2. INTRODUCTION
A glycoside is any molecule in which a sugar group is bonded through its
anomeric carbon to another group via glycosidic bond. A glycosidic bond is a certain
type of chemical bond that joins a sugar molecule to another molecule.
Specifically, a glycosidic bond is formed between the hemiacetal group of a
saccharide (or a molecule derived from a saccharide) and the hydroxyl group of an
alcohol. A substance containing a glycosidic bond is a glycoside. The glycone and
aglycone portions can be chemically separated by hydrolysis in the presence of acid.
There are also numerous enzymes that can form and break glycosidic bonds.
The sugar group is known as the glycone and the nonsugar group as the aglycone
or genin part of the glycoside. The glycone can consist of a single sugar group
(monosaccharide) or several sugar groups (oligosaccharide). The sugars found in
glycosides may be glucose and rhamnose (monosaccharides) or, more rarely, deoxysugars
such as the cymarose found in cardiac glycosides.
3. INTRODUCTION
In plants glycosides are both synthesized and hydrolysed under the influence of
more or less specific enzymes. They are crystalline or amorphous substances that are
soluble in water or alcohols and insoluble in organic solvents like benzene and ether.
The aglycone part is soluble in organic solvents like benzene or ether. They are
hydrolysed by water, enzymes and mineral acids. They are optically active. While
glycosides do not themselves reduce Fehling’s solution, the simple sugars which they
produce on hydrolysis will do so with precipitation of red cuprous oxide.
The sugars present in glycoside are of two isomeric forms, that is, α form and β
form, but all the natural glycosides contain β-type of sugar.
The term ‘glycoside’ is a very general one which embraces all the many and varied
combinations of sugars and aglycones.
4. CLASSIFICATION
The glycosides can be classified by the glycone, by the type of glycosidal
linkage, and by the aglycone.
On the Basis of Glycone
If the glycone group of a glycoside is glucose, then the molecule is a
glucoside; if it is fructose, then the molecule is a fructoside; if it is glucuronic
acid, then the molecule is a glucuronide, etc.
5. CLASSIFICATION
On the Basis of Glycosidic Linkage
▪ O-glycosides: Sugar molecule is combined with phenol or –OH group of
aglycon, for example, Amygdaline, Indesine, Arbutin, Salicin, cardiac
glycosides, anthraxquinone glycosides like sennosides etc.
▪ N-glycosides: Sugar molecule is combined with N of the –NH (amino
group) of aglycon, for example, nucleosides
▪ S-glycosides: Sugar molecule is combined with the S or SH (thiol group) of
aglycon, for example, Sinigrin.
▪ C-glycosides: Sugar molecule is directly attached with C—atom of aglycon,
for example, Anthraquinone glycosides like Aloin, Barbaloin, Cascaroside
and Flavan glycosides, etc.
19. CHEMICAL TESTS OF GLYCOSIDES
Chemical Tests for Anthraquinone Glycosides
Borntrager’s test
To 1 gm of drug add 5–10 ml of dilute HCl boil on water bath for 10 min and filter.
Filtrate was extracted with CCl4/benzene and add equal amount of ammonia solution to
filtrate and shake. Formation of pink or red colour in ammonical layer due to presence
of anthraquinone moiety.
Modified borntrager’s test
To 1 gm of drug, add 5 ml dilute HCl followed by 5 ml ferric Chloride (5% w/v). Boil for
10 min on water bath, cool and filter, filtrate was extracted with carbon tetrachloride or
benzene and add equal volume of ammonia solution, formation of pink to red colour
due to presence of anthraquinone moiety. This is used C-type of anthraquinone
glycosides.
20. CHEMICAL TESTS OF GLYCOSIDES
Chemical Tests for Saponin Glycosides
Haemolysis test
A drop blood on slide was mixed with few drops of aq. Saponin solution, RBC’s
becomes ruptured in presence of saponins.
Foam test
To 1 gm of drug add 10–20 ml of water, shake for few minutes, formation frothing
which persists for 60–120 s in presence of saponins.
21. Chemical Tests for Steroid and Triterpenoid Glycosides
Libermann burchard test
Alcoholic extract of drug was evaporated to dryness and extracted with CHCl3, add few drops of acetic anhydride
followed by conc. H2 SO4 from side wall of test tube to the CHCl3 extract. Formation of violet to blue coloured ring at
the junction of two liquid, indicate the presence of steroid moiety.
Salkowaski test
Alcoholic extract of drug was evaporated to dryness and extracted with CHCl3, add conc. H2 SO4 from sidewall of test
tube to the CHCl3 extract. Formation of yellow coloured ring at the junction of two liquid, which turns red after 2 min,
indicate the presence of steroid moiety.
Antimony trichloride test
Alcoholic extract of drug was evaporated to dryness and extracted with CHCl3, add saturated solution of SbCl3 in
CHCl3 containing 20% acetic anhydride. Formation of pink colour on heating indicates presence of steroids and
triterpenoids.
Trichloro acetic acid test
Triterpenes on addition of saturated solution of trichloro acetic acid forms coloured precipitate.
Tetranitro methane test
It forms yellow colour with unsaturated steroids and triterpenes.
Zimmermann test
Meta dinitrobenzene solution was added to the alcoholic solution of drug containing alkali, on heating it forms violet
colour in presence of keto steroid.
CHEMICAL TESTS OF GLYCOSIDES
22. CHEMICAL TESTS OF GLYCOSIDES
Chemical Tests for Cardiac Glycosides
Keller-kiliani test
To the alcoholic extract of drug equal volume of water and 0.5 ml of strong lead acetate solution was added,
shaked and filtered. Filtrate was extracted with equal volume of chloroform. Chloroform extract was evaporated
to dryness and residue was dissolved in 3 ml of glacial acetic acid followed by addition of few drops of FeCl3
solution. The resultant solution was transferred to a test tube containing 2 ml of conc. H2SO4. Reddish brown
layer is formed, which turns bluish green after standing due to presence of digitoxose.
Legal test
To the alcoholic extract of drug equal volume of water and 0.5 ml of strong lead acetate solution was added,
shaked and filtered. Filtrate was extracted with equal volume of chloroform and the chloroform extract was
evaporated to dryness. The residue was dissolved in 2 ml of pyridine and sodium nitropruside 2 ml was added
followed by addition of NaOH solution to make alkaline. Formation of pink colour in presence of glycosides or
aglycon moiety.
Baljet test
Thick section of leaf of digitalis or the part of drug containing cardiac glycoside, when dipped in sodium picrate
solution, it forms yellow to orange colour in presence of aglycones or glycosides.
3,5-dinitro benzoic acid test
To the alcoholic solution of drug few drops of NaOH followed by 2% solution of 3,5-dinitro benzoic acid was
added. Formation of pink colour indicates presence of cardiac glycosides.
23. CHEMICAL TESTS OF GLYCOSIDES
Chemical Tests for Coumarin Glycosides
FeCl3 test
To the concentrated alcoholic extract of drug few drops of alcoholic FeCl3 solution was added. Formation of deep
green colour, which turned yellow on addition of conc. HNO3, indicates presence of coumarins.
Fluorescence test
The alcoholic extract of drug was mixed with 1N NaOH solution (one ml each). Development of blue-green
fluorescence indicates presence of coumarins.
Chemical Tests for Cynophoric Glycoside
Sodium picrate test
Powdered drug was moistened with water in a conical flask and few drops of conc. Sulphuric acid was added.
Filter paper impregnated with sodium picrate solution followed by sodium carbonate solution was trapped on
the neck of flask using cork. Formation of brick red colour due to volatile HCN in presence of cynophoric
glycosides takes place.
24. Chemical Tests for Flavonoid Glycosides
Ammonia test
Filter paper dipped in alcoholic solution of drug was exposed to ammonia vapor. Formation of yellow spot on
filter paper.
Shinoda test
To the alcoholic extract of drug magnesium turning and dil. HCl was added, formation of red colour indicates
the presence of flavonoids. To the alcoholic extract of drug zinc turning and dil. HCl was added, formation of
deep red to magenta colour indicates the presence of dihydro flavonoids.
Vanillin HCl test
Vanillin HCl was added to the alcoholic solution of drug, formation of pink colour due to presence of
flavonoids.
CHEMICAL TESTS OF GLYCOSIDES
25. ISOLATION
Stas-Otto Method
The general method of extraction of glycosides is outlined here. The drug containing
glycoside is finely powdered and the powder is extracted by continuous hot percolation
using soxhlet apparatus with alcohol as solvent. During this process, various enzymes
present in plant parts are also deactivated due to heating. The thermolabile glycosides,
however, should be extracted at temperature preferably below 45°C.
The extract is treated with lead acetate to precipitate tannins and thus eliminate
nonglycosidal impurities. The excess of lead acetate is precipitated as lead sulphide by
passing hydrogen sulphide gas through solution.
The extract is filtered, concentrated to get crude glycosides. From the crude extract,
the glycosides are obtained in pure form by making use of processes like fractional solubility,
fractional crystallization and chromatographic techniques such as preparative thin layer
and column chromatography.
The characterization of isolated purified compounds is done by IR, UV, visible, NMR
and mass spectrometry and elemental analysis.
26. ANTHRACENE GLYCOSIDES
Anthraquinone is an aromatic organic
compound and a derivative of anthracene. It has
the appearance of yellow or light grey to grey-green
solid crystalline powder. Its chemical formula is
C14H8O2. It melts at 286°C, boils at 379.8°C. It is
insoluble in water or alcohol, but dissolves in
nitrobenzene and aniline. It is chemically fairly
stable under normal conditions.
Anthraquinone naturally occurs in some
plants (e.g. aloe, senna, rhubarb and cascara),
fungi, lichens and insects, where it serves as a basic
skeleton for their pigments. Natural anthraquinone
derivates tend to have laxative effects.
27. ANTHRACENE GLYCOSIDES
These glycosides are characterized by a
chemical test, known as Borntrager test and show
the property of microsublimation. Most of the
glycosides are O-glycosides and S-glycosides, by
their hydrolysis derivatives of 1,8-dihydroxy
anthraquinone, anthranol, anthrone, or dianthrone
are obtained.
The common aglycones are aloe-emodin,
emodin, rhein, chrysophanol and physcion which
may exist as anthraquinones, anthranols or
anthrones. The sugars presents are usually
arabinose, rhamnose and glucose.
29. ANTHRACENE GLYCOSIDES
ALOE
Biological Source
Aloe is the dried juice collected by incision, from the bases of the leaves of various species of Aloe. Aloe
perryi Baker, Aloe vera Linn or Aloe barbadensis Mil and Aloe ferox Miller., belonging to family Liliaceae. Aloe perryi
Baker is found in Socotra and Zanzibar islands and in their neighbouring areas and so the aloes obtained from this
species is known as Socotrine or Zanzibar aloe.
Aloe vera Linn is also known as Aloe vulgairis Lamarek, or Aloe barbadensis Mil. or Aloe officinalis Forskal. It
was formerly produced on the island of Barbados, where it was largely cultivated, having been introduced at the
beginning of the sixteenth century. It is now almost entirely made on the Dutch islands of Curacoa, Aruba and Bonaire.
The aloes obtained from this species is known as Curacao or Barbados aloe. Aloe ferox Miller and hybrids of this
species with Aloe africana and Aloe spicata, A. platylepia and other species of Aloe grows in Cape Colony and so is
known as Cape aloe.
30. ANTHRACENE GLYCOSIDES
Uses
The drug Aloes is one of the safest and stimulating
purgatives, in higher doses may act as abortifacient. Its action is
exerted mainly on the large intestine; also it is useful as a
vermifuge. The plant is emmenagogue, emollient, stimulant,
stomachic, tonic and vulnerary.
Extracts of the plant have antibacterial activity. The
clear gel of the leaf makes an excellent treatment for wounds,
burns and other skin disorders, placing a protective coat over
the affected area, speeding up the rate of healing and reducing
the risk of infection.
To obtain this gel, the leaves can be cut in half along
their length and the inner pulp rubbed over the affected area of
skin. This has an immediate soothing effect on all sorts of burns
and other skin problems.
31. STEROL OR CARDIAC GLYCOSIDES
Cardiac glycosides are composed of two structural features: the sugar (glycone) and the nonsugar
(aglycone–steroid) moieties. The steroid nucleus has a unique set of fused ring system that makes the
aglycone moiety structurally distinct from the other more common steroid ring systems. The steroid nucleus
has hydroxyls at 3- and 14-positions of which the sugar attachment uses the 3-OH group. 14-OH is normally
unsubstituted. Many genins have OH groups at 12- and 16-positions. These additional hydroxyl groups
influence the partitioning of the cardiac glycosides into the aqueous media and greatly affect the duration of
action. The lactone moiety at C-17 position is an important structural feature.
The size and degree of unsaturation varies with the source of the glycoside. Normally plant sources
provide a five-membered unsaturated lactone while animal sources give a six-membered unsaturated
lactone. One to four sugars are found to be present in most cardiac glycosides attached to the 3β-OH group.
The sugars most commonly used include L-rhamnose, D-glucose, D-digitoxose, D-digitalose, D-digginose, D-
sarmentose, L-vallarose and D-fructose. These sugars predominantly exist in the cardiac glycosides in the β-
conformation. The presence of acetyl group on the sugar affects the lipophilic character and the kinetics of
the entire glycoside. Two classes have been observed in nature—the cardenolides and the bufadienolides.
32. STEROL OR CARDIAC GLYCOSIDES
The cardenolides have an unsaturated butyrolactone
ring while the bufadienolides have a pyrone ring. The lactone
of cardenolides has a single double bond and is attached at the
C-17 position of steroidal nucleus.
They are five-membered lactone ring and form a C23
steroids (Leguminosae, Cruciferae, Euphorbiaceae, etc.), while
the lactone of bufadienolids have two double bond which is
attached at the 17 α-position of the steroidal nucleus. They are
six-memberd lactone ring and form C24 steroids (Liliaceae,
Ranunculaceae).
33. STEROL OR CARDIAC GLYCOSIDES
DIGITALIS LEAVES
DIGITALIS LANATA
THEVETIA
RED SQUILL/ SQUILL
INDIAN SQUILL
STROPHANTHUS OLEANDER
34. STEROL OR CARDIAC GLYCOSIDES
DIGITALIS LEAVES
Biological Sources
Digitalis consists of dried leaves of Digitalis purpurea Linn.,
belonging to family Scrophulariaceae.
Chemical Constituents
Digitalis leaves contains 0.2–0.45% of both primary and secondary glycosides. Purpurea
glycosides A and B and glucogitoloxin are primary glycosides. Because of greater stability of secondary
glycosides, and lesser absorption of primary glycosides a higher content of primary glycosides are not
considered ideal and secondary glycosides are used.
Purpurea glycosides A and B are present in fresh leaves and by their hydrolysis digitoxin and
glucose or gitoxin and glucose are obtained respectively. Hydrolysis of purpurea glycosides can take
place by digipuridase (enzyme) present in the leaves. Digitoxin yields on hydrolysis digitoxigenin and
three digitoxose. By hydrolysis of verodoxin, gitaloxigenin and digitalose are obtained. Digitalis leaves
also contains glycosides like odoroside-H, gitaloxin, verodoxin and glucoverodoxin.
36. STEROL OR CARDIAC GLYCOSIDES
DIGITALIS LEAVES
Uses
The foxglove is a widely used herbal medicine with
a recognized stimulatory effect upon the heart. It is also
used in allopathic medicine in the treatment of heart
complaints. It has a profound tonic effect upon a diseased
heart, enabling the heart to beat more slowly, powerfully
and regularly without requiring more oxygen. At the same
time it stimulates the flow of urine which lowers the volume
of the blood and lessens the load on the heart.
It has also been employed in the treatment of
internal haemorrhage, in inflammatory diseases, in delirium
tremens, in epilepsy, in acute mania and various other
diseases. Digitalis has a cumulative effect in the body, so
the dose has to be decided very carefully.
37. SAPONIN GLYCOSIDES
Saponins are glycoside compounds often referred to as a ‘natural detergent’
because of their foamy texture. They get their name from the soap wort plant
(Saponaria), the root of which was used historically as a soap (Latin sapo—soap).
Foremost among this is the strong tendency to froth formation when shaken with
water. The other properties are hemolytic activity, sneezing effect, toxicity, complex
formation with cholesterol and antibiotic properties.
Saponins have long been known to have strong biological activity. When
studying the effect that saponins have on plants, it has been discovered that saponins
are the plants active immune system. They are found in many plants, they consist of a
polycyclic aglycone that is either a choline steroid or tritetpenoid attached via C3 and
an ether bond to a sugar side chain. The aglycone is referred to as the sapogenin and
steroid saponins are called sarsaponins. The ability of a saponin to foam is caused by
the combination of the nonpolar sapogenin and the water soluble side chain.
38. SAPONIN GLYCOSIDES
Steroid Saponins
Steroid saponins are similar to the sapogenins and related to the cardiac glycosides. They have ability
to interact medically and beneficially with the cardiac glycosides, sex hormones, Vitamin D and other factors,
render these phytochemicals components of great medical significance.
Diosgenin is the important steroid sapogenin. Recently from these saponins steroid hormones like
progesterone, cortisone etc. are obtained by partial synthesis and thus their importance has increased
considerably. Some of the families with steroidal saponins are Solanaceae, Apocynaceae, Liliaceae,
Leguminosae, etc.
Triterpenenoid Saponins
Triterpenoid saponins, or sapogenins, are plant glycosides which lather in water and are used in
detergents, or as foaming agents or emulsifiers, and have enormous medical implications due to their
antifungal, antimicrobial, and adaptogenic properties.
Triterpene saponins are usually α -amyrine derivatives and some are also α-amyrine and lupeol
derivatives. It has a pentacyclic triterpenoid nucleus which is linked with either sugar or uronic acid.
Glycyrrhizin, from licorice root, is an example of a saponin used for antiinflammatory purposes in place of
cortisone. They are commonly available in dicot plants belonging to the family Rubiaceae, Compositae,
Rutaceae, Umbelliferae, etc.
40. SAPONIN GLYCOSIDES
GINSENG
Biological Source
It consists of dried roots of Panax ginseng C.A. Mey and other
species of Panax like Panax japonicus (Japanese Ginseng), Panax
pseudoginseng (Himalayan Ginseng), Panax quinquefolius
(American Ginseng), Panax trifolius (Dwarf Ginseng) and Panax
vietnamensis (Vietnamese Ginseng), belonging to family
Araliaceae.
Chemical Constituents
Several saponin glycosides belonging to triterpenoid group,
ginsenoside, chikusetsusaponin, panxoside. More than 13
ginsenosides have been identified. Ginsenosides consists of
aglycone dammarol where as panaxosides have oleanolic acid as
aglycone. It also contains large amount of starch, gum, some
resin and a very small amount of volatile oil.
41. SAPONIN GLYCOSIDES
GINSENG
Uses
The root is adaptogen, alterative, carminative, demulcent, emetic,
expectorant, stimulant and tonic. The saponin glycosides, also known as ginsenosides
or Panaxosides, are thought responsible for Panax ginseng’s effects. Ginsenosides have
both stimulatory and inhibitory effects on the CNS, alter cardiovascular tone, increase
humoral and cellular-dependent immunity, and may inhibit the growth of cancer in
vitro.
It encourages the secretion of hormones, improves stamina, lowers blood
sugar and cholesterol levels. It is used internally in the treatment of debility associated
with old age or illness, lack of appetite, insomnia, stress, shock and chronic illness.
Ginseng is not normally prescribed for pregnant women, or for patients under the age
of 40, or those with depression, acute anxiety or acute inflammatory disease.
It is normally only taken for a period of 3 weeks. Excess can cause headaches,
restlessness, raised blood pressure and other side effects, especially if it is taken with
caffeine, alcohol, turnips and bitter or spicy foods.
42. CYANOGENIC GLYCOSIDES
These are the glycosides which on hydrolysis yields hydrocynic acid
(HCN), benzaldehyde and sugars. The medicinal activity of
cyanogenetic glycosides is due to presence of hydrocyanic acid and
these are the characteristics of family rosaceae. For examples
Amygdalin obtained from bitter almond (Prunus amygdalus),
Prunasin obtained from wild cherry bark.
ALMOND
Biological Source
Almond oil is a fixed oil obtained by expression from the seeds of
Prunus amygdalus (Rosaceae) var. dulcis (sweet almonds), or P.
amygdalus var. amara (bitter almonds).
Chemical Constituents
Both varieties of almond contain 40–55% of fixed oil, about 20%
of proteins, mucilage and emulsin. The bitter almonds contain in
addition 2.5–4.0% of the colourless, crystalline, cyanogenelic
glycoside amygdalin.
Uses
Expressed almond oil is an emollient and an ingredient in
cosmetics. Almond oil is used as a laxative, emollient, in
the preparation of toilet articles and as a vehicle for oily
injections. The volatile almond oils are used as flavouring
agents.
44. ISOTHIOCYNATE GLYCOSIDES
These are sulphur-containing compounds rich in family
cruciferae, also known as glucosinolates and on hydrolysis
yields isothiocyanate (-NCS) group. These glycosides are
generally irritant and hence used externally as counter
irritant, for example, Sinigrin from black mustard, sinalbin
from white mustard and gluconapin from rapeseed.
MUSTARD
Biological Source
It is a fixed oil obtained from matured seeds of Brassica nigra (L)
Koch or Brassica juncea L. Czern, belonging to family Cruciferae
(Brassicaceae).
Chemical Constituents
Mustard oil contains glycerides of arachidic (0.5%),
behenic (2–3%), eicosenoic (7–8%), erusic (40–60%),
lignoceric (1–2%), linoleic (14–18%), linolenic (6.5–
7.0%), oleic (20–22%) and myristic (0.5–10%) acids.
Black mustard seeds contain 35–40% of fixed oil and a
glycoside known as sinigrin alongwith an enzyme
myrosin. Allyl isothiocynate is responsible for the
strong acrid smell of volatile oil of mustard produced
on hydrolysis of glycoside.
Uses
Fixed oil is used as edible oil after refining, but medicinal properties
are due to allyl isothiocynate, which is a local irritant and emetic. If
applied externally, it is rubefacient and vasicant. It is also used as
condiment and in manufacture of soap. Refined mustard oil is used
in vegetable ghee.
45. FLAVONE GLYCOSIDES
These are complex organic compounds containing
phenylbenzopyrone ring system. Flavones are present in
plants in a free state or in glycosidal state (O-glycoside or C-
glycoside) with its different derivatives like flavane, flavonol,
flavonone, isoflavone and chalcones, for example, Rutin,
quercitrin, hyperoside, diosmin (buchu leaf), hesperidin
(lemon and orange peel) and vitexin (Carategus).
GINKGO
Biological Source
The leaves of
Ginkgo are obtained
from the dioeceous
tree Ginkgo biloba,
belonging to family
Ginkgoaceae.
Chemical Constituents
The diterpene lactones and flavonoids possess
therapeutic activity. Five diterpene lactones (ginkgolides A, B,
C, J, M) have been characterized; these have a cage structure
involving a tertiary butyl group and six 5-membered rings
including a spirononane system; a tetrahydrofuran moiety and
three lactonic groups. These compounds are plateletactivating
factor (PAF) antagonists and as they do not react with any
other known receptor, their effect is very specific.
A tertiary butyl group is present in the
sesquiterpene bilobalide; no PAF-antagonist activity has been
demonstrated for this compound. About 40 flavonoids have
now been isolated from the leaves including glycosides of
kaempferol, quercetin and isorhamnetin derivatives. The tree
also synthesizes anumber of biflavonoids based on
amentoflavone.
Uses
Ginkgo is used as an antiasthmatic and bronchodilator. Extracts
of the leaf containing selected constituents are used for
improving peripheral and cerebral circulation in those elderly
with symptoms of loss of short-term memory, hearing and
concentration; it is also claimed that vertigo, headaches, anxiety
and apathy are cured.
46. COUMARIN AND FURANOCOUMARIN GLYCOSIDES
In these type of glycosides the aglycone is coumarin. Coumarin is a chemical compound
found in many plants, notably in high concentration in the tonka bean, woodruff, and sweet grass.
They are benzopyrone derivative have aromatic smell and their alcoholic solutions when made
alkaline show blue or green fluorescence. The biosynthesis of coumarin in plants is via hydroxylation,
glycolysis and cyclization of cinnamic acid. It has clinical value as the precursor for several
anticoagulants, notably warfarin. Some naturally occuring coumarin derivatives include
umbelliferone (7-hydroxycoumarin), herniarin (7-methoxy-coumarin), psoralen and imperatorin.
Coumarins have flavouring property but they cause damage to liver. Coumarin drugs also
cause drug interactions with many other drugs. Medicinally, coumarin glycosides have been shown
to have hemorrhagic, antifungicidal and antitumor activities.
Furanocoumarins are toxic compounds that consist of a coumarin nucleus bonded to a furan
ring. Several plants contain the psoralens that are generally the precursors of furocoumarins.
Furanoccumarins are found especially in Rutaceae, Umbelliferae and Leguminosae. They are also
produced by some plants, for example, celery and parsnips, in response to fungal infestation.
47. COUMARIN AND FURANOCOUMARIN GLYCOSIDES
VISNAGA
Biological Source
These are the fruits of Ammi visnaga
Linn., belonging to family Umbelliferae.
Chemical Constituents
The drug contains furanocoumarin compounds. The chief
constituents are khellin and visnagin, which are -benzopyrone
derivatives. Khellol and khellol glucoside are also present. In
addition it contains pyranocoumarin esters visnadin, samidin
and dihydrosamidin. Fixed oil and proteins are also present.
Uses
Visnaga is an effective muscle relaxant and has been used for centuries to alleviate the excruciating
pain of kidney stones. Khellin is used in treatment of asthma. The seeds are diuretic, antiasthmatic
and lithontripic. The seeds have a strongly antispasmodic action on the smaller bronchial muscles;
they also dilate the bronchial, urinary and blood vessels without affecting blood pressure.
49. ALDEHYDE GLYCOSIDES
VANILLA
Biological Source
Vanilla (Vanilla Pods) consists of the cured fully
grown but unripe fruits of Vanilla fragrans
(Salis.), belonging to family Orchidaceae.
Chemical Constituents
Green vanilla contains glycosides, namely gluco-vanillin (vanilloside) and glucovanillic
alcohol. During the curing these are acted upon by an oxidizing and a hydrolysing enzyme which
occur in all parts of the plant. Glucovanillic alcohol yields on hydrolysis glucose and vanillic alcohol;
the latter compound is then by oxidation converted into vanillic aldehyde (vanillin). Glucovanillin
yields on hydrolysis glucose and vanillin.
The vanilla species differ in their relative contents of anisyl alcohol, anisaldehyde, anisyl
ethers, anisic acid esters, piperonal and p-hydroxybenzoic acid. These minor components, together
with the two diastereoisomeric vitispiranes, add to the flavour of the pods.
Uses
Vanilla pods are widely used in confectionery
and in perfumery.
50. PHENOL GLYCOSIDES
Biological Source
These are the dried leaves of Arctostaphylous uva-ursi
(Linne) Sprengel, belonging to family Ericaceae.
BEARBERRY
Chemical Constituents
The leaves contain a glycoside called arbutin which
contains phenolic aglycone. The leaves also contain methyl
arbutin, quercetin, ursone, iriodoids, quinones, tannins
(6–10%), gallic acid ursolic acid, α-amyrin, β-amyrin and
terpenoids.
Uses
The leaves have diuretic and astringent properties. As an
infusion, it is used in urethritis and cystitis.
51. STEROIDAL GLYCOSIDES
SOLANUM
Biological Source
It consists of dried berries of Solanum khasianum C.B.
Clarke, belonging to family Solanaceae.
Chemical Constituents
The berries contain about 3% of steroidal glycoalkaloid called solasodine. A
new glycoalkaloid solakhasianin having rhamnose and galactose as sugar
components have been isolated. Mucilage surrounding part of the seeds
contain highest amount of alkaloid. Immatured and over-ripe fruits contain
negligible content of alkaloid, while it is maximum when fruits change colour
from green to yellow. Colour change of fruits takes place about two months
after setting the fruits to the plants. The berries also contain 8–10% of
greenish-yellow fixed oil.
Uses
Solasodine is used as a precursor for steroidal synthesis. Like
diosgenin, it is first converted to 16-dehydro-pregnenelone
acetate. The latter is a precursor for steroids, like
corticosteroids, pregnane and androstanes. All of these are
useful as sex hormones, oral contraceptives, etc.
52. BITTER AND MISCELLANEOUS GLYCOSIDES
Bitter glycosides are a class of compounds that plays
an important role in the digestive process. Bitter
drugs and bitter constituents are used since a very
early period as stomachics, febrifuges, and bitter
tonics and in digestive disturbances.
GENTIAN PICRORHIZA QUASSIA
53. Biological Source
Kalmegh consists of leaves or entire aerial part of Andrographis
paniculata Nees., belonging to family Acanthaceae.
BITTER AND MISCELLANEOUS GLYCOSIDES
Chemical Constituents
The plant possesses kalmeghin, a bitter crystalline diterpene
lactone, such as, andrographolide flavonoids and phenols. The
lactones isolated from Kalmegh are andrographolide, 14-deoxy-ll-
oxo-andrographolide, 14-deoxy-11, 12 didehydroandrographolide,
14-deoxyandrographolide and neoandrographolide.
The leaves contain -sitosterol glucoside, caffeic, chlorogenic and
dicaffeoyl-quinic acids, carvacrol, eugenol, myristic acid,
hentriacontane, tritriacontane, oroxylin A, wogonin,
andrograpanin, 14-deoxy-12-methoxyandrographolide,
andrographidines A-F and stigmasterol.
KALMEGH
54. BITTER AND MISCELLANEOUS GLYCOSIDES
Uses
Kalmegh has febrifuge, tonic, alterative, anthelmintic,
astringent, anodyne, alexipharmic and cholagogue properties.
It is useful in debility, cholera, diabetes, swelling, itches,
consumption, influenza, piles, gonorrhoea, bronchitis,
dysentery, dyspepsia, fever and in weakness. A decoction
of the plant is used as a blood purifier and as a cure for
torphid and jaundice. The pills prepared from macerated
leaves and certain spices (e.g. Cardamom, Clove and
Cinnamon) are given for stomach ailments of infants.
