Glycosides and Glycoside Containing Drugs - Md. Ahad Ali...
Transcript of Glycosides and Glycoside Containing Drugs - Md. Ahad Ali...
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)