Glycosides introduction

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GLYCOSIDES(ANTHRAQUINONES)
Presented by;
M Pharm (Pharmaceutical Chemistry) students
Gunturu. Aparna
Akshintala. Sree Gayatri
Thota. Madhu latha
Kamre. Sunil
Daram. Sekhar
University College Of Pharmaceutical Sciences
Department Of Pharmaceutical Chemistry
Acharya Nagarjuna University
Guntur

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Glycosides
 Definition:
Organic natural compounds present in a lot of
plants and some animals, these compounds upon
hydrolysis give one or more sugars (glycone)
β- form and non sugar (aglycone) or called genin.

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Glycosides
 More important in medicine than a lot of drugs.
 Occur in higher plant tissues in very small
amounts
 Also fungal and bacterial cells (exuded in
medium) and animals
 Formed by a biochemical reaction that makes a
water insoluble compound more polar than a
water soluble molecule
 Hence can be removed from an organic system
 Man forms them in the liver as part of the process
of detoxification and they are excreted via urine
 Mammalian glycosides are simple compounds
whereas plant glycosides are much larger and
chemically more complex

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 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.

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Separation between glycosides parts:
Glycosides glycone +aglycone +HCl
G + A +salt+H2O
(H2O+G) + A (H2O+G) + (chloroform+A)
We can separate them by using separating funnel.
The best solvent to extract aglycone is Ethyl acetate because:
A. Immiscible in water.
B. Always presents in the upper layer.
Neutralization by
Using alkaline
Filtration
chloroform
Hydrolysis
+HCLdil

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Note:
Alcohol and acetone are water miscible
compounds , so we can't use them as organic
solvents for aglycone separation.

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Physico-chemical properties of
glycosides(general)
 Colorless, solid, amorphous, nonvolatile
(flavonoid- yellow, anthraquinone-red or
orange).
 Give positive reaction with Molisch's and
Fehling's solution test (after hydrolysis).
 They are water soluble compounds,
insoluble in organic solvents.
 Most of them have bitter taste.
(except: populin, glycyrrhizin, stevioside).

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 Odorless except saponin (glycyrrhizin).
 when a glycosides has a lot of sugars its
solubility in water decrease.
 Glycosides hydrolyzed by using mineral
acids and temperature or by using
enzymes such as:
a. Emolsin Bitter almond seeds.
b. Myrosin or Myrosinase black
mustard seeds.
c. Rhamnase glycosides containing
rhamnose as sugar part.

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The function or the role of glycosides
in the plant organism
 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(pollenation
process).

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 Some glycosides have antibacterial activity, so
they protect the plants from bacteria and
diseases.
Bitter almond Amygdalin
bacteria
HCNhydrolysis
kill
Eomlsin
enzyme

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Classification of
glycosides

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Classifications of glycosides according to
their therapeutic effects
 CHF(Congestive Heart Failure)and cardiac
muscles stimulators such as:
a. Digitalis glycosides: digoxin, digitoxin, gitoxin
(Fox glove leaves).
b. Ouabain: Strophanthus gratus seeds.
c. K-strophanthin -Strophanthus kombe seeds.
d. Scillaren A,B which isolated from red and white
Squill bulbs.
e. Convolloside:Convallaria majalis – Lily of the
Valley.

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 Laxative group of glycosides:
a. Sennoside A,B,C,D (Senna leaves and fruits).
b. Cascaroside A,B (Cascara bark).
c. Frangulin and glucofrangulin(Frangula bark).
d. Aloin and barbaloin (Aloe vera and Aloe
barbadensis juice).

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 Local irritant group:
a. Sinigrin (Black mustered seeds-Brassica nigra)
b. Sinalbin (White mustered seeds-Brasica alba)
 Analgesics and antipyretics:
Salicin Salisylic acid -Willow or Salix bark.
 Keeping elasticity of blood vessels
like:
Rutin -Rutoside (Bitter orange peels, Lemon peels)
 Anti-inflammatory group:
a. Aloin for 1)acne 2)peptic ulcer
b. Glycyrrhizin
hydrolysis

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Classification of glycosides according to
glycone part
 Glucose -glucoside group like in
Sennoside.
 Rhamnose -Rhamnoside like in frangullin.
 Digitoxose -Digitoxoside like in digoxin.
 Glucose and Rhammnose
Glucorhamnoside -glucofrangulin.
 Rhamnose and glucose -
Rhamnoglucoside -Rutin.

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Classification of glycosides on the basis of the
linkage between glycone and aglycone part
 O-glycosides : In these glycosides the sugar part
is linked with a oxygen atom of aglycone .
 S-glycosides : In these glycosides the sugar
attached to a Sulfur atom of aglycone ,for
example sinigrin.
 N-glycosides : In these glycosides the sugar
linked with Nitrogen atom of (-NH2,-NH-)amino
group of aglycone ,for example nucleosides
DNA,RNA.
 C-glycosides : In these glycosides the sugar
linked (condensed) directly to Carbon atom of
aglycone ,for example aloin.

Most of glycoside may be named according to the plant from
which they isolated for example:
1. Salicin from salix
2. Cascarosides from cascara
3. Aloin from Aloe vera
4. Sennosides from senna
5. Frangulin from frangula
6. Glycyrrhizin from glycyrrhiza
GENERAL EXTRACTION PROCESS OF GLYCOSIDES;
 Always glycosides founded in the plant with the enzymes which hydrolyzed
them.
We must damage these enzymes first to extract these glycoside by the
following steps:
STEP 1. Drying the plants fresh in special oven at 1000c for 30 minutes.
STEP 2. Boiling them with organic solvents for 20 minutes
STEP 3. Boiling them with acetone 5 minutes 17

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METHYL GLYCOSIDES
 Methylglucoside is a monosaccharide derived
from glucose. It can be prepared in the laboratory by
the acid-catalyzed reaction of glucose with methanol.

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USES:
chemical intermediate in the production of a
variety of products including
 Emollients.
 Emulsifiers.
 humectants.
 moisturizers.
 thickening agents.
 plasticizers.
 Surfactants.
 varnishes and resins.

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Preparation of methyl glycoside
STEP 1:
 Methyl glucoside is prepared by the acid-catalyzed reaction
of glucose and methanol .
 In the reaction glucose, methanol and acid catalyst,
anhydrous hydratable CaSO4 are required .
 In the .preparation of methyl glycoside CaSO4 :glucose
weight ratio of at least 1:1, maintaining the reaction mixture
within the temperature range of about 50 C and 200 C until
formation of methyl glucoside ceases.

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 cooling the reaction mixture, neutralizing the acid
catalyst with a base capable of forming a salt of
neutralization which is insoluble in the reaction mixture .
acid catalystC6 H12 O6 +CH3 OH⇋methylglucoside+H2 O (I)

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2. Process according to step 1, wherein the CaSO4 is
incorporated in the reaction mixture in an amount sufficient
to provide a CaSO4:glucose weight ratio from about 1:1 to
about 3:1
3. Process according to step 1, wherein the CaSO4 :glucose
weight ratio is from about 1:1 to about 2:1
4. Process according to claim 1, wherein the acid catalyst is
H2 SO4.
5. Process according to step 4, wherein the base is selected
from the group consisting essentially of Ca(OH)2,
Mg(OH)2, Ba(OH)2, Sr(OH)2and mixtures there of.
6. Process according to step 1, wherein the reaction is carried
out in a closed vessel within the temperature range of about
100 C and 150 C

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Anthraquinone Glycosides
(
Anthraquinone
Anthraquinone derivatives

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Aloe
barbadensis
Cassia
senna
Rhamnus
purhsianus -
Cascara
Rheum palmatum.
Chinese
Rhubarb

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Introduction to Anthraquinones
 Historically: Rhubarb, Senna, Aloes and Cascara
were all used as purgative drugs.
 Monocotyledons: Only Liliaceae.
Most commonly C-glycoside: barbaloin.
 Dicotyledons: Rubiaceae, Leguminosae,
Polygonaceae, Rhamnaceae, Ericaceae,
Euphorbiaceae, Lythraceae, Saxifragaceae,
Scrophulariaceae andVerbenacacea. Also in certain
fungi and lichen.

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 Reduced derivatives of anthraquinones
 Oxanthrones, anthranols and anthrones
 Compounds formed by the union of 2 anthrone
molecules
 Dianthrones
 Aglycones:
 Chrysophanol/Chrysophanic acid  Rhubarb and
Senna.
 Rhein  Rhubarb and Senna
 Aloe-emodin  Rhubarb and Senna
 Emodin  Rhubarb and Cascara

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Anthraquinones – Chemical Properties
 Anthraquinone derivatives: orange-red compounds
 Soluble in hot water/dilute alcohol.
 Identified via Borntrager’s test
 Powdered drug – macerated with ether
 Filter
 Add ammonia/caustic
 Shake  pink, red or violet colour – positive for
anthraquinone derivatives
 If the Anthraquinones are reduced (within the herb) or
stable (glycosides) test will be negative

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Anthranonls andAnthrones
 Reduced anthraquinone derivatives.
 Occur either freely (aglycones) or as glycosides.
 Isomers.
 Anthrone: Parent structure (pale yellow, non-
soluble in alkali, non-fluorescent)
 Anthronol: brown-yellow, soluble in alkali, strongly
fluorescent
 Anthronol derivatives (e.g. in Aloe – have similar
properties – fluorescence used for identification)

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Oxanthrones
 Found in Cascara bark
 Intermediate products (between anthraquinones
and anthranols)
 When oxidised oxanthrones it form
anthraquinones
 Oxanthrones are detected by Modified
Borntrager’sTest
(oxanthrones oxidised using hydrogen peroxide)
oxanthrone

Dianthrones
 Derived from 2 anthrone
molecules
 2 molecules may/not be
identical
 Dianthrones are form easily
due to mild oxidation of
anthrones
 It form important
aglycones
 Cassia
 Rheum
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General structure of glycoside
Structure-Activity Relationship

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 Glycosylation is essential for activity.
 Hydroxylation at C-1 and C-8 is essential for activity.
 Oxidation level at C-9 and C-10 is important:
 Highest level of oxidation (anthraquinones) have the lowest
activity.
 Oxanthrones are less active than anthrones.
 Complete reduction of C-9 and C-10 eliminates the activity.
 Substitution at C-3 have great impact on activity:
CH2OH > CH3 > COOH

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Mechanism of Action:
 The glycosides are absorbed from the small
intestine and re-excreted in the large intestine
where they increase the motility so produce
laxation.
 Aglycones produce griping effect so it is
recommended to prescripe antispasmodic with
them.

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Mechanism of action
 Molecules have to possess certain features for
activity:
[1] glycosides
[2] carbonyl keto function on centre ring
[3] 1,-8- positions have to have –OH
 Potency:
 anthrone > anthraquinone> dianthrone
 Aglycones not therapeutically active in animals ,
lipid soluble absorbed in stomach and never reach
colon to produce a local effect.

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 Highly active phenolic group irritant to mucosa
 Glycosides very water soluble – reach large intestine
where they are hydrolysed by E.coli enzymes and
become lipid soluble and absorbed into circulation.
 5-8 hours to act
 take night before
 in low doses – drug metabolised by liver and recirculated
via bile to give more effect
 people especially elderly can become reliant on them
needing higher dose to produce an effect
 carcinogenic to melanosis coli

Senna - Leguminosae
 Definition: Consists of
the dried leaflets of
Cassia senna
(Alexandrian senna), or
Cassia angustifolia
(Tinnevelly senna).
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Cassia - Senna
 Indigenous to Africa
(tropical regions)
 Used since 9th and 10th
century
 Itroduced into medicine
byArab physicians (used
both the leaves and
pods)
 Exported by Alexandria –
name of the Sudanese
drug.
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Senna - Collection
 Collected in September
 Whole branches
bearing leaves are
dried in the sun.
 Pods and large stalks
are separated with
sieves.
 Leaves are graded
(whole leaves and half-
leave mix, siftings).
 Whole leaves – sold to
public
 Rest – used for
galenicals.
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Senna - Constituents
 Senna consist four types of glycosides:
Sennoside A
Sennoside B
Sennoside C
Sennoside D
In their active costituents are sennoside A, sennosides B
 Upon hydrolysis of sennosides it gives two molecules
glucose+aglycones: Sennidin A and Sennidin B.
 Sennoside C & Sennoside D
 Rhein
 Aloe-emodin
 Palmidin A (Rhubarb)

Senna - Constituents
 Kaempferol (yellow
flavanol)
+ glucoside
(kaempferin)
 Mucilage
 Calcium oxalates
 Resin
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Comparison of
Alexandrian and Tinnevelly Senna
 Macroscopical
 Seldom larger than 4 cm
in length
 Grey-green
 Asymmetric at base
 Broken and curled at
edges
 Few press markings
 Macroscopical
 Seldom exceeds 5cm in
length
 Yellow-green
 Less asymmetric at base
 Seldom broken and
normally flat
 Often shows
impressions (mid vein)
44

Comparison between
 Microscopical
 Hairs – numerous
(approximately three
epidermal cells apart)
 Most stomata have two
subsidiary cells
 Microscopical
 Hairs less numerous
(approximately six
epidermal cells apart)
 Stomata have 2-3
subsidiary cells with the
respective ratio 7:3
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Comparison between
 ChemicalTests
 Ether extract of
hydrolysed acid solution
of herb with methanolic
magnesioum acetate
solution gives
 Pink colour in daylight
 Pale green-orange
colour in filtered UV
light
TLC
 Hydroxymusizin
glycoside present
 ChemicalTests
 SameTest
 Orange colour in
daylight
 Yellow-green colour in
filtered UV light
TLC
 Tinnevellin glycoside
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Senna – Allied Drugs &
Substitutes
Allied drugs
 Bombay, Mecca and Arabian
Sennas (found in Cassia
angustifolia from Arabia).
 Dog senna – Cassia obovata
 Cassia auriculata – Indian
Senna
 Cassia podocarpa
 Substitutes or
Adulterants
 Argel leaves –
Solenostemma argel
 Coriario myrtifolia
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Senna Fruit
 Definition: Senna pods
are the dried, ripe fruits
of Cassia senna and
Cassia angustifolia,
which are
commercially known as
Alexandrian and
Tinnevelly senna pods
respectively. Both
have separate
monographs
48

Senna Fruit - Collection
 Pods are collected with
the leaves and dried in
a similar fashion.
 After separation of the
leaves, the pods are
hand-picked into
various qualities, the
finer being sold
(commercially), while
the finer pieces are
used to make
galenicals.
49

Senna Fruit - Constituents
 Active constituents are
found in the pericarp.
 Similar to those actives
of the leaves
 Sennoside A
 Sennidin
50

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Senna - Uses
 Laxatives (habitual constipation or occasional
use).
 Lacks astringent after-effect (Rhubarb)

Senna –Additional uses
 Medicinal Actions
 Vermifuge, diuretic,
febrifuge
 Other uses: laxative candy
(bitter taste).
 Also used to treat
flatulence, gout, fever.
 Topically: poultice
prepared with vinegar to
treat pimples.
 NOTE: Senna may cause
urine to become reddish –
no clinical significance.
Contra-indications
 Gout, colitis, GI
inflammation.
 Should not be used with cardiac
glycosides.
 Seeds/pods give gentler action
than leaves: more appropriate for
the young, elderly and those
prone to stomach cramps.
 NB: Over-use causes
dependency.
 Overdose: nausea, bloody
diarrhoea, vomiting and nephritis.
 Long-term use: dehydration &
electrolyte depletion, worsening
constipation and weakening
intestinal muscles. 52

Cascara Bark- Rhamnaceae
 Definition: Official
cascara sagrada is the
dried bark of Rhamnus
purshianus. Bark is
collected from wild
trees
(depletion is leading to
the increase of
cultivation)
53

Rhamnus purhsianus - Cascara
 Etymology
 Rhamnos – Greek, branch,
shiny shrub. Purshiana after
Pursh, botanist 1st described
herb in 1814
 Other Common Names
 Bearwood, bitterbark,
buckthorn, coffeeberry,
mountain cranberry,
persiana, sacred bark.
54

Cascara Bark - History
 Recently introduced to
Modern Medicine.
 Known to early
Mexican and Spanish
priests.
 Not introduced to
medicine until 1877.
55

Cascara – Collection &
Preparation Collected form mid-April to end
ofAugust, when it separates
readily from the rest of the
trunk.
 Longitudinal incisions are made
10cm apart and the bark
removed.
 Tree is then usually felled and
the branch bark separated.
 Bark is then dried in the shade
with the cork facing upwards.
This is referred to as ‘natural’
cascara. Commercial supplies
are comminuted to give small,
even fragments called
‘evenized’, ‘processed’, or
‘compact’ cascara. 56

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Cascara Bark - Storage
 During preparation and storage the bark should
be protected from rain and damp (partial
extraction of constituents may occur or bark may
become mouldy).
 Should be stored for at least 1 year before use .
 Bark appears to increase in medicinal value up
unto its 4 years old (stored bark)

Cascara Bark – Why Stored for
a Year?
 When stored for at least a
year – better tolerated by
patient (less griping pains due
to increased peristalsis)
 Yet as effective as fresh bark.
 Reason?
 Due to Hydrolysis and other
changes that occur during
storage.
 Bitter taste of Cascara can also
be reduced by treating the
bark with alkali (alkali earths or
MgO).
58

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Cascara Bark – Constituents
 Four main glycosides – Called Cascarosides
 CascarosideA
 Cascaroside B
 CascarosideC
 Cascaroside D

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 Two aloins:
 C – Glycosides
 Breakdown products of CascarosidesA-D
 Barbaloin (derived from aloe-emodin)
 Chrysaloin (derived from chrysopanol anthrone)

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 O-glycosides
 Derived from
 Emodin
 Emodin oxanthrone
 Aloe emodin
 chrysophanol

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 Dianthrones
 Emodin
 Aloe-emodin
 Chrysophanol
 Hetrodianthrones
 Palmidin A, B and C (Rhubarb)

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Cascara Bark - Substitutes
 Rhamnus alnifolia (too rare)
 Rhamnus crocea (bark is very different from
official drug)
 Rhamnus californica (so closely related to
Rhamnus purshianus some botanists do not
consider them to be separate species).
 Rhamnus fallax

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Cascara Bark - Uses
 Purgative
 Similar to Senna
 Normally as a tablet
 Also used on animals

Cascara Bark –Additional uses
 Physiological Action
 Astringent (bark – tannins),
bitter tonic, chologogue,
emetic, hepatic, stomachic.
 Medicinal Uses
Move stagnation, clear heat.
The most widely used laxative
world-wide.
Topically: Used as a wash for
herpes lesions
 Excessive use: nausea,
vomiting, heamatorrhoea.
Long term use: Weakens
intestinal muscles.
 Contra-indications:
children younger than 14,
during pregnancy,
lactation, IBS, Crohn’s,
intestinal obstruction, and
idiopathic abdominal pain.
65

Rhubarb - Polygonaceae
 Definition:
Rhubarb/Chinese
Rhubarb is the rhizome
of Rheum palmatum.
Other species and
hybrids of Rheum,
except R. rhaponticum,
may also be included.
66

Chinese Rhubarb - History
 Chinese Rhubarb has a
long history.
 Mentioned in a herbal
of 2700BC.
 Formed an important
article of commerce on
the Chinese trade
routes to Europe.
 Still used medicinally
today.
67

Chinese Rhubarb – Collection &
Preparation
 Rhizomes are grown at
high altitudes (+3000m).
 Collected in Autumn or
spring (6-10yrs old)
 Cork is removed, cut.
 Artificially dried.
 Packed in tin-lined wooden
cases.
 Inferior quality herbs are
packed in hessian bags
68

Chinese Rhubarb - Constituents
1. Anthraquinones without a
carboxyl group –
chrysophanol, emodin,
aloe-emodin & physcion.
Also the glycosides of
these substances.
2. Anthraquinones with a
carboxyl group (rhein and
its glycoside: glucorhein).
69

3. Anthrones and
dianthrones of
chrysophanol,
emodin, aloe-emodin
or physcoin.
4. Dianthrone glucosides
of rhein (Sennosides
A and B).
5. Hetrodianthrones
derived from 2
different anthrone
molecules: Palmidin A
and Palmidin B.
70

 Free anthraquinones:
chrysophanol, emodin,
aloe-emodin and rhein.
 Some of the above
constituents may also
occur as glycosides.
71

Chinese Rhubarb - Uses
• Bitter stomachic
• Diarrhoea (low doses) –
contains tannins
• Purgative (high doses)
– followed by an
astringent effect.
• Suitable only for
occasional for
occasional use, not for
chronic constipation.
72

Rhubarb – Additional Uses
 Etymology
 Rheo – Greek, ‘to flow’, in
reference to the purgative
properties.
 Medicinal Actions
 Anti-helminthic, anti-
bacterial, anti-inflammatory,
antiseptic, astringent (low
doses), sialagoge, vulnerary
 Topical Uses:
 Poultice to treat boils, burns,
wounds. Used to stop
bleeding (tannins – stypic and
astringent). Used as a
mouthwash for oral ulcers.
 Other uses: Acid content:
fresh root can be used to
polish brass.
 Caution
 Leaves should be avoided –
high calcium oxalate - toxic
73

Aloe - Liliaceae
 Definition: Aloes are the solid
residue obtained by
evaporating the liquid which
drains from the transversely
cut leaves of various Aloe
species.
 The juice is usually
concentrated by boiling and
solidifies on cooling.
 Official varieties are the Cape
Aloes from SA and Kenya
(Aloe ferox), and the Curacao
Aloes from West Indies (Aloe
barbadensis).
74

75
Preparation of Cape Aloes
 Cape Aloes are prepared from the wild plants of Aloe ferox.
 Leaves are cut transversely near the base.
 Two hundred leaves arranged around a shallow hole in the
ground (lined with canvas or goatskin).
 Cut ends overlap & drain into the canvas.
After 6hrs all the juice is collected.
 Transferred to a drum.
 Boiled for 4hrs on an open fire.
 Poured into tins while hot  solidifies.

Cape Aloes - Characteristics
 Dark brown or Green-
brown
 Glassy masses
 Thin fragments have a
deep olive colour
Semi-transparent.
77

Cape Aloes - Characteristics
 Powder: green-yellow
 When rubbed two pieces
of drug together – powder
is found on the surfaces.
 Characteristic sour odour
(rhubarb/apple-tart odour).
 Taste: nauseous and bitter.
 Microscopy: powder in
lactophenol – amorphous. 78

Characteristics of CuracaoAloes
 Colour: yellow-brown –
chocolate brown.
 Poor qualities (overheated)
black colour.
 Opaque
 Breaks with a waxy facture
 Semi-transparent
 More opaque on keeping.
 Nauseous and bitter taste.
 Characteristic iodoform
odour.
 Microscopy: lactophenol –
acicular crystals
79

Aloes - Constituents
 C-glycosides
 Resins
 Glycosides
 Aloin
 Barbaloin
 Isobarbaloin
 Aloe-emodin
Cape Aloes: Also Contain
Aloinoside A & Aloinoside B
(O-glycosides of barbaloin)
80

Aloe Constituents & Chemical
Tests:
 Unlike C-glycosides, O-glycosides of
Aloe are not hydrolysed by heating
with dilute acids or alkali.
 Can be decomposed with ferric
chloride & dilute HCl - NB: Modified
Borntrager’sTest – oxidative
hydrolysis. Anthraquinones give a red
colour when shaken with dilute
ammonia.
 NB: All Aloes give a strong green
fluorescence with borax
(characteristic of anthranols) -
General test for aloes. 82

Aloe - Uses
 Purgative
 Seldom prescribed alone –
activity is increased when
administered with small
quantities of soap or
alkaline salts;
Carminatives moderate
griping tendency.
 Ingredient in Friar’s
Balsam.
83

Aloe – Additional uses
 Medicinal Uses:
 Anti-bacterial, anti-fungal,
chologoge, emmenogogue,
anti-inflammatory (juice),
anti-inflammatory ,
demulcent, vulnerary,
immune-stimulating (gel).
Radiation burns (internal and
external use)
 Contra-indications
Pregnancy & lactation (internal
uses)
 Etymology
 Name derives from Arabic
alu, meaning shiny or bitter in
reference to the gel.
 Other uses
 Khoi-San hunters rub gel on
their bodies to reduce
sweating and mask their
scent.
 Used to break nail-biting
habit.
84

Aloe vera Products
 These are derived from the
mucilage gel – parenchyma
cells
 Should not be confused
with aloes (juice of
pericycle – juice used for
laxative effect).
 Cosmetic industry
(usefulness often
exaggerated) - Used as
suntan lotions, tonics and
food additives.
 Mucilage = polysaccharide
of glucomannans and
pectin 85

Cochineal
 Definition: Cochineal
is the dried female
insect, Dactylopius
coccus, containing eggs
and larvae.
 Insects are indigenous
to Central America,
commercial supplies
are derived from Peru.
86

Cochineal
 Eggs are protected during the
rainy season are ‘sown’ on
cacti – on which it is intended
to breed.
 Both male and females arise.
After a time, fecundation
occurs. Females attach
themselves to the cacti and
the males die out.
 Females swell to x2 their
original size due to
developing larvae & develop
red colouring matter.
87

88
Cochineal
 Larvae mature after 14days and escape from the now
dead body of the parent.
 Only a small portion develop into males.
 For next 2 weeks, males fly and young females crawl on
the plant.
 Life cycle = 6 weeks.
 3-5 generations may be produced in 1 season

89
Cochineal - Collection
 Insects are brushed from plants with small brooms
and killed (some left to provide for subsequent
crops).
 First crop killed contains the most colouring matter.
 Insects are killed by plunging them in boiling water,
stove heat or exposure to fumes by burning sulphur
or charcoal.
 If heat is used – insects change to purple – black –
called ‘black grain’.
 Fume killed – turn purple-grey called ‘silver grain’.
 Small immature insects and larvae which can be
separated by sieves are sold as ‘granilla’ or siftings.

Cochineal - Characteristics
 Oval in shape
Half cm in length
 Examined
microscopically after
removing the colouring
matter (ammonia
solution).
 Each insect contains 60
to 450 eggs and larvae.
91

92
Cochineal - Constituents
 C-glycoside example anthraquinone
derivative is bright purple, water-soluble
colouring matter
 Carminic acid
 Fat
 Wax
 Adulteration: occurs by increasing the
weight of the insects by ‘dressing’ it with
inorganic matter in a colour which blends in
with that of the insect.
 Detected when insects are placed in water

93
Chemical test
Borntrager’s and Modified Borntrager’s test:
 For Aglycones:
 Extract plant material with organic solvent.
 Shake with NH4OH OR KOH.
 For O-Glycosides:
 Boil plant material with dil. HCl for 10 min, filter and shake with organic solvent
(Ether or Benzene).
 Separate the organic solvent.
 For C-Glycosides:
 Boil plant material with dil. HCl/FeCl3, filter and shake with organic solvent
(Ether or Benzene).
 Separate the organic solvent.
 Positive result indicated by Rose Red colour in the aqueous
alkaline layer.

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