Glycosides and Glycoside

Containing Drugs

MD AHAD ALI KHAN

DEPARTMENT OF PHARMACY

SUB

Glycosides

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.

Aglycone and Glycone

Aglycone / non-sugar compound

After replacement of the glycosyl group from a

glycoside by a hydrogen atom

Methyl alcohol, glycerol, a sterol, a phenol, etc.

Glycones / Sugars

> Monosaccharides

Glucose, Rhamnose, Fructose

> Deoxysugars (more rare)

Cymarose

Those found in the cardiac glycosides

Physico-chemical properties of

glycosides(general)

1) Colorless, solid, amorphous, nonvolatile (flavonoid- yellow, anthraquinone-red or orange.

2) Give positive reaction with Molisch's and Fehling's solution test (after hydrolysis).

3) They are water soluble compounds, insoluble in 3) They are water soluble compounds, insoluble in organic solvents

4) Most of them have bitter taste (except: populin, glycyrrhizin, stevioside).

5) Odorless except saponin (glycyrrhizin).

6) When a glycosides has a lot of sugars its solubility in water decrease.

7) Glycosides hydrolyzed by using mineral acids and temperature or by using enzymes such as:

a- Emolsin Bitter almond seeds.b- Myrosin or Myrosinase black mustard b- Myrosin or Myrosinase black mustard

seeds.c- Rhamnase glycosides containing

rhamnose as sugar part.

Hydrolysis of Glycoside

Glycosides glycone +aglycone

+HCL G + A +salt+H2O

(H2O+G)+A

(H2O+G)+(chloroform+A)

We can separate them by using separating

Hydrolysis +HCL (dil)

Neutralization byUsing alkaline

Filtration chloroform

We can separate them by using separating

funnel

The best solvent to extract aglycone is Ethyl

acetate because:

-immiscible in water.

- always presents in the upper layer.

Biosynthesis of glycosides (O-

glycosides)

UTP(Uridine Triphoshate) +sugar-1-phoshate

UDP-sugar + ppi(Pyrophosphate inorganic).

Uridylyl transferase Enzyme

UDP-sugar + ppi(Pyrophosphate inorganic).

UDP-sugar +acceptor (aglycone)

Acceptor-sugar +UDP

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.

� Source of energy (sugar reservoir).� Source of energy (sugar reservoir).

� Storing harmful products such as phenol.

�Regulation for certain functions(growth).

� Some have beautiful colours(pollenationprocess).

Some glycosides have antibacterial activity, so

they protect the plants from bacteria and

diseases.

bacteria

Bitter almond Amygdalin

bacteria

HCNhydrolysis

kill

Eomlsin

enzyme

In Nature Glycosides are

formed by the

interaction of the

nucleotide of a sugar

group with the alcoholic

or Phenolic group of a

2nd compound.

EC 2.3.1.173: flavonol-3-O-

triglucoside O-

coumaroyltransferase

EC 2.4.1.239: flavonol-3-O-

glucoside glucosyltransferase

EC 2.4.1.240: flavonol-3-O-

diglycoside glucosyltransferase

Glycosides themselves do not reduce Fehling’s

solution, But the simple sugars they produce on

Glycosidal Reduction

solution, But the simple sugars they produce on

hydrolysis (aglycones) do (precipitate red cuprous

oxide)

Terms used to Describe GlycosidesA Glycoside is a

�Glucoside

�Has glucose as the sugar component

�Pentoside

�Has a sugar such as arabinose

Rhamnosides�Rhamnosides

�Contains rhamnose

�Rhanmoglucosides

�Contains both rhamnose and glucose

Terms used for Aglycones

Normally self-explantory

�E.g. Phenol

�Anthroquinone

�Sterol glycoside

Other Glycosidal TermsSaponin (soap-like)

Cyanogenic (producing hydrocyanic acid)

Cardiac (having an action on the heart)

Terms: Are used to group glycosides together

which have similar functions & chemical

structure.

GLYCOSIDE STRUCTURE

� 2 types of genin are distinguished

� Based on the structure of the lactone ring

� 5-membered ring � bufanolides or bufadienilolides

� E.g. scillarenin

� 6-membered ring � cardinolides or cardiac active

glycosides (medicinally more significant)