UNIT 2.2 glycosides introduction, classification,

Glycosides

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UNIT 2.2 Glycosides
Glycosides are the naturally occurring organic compounds found in plants
and some animals, which upon hydrolysis(either acid or enzymatic) gives
one or more sugar(glycone) moiety and non sugar(aglycone) moiety. The
non sugar or aglycone moiety is called genin. The pharmacological activity
of any glycoside is mainly due to the presence of genin part whereas
glycone part facilitates the transportation of genin part to the site of action.
Sugar (Glycone) + Non Sugar (Genin) Sugar – Non sugar
•β-D-glucose
•Rhamnose
•Xylose
•Fructose
•Digitoxose
•Cymarose
Cyclic structures-
•Steroidal moiety
•Anthracene moiety
•Phenol
•Flavanoids etc….

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CLASSIFICATION OF GLYCOSIDES
(a)On the Basis of the Linkage:
1.O-glycosides: In these glycosides the sugar part is linked with alcoholic or
phenolic hydroxyl or carboxyl group.
2.S-glycosides: In these glycosides the sugar is attached to a sulfur atom of
aglycone such as in sinigrin.
3.N-glycosides: In these glycosides the sugar linked with nitrogen atom of (-NH2,-
NH-) amino group of aglycone like in nucleosides DNA,RNA.
4.C-glycosides: In these glycosides the sugar linked (condensed) directly to carbon
atom of aglycone like in aloin

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b. According to glycone part:
1.Glucose: Glucoside group like in Sennoside.
2.Rhamnose: Rhamnoside like in frangulin.
3.Digitoxose: Digitoxoside like in digoxin.
4.Glucose and Rhammnose: Glucorhamnoside-glucofrangulin.
5.Rhamnose and glucose: Rhamnoglucoside – Rutin

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Alcohol Salicin
Aldehyde Glucovanillin
Phenol Arbutin
Cyanone Amygdalin
Thio Sinigrin
Anthracene Sennosides, aloin
Steroid Cardiac and
Saponin
Flavone Flavonoid gly
Tri terpenoids Glycyrrhizin,
Ginsenosides
If aglycone part is
c. According to aglycone part:
In Syllabus
•Cardiac – Digitalis
•Saponin – Dioscorea & Liquorice
•Anthraquinones - Senna, Aloe
•Cyanone – Bitter almond

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PHYSICO-CHEMICAL PROPERTIES
•They are colorless, amorphous, solid, non-volatile compounds.
•They give positive test with Molisch and Fehling's solution test.
•They have solubility in water but insoluble in organic solvents.
•Most of them possess bitter taste but some exceptions are populin,
glycyrrhizin, stevioside.
•They are odorless compounds except saponin (glycyrrhizin).
Glycosides gets hydrolyzed by mineral acids and temperature or by enzymes
like
(a) Emolsin: Bitter almond seeds.
(b) Myrosin or Myrosinase: Black mustard seeds.
(c) Rhamnase: Glycosides containing rhamnose assugar part.

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Anthraquinone Glycosides
1. Senna
Synonyms: Senna leaf, Tinnevelly senna, Alexandrian senna, Cassia senna,
Indian senna.
Biological source: It consists of dried leaflets of Cassia angustifolia or
Cassia senna Vahl (Tinnevelleysenna) and Cassia acutifolia Delile
(Alexandrian Senna), belongs to Leguminosae
Geographical source: C. angustifolia (Indian senna) is cultivated in
Tinnevelley, Madurai, Tamilnadu (Ramanathapuram district), Andhra
Pradesh, Gujarat and Rajasthan.
Cassia acutifolia (Alexandrian senna) is indigenous to tropical Africa and is
cultivated in Sudan, Middle and upper Nile territory

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Macroscopic Character:
Colour: Yellowish green.
Odour: Slight.
Taste: Mucilaginous and bitter.
Size: 20- 60 mm in length and 7 to 8 mm in width.
Shape: Leaves are lanceolate, entire apex is acute with spine at the top.
Chemical Constituents:
The major components of the dried drug are sennosides which are
glycosides of dianthrone type aglycone in other words Sennidins.
Sennoside A and B are major components.

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Chemical Test: Borntrager’s test:
The drug is boiled with dilute sulphuric acid and filtered. To the filtrate add
benzene or ether or chloroform and shake well. Separate the organic layer
and slowly add ammonia into it. Pink to red color showed in ammoniacal
layer which confirms the presence of anthraquinone glycosides.

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Uses:
Senna and its preparation uses as purgative in habitual constipation. The
anthraquinone part of senna gets absorbed in intestinal tract after which
the aglycone part is separated and excreted in the colon. These excreted
anthraquinones irritates and stimulates the colon which increases the
movements of colon due to local action.

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2. ALOES
Synonyms: Aloe, Musabbar, Kumari.
Biological source: Aloes are the dried juice obtained by transversely cut
leaves of various species of Aloe barbedensis Miller (known as Curacao
aloes), Aloe perryi Baker (Socotrinealoes), Aloe spicata Baker and Aloe
Africana Miller(Capealoes). Family: Liliaceae
Geographical source: It is indigenous to eastern and southern Africa and
cultivated for commercial purpose in West Indian islands off the
northcoast of South America.

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Morphology:
Colour: from yellowish or reddish brown to chocolate brown,
Taste: bitter taste
Odour: strong penetrating
Chemical Constituents:
•Aloe is the main source of glycosides i.e. anthraquinone glycosides
•Aloin (Barbaloin)

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Chemical Tests:
1.Borax test: Aloe solution in boiling water (1%), cool it and add
kiesselguhr to clear it. Take10ml clear filtrate, add 0.25gm borax and heat
it till it dissolves. Then pour some dark fluid into water till green
fluorescence produce. The green fluorescence is formed due to the
hydrolysis of barbaloin which produces aloe emodin anthranol.
2.Bromine test: To some clear solution of aloes, as prepared earlier, add
freshly prepared saturated bromine solution. A yellow precipitate observes
due to the formation of tetrabromaloin.
3.Nitric acid test: To 5ml of 1% clarified solution add 2ml nitric acid. A
vivid green colour produced (in Cape aloes), a deep brownish red colour
develops (in Curacao aloes) or pale brownish yellow colour seen (in
Socotrinealoes

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Uses:
All the varieties of aloes have more or less purgative action. It improves
the digestion and does not lose its activity by repetition. It mainly affect on
colon and have much potent purgative activity than other anthraquinone
glycosidal drugs.
Aloe gel is used in topical preparations and cosmetics. It possess good
moisturing property, anti inflammatory property, anti wrinkle property,
protective etc. Fresh gel has a role in burns and wounds

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Cyanogenetic glycosides
BITTER ALMOND
Synonym: Amygdala amara
Biological source: It consists of dried ripe seeds of plant Prunus amygdalus
Batsch var amara. Family: Rosaceae.
Geographical source: It is indigenous to Iran and Asia and cultivated in
Sicily, Italy, Protugal, Morocco and South France.
Macroscopical Characters:
Colour: Brown.
Odour: None.
Taste: Bitter.
Size: 20 mm length, 120 mm width and 10 mm thickness.
Shape: Flat, Oblong, Ovoid having marks on testa

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Chemical Constituents:
Bitter almond contains fixed oil (40-50%), Protein (20%), enzyme emulsin
and bitter glycoside amygdalin (1-3%). It also contains volatile oil (0.5%).
Amygdalin gives benzaldehyde and hydrocyanic acid upon hydrolysis.
Bitter almond oil contains 80 percent benzaldehyde and 2-6% hydrocyanic
acid.

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Uses:
•It is used as sedative.
•The oil is used in skin lotion as demulcent. It is also used for the
preparation of amygdalin, bitter almond water, in perfume industry and
liquors preparation, due to the presence of hydrocyanic acid it is not used
as flavoring agent in food industry

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Cardiac glycosides – Cardio Tonic Function

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Chemical tests:
Libermann-Burchard test : Steroidal moiety
Killer-killani test : Deoxy sugars
Baljet reaction : Lactone ring
Legal test : Lactone ring

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DIGITALIS
Synonym: Digitalis leaf, Foxglove leaves
Biological source: Digitalis (purple foxglove leaves) consist of the dried
leaves of Digitalis purpurea, Family: Scrophulariaceae.
Geographical Source: Digitalis is native of Western Europe, British Island
and USSR countries.
Macroscopic Characters:
It is erect branched biennials attaining a height of 60-90cm
Colour: dark greyish green
Odour: odourless
Taste: bitter taste
Shape: ovate lanceolate to broadly ovate

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Uses:
Most frequent use of digitalis is the treatment of congestive heart failure.
Another major use of digitalis is slowing ventricular rate in atrial
fibrillation, artrial flutter, supraventricular tachycardia and premature
extra systole.

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DIGITALIS LANATA
Synonyms: Woolly fox glove leaves, Australian digitalis.
Biological source: It consists dried leaves of Digitalis lanata Ehrhart.
Family: Scrophulariaceae
Chemical Constituent:
It mainly contains five primary glycosides and about 70 cardiac glycosides.
The primary glycosides are identified as lanatosides A, B, C, D & E

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Saponin Glycosides
DIOSCOREA
Synonyms: Yam, Rheumatism root, Greater Yam, Asiatic Yam.
Biological source: It consist of dried tubers of the plants Dioscorea deltoidea,
D.composita, D. floribunda. Family: Dioscoreaceae
Geographical source: It is found in Africa, Asia, Europe, Mexico, South
America, USA, China and India
Macroscopic Character:
Colour: Slightly brown
Odour: Odourless or none
Taste: Bitter
Size: Variable (depending upon age of rhizomes)

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Chemical Constituents:
•Dioscorea have long been used for food as they are rich in starch. It
contains about 75% starch but many species are non edible because they
possess bitter taste.
•Diosgenin is the chief active constituent of dioscorea which is the
hydrolytic product of saponin dioscin.

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Uses:
•Commercial use: Diosgenin, a steroidal sapogenin obtained from the
drug is the major base chemical for the synthesis of several steroidal
hormones, cortisone, corticosteroids and oral contraceptive pills.
•Therapeutical use: Dioscorea is used in the treatment of rheumatic
arthritis.

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LIQUORICE/ GLYCYRRHIZA
Synonyms: Glycyrrhiza, Liquorice root, Mulethi
Biological source: It consists of dried roots and stolons, whole or cut, peeled
or unpeeled of Glycyrrhiza glabra Linn and other species of Glycyrrhiza.
Family: Leguminosae (Fabaceae)
Geographical source: Liquorice obtained from wild plants and from semi
wild plants cultivated in Iraq, Syria, Afghanistan, Spain, Sicily and England.
Macroscopical Character:
Colour: Unpeeled drug is yellowish brown or dark brown in color externally
and yellowish colored internally but peeled liquorice is pale yellow in colour.
Odour: Typical odour, faint and characteristics.
Taste: Sweet.
Size: Stolons are several meter in length and are cut in pieces having 20-50
cm length and 1 to 2 cm diameter fragments.
Shape: Cylindrical pieces sometimes straight or irregular peeled or unpeeled

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Chemical Constituents:
Liquorice owes most of its sweet taste due to glycyrrhizin or glycyrrhizic acid
which is potassium and calcium salt of glycyrrhizinic acid which has a
triterpenoid structure

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Uses:
•Traditionally it is used as flavouring agent, demulcent and mild expectorant.
It is used in the preparation of cough syrups.
•The flavonoidal content of liquorice i.e. Isoliquiritin possess antigastric
activity so used in peptic ulcer treatment for healing purpose (in
deglycyrrhized liquorice form known as DGL).
•The Isoliquiritin also have antispasmodic activity. The glycyrrhetinic acid
possesses minerocorticoid activity so it is also used in the treatment of
rheumatoid arthritis, inflammation addison’s disease.
•Anti-inflammatory effect
•As foam stabilizer in fire extinguishers.