This document discusses glycosides, which are organic compounds that can be found in plants and animals. It provides information on the four main types of glycosidic linkages: O-glycosides, S-glycosides, N-glycosides, and C-glycosides. It also describes some important glycosides like senna, rhubarb, and aloe, detailing their botanical sources, chemical constituents, properties, uses, and production methods. The document provides classification schemes for glycosides and outlines some common chemical tests used to identify them.

1. Glycosides
• Class: Second Year B. Pharm Sem: IV
• Subject: Pharmacognosy & Phytochemistry – I
• Chapter No.: 3
By: Vipul Dhasade
Department of Pharmacognosy

2. • Primary metabolites :
• Secondary metabolites : Glycosides, Flavonoids,
Alkaloids, Essential oils, Tannins.
• Phytopharmaceuticals: Significance

3. Glycosides
They are secondary products formed from one
or more sugar molecules added to a non-sugar
biologically active molecule
– Sugar most commonly found is glucose
– Non-sugar molecule known as the aglycone and may
be
• amino acid derivatives
• steroids
• triterpenes

4. Glycosides
 Glycosides consist of
a sugar residue covalently bound
to a different structure called the
aglycone.
The sugar moiety can be joined
to the aglycone in various ways:
1. Oxygen (O-glycoside)
2. Sulphur (S-glycoside)
3. Nitrogen (N-glycoside)
4. Carbon (Cglycoside)

5.  Definition:: The organic compounds from plant or animal
source which on enzymatic or acid hydrolysis give one or more
sugar moieties along with non-sugar moieties.
Glycone -------- (Glycosidic linkage)-------- Aglycone (genin)
 Almost all plants that contain glycosides also contain enzymes that
bring about their hydrolysis (glycosidases).
 -Glycosides and -glycosides are distinguished by the
configuration of the hemiacetal hydroxyl group.
 The majority of naturally-occurring glycosides are -glycosides.
 O-Glycosides can easily be cleaved into sugar and aglycone by
hydrolysis with acids or enzymes.

6. 1.1 O-Glycosides
• The O-glycosides are usually represented as follows:
• Glycone---- (OH + H)---C—Aglycone……… O-Glycoside
• Glycone---- C—Aglycone + H2O
• such as: senna, rhubarb and frangula.
• Examples: Rhein-8-glucoside obtained from rhubarb.
•
1.2 S-Glycosides
• The S-glycosides are normally designated as below:
• Glycone---- (OH + H)---S—Aglycone……… S-Glycoside
• Glycone---- S—Aglycone + H2O
• —SH HO—C6H11O5 ——> S—C6H11O5….. S-Glycoside
• such as: Sinigrin, obtained from
• black mustard seeds.
• (i.e., Brassica campestris Family: Cruciferae)

7. 1.3 N-Glycosides
• The N-glycosides may be represented as shown below:
• Glycone---- (OH + H)---N—Aglycone……… N-Glycoside
• Glycone---- N—Aglycone + H2O
• =N—H HO—C6H11O5 ——> =N—C6H11O5 N-Glycoside
• The most typical example of N-glycosides is the
nucleosides, wherein the respective amino group of the base
ultimately reacts with —OH group ribose/deoxyribose.
• Examples: Adenosine: It is widely distributed in
nature e.g.; from yeast nucleic acid.
• 1.4 C-Glycosides
• The C-glycosides may be designated as shown under:
• Glycone---- (OH + H)---C—Aglycone……… C-Glycoside
• Glycone---- C—Aglycone + H2O
• CH HO—C6H11O5 ——> C—C6H11O5 C-Glycoside
• C-Glycosides are present in a variety of plant substances,
such as: aloin in Aloe; cascaroside in Cascara.
• E.g. Aloin or Barbaloin:

8. Physical Characters:
 Solids either amorphous or crystalline.
 Non volatile.
 Usually bitter in taste.
 Soluble in water and polar organic solvents.
 Reduce Fehling’s solutions only after hydrolysis.

9. Properties:
 Glycosides are usually soluble in water and in polar
organic solvents, where as aglycone are normally
insoluble or only slightly soluble in water.
 It is often very difficult to isolate intact glycosides
because of their polar character.
 Many important drugs are glycosides and their
pharmacological effects are largely determined by the
structure of the aglycone.

10. Extraction and Isolation
 Because of the wide range of physical and chemical properties of glycosides and
other constituents associated with them, no common general method for their
isolation is recommended.
 Water, methanol, water-ethanol and ethanol are the most common solvents for
extraction of glycosides.
 Precautions before extraction
 Deactivation of enzymes:
 Drying for 15-30 min at 100 oC followed by slow drying at a low temperature.
 Dipping the fresh material into boiling water or boiling alcohol for 10-20 min.
 Boiling the fresh plant material with acetone.
 Carrying out the extraction at very low temp.
 Freeze-drying of the plant material before extraction (lyophilization).
 Carrying the extraction in the presence of (NH4)2SO4.

11. Classification:
• According to chemical nature of aglycone part/ therapeutic activity exhibited
by the same
1. Anthraquinone / anthracene Glycosides- Senna, Aloe, Rhubarb, Cascara
2. Cardiac / sterols Glycosides- Digitalis, Squill, Strophanthus, Quabain
3. Saponin Glycosides- Dioscorea, Shatavari, Brahmi, Ginseng,
4. Cynogenetic / cynophoretic Glycosides- Bitter almond, wild cherry bark
5. Isothiocynate Glycosides- Mustard (black)
6. Flavonoids / flavonol Glycosides- Silymarin, Gingko, Citrus fruits
7. Coumarins and Furanocoumarin Glycosides- Visnaga, Psoralea
8. Aldehyde Glycosides-Vanilla, Anantmul
9. Phenol Glycosides- Bearberry
10. Steroidal Glycosides-Solanum
11. Bitter Glycosidal / miscellaneous Glycosides- Gentain, Chirata, Quassia, Kalmegh, Guduchi

12. • Atom from the aglycone involved in the glycosidic linkage:
• Aglycone- O- Sugar O-glycosides
• Aglycone- C- Sugar C-glycosides
• Aglycone- S- Sugar S-glycosides
• Aglycone- N- Sugar N-glycosides
• Number of sugars:
• One sugar monosides e.g. Salicin.
• Two sugar Biosides e.g. Diosmin.
• Three sugars Triosides e.g. Digoxin.
• Nature of the glycoside:
• Primary glycosides: Originally present in the plant e.g. Purpurea A
• Secondary glycosides: Resulted from removal of one sugar from the
primary glycosides e.g. Digitoxin
Classification:

13. • Type of the glycosidic linkage:
• - glycosides
• - glycosides
• Botanical source:
• Digitalis glycosides
• Senna glycosides.
• Therapeutic use:
• Analgesic glycosides.
• Purgative glycosides.
• Cardiac glycosides.
• Chemical nature of the aglycone:
• Flavone glycosides.
• Steroidal glycosides.
• Aldehydic glycosides.
• Etc…….

14. According to chemical nature of aglycone part/ therapeutic
activity exhibited by the same
1.Anthraquinone / anthracene Glycosides-
Example: Senna, Aloe, Rhubarb, Cascara
Major class of glycosides. Present mainly in Dicot plants.
These group having aglycone moieties like anthraquinone,
anthrone, dianthrone, anthronol, dianthronol. Oxanthronol.

16. Anthraquinone Glycosides

17. • 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

18. Anthraquinones –
Chemical Properties
• Anthraquinone derivatives: orange-red compounds
• Soluble in hot water/dilute alcohol.
• Identified via Borntrager’s test
1. Powdered drug – extrcted with ether
2. Filter
3. Made alkaline by adding ammonia/caustic soda
4. Shake  Aqueous layer shows pink, red or violet colour –
positive for anthraquinone derivatives
– If the Anthraquinones are reduced (within the herb) or
stable (glycosides) test will be negative

19. Senna
• Indian Senna • Alexandrian Senna

20. Senna
 Synonym: Senna Leaf;
Sennae folium; Senna-ki-patti
 Biological Source: It Consists
of the dried leaflets of Cassia
angustifolia (Tinnevelly
senna, / Indian Senna ) or
Cassia acutifolia (Alexandrian
senna / Egyption)
 Family: Leguminosae

21. Senna - Constituents
• 2 Active glycosides: Sennoside A
Sennoside B
– Both hydrolyse: 2 molecules glucose + aglycones:
Sennidin A and Sennidin B.
• Sennoside C & Sennoside D
• Rhein
• Aloe-emodin
• Palmidin A (Rhubarb)
Chemical Test: Borntrager’s Test positive due to anthaquinone
in leaves.

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

24. Senna - Additional
• 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.
 Overdose: nausea, bloody
diarrhoea, vomiting and nephritis.
 Long-term use: dehydration &
electrolyte depletion, worsening
constipation and weakening
intestinal muscles.

25. Rhubarb
 Synonym: Radix rhei; Rheum; Revandchini
 Bio. Source: It consist of the dried rhizome of
Rheum emodi Wall (Indian rhubarb) , Rheum
palmatum Linn(Chinese rhubarb).
 Family: - Polygonaceae
 Geographical Source: Kashmir, Sikkim, China,
Tibet, Korea etc.
 Collection and Preparation: It collected from
rhizomes 6-10 year old plants. Allow to dry and
decorticated , cut longitudinally – transversely.
 Macroscopy: Small pieces from rhizome 8-
10cm length, 4cm thickness, yellow, brown
colour observed.

26. Rhubarb – Chemical Constituents
1. Anthraquinones without a carboxyl
group – chrysophanol, emodin,
aloe-emodin & physcion.
2. Anthraquinones with a carboxyl
group
(rhein and its glycoside: glucorhein).
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.
Chemical Tests
1. The Rhubarb powder on being treated with ammonia gives rise to a pink colouration.
2. Rhubarb gives a blood-red colouration with 5% potassium hydroxide.
3. It gives a positive indication with modified Borntrager’s test (see under Aloes).

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

28. Rhubarb - Additional
• Etymology
– Rheo – Greek, ‘to flow’,
in reference to the
purgative properties.
• Medicinal Actions
– Anti-helminthic, anti-
bacterial, anti-
inflammatory, antiseptic.
• Topical Uses:
– Poultice to treat boils,
burns, wounds. Used to
stop bleeding (tannins –
stypic and astringent).
Used as a mouthwash
for oral ulcers.
• Caution
– Leaves should be
avoided – high calcium
oxalate - toxic

29. Aloes

30. 1. Aloes:
• Synonym: Aloe, Musabbar, Kumari
• Biological Source: Aloe is the dried latex of leaves of various species of Aloes, namely:
 Aloe barbadensis Miller (or Curacao Aloe);
 Aloe ferox Miller (or Cape Aloe);
 Aloe perryi Baker (or Socotrine Aloe);
 Aloe africana Miller and Aloe spicata Baker (or Cape Aloe).
 All these species belong to the family Liliaceae.
• Geographical Source
 Curacao, Barbados, Aruba : Curacao Aloes or Barbados Aloes and Bonaire (West Indian Islands)
 Cape Town (South Africa) : Cape Aloes
 Socotra and Zanzibar Islands : Socotrine or Zanzibar Aloes
 It is also cultivated in Europe and the North West Himmalayan region in India.
Aloes

31. Preparation of Cape Aloes
 Cape Aloes are prepared from the wild plants of Aloe ferox.
 Leaves are cut transversely near the base.
 200 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 and Boiled for 4hrs on an open fire.
 Poured into tins while hot  solidifies.

32. Collection & Preparation of Cape Aloes

33. Aloes - Constituents
C-glycosides
Resins
Glycosides
Aloin
Barbaloin
Isobarbaloin
Aloe-emodin
Cape Aloes:
Aloinoside A &
Aloinoside B (O-
glycosides of
barbaloin)

34. 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
HLC - Modified Borntrager’s Test – oxidative
hydrolysis. .........Anthraquinones give a red colour
when shaken with dilute ammonia.
 All Aloes give a strong green fluorescence/ rose-
pink with borax (characteristic of anthranols) -
General test for aloes.

35. General test Type Observation
Bromine test
1gm sub powder + Δ boil in 10 ml water+Bromine sol
-- Pale Yellow ppt.
Schoenteten’s Reaction(Borax test)
1gm sub powder+ Δ in 10 ml water+borax---Dilute with
water
-- Green fluroscence
Special Test Type Observation/ Colour
1. Nitrous acid Test:
Sodium nitrite + Acetic acid in aq. Solution of
aloes
Curacao Dark Pink
Cape Faint Pink
Socotrine ,
Zinzibar
No Change
2. Nitric acid Test:
Drop of Nitric acid + Aq. Sol. Of aloes
Curacao Brown
Cape Brown---=----Green
Socotrine Brownish yellow
Zinzibar Yellowish brown
3. Cupraloin Test {Klunege’s isobarbaloin test}
Aq. Sol. Of aloe +CuSO4+NaCl+90%Alcohol
Curacao ---
Cape ----
Wine Red
Yellow Colour
Aloe Chemical Tests:

36. 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.

37. Aloe – Additional Notes
• 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
– reduce sweating and mask
scent.
– Used to break nail-biting
habit.

38. 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

39. Cascara

40. Other points