GLYCOSIDES - Jiwaji University
Transcript of GLYCOSIDES - Jiwaji University
GlycosidesIntroduction & Classification
By
Dr. Mukul TailangProfessor
School of Studies in Pharmaceutical Sciences
Jiwaji University
Gwalior (M.P.)
GLYCOSIDESGlycosides are the molecules in which a sugar
part is bound to some other non-sugar part. Glycosides play numerous important roles in
living organisms. Plants store important chemicals in the form
of inactive glycosides; if these chemicals are needed, the glycosides are brought in contact with water and an enzyme and the sugar part is broken off, making the chemical available for use. Many such plant glycosides are used as
medications.
GLYCOSIDESFormally, a glycoside is any molecule in
which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond.
The sugar group is known as the Glyconeand the non-sugar group as the Aglyconeor Genin part of the glycoside.
The glycone can consist of : ◦ Single sugar group (Monosaccharide) or
◦ Several sugar groups (Oligosaccharide).
Glycosidal Sugars:Sugars found in glycosides may be
• Monosaccharides
–Glucose
–Rhamnose
– Fructose
• Deoxysugars (more rare)
–Cymarose
• found in the cardiac glycosides
TERMS USED TO DESCRIBE GLYCOSIDES
A Glycoside is a
• Glucoside –Has glucose as the sugar component
• Pentoside –Has a sugar such as arabinose
• Rhamnosides–Contains rhamnose
• Rhanmoglucosides–Contains both rhamnose and glucose
Glycosidic bond
• A glycosidic bond is a certain type of a functional group that joins alcoholic group of a Carbohydrate molecule to an aglycone molecule.
• A substance containing a glycosidic bond is a Glycoside.
Glycosidic bond
Classification of GlycosidesGlycosides can be classified by :
• The nature of Glycone
• Number of sugars
• Nature of the glycoside
• Botanical source
• Therapeutic use
• The type of Glycosidic Bond
• The Glycosidal Linkage and
• Chemical nature of Aglycone.
By Glycones• If the glycone group of a glycoside is
glucose, then the molecule is a Glucoside.
• If it is fructose, then the molecule is a Fructoside.
• If it is glucuronic acid, then the molecule is a Glucuronide.
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
•Botanical source:•Digitalis glycosides
•Senna glycosides.
•Therapeutic use:•Analgesic glycosides.
•Purgative glycosides.
•Cardiac glycosides.
Classifications of glycosides according to their therapeutic effects
CHF and cardiac muscles stimulators: • Digitalis glycosides: digoxin, digitoxin,
gitoxin (Fox glove leaves)
• Ouabain: Strophanthus gratus seeds
• K-strophanthin -Strophanthus kombe seeds
• Scillaren A,B which isolated from red and white Squill bulbs
• Convolloside: Convallaria majalis – Lily of the Valley.
Laxative group of glycosides:
– Sennoside A,B,C,D (Senna leaves and fruits)
– Cascaroside A,B (Cascara bark)
– Frangulin and glucofrangulin (Frangula bark)
– Aloin and barbaloin (Aloe vera and A. barbadensis)
Local irritant group:
– Sinigrin (Black mustered seeds_Brassica nigra)
– Sinalbin (White mustered seeds_Brasica alba)
Analgesics and antipyretics:
– Salicin Salisylic acid (Willow or Salix bark)
Keeping elasticity of blood vessels like:
– Rutin, Rutoside (Bitter orange peels, Lemon peels)
Anti-inflammatory group:
– Aloin for acne &
– Glycyrrhizinin the treatment of peptic ulcer
hydrolysis
By type of glycosidic bondDepending on whether the glycosidic bond lies "above" or "below" the plane of the cyclic sugar molecule, glycosides are classified as:
»α-glycosides
»β-glycosides
α- & β-glycosides
OH
H OH
OH H
H OH
H
H
O
O CH3
OH
H OH
OH H
H OH
H
O
HH3CO
O
CH2OH
H
H
OH
OH
HH
OH HO CH
3
O
CH2OH
H
H
OH
OH
H
OH HH
O CH3
methyl glucoside methyl glucoside
methyl glucoside methyl glucoside
By Linkage
- O - C6H
11O
5- O - H H - O - C6H
11O
5+O - Glycoside
C - H C - C6H
11O
5H - O - C
6H
11O
5+C - Glycoside
N - H N - C6H
11O
5H - O - C
6H
11O
5+N - Glycoside
- S - H - S - C6H
11O
5H - O - C6H
11O
5+S - Glycoside
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
O,C,S & N – GLYCOSIDES
CH2 = CH - CH
2 - C = N - O - SO
3K
S - Glucose
OO OH
R1
R2
OHO O
C6H
11O
5.
C6H
11O
5.
OH OH
CH2OH
O
O
CH2OH
H
H
OH
OH
H
OH HH
O
H
H
OH
H
OH
H
OH
N
N
N
N
NH2
Sinigrin
10
10'
Barbaloin
(S - Glycoside)
Sennoside
(O - Glycoside)(C - Glycoside)
Adenosine
(N - Glycoside)
By aglycone Glycosides are also classified according to the chemical nature of the aglycone.
For purposes of biochemistry and pharmacology, this is the most useful classification.
»Anthraquinone glycosides
»Simple phenolic glycoside
»Thioglycosides
»Flavonoid glycosides
»Steroidal glycosides or cardiac glycosides.
»Saponins
»Coumarin glycosides
»Cyanogenic glycosides
Anthraquinone glycosidesO
O
OH
O
H H
O
H OH
O
O
OH OH
O
O
OH OH
CH3
OH
O
O
OH OH
CH2OH
O
O
OH
OH
OOH OH
CH3
OH
O
CH3
OH
OH OH
OOH OH
O
CH3
OH OH
OH OHO
O
COOH
O
O
OH OH
CH3
OH
A B C
(I) Anthraquinone (II) Anthranol
(III) Anthrone (IV) Oxyanthrone Fizacine
Emodine Aloe emodine Alizarine
EmodindianthronRizofanoldianthron
Rhein
Frangula emodine
Simple phenolic glycosideO OMe
O CH2CH
2 OHO
CH2OH
O
OH
COOH
OO
CH2OH
H
H
OH
OH
H
OH HH
O
CH2OH
H
H
OH
OH
H
OH HH
O
CH2OH
H
H
OH
OH
H
OH HH
O
CH2OH
H
H
OH
OH
H
OH HH
O
CH2OH
H
H
OH
OH
H
OH HH
Methyl arbutin
SalidrozineSalicine
Glycoside of Salysilic acid
Arbutin
Thioglycosides
CH2 = CH - CH
2 - C = N - O - SO
3K
S - Glucose
O
MeO
MeO
O5H
11C
6 - S : N - H
2C CH : CH . CO
OCH2.CH
2.N(CH
3)3.H
2SO
4
Sinigrin
+
Sinalbin
Flavonoid glycosidesO
O
O
O
O
OH
O
O
OH
O
O
O
O
O
OH
OH
OHOH
R
R'
O
OH
O
O
O
CH
O
O
OH
OH
Glucose - O
Rhamnose
O
OH
OH
O
O - Glucose - Rhamnose
OH
OH
O
OH
OH
OHOH
OH
H
Flavone
Flavan
Flavanol
Flavanone Flavanonol
+
Anthocyanidine
Chalcone
Catechine
Aurones
Pelargonidine - R=H, R'=H
Cynadine - R=OH, R'=H
Naringin
Rutin
+
Cynadine
Steroidal glycosides or cardiac glycosides
CH3
OH
OHH
H
H
H
OH
OH
O O
HO
O
O O
CH3
OH
OHH
H
H
HOH
O O
CH3
OH
OHH
H
H
HO-C-H
O O
O
CH3
OH
OHH
H
H
H
O O
Digitoxigenin
C
Strophanthidin
H-C-H
OH
OH
OH
HO
Gellebrigenol
Gitoxigenin
Gitaloxigenin
Digitoxigenin
Saponins
OH
O
O
OH
O
O
O
OHOH
OH
O
DiosgeninHecogenin
-amyrin -amyrin
Lupeol
Damaran
Coumarin glycosides
O O
Coumarin
Cyanogenic glycosides
O
CH2OH
H
H
OH
H
H
OH H
O
CH2
H
H
OH
OH
H
OH H
CH(CN)
C
CH3
O-C6H
11O
5
CNCH3
O
O
Amygdalin
Linamarin