Glycosides Note

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Edited By: Jaytirmoy Barmon Glycosides
Lecturer, Pharmacy, Varendra University
Glycosides
Tripti Rani Paul
Assistant Professor
Department of Pharmacy
Varendra University, Rajshahi
Jaytirmoy Barmon Likhon
Lecturer
Department of Pharmacy
Varendra University, Rajshahi
Q: What are glycosides? Describe the chemical composition and physicals properties of
glycosides?
Glycosides:
Glycosides are non-reducing compounds that yield one or more sugars among the products of
hydrolysis. The most frequently occurring sugar is β-D glucose, although rhamnose, digitoxose
and other sugars are components of glycosides.
The sugar part of glycosides is known as glycone and non-sugar part is called aglycone. The
aglycone may be an alcohol, phenol and heterocyclic hydroxy compound.
Chemical composition:
Chemically the glycosides are acetals (sugar ethers) in which the hydroxyl group of the sugar
is condensed with the hydroxyl group of the non-sugar component.
Glycosides Sugar (Glycone) + Non – sugar (Aglycone)
R –OH + H-O-X ROX + H2O
e.g. C6H11O5OH + OHC6H4CH2OH C6H11O5O-C6H4CH2OH + H2O
glucose salicyl alcohol salicin
Glycosides itself can’t reduce Fehling’s solution but after hydrolysis the simple sugars that are
produced can reduce Fehling’s solution.
Physical properties:
The properties of glycosides are as follows:
i. Most of the glycosides are colourless and crystalline compounds.
ii. Anthracene glycosides are red or orange
iii. Flavone glycosides are yellowish in colour.
iv. They are soluble in water and alcohol.
v. They are insoluble in organic solvents such as petroleum ether, chloroform, carbon
tetrachloride etc.
vi. Glycosides are optically laevorotory.

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Q: Write down the classification of glycosides?
Various types of classification of glycosides are given below:
A. On the basis of linkage of sugar molecule to aglycone, they are divided as follows:
i. O-Glycosides: Here the sugar is condensed with alcoholic or phenolic hydroxyl group
of aglycone. e.g. digitoxin.
ii. N- Glycosides: Here the sugar is condensed with nitrogen of amino group. e.g.
Nucleoside.
iii. S-Glycosides: Here, the sugar is condensed with sulphur of the aglycone. e.g.
isothiocyanate glycosides.
iv. C-Glycosides: Here the sugar is condensed with a carbon of aglycone. e.g. aloin and
cascaroside.
B. On the basis of the chemical nature of aglycone, the glycosides are as follows:
i. Steroidal glycosides: These glycoside contain an sterol as an aglycon. e.g.
digitoxigenin.
ii. Flavonoid Glycosides: A flavonoid aglycon is present in these glycosides. e.g. Rutin
iii. Anthracene Glycosides: These glycosides contain anthracene as an aglycon. e.g.
Barbaloin.
iv. Cyanophoric Glycosides: Cyanogen is the aglycon part. They yield hydrocyanic acid
on hydrolysis. e.g. amygdalin, Prunasine.
v. Triterpenic Glycosides: A terpene molecule is condensed with a sugar sugar
component. e.g. Glycyrrhizin.
vi. Alcohol Glycosides: An alcohol aglycone is present in these glycosides. e.g. Salicin.
vii. Lactone Glycosides: A lactone aglycone is present in these glycosides. e.g. coumarin
glycosides.
viii. Isothiocyanate Glycosides: These glycosides contain isothiocyanate group as an
aglycone. e.g. Sinigrin.
ix. Saponin Glycosides: These glycosides contain saponine group as an aglycone. e.g.
Dioscin.
x. Aldehyde glycoside: These glycosides contain aldehyde group as an aglycone. e.g.
vanillin
C. On the basis of nature of sugars, the glycosides are:
i. Glucosides
ii. Fructosides
iii. Galactosides
iv. Rhamnosides
v. Ribosides.

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D. On the basis of therapeutic activity, they may be classified as:
i. Laxative Glycosides: senna, aloe.
ii. Local irritant glycosides: isothiocyanate.
iii. Analgesic glycosides: Methyl salicylate.
iv. Cardio active glycosides: Digitalis for heart disease.
Simple Phenol Glycosides
Vanilla
Vanilla is the full grown, unripe fruit of Vanilla planifolia.
Family: Orchidaceae
Geographical Sources: Vanilla is grown in Eastern Mexico and cultivated in Java, Ceylon,
Indonesia etc.
Chemical Constituents: Green vanilla contains two glycosides, glucovanillin and
glucovanillic alcohol. The chief constituents is vanillin which is an aldehyde aglycone. It also
contains 10% sugar, 10% fixed oil and calcium oxalate.
Uses:
i. Vanilla is the form of vanilla tincture is used as a flavouring agent and a
pharmaceutical aid.
ii. It is a good source of vanillin.
iii. It is widely used in perfumery and confectionary.
Glucovanillin
Vanillin

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Capsicum
It is the dried ripe fruits of Capsicum frutescens. It is known as African chillies.
Family: Solanaceae
Geographical Sources: Capsicum is indigenous to tropical America and cultivated in tropical
regions of India, Japan, Africa, Mexico and Sri Lanka.
Chemical Constituents: The fruit of most species of Capsicum contains capsaicin (methyl-n-
vanillyl nonenamide), a lipophilic chemical that can produce a strong burning sensation
(pungency or spiciness) in the mouth. Capsicum contains fixed oils, Oleoresin, carotenoids,
capsicol (a volatile alkaloid), volatile oil and ascorbic acid.
Uses:
i. Capsaicin is used in modern medicine, mainly in topical medications as a circulatory
stimulant and analgesic.
ii. In more recent times, an aerosol extract of capsaicin, usually known as capsicum or
pepper spray, has become used by law enforcement as a nonlethal means of
incapacitating a person, and in a more widely dispersed form for riot control, or by
individuals for personal defense.
iii. Capsicum is used as an irritant and carminative.
iv. It is used as a rubefacient.
v. It is also used as stimulant and a condiment.
vi. They are also frequently used both chopped and raw in salads, or cooked in stir-fries
or other mixed dishes.

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Anthraquinone glycosides
Cascara Sagrada
It is the dried bark of Rhamnus purshiana.
Family: Rhamnaceae
Geographical Sources: The plant is a tree indigenous to pacific coast of North America,
Washington, Columbia, California and Kenya.
Chemical Constituents: Cascara contains anthracene derivatives which are normal O-
glycosides about 10-20% and C-glycosides 80-90% and free anthraquinones. It contains the
following groups:
 Four primary glycosides i.e. Cascaroside A, B, C & D.
 Two aloins: a) Barbaloin b) Chrysaloin
 A number of other glycosides are derived from emodin, aloe – emodin and
chrysophenol.
Uses:
i. Cascara sagrada is used as a cathartic.
ii. Its principal use is in the correction of habitual constipation.
iii. It is used in veterinary work.
iv. It is generally used in the form of liquid extract, elixir or tablets prepared from a dry
extract.
v. It is also used as a laxative.

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Aloe
Aloe is the dried latex of the leaves of Aloe barbadensis.
Family: Asphodelaceae (Liliaceae).
Geographical Sources: The plant is a perennial herb which are indigenous to Africa, West
Indies and Europe.
Chemical Constituents: Aloe contains a large number of anthraquinone glycosides. The
principal constituent is barbaloin. Other glycosides are β-barbaloin, Iso- barbaloin, aloe-
emodin & chrysophanic acid. Aloe also contains resin, volatile oil, flavonol, sterol, vit- C,
and vit- B complex.
Uses:
i. Aloe is used as a cathartic, purgative and laxative.
ii. It is a pharmaceutical aid for compound benzoin tincture.
iii. Ointment of aloe – gel is used to cure burns caused by heat, sun or radiation and skin
irritations.
iv. It is used as hair tonic.
v. The plant is valued to cure many skin diseases, ulcerative skin conditions, wounds,
burns, snake bite.
vi. It is used as a febrifuge and emmenagogue to relieve burning sensation.

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Senna
Senna consists of the dried leaves of Cassia acutifolia.
Family: Leguminosae.
Chemical Constituents: Senna contains dianthrone glycosides, the sennoside A & B. After
hydrolysis these glycosides produce the aglycone Sennidin A and B. It also contains small
quantities of sennoside C and D. Senna also contains flavonoids, mucilage, calcium oxalate
and resin.
Uses:
i. Senna is used as purgative and cathartic.
ii. It is also used as stimulant laxative.
iii. The drug is used in acute constipation
Rhubarb
Rhubarb consists of dried rhizomes and roots of Rheum officinale.
Family: Polygonaceae.
Geographical Sources: Chinese rhubarb are grown in China and Indian rhubarb are native to
India, Pakistan and Nepal.
Chemical Constituents: Rhubarb contains glycosides (3-12%) such as chrysophanol, aloe
emodin, sennoside A and B. It also contains glucogallin, gallic acid, catechin, cinnamic acid
and calcium oxalate.
Uses:
i. Rhubarb is used as laxative, stomachic and in the treatment of diarrhea.
ii. It has been used in cathartic preparations.
iii. In large doses, it acts as a purgative.

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Steroidal glycosides
Glycyrrhiza or Licorice
Glycyrrhiza is the dried roots and rhizomes of Glycyrrhiza glabra.
Family: Leguminosae.
Geographical Sources: The liquorice plant is an herbaceous perennial legume native to the
Western Asia and southern Europe. It grows in Italy, England, France and Germany.
Chemical Constituents: Glycyrrhiza contains a saponine like glycoside, glycyrrhizin which
is 30-50 times as sweet as sugar. Other constituents include umbelliferone, asparagines,
glucose, mannitol and about 20% starch.
glycyrrhizin
Umbelliferone
Uses:
i. It is used as a demulcent, mild expectorant and laxative.
ii. It is used as a flavoring agent and is frequently employed to mask the taste of bitter
drugs such as aloe, quinine etc.
iii. It facilitate absorption of poorly absorbed drugs.
iv. It is commonly used as an additives of chewing gums, chocolate, candy, cigarettes,
smoking mixtures and chewing tobacco.

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Ginseng
Ginseng is of slow-growing perennial plants with fleshy roots of Panax ginseng.
Family: Araliaceae.
Geographical Sources: Ginseng is found in North America and in eastern Asia (mostly Korea,
northeast China, Bhutan, eastern Siberia), typically in cooler climates.
Chemical Constituents: Ginseng is characterized by the presence of ginsenosides and
gintonin.
ginsenosides
Uses:
i. The root is most often available in dried form, either whole or sliced. Ginseng leaf,
although not as highly prized, is sometimes also used.
ii. Roots, including roles as an aphrodisiac (An aphrodisiac is a substance that, when
consumed, increases sexual desire), stimulant, type II diabetes treatment, or cure for
sexual dysfunction in men.
iii. Ginseng may be included in small doses in energy drinks or herbal teas, such as
ginseng coffee.
iv. It may be found in hair tonics and cosmetic preparations

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Cyanogenic glycosides
Wild Cherry
Wild cherry bark is the dried stem bark of Prunus serotina.
Family: Rosaceae.
Geographical Sources: The plant is a tree at a height of 30m or more which grows in United
States and Canada. However commercial supply comes from Mississippi, Virginia, North
Carolina etc.
Chemical Constituents: Wild cherry bark contains a cyanogenic glycoside prunasine. It also
contain the enzyme prunase, benzoic acid, trimethyl gallic acid, p- coumaric acid, starch, tannin
and volatile oil
p- coumaric acid
Uses:
i. The bark has mild tonic and sedative property.
ii. Wild cherry is used in cough preparations as sedative expectorant.
iii. As a flavoring agent.

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Cardioactive glycosides
Digitalis
Digitalis consists of the dried leaves of Digitalis purpurea.
Family: Plantaginaceae.
Geographical Sources: It is indigenous to Central and Southern Europe and naturalized in
various parts of Europe and northern and Western parts of United States and Canada.
Chemical Constituents: Digitalis contains about 35 glycosides and most important of these
glycosides are digitoxin, gitoxin and gitaloxin. In addition to cardiac glycosides, the presence
of tannins, inositol, fatty acids and pectin have been reported.
digitoxin
Uses:
i. It is used as a cardiac stimulant and tonic.
ii. It is useful in congestive heart failure, atrial flutter and atrial fibrillation.

Glycosides Note

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Glycosides Note