glycosides are in pharmacognosy

1. Glycosides
 A number of medicinal plants contain complex organic
molecules which are in conjugation with sugar moieties,
monosaccharides. Such compounds are known as
glycosides.
 Glycosides may be defined as “Organic compounds from
plants or animal sources which on enzymatic or acid
hydrolysis give one or more sugar moieties along with
non-sugar moiety”.
1

2.  The sugar part of the compound is known as glycone
and the other part is known as aglycone or genin.
 The sugar involved in glycosides are of different types
but most commonly, it is β-D-glucose. The other sugars
found are galactose, mannose, rhamnose, digitoxose,
cymarose etc.
2

3.  Glycosides are colorless (some are colorful), crystalline or
amorphous solid substances and generally poisonous in
nature (not all glycosides are poisonous).
 Flavonoid glycosides are yellow whereas anthracene
glycosides are red to orange in color.
 Many glycosides are therapeutically significant used in
traditional and modern medicines as cardiotonic,
purgative, analgesic, anti-rheumatic actions.
3

4.  These are soluble in water and alcohol but insoluble in
ether and chloroform
 After complete hydrolysis aglycone moiety is soluble in
organic solvents like ether and chloroform
 These are optically active and usually levorotatory
4

5. 5
Phytochemical Tests

6. a) Chemical Tests for Anthraquinone Glycosides
1) 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 color in ammonical layer due to
presence of anthraquinone moiety.
6

7. 2) 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 color due to presence of
anthraquinone moiety. This is used for C-type of
anthraquinone glycosides
7

8. b) Saponin glycosides
1) Hemolysis Test: A drop blood on slide was mixed with
few drops of aqueous saponin solution, RBC’s becomes
ruptured in presence of saponins.
2) Foam Test: To 1 gm of drug add 10-20 ml of water, shake
for few minutes, formation of frothing which persists for
60-120 sec in presence of saponins.
8

9. c) Steroid and Triterpenoid glycosides
a) Libermann-Burchard test:
 Alcoholic extract of drug was evaporated to dryness and
extracted with CHCl3, add few drops of acetic anhydride
followed by conc. H2SO4 from side wall of test tube to the
CHCl3 extract.
 Formation of violet to blue colored ring at the junction of
two liquid, indicate the presence of steroid moiety.
9

10. b) Salkowski test:
 Alcoholic extract of drug was evaporated to dryness and
extracted with CHCl3, add conc. H2SO4 from sidewall of
test tube to the CHCl3 extract.
 Formation of yellow colored ring at the junction of two
liquid, which turns red after 2 min, indicate the presence
of steroid moiety.
10

11. c) 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
color on heating.
d) Trichloro acetic acid test:
 Triterpenes on addition of saturated solution of trichloro
acetic acid forms colored precipitate.
11

12. e) Tetra nitro methane test:
 It forms yellow color with unsaturated steroids and
triterpenes.
f) Zimmermann test:
 Meta dinitro benzene solution was added to the alcoholic
solution of drug containing alkali, on heating it forms
violet color in presence of keto-steroid.
12

13. d) Chemical tests for cardiac glycosides
a) Keller Killiani test:
 To the alcoholic extract of drug equal volume of water
and 0.5 ml of strong lead acetate solution is added,
shake and filtered. Filtrate is extracted with equal volume
of chloroform.
 Chloroform extract is evaporated to dryness and residue
is dissolved in 3 ml of glacial acetic acid followed by
addition of few drops of FeCl3 solution.
13

14.  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.
b) 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.
14

15.  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 2 ml of
sodium nitroprusside, followed by addition of NaOH
solution to make alkaline.
 Formation of pink colour in presence of glycosides or
aglycone moiety.
15

16. 16
c) Baljet test:
 Thick section of digitalis leaf or the part of drug
containing cardiac glycoside, when dipped in sodium
picrate solution, it forms yellow to orange color in
presence of aglycones or glycosides.

17. e) Flavonoid glycosides
a) Ammonia test: Filter paper dipped in alcoholic solution
of drug was exposed to ammonia vapor. Formation of
yellow spot on filter paper.
b) Shinoda test:
 To the alcoholic extract of drug, magnesium turning and
dil. HCl was added, formation of red colour indicates the
presence of flavonoids.
17

18.  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.
c) Vanillin-HCl test: Vanillin-HCl was added to the alcoholic
solution of drug, formation of pink color due to presence
of flavonoids.
18

19. 19
f) Anthracene glycosides
a) Schonteten´s (Aloe)
 To aqueous solution of aloe, add borax and heat to
dissolve completely. Few drops of this mixture are
poured in a test tube filled with water. Green
fluorescence is produced.
b) Bromine test (Aloe)
 Pale yellow ppt of tetrabromaloin is formed on addition
of bromine.

20. 20
c) Nitric acid (Aloe)
 On addition of nitric acid to a solution of aloe, Cape aloe
forms brown color which changed to green; Curacao
gives brownish-red, Socotrine gives pale brownish yellow
and Zanzibar gives yellowish-brown.
d) Nitrous acid test (Aloe)
 To an aqueous solution of aloe, small amount of sodium
nitrite and few ml of acetic acid is added. Pink color is
developed.

21. 21
f) Modified Borntrager's test (Aloe)
 Aloe is boiled with dil. HCl and 5% solution of FeCl3 for 5
min. Solution is cooled, filtered and filtrate is shaken with
benzene. Benzene layer is separated, ammonia solution is
added, pink color is formed.
g) Klunge´s isobarbaloin test (Aloe)
 To an aqueous solution of aloe, CuSO4 solution, NaCl and
alcohol (90%) is added. A purple color is formed for
Curacao Aloe.

22. 22
g) Cyanogenetic glycosides
a) Sodium picrate test
 A strip of filter paper is dipped in 10% aqueous solution
of picric acid. It is drained and re-dipped in 10% Na2CO3
solution and drained again. Then paper is kept on mouth
of flask, hydrocyanic acid vapor turn paper brick red or
maroon colored.

23. Classification of Glycosides
 The classification of glycosides is based either on the
chemical nature of aglycone part or therapeutic activity
exhibited by the same.
 Another mode of classification is based on the type of
linkage existing between the glycone and aglycone part.
 Brief discussion about classification of glycosides is given
here:
23

24.  According to chemical nature of aglycones moiety, they
are classify as:
1. Anthraquinone or anthracene glycosides
2. Sterols or cardiac glycosides
3. Saponin glycosides
4. Cyanogenetic or cyanophoric glycosides
5. Isothiocynate glycosides
6. Flavonoids/ flavonol glycosides
7. Coumarins and furanocoumarin glycosides
24

25. 8. Aldehyde glycosides
9. Phenol glycosides
10. Steroidal glycolkaloids glycosides
11. Glycosidal bitters or miscellaneous glycosides
 The glycosides may be classified in relation to their
therapeutic activity into different groups like cathartics,
cardiotonic, analgesics, anti-rheumatics, anti-ulcer etc.
25

26.  Some times glycosides are also classified on the basis of
Type of Sugar or the glycone part of their structure.
 Accordingly, there are glucosides with glucose,
rhamnosides with rhamnose pentosides with pentose
like ribose, etc.
 The sugar involved in the structure are normally the
common type of sugars.
26

27.  Only in few cases, sugar like digitoxose, cymarose are
present.
 Another approach for their classification is by considering
the linkage across glycone and aglycone part.
 All types of glycosidal linkages are occurred by interaction
of –OH group of glycone and hydrogen coming from any
of the radicals like CH, -OH, -SH and -NH present on
aglycone part
27

28.  Hence by elimination of one water molecule, linkage or a
bridge is formed and the type of glycoside formed is
named by putting the element as prefix like C-glycoside,
N-glycoside, O-glycoside or S-glycoside.
 To illustrate the individual pattern, the following brief
account of such glycosides is given:
28

29. 1. C-glycosides:
 In C-glycosides the sugar moiety is linked to carbon atom
of aglycone part.
 Some Anthraquinone glycosides such as cascarosides
from cascara and aloin from aloe as well as some
members of flavone glycosides show the presence of C-
glycosides.
 Cochineal contains C-glycoside in the form of a coloring
matter called carminic acid.
29

30.  These are also called as aloin type glycosides are mainly
present in family Liliaceae.
 Hydrolysis of these glycosides by heating with dilute
acid/alkali is not possible but oxidative hydrolysis with
ferric chloride is possible.
30

31. Carminic acid
31

32. 2. O-glycosides:
 In O-glycosides the sugar moiety is linked to oxygen atom
of aglycone part.
 These are very common in higher plants e.g. Senna,
rhubarb, digitalis etc.
 They are hydrolyzed by acid or alkali into aglycones and
sugar i.e. glucovanillin, amygdalin.
32

33. 3. S-glycosides:
 In S-glycosides the sugar moiety is linked to sulphur
atom of aglycone part.
 Their occurrence is restricted to Isothiocyanate
glycosides like sinigrin from black mustard.
 They are formed by interaction of sulfhydryl group of
aglycones and hydroxyl group of glycone.
33

34. 4. N-glycosides:
 In N-glycosides the sugar moiety is linked to nitrogen
atom of aglycone part. Ex., Nucleoside
 The most typical representative example of N-glycosides
is nucleotides, where the amino group of base reacts
with OH group of ribose/deoxyribose and ultimately
gives N-glycosidic form.
34

35. Cardiac or Steroidal glycosides
 Aglycone is steroidal in nature.
 They are C23 or C24 steroids with 5- and 6-membered
lactones ring respectively.
 5-membered lactones ring are Cardenolides while 6-
membered lactones ring are Bufadienolides
 In cardenolides & bufadienolide lactones' contain one &
two double bond respectively and it attached to steroid
nucleus, through C-17β position.
35

36.  The sugar part is attached to C-3β position.
 Various sugars have been present in cardiac glycosides,
such as cymarose, digitoxose, digitalose, fucose, glucose,
rhamnose etc.
 The sugar part not potentiate the medicinal properties of
aglycone part but useful in solubilization, absorption and
distribution in the body
36

37. Cardenolides
Digitoxose Digitalose

38.  At a time upto three sugar molecules are attached to
aglycone.
 It has been also shown that increase in number of -OH
groups on aglycone leads to quicker onset of action.
 A number of plants contain cardiac glycosides, they are
broadly restricted to angiosperms.
38

39.  Leguminosae, Sterculiaceae, Cruciferae,
Scrophulariaceae, Euphorbiaceae etc. families show
presence of Cardenolides
 Very few families like Liliaceae and Ranunculaceae
contain Bufadienolides.
 Congestive heart failure (CHF), is treated by cardiac
glycosides.
39

40. Digitalis
Synonym: Digitalis leaves, Foxglove leaves.
Biological source:
 Dried leaves of Digitalis purpurea (family
Scrophulariaceae).
Chemical constituents:
 Cardiac glycosides (cardenolides), Purpurea glycoside A
& B and digitoxin
 Digitoxigenin is aglycone moiety of digitoxin
40

41. Uses:
 Treatment of congestive heart failure (CHF).
 Digitalis blocks the sodium potassium ATPase pump of
the cardiac muscles, so that intracellular concentration of
sodium is increased.
 This leads to increase in calcium ions from sarcolemma
and proteins (actin & myosin) which exhibited more
forceful contractions of myocardium.
41

42. 42
Digitoxin
Digoxin

43. Saponin Glycosides
 Most of the plants containing saponin glycosides are
medicinally important.
 As the name indicates, the aglycone part of these
glycosides has soap like action.
 They exhibit some properties like foaming action by
shaking with water and hemotoxic because they cause
Hemolysis of erythrocytes.
43

44.  They are mostly non-crystalline, soluble in water and
alcohol but insoluble in non-polar solvents.
 Chemically they contain aglycone called as sapogenin,
which are high molecular weight substances.
 The harmful saponins are called sapotoxins.
 Depending on the nature of aglycone, these are
categorized into two groups:
44

45. i) Steroidal saponins
a) Tetracyclic Triterpenoid Saponin:
CH3
CH3
C
H3
CH3
CH3
Steroid Pattern of saponin
(Tetracyclic Triterpenoids)
45

46. The steroidal saponins are used as raw material for the
synthesis of medicinally useful steroids:
 Vitamin D
 Cardiac glycosides
 Corticoids like betamethasone and cortisone acetate
 Sex hormones like progesterone, testosterone and
Estradiol
46

47.  Oral contraceptives such as mestranol and norethisterone
 Spironolactone is a diuretic steroid
 Steroidal sapogenins like diosgenin and hecogenin are
example of this group
 In dicot plants, important sources are Leguminosae,
Solanaceae, Apocynaceae etc.
 In monocots sources are Liliaceae, Dioscoreaceae,
Amaryllidaceae

48. 48
Diosgenin
Hecogenin

49.  Pentacyclic triterpenoid nucleus, which is linked with
sugars or uronic acids.
 The sapogenin is further differentiated into:
a) α-amyrin type b) β-amyrin type c) Lupeol
 Important derivatives of this group are triterpenoid acids.
These acids are present in various drugs formed by
substitution of carboxylic group at C-4, C-17 and C-20.
4
b) Pentacyclic Triterpenoid Saponins

50.  Besides the chemical structure, these types of saponin
are differ from steroidal saponins by their distribution.
 Pentacyclic triterpenoid saponins are available from
various Dicot families like Polygonaceae,
Caryophyllaceae, Berberidaceae, Umbelliferae,
Rubiaceae, Compositae, Primulaceae, Rutaceae,
Chenopodiaceae etc.
 They are rarely found in monocot plants.
50

51. Lupeol
CH3
CH3
C
H3
CH3
CH3
Pentacyclic Triterpenoids

52. CH3
C
H3
COOH
R''
CH3
CH3
CH3
O
H
C
H3 R' Triterpenoid acids
52

53. Dioscorea
Synonym: Yam and Rheumatism root
Biological source: Tubers of Dioscorea deltoidea, Dioscorea
composita (family Dioscoreaceae).
Chemical constituents: Chief active constituent of
dioscorea is dioscin (Glucose + 2 Rhamnose + diosgenin)
and 75% of starch.
Uses: Precursor for corticosteroids synthesis, In rheumatic
arthritis
53

54. Diosgenin
54

55. Liquorice
Synonym: Mulhatti, Madhuka
Biological source: Glycyrrhiza glabra roots (family
Fabaceae).
Chemical constituents:
 Glycyrrhizin (pentacyclic triterpene saponin) is 60 times
sweeter than cane sugar
 Flavonoid rich fractions include liquiritin, isoliquiritin
liquiritigenin and rhamnoliquirilin
55

57. Mechanism of Action:
 Glycyrrhizic acid shows mineralocorticoid &
glucocorticoid activity
 Inhibition of phospholipase A2 (Anti-inflammatory)
 Inhibit the generation of ROS
 Hepatoprotective by lowering serum liver enzyme levels
Uses:
 Anti-inflammatory, Expectorant, hepatoprotective
 Used internally for Addison's disease, Asthma, Bronchitis,
Peptic ulcer, Arthritis, Allergic
57

58. Activity Chemical constituents Class
Antiulcer Glycyrrhizinic acid Saponin glycoside
Analgesic & uterine relaxant Isoliquiritigenin Flavonoid
Antioxidant activity isoliquiritigenin Flavonoid
Memory enhancer Glabridin Flavonoid
Corticosteroid 18-β-glycyrrhetinic acid Triterpenoid saponin
Anti-allergic Glycyrrhizin Triterpenoid saponin
Hepatoprotective Glycyrrhizin Triterpenoid saponin
Anti-inflammatory Glycyrrhetic acid Chalcone
Anticancer Glycyrrhetic acid, Glycyrrhizin Triterpenoid saponin
Antiviral Glycyrrhizin Triterpenoid saponin
Antihyperglycemic Glycyrrhetinic acid, glycyrrhizin Triterpenoid saponin
Liver carcinoma Glycyrrhizin Triterpenoid saponin
Antitussive Glycyrrhizin Triterpenoid saponin
Immunostimulating Glycyrrhetic acid Triterpenoid saponin
Anti HIV Glycyrrhizin Triterpenoid saponin
Chronic hepatitis C Glycyrrhizin Triterpenoid saponin

59. Anthracene Glycosides
 These constitute a major class of glycosides.
 They are mainly found in the Dicot plants of families
Ephorbiaceae, Ericaceae, Lythraceae, Polygonaceae,
Rhamnaceae, Rubiaceae, Leguminosae etc.
 The family Liliaceae from Monocots also shows the
presence of C-glycosides of anthracene group.
59

60.  Some of the fungi and lichens also contain
anthraquinone glycosides.
 It is postulated that the aglycone part of these
glycosides is formed by head to tail condensation of
acetate units
 This group of glycosides comprises of different aglycone
moieties like anthraquinone, anthrone, anthranol,
dianthranol, oxanthrone and dianthrone
60

61.  In different drugs like aloe, senna, rhubarb, cascara,
aglycones are present in their derivative forms.
 The parent molecule for all these aglycones is
anthraquinone which is present in different forms along
with methyl, hydroxymethyl, carboxyl, dihydroxy phenol,
trihydroxy phenol or free carboxylic acid groups.
61

62. Anthranol

63. 63
Anthracene

64. Aloes
Synonyms: Aloe, Musabbar, Ghrit kumari
Biological source: Dried juice of the leaves of Aloe
barbadensis Miller (Curacao) or Aloe perryi Baker
(Socotrine/Zanzibar) or Aloe ferox (Cape) Miller (family
Liliaceae).
Chemical constituents:
 Aloin which is mixture of glucosides among which
barbaloin is the chief constituent.
64

65.  Isobarbaloin, β-barbaloin, aloe emodin and resin
(principle compound is Aloesin).
 Chrysophanic acid, chrysamminic acid, aloetic acid etc.
Uses:
 Strong purgative, Aloe gel is used in cosmetics, anti-
inflammatory, wound healing, hair tonic, febrifuge,
emmenagogue, relieve burning sensation
65

66. Aloin-A
66

67. Indian Senna
Synonyms: Senna leaf, Sennae folium, Senai ki patti,
Tinnevelly senna, Cassia senna.
Biological source: Dried leaflets of Cassia angustifolia,
(Indian) and Cassia acutifolia (Alexandrian) (Leguminosae)
Microscopic constant: The microscopical constant are
helpful to differentiate the Indian and Alexandrian Senna.
67

68. Alexandrian Senna
Synonyms: Folia sennae, Alexandriana, Cassia senna,
Egyptian senna.
Biological source: Dried leaflets of Cassia acutifolia Delile,
(family Leguminosae).
Parameters Indian Senna Alexandrian Senna
Vein-islet number 19.5-22.5 25-29.5
Stomatal index 17-20 11.4-13.3
Palisade ratio 7.5 (upper epidermis)
5.1 (lower epidermis)
7.0-9.5

69. 69
Chemical constituents:
 Anthraquinone glycosides, Sennosides A & B
 Small amount of Sennosides C and D, anthrone, aloe-
emodin, Kaempferol, isorhamnetin
 Naphthalene glycosides like Tinnevelly glycosides (Indian
senna), 6-hydroxy musizin.
Uses: Purgative and cathartic

70.  Sennosides
10'
10
R
OH
O
O
-
Glu
O
O
-
Glu
COOH
OH
R 10-10’ Glycoside
COOH trans Sennoside A
COOH meso Sennoside B
CH2OH trans Sennoside C
CH2OH meso Sennoside D
CH3
CH3
O
O
Glu
Tinnevelly glucoside
70

71. 71
6-Hydroxy musizin