Glycosides
•
Definition:
Organic natural compounds present in a lot of
plants and some animals, these compounds upon
hydrolysis give one or more sugars (glycone)
β_form and non sugar (aglycone) or called genin.
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Solubility:
glycosides are water soluble compounds
and insoluble in the organic solvents.
Glycone part: water soluble, insoluble in
the organic solvents.
Aglycone part: water insoluble, soluble in
the organic solvents.
Some glycosides soluble in alcohol.
Separation between glycosides parts:
Glycosides glycone +aglycone +HCL
G + A +salt+H2O

(H2O+G)+A (H2O+G)+(chloroform+A)
We can separate them by using separatory
funnel
The best solvent to extract aglycone is Ethyl
acetate because:
A- immiscible in water.
B- always presents in the upper layer.
Neutralization by
Using alkaline
Filtration
chloroform

a- Emolsin Bitter almond seeds.
b- Myrosin or Myrosinase black mustard
seeds.
c- Rhamnase glycosides containing rhamnose
as sugar part.
Biosynthesis of glycosides
(O-glycosides)
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UTP(Uridine Triphoshate) +sugar-1-phoshate
UDP-sugar + ppi(Pyrophosphate inorganic).
•
UDP-sugar +acceptor (aglycone)
Acceptor-sugar +UDP
Uridylyl transferase
Enzyme
Glycosyl transferase
Enzyme
Glycosyl transferase
Enzyme
The function or the role of
glycosides in the plant organism
•
Converting toxic materials to non or less
toxic.
•
Transfer water insoluble substances by
using monosaccharide.
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Source of energy (sugar reservoir).
•

Squill bulbs.
e- Convolloside:Convallaria majalis – Lily of the
Valley.
Cont…
•
Laxative group of glycosides:
a- Sennoside A,B,C,D (Senna leaves and
fruits).
b- Cascaroside A,B (Cascara bark).
c- Frangulin and glucofrangulin(Frangula
bark).
d- Aloin and barbaloin (Aloe vera and Aloe
barbadensis juice).
Cont…
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Local irritant group:
a-Sinigrin(Black mustered seeds_Brassica nigra)
b-Sinalbin(White mustered seeds_Brasica alba)
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Analgesics and antipyretics:
Salicin Salisylic acid - Willow or Salix bark.
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Keeping elasticity of blood vessels like:
Rutin_Rutoside (Bitter orange peels, Lemon peels)
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Anti-inflammatory group:
a- Aloin for 1)acne 2)peptic ulcer
b-Glycyrrhizin
hydrolysis
Classification of glycosides

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C-glycosides : in these glycosides the sugar
linked (condensed) directly to Carbon atom of
aglycone like in aloin.
N.B C-glycosides are not hydrolyzed by acids or alkalis or by
enzymes mainly .
Classification of glycosides according to a glycone part :
1- if a glycone part alcohol -this group called alcoholic group like Salicin
2- if a glycone part aldehyde- this group called aldehydic gr. like
glucovanillin.
3- if phenol called phenolic group like arbutin .
4-if cyanone called cyanogenic or cyanophoric or cyanoside like
amygdalin.
5-if thio called glycosides or isothiocyanate glycoside like sinigrin or
sinalbin (-S=C=N-) (SCN)
6-anthracene > anthraquinone glycoside –sennoside
7-steroid  steroidal glycoside (cardiac) Digoxin
8-flavone ,flavonol, flavanone –flavonoid glycoside
9-triterpenoid –saponin glycoside –glycyrrhizin ,melanthin (nigella
seeds) or ginsenoside .

Most of glycoside may be named according to the plant from which they isolated
for example:
1-salicin –salix-
2-cascaroside _cascara
3-aloin- Aloe vera
4- sennoside – senna-
5-frangulin – frangula
6- glycyrrhizin – glycyrrhiza
And others.

Sweet taste : solution in H2O bitter taste insoluble in H2O
expectorant anti-inflammatory

Ginseng roots
Panax roots
Panax quinquefolius ,panax ginseng -contains saponin glycoside –
ginsenoside ( panaxoside)
Triterpenoid + steroidal nucleus
Ginseng root uses : 1- stimulant 2- Tonic 3- anti-stress
4-adaptogenic agent .
Drugs :
1- geriatric pharmaton
2- gerimax
3- polyvit
Anthraquinone group of
glycosides
1. They are anthracene derivatives (anthracene = is
the main nucleus for anthraquinone compounds.
2. In the plant they biosynthesized from acetyl-CoA
and malonyl-CoA.
3. They have cathartic property (laxatives and
purgative but some of them have anti-
inflammatory activity.
4. With hydrolysis they give aglycone part which is
di,tri or tetra hydroxy anthracene derivatives.
5. They hydrolyzed only by acids or by enzymes, but
not hydrolyzed by alkalines.
6.They have orange or red color (most of them)
7.Soluble in water, insoluble in the organic solvents.
8. They have bitter taste and slightly characteristic