes that occurs in living organisms in
order to maintain life. Thousands of chemical
compounds are involved in the metabolism of
living organisms. These compounds are
called metabolites and they are intermediates
and products of metabolism.

• Primary metabolites and secondary metabolites are the
two categories of metabolites found in living organisms.
• Both of them are small molecules
• which act as signalling molecules, catalysts, stimulators,
or inhibitors for any metabolic activity in the body.
• The main difference between primary metabolites and
secondary metabolites is that primary metabolites are
directly involved in primary growth development
and reproduction
• secondary metabolites are indirectly involved in
metabolisms while playing important ecological
functions in the body.

Mr.
Vishal
S
Bagul,
Assistant
Professor.,
HRPIPER
• Ethanol, lactic acid, nucleotides, vitamins, and some amino
acids are considered as primary metabolites. In industrial
microbiology
• Ethanol is the most common primary metabolite produced in
large-scale by fermentation
• Secondary metabolites do not play a role in growth,
development, or reproduction. However, they play a role in
ecological functions like defence mechanisms, serve as
antibiotics, and produce pigments.
• Eg; Atropine and antibiotics like erythromycin and are
commercially important secondary metabolites produced in
large-scale.

Primary Metabolite Examples
Alcohol Ethanol
Amino acids Glutamic acid, Aspartic acid
Nucleotides 5’ guanylic acid
Antioxidants Isoascorbic acid
Polyols Glycerol
Vitamines Vitamin B2
Secondary Metabolite Examples
Pigments Carotenoids, Anthocyanins
Alkaloids Morphine, Codeine
Terpenoieds Monoterpenes, Diterpenes
Essential oils Lemongrass oil
Toxins Abrin, Ricin
Lectins Concanavalin A
Polymeric substances Rubber, Gum, Cellulose

ALKALOIDS
• Alkaloids are a large and complex group of highly diverse natural products.
• The name "alkaloids" (Derived from Alkali) was introduced in 1819 by the
German chemist Carl Friedrich.
• They are cyclic compounds group of compounds contain one or more basic
nitrogen atoms in a heterocyclic ring.
• They have low molecular weight.

• Alkaloids can occur in plant kingdoms; among the angiosperms, the
Leguminosae, Papaveraceae, Ranunculaceae, Rubiaceae,
Solanaceae, and Berberidaceae are outstanding alkaloid-yielding
plants.
• The Labiatae and Rosaceae are almost free of alkaloids.
• Derosne (French chemist) isolated Narcotine (1803) from tobacco
• Ser turner (1803) isolated morphine from opium

• Alkaloids are more important because they have
valuable biochemical, pharmacological, and
medical effect Such as
1. pain relief
2. Anti-tumor
3. Stimulant
5. Muscle relaxant

Mr.
Vishal
S
Bagul,
Assistant
Professor.,
HRPIPER
all parts (E.g. Datura),
Bark (E.g. Cinchona),
Seeds (E.g. Nux vomica),
Roots (E.g. Aconite),
Leaves (E.g. Tobacco),
Fruits (E.g. Black pepper)
Latex (E.g. Opium)
About 25% higher plants are produce alkaloids and they are procured from various parts of
the plants such as

Physical Properties
• Alkaloids are crystalline in nature but few are amorphous solid
• Alkaloids are insoluble in water but soluble in most of the organic
solvents.
• Caffeine, cocaine, codeine, nicotine are slightly soluble in water.
• Alkaloids are bitter in taste.
• They have molecular weight in between 100-900.

Chemical Properties
• Alkaloids are naturally occurring organic compound.
• They mostly contain basic lone pair electron on
nitrogen; hence they are basic in nature.
• Alkaloids react with acids to form salts. These salts
are usually freely soluble in water (Example: Quinine
sulfate is water soluble)
• They form precipitate with heavy metal iodides.
• They decomposed at temperature above 70°C for long
time

Classification

A. Based on Chemical Nature and Structure

• Monocyclic alkaloids: They contain
a single, unfused ring. (Example:
Nicotine)
• Bicyclic alkaloids: They consist of
molecules with a 1,4-nitrogen bridged
structure. (Examples: Atropine,
Cocaine)
• Polycyclic alkaloids: They are
having more than two rings.
(Examples: Morphine, Codeine)

Non-heterocyclic alkaloids

Based on Nature/Basicity
• Primary amines (R-NH2)
Example: Norephedrine
• Secondary amines (R2-NH)
Example: Ephedrine
• Tertiary amines (R3-N)
Example: Atropine
• Quaternary ammonium salt (R4-N)
Example: d-Tubocurarine

Based on Hegnauer’s Classification
True Alkaloids:
• They are the alkaloids that derived directly from amino acid.
• They contain nitrogen in their heterocyclic ring.
• They are basic in nature due to presence of lone pair of electron on nitrogen atom and strong toxic in
nature.
• They are also very effective.
• They give positive test for common tests for alkaloids.
• Examples: Quinine, Morphine, Atropine etc.

Proto alkaloids:
• They do not have nitrogen in their heterocyclic ring.
• They are derived from Tyrosine.
• They give positive test for common tests for
alkaloids. Examples: Ephedrine.
Pseudo alkaloids:
• They are not derived from amino acids
• They have nitrogen in a heterocyclic ring.
• They do not give positive test for common tests for
alkaloids. Examples: Caffeine

Based on Pharmacological action

Based on Taxonomical Origin
• Alkaloids are classified on the basis of the biological source.
• Examples: Quinine from bark of Cinchona calisaya, Rauwolfia from roots of Rauwolfia
serpentina, Morphine from dried latex of Papaver somniferum etc

Functions of Alkaloids
• They act as plants stimulants and regulators in activities such as growth,
metabolism and reproduction.
• They are as end products of the metabolism or waste products.
• They are storage reservoir of nitrogen for protein synthesis.
• They act as protective agent for the plants against attack by parasites
• They act as a detoxification agent, which renders harmless certain
substances

Chemical Tests
• Alkaloid sample reacts with Dragendorff’s reagent
(Potassium-bismuth-iodide solution) which gives
reddish-brown precipitate.
• Alkaloid sample reacts with Mayer reagent (Potassium-
mercuric-iodide solution) which gives cream colour
precipitate.
• Alkaloid sample reacts with Wagner reagent (Iodine-
potassium-iodide solution) which gives Brown colour
precipitate.

General Extraction
Methods
Stas-Otto method
The method is based on the distribution of
alkaloidal bases between acid or aqueous
solution and immiscible organic solvent

Procedure

FLAVONOIDS
• Flavonoids are polyphenolic compound and vastly
available in maximum plant species.
• They are generally yellow coloured pigments.
They are larger group of glycoside.
• Flavonoids are the largest group of naturally
occurring phenols and occur in free states in the
plants as glycosides.
• Non-Nitrogenous Universal Plant Pigment
• Chemically 15 Carbon Skeleton (2-phenylbenzo
pyrone)

Physical Properties
of Flavonoids
• They are crystalline substances with certain melting point.
• Catechins, Flavanes, Isoflavanes, Flavanones, Flavanonoles are
colourless crystals. whereas Flavones, Flavonols are yellow coloured
crystals. Anthocyanidins are red in acidic media and blue in alkaline
media.
• Anthocyanins are sap pigments. The actual colour of the plant organ is
determined by the pH of the sap.
• Example: Blue colour of the cornflower and red colour of roses are due
to these glycosides.
• Flavonoid glycosides are generally soluble in water and alcohol but
insoluble in organic solvents.

Chemical Properties of
Flavonoids
• Chemically flavonoids are based upon a fifteen-carbon
skeleton (C15) consisting of two benzene rings (A and B)
linked via a heterocyclic pyrane ring (C).
• Six-member ring condensed with the benzene ring is either a
U-pyrone (flavonols and flavanones)
• The position of the benzenoid substituent divides the
flavonoid class into flavonoids (2-position) and iso
flavonoids (3-position).
• The glycosidic linkage is normally located in flavonoid at
positions 3 or 7.

Eg. Apigenin
Luteolin
Eg. Quercetin
Myricetin
Eg. Catechin
Eg. Hesperetin
Naringenin

Classification of Flavonoids as per group

Chemical Tests
for Flavonoid
1. Shinoda Test: The alcoholic solution of flavone or flavonol when
treated with metallic magnesium (or Zinc) and hydrochloric acid gives an
orange, red or violet colour.
2. Lead Sub acetate Test: To small quantity of residue, add lead sub
acetate solution. Yellow coloured precipitate is formed. Addition of
increasing amount of sodium hydroxide to the residue shows yellow
colouration, which decolouration after addition of acid.
3. Wilson’s Reaction: Flavonoids form complexes with boric acid which
is not destroyed by addition of citric acid alcoholic solution (or oxalic
acid).
4. Antimony Penta chloride Test: Alcoholic solution of sample when
reacts with antimony penta chloride the solution produces red or violet
colour.

Extraction Method

Functions
They act as powerful antioxidant
like Quercetin, Xanthohumol etc.
They control the plant growth.
They inhibit and activate plant
enzymes.
They having a role in the
biochemistry of reproduction.

Tannins
• Complex substances that usually occur as mixtures of polyphenols that
are very difficult to separate since they don't crystallize, are called
tannins.
OR
• Tannins are polyhydroxy phenolic compounds.

Physical Properties
• Tannins are dark brown or reddish brown.
• They are amorphous, non-crystalline in nature.
• They are available in the form of powder, flakes or spongy mass.
• They are water, alkali, alcohol soluble but sparingly soluble in chloroform and other
• organic solvents.
• They form colloidal solution with water.
• They form protective coating in place of wound injury.
• They have astringent taste.
• They combine with skin and hide to form leather. They react with gelatine to form
an insoluble compound.

Chemical properties
• Tannins form precipitation with proteins, gelatine, alkaloids etc.
• They have antioxidant properties due to presence of polyhydroxy phenolic compounds.
• They have astringent properties due to formation of precipitation with proteins.
• They yield purple, violet or black precipitate with iron compounds. Examples:
Hydrolysable tannins reacts with ferric salt to form blue black precipitation whereas
condensed tannins form brownish green precipitation with the same.
• They react with potassium ferricyanide in presence of ammonia to form deep red colour
solution.
• They are precipitated by metallic salts like potassium dichromate, and lead acetate and
sub-acetate.
• They are used in the clarification of wine and beer.
• As a constituent it reduces viscosity of drilling mug for oil wells.

Hydrolysable tannins
• These tannins are hydrolyzed by enzymes or acids. These tannins are basically esters of sugar mainly
glucose with one or more trihydroxybenzene carboxylic acid.
• These tannins are hydrolyzed by acids, or enzyme (Tannase). Their structures composed with several
polyphenolic acid molecules such as gallic acid and ellagic acid which are bound through ester
linkage to a central glucose molecule.
• Hydrolysable tannins are also known as pyrogallol tannins as the component of phenolic acid on dry
distillation converts pyrogallols and phenolic compounds.

Condensed tannins
• These tannins are resistant to hydrolysis (do not
contain sugar moiety) and they derived from the
flavonols, catechins and flavan-3, 4-diols.
• Catechin occurs with tannins and flavan-3, 4-diols are
intermediates in the biosynthesis of polymeric
molecules. On treatment with acids or enzymes they
are decomposed into phlobaphenes (Red insoluble
compound). On dry distillation they produce catechol
hence they are also known as catechol tannins.

Complex tannins
• They are the group of tannins that biosynthesized from both hydrolysable tannin (C-
glucoside ellagitannin) and condensed tannin (Flavono-ellagitannin). Example:
Acutissimin.
• It is prepared by reacting a substance called vescalagin, extracted from oak wood, with
a flavanoid from grapes called catechin. Some other examples like tea (Thea sinensis),
Oak (Quercus infectoria), hamamelis (Hamamelis virginiana) leaves and bark,
chestnuts (Castanea sativa) contain both hydrolysable and condense tannins.

Pseudo tannins
True tannins
Phenolic compounds of plant
origin that don't convert animal
hide to leather but do give
positive Gold beater’s skin test,
are called pseudo tannins.
Polyhydroxy phenolic compounds
which convert animal hide to
leather by precipitating proteins
and give positive Gold beater’s
skin test, are called true tannins.
Molecular weight is less than true
tannins.
Molecular weight is 1000-5000

Identification tests
1. Gelatin Test: To a solution of tannin, aqueous solution of gelatin and sodium chloride are added. A white buff coloured
precipitate is formed.
2. Goldbeater’s Skin Test: A small piece of goldbeater skin (membrane prepared from the intestine of an ox) is soaked in
20% hydrochloric acid, rinsed with distilled water and placed in a solution of tannin for 5 minutes. The skin piece is
washed with distilled water and kept in a solution of ferrous sulphate. A brown or black colour is produced on the skin
due presence of tannins.
3. Phenazone Test: A mixture of aqueous extract of a drug and sodium acid phosphate is heated then cooled and filtered.
A solution of phenazone is added to the filtrate. A bulky coloured precipitate is formed.
4. Matchstick Test: A matchstick is dipped in aqueous plant extract, dried near burner and moistened with concentrated
hydrochloric acid. On warming near flame, the matchstick wood turns pink or red due to formation of phloroglucinol.
This test is also known as Catechin test.

General
Extraction
Both hydrolysable and condense tannins are
water and alcohol soluble but insoluble in organic
solvents. Hence, tannin containing compound
(Gallic acid, ellagic acid, other tannins) are
extracted with using water or alcohol as solvent.
Chloroform containing drugs are removed
through ether extraction. Collected aqueous layer
and concentrated to get crude extract of tannins

Functions
• Medicinally they used as antidotes, antiseptics, astringent properties.
• They used in ink manufacturing industries.
• They used as preservatives.
• They used for vegetable tanning.
• They used to inhibit lipid peroxidation and plasmin.
• They used for lipolysis in fat cells.
• They are used to treat tonsillitis, pharyngitis, hemorrhoids, and skin eruptions.

Glycosides
• Glycoside is an organic compound contains C, H, and O in their structure. They are
natural carbohydrate substances that is composed of a sugar portion linked to a non-
sugar moiety. The sugar portion is called glycone, while the non-sugar portion is called
aglycone.. They are obtained from maximum higher plants but in less quantity.
• The hydroxyl group of sugar is condensed with hydroxyl group of non-sugar
components
R-OH + HO-X R-OX + H2O

Physical Properties
• Glycosides are solid and amorphous powder.
• They are colorless but some are colored (Except: Anthraquinone is red or orange, Flavoniods are
yellow).
• They are water soluble but insoluble in organic solvents.
• They are non-volatile in nature.
• Many sugar containing glycosides are insoluble in water but soluble in alcohol.
• Glycone part is water soluble whereas aglycone part is alcohol soluble.
• After hydrolysis they react with Molish’s reagent and Fehling’s test.

Chemical Properties
• With acid hydrolysis glycoside separated into sugar and non-sugar parts.
• The acetal linkage is more readily cleaved than the linkage between the individual
sugars of the sugar chain. But C-glycosides are resistant to acid hydrolysis.
• With strong and mild alkali, they are hydrolyses the ester group. They open lactone
rings. Example: Cardiac glycosides.
• With enzymatic hydrolysis sugars are splits stepwise from the terminal sugars. Enzymes
are specific for some types of glycosides to split. Like Emulsin hydrolyses beta-
glycosides, Invertase hydrolyses alpha-glycosides, Myrosin hydrolyses
sulphurglycosides etc.

Solubility
• Solubility: glycosides are water
soluble compounds and insoluble in the organic
solvents.
• Glycone part: water soluble, insoluble in the
organic solvents.
• Aglycone part: water insoluble, soluble in the
organic solvents.
• Some glycosides soluble in alcohol.

Role of glycosides in the plants
Converting toxic materials to non or less toxic.
Transfer water insoluble substances by using monosaccharide.
Source of energy (sugar reservoir).
Storing harmful products such as phenol.
Regulation for certain functions( growth).
Some have beautiful colours (pollination process).
Some glycosides have antibacterial activity, so they protect the plants from bacteria
and diseases.

Based on Linkage:
• Glycosides are classified based on linkage between glycone and aglycone part where OH groups reacting
with any of the medicates like, OH, CN, SH, NH product in aglycone part and as per that.
(a) C-glycoside: Glycone-OH + HC –aglycone ¾
Glycone-C-aglycone + H2O Some of the anthraquinone
glycosides like cascaroside in cascara, aloin in aloes
shows the linkage. C-glycosides are called aloin type
glycoside present in aloes. They do not hydrolyze by
heating with dilute acid or alkalis but occur by oxidative
hydrolysis with FeCl3.

(b) O-glycoside
• Glycone-OH + HO-aglycone ¾ Glycone-O-aglycone + H2O
• They are common in higher in plants. Example: Senna,
Rhubarb. They are hydrolysed by treatment with acid or
alkali into glycone and aglycone portion.
(c) S-glycoside
• Glycone-OH + HS–aglycone ¾® Glycone-S-
aglycone + H2O
• They occurrence of this glycoside is in
isothiacyanate glycoside like sinigirin in black
mustard formed by the condensation of
sulphohydryl group aglycone to OH group of
glycone

Based on the
Chemical
Nature of
aglycone
(Non-sugar)
Moiety

Based on the Nature of glycone
(Sugar) Moiety:
(a) Glucoside: Sugar portion is glucose.
(b) Rhamnoside: Sugar portion is rhamnose.
(c) Pentoside sugar portion is pentose.
(d) Fructoside sugar portion is fructose.
(e) Arabinoside sugar portion is arabinose.

Based on
Therapeutic
Nature of
Glycoside:
• Cardiac glycoside: Examples: Digitalis, Squill.
• Laxative glycoside: Examples: Senna, Aloe.
• Anti-ulcer glycoside: Examples: Liquorice.
• Bitter glycoside: Examples: Chirata, Quassia
wood.
• Local irritant: Examples: Black and white
mustard.
• Analgesic and antipyretic: Example: Salix bark.

General
Extraction
(Stas-otto method)
• The drug containing glycoside is finely powdered and
subjected to successive extraction in a Soxhlet apparatus
with alcohol or suitable solvent. After extraction, extract is
collected and treated with lead acetate to precipitate tannins.
Filtered the solution and to the filtrate H2S gas is passed.
Precipitate of lead sulphide form which is removed by
filtration. The filtrate is subjected to fractional
crystallization, distillation or chromatography gives pure
glycoside. Further the molecular structure is determined by
the Spectrophotometer, Ultra Red assays, Infra-red, NMR
and Mass spectroscopy etc.

Resins
• in the most specific meaning of the term, is a hydrocarbon secretion of many
plants, particularly coniferous trees. It is distinct from other liquid compounds
found inside plants or exuded by plants, such as sap, latex, or mucilage.
• the term "resin" is also used for many thick liquids, some of them artificial polymer
bases (synthetic resins).
• Resins and related resinous products are produced in plants during normal growth
or secreted as a result of injury to the plants
( Non nitrogenous compounds)

Physical Properties
• When heated, they form smoky flame
• Resins are transparent or translucent solids, semisolids or liquid substances.
• They are brittle solid in nature.
• They are fusible and flammable organic substances.
• They are not soluble in water but heavier than water.
• They are soluble in volatile oils, ether and alcohol.
• They become harden when exposed to air.
• They are generally produced by woody plants

Chemical Properties
• Resins are mixture of essential oils.
• They are oxygenated products of terpene and carboxylic acid.
• Chemically they contain esters, acids and alcohols.
• Some resins are chemically inert, known as resenes.
• Resins generally form soap when boiled with alkali.
• They are associated with volatile oils (oleoresins), with gum (gum resins) or with oil and gum (oleo-gum
resins).
• Electrically they are non-conductive masses.
• Specific gravity is 0.90-1.25.

Chemical Classification
• These types of resins are classified as per the predominating chemical constituents
present in the resin structure:
• (a) Acid Resins: They are mixtures of carboxylic acids, found in tree. They have the
basic skeleton of three fused ring fused with the empirical formula C19H29COOH.
Resin acids are tacky, yellowish gums that are water-insoluble. They are used to
produce soaps.
Examples: Abietic acid from Colophony, Commiphoric acid from Myrrh, Alleuritic acid
from Shellac etc

Mr.
Vishal
S
Bagul,
Assistant
Professor.,
HRPIPER
• Ester Resins Ester groups are present in the basic structure of the resins. Examples: Benzyl
benzoate in Benzoin, Cinnamyl cinnamate in Storax etc.
• Alcohol Resins High molecular weight alcoholic group and present in the structure of resins. They
sometimes form complex and are found either in free state or as ester form. Examples:
Peruresinotannol from Balsam of Peru, Guaicresinol from Guaiam, Gurjuresinol from Gurjan etc.
• Resin alcohols are of two types, namely resinotannols and resinols. Resinotannols are the alcohol
that gives specific tannin reaction with iron salts. They are of various types like Aloe resinotannoil
(e.g: Aloes), Ammo resinotannol (eg: Ammoniacum), Galba resinotannol (e.g.: Galbanum), Peru
resinotannol (e.g.: Balsam of Peru), Sia resinotannol (e.g.: Benzoin) and Tolu resinotannol (e.g.:
Balsam of Tolu).

Mr.
Vishal
S
Bagul,
Assistant
Professor.,
HRPIPER
• Resinols: They are the resins that gives sowing negetive specific tannin reaction with iron
salts. They are of different types like Benzo resinol (e.g.: Benzoin), Sto resinol (e.g.: Storax),
Gurju resinol (e.g.: Gurjun balsam) and Guaia resinol (e.g.: Guaiacum resin).
• Glycoresins: They are the combination of resin and sugar. Examples: Jalap resin from jalap,
Podophylloresin from dried roots and rhizome from Podophyllum hexandrum etc.
• Resenes Resins: They are chemically inert substances and have no chemical properties.
They do not undergo hydrolysis or any salt formation. Examples: Dracoresens from Dragon’s
blood, Fluavil from Gutta percha, Mastic from Pistacia lentiscus etc

They are classified as per the major constituents present in the resins or in resin combinations.
They are further sub-classified as:
Resins: They are unorganized hydrocarbon compounds present in the plants. They are produced
in resin ducts and are excreted through canals or glands.
• Examples: Colophony, Cannabis.
Oleoresins: They are concentrated liquid form of the spice. Oleoresins can be defined as the true
essence of the spices and can replace whole/ground spices without impairing any flavor and
aroma characteristic. A naturally occurring mixture of essential oils and a resin, extracted from
various plants. They obtained by extraction with a non-aqueous solvent followed by removal of
the solvent by evaporation and by super critical fluid extraction.
• Examples: Copaiba, Ginger, Pine, Balsam.
Classification Based on Constituents of Resin:

• Easy to store and transport
• More stable when heated
• More economical to use
• Easier to control quality and cleaner than the equivalent ground spices
• Free from contamination
Advantages of Oleoresins

• Oleo Gum Resins: It is a solid plant exudation consisting of a mixture of volatile oil, gum
and resin. It is a combination of oleo gum and resin. Therefore, an oleo-gum- resin
• has a nature that is partly soluble in water and alcohol and looks oily.
• Examples: Asafoetida, Myrrh, Turmeric.
• Balsams: They are also known as turpentine. They are the resinous exudate or sap from
certain kinds of trees and shrubs. They mainly contain cinnamic and benzoic acid or their
esters in the structures.
• Examples: Balsam of Tolu, Balsam of Peru, Balsam of Mecca (Liquid balsam obtained from
the tree Commiphora gileadensis).

Chemical
Tests

Volatile Oil
• Volatile oils are the complex mixtures which easily evaporate when exposed to air
at ordinary temperature, and which are used for either their specific therapeutic
activity or their aroma.
• Volatile (Latin volare) or ethereal oils indicate that they easily evaporate on
exposure to air at ordinary temperature.
• Essential oils (Latin essentia) represents the essences or odoriferous constituents
of the plants.

VO accumulate
in all the type of
vegetative
organs
1. Flowers (Rose, Jasmine)
2. Leaves (Citronella, Eucalyptus)
3. Bark (Cinnamon)
4. Wood (Sandalwood, rosewood)
5. Roots (Vetiver)
6. Rhizomes (Ginger, Turmeric)
7. Fruits (Fennel, Coriander)
8. Seeds (Nutmeg)

Physical
properties of
volatile oils
Although volatile oils differ greatly in their chemical
constitution, they have a few physical properties in common:
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 (the
essential oils of sassafras, clove, or cinnamon are the
exceptions).
5. As a rule, volatile oils are immiscible with water, The
aromatic waters are dependent on this slight solubility.
6. Volatile oils are soluble in alcohol, ether and other organic
solvents.

Chemical
Nature/Chemical
composition
Volatile oils are divided into 2 main classes
based on their biosynthetic origin
Terpene derivatives (formed via the Acetate
Mevalonic acid pathway)
Aromatic compounds (formed via the Shikimic
acid-Phenylpropanoid route)
Miscellaneous Origin

Classification of Volatile oils
• Depending on the functional group present
1. Alcohol volatile oils (e. g. Peppermint, Cardamom),
2. Aldehyde volatile oils (e. g. Cinnamon, Lemon peel),
3. Ester volatile oils (e. g. Mustard, Lavender),
4. Hydrocarbon volatile oils (e. g. Turpentine, Black pepper),
5. Ketone volatile oils (e. g. Caraway, Musk),
6. Oxide volatile oils (e. g. Eucalyptus, Chenopodium),
7. Phenolic ether volatile oils (e. g. Anise, Nutmeg),
8. Phenol volatile oils (e. g. Clove, Thyme).

General
Extraction
methodology
1. Extraction by distillation
a) Water (Hydro) distillation E.g. Turpentine oil
b) Water & steam distillation E.g. Cinnamon oil, Clove oil
c) Steam distillation E.g. Peppermint oil, Spearmint oil
2. Extraction by mechanical means (Expression)
3. Extraction by using volatile & non-volatile solvents
4. Other methods (Steam distillation by microwaves)

Applications

Chemical
Test

SECONDARY METABOLITIES .pdf

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