FATHIMA INSTITUTE OF PHARMACY
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PHARMACOGNOSY II K. Bharath (B.Pharm)

Glycosides:

 Glycosides are organic compounds of plant and animal sources.
 Glycosides give sugar and non sugar moieties, on hydrolysis.
 Sugar moiety is called glycon and non sugar moiety is aglycone.
 Glycosides are acetals/sugar ethers formed by the interaction of hydroxyl groups of sugar and non sugar moiety, by loosing water molecule.
 β-D-glucose is involved in the glycosides.
 The sugars are galactose, mannose, rhamnose, digitoxose,cymarose etc.
 The linkage between glycone and aglycone is called glycosidic linkage.
 Based in this, glycosides are classified into α and β glycosides.

Classification of glycosides is done based on three things

o Chemical nature of aglycone part.
o
o Therapeutic activity of aglycone part.
o
o Linkage between glycone and aglycone part.




According to chemical nature of aglycone moiety:



Therapeutic activity:
i. Cathartics
ii. Cerbiotonics
iii. Analgesics
iv. Anti-rheumatics
v. Anti-ulcer
Linkage across glycone and aglycone part:
Actually link is between ’OH’ group of glycone and radicals like CH, -OH, -SH, and –NH of aglycone part by removing water molecule.
If CH is taken as radical for aglycone part then it is
C-glycoside
OHO-glycoside
NHN-glycoside
SHS-glycoside

C-glycosides:
Glycone –OH+HC-aglyconeglycone-C—aglycone+water
Ex: Aloe(Liliaceae), cascara
O-glycoside:
Glycone-OH+HO-aglyconeglycone-O-aglycone+water
Ex: Senna, rhubarb frangula etc,.
S-glycoside:
Glycone-OH+HS-aglyconeglycone-S-aglycone+water
Ex: Isothiocyanate glycosides
N-glycoside:
Glycone-OH+HN-glyconeglycone-N-glycone+water
Ex: Nucleosides
●Expect resin glycosides all the glycosides are soluble in water and dilute alcohol & insoluble in chloroform or Ether but aglycone moiety is soluble in chloroform & Ether

SAPONIN GLYCOSIDES
Saponin:
 These are the glycosides which give foam on shaking with NaHCO3.
 The saponin glycosides have soap like action.
 They are called haemotoxic because they cause haemolysis of erythrocytes(Red blood cells).Because of this, these are used as fish poisons.
 They cause irritation of Mucous membrane.
 Soluble in water and alcohol, but insoluble in non-polar organic solvents.
 The aglycone part is called sapogenin. Depending on the nature and structures they are divided into two groups
1. Steroidal saponins[Tetracyclic triterpenoid]
2. Pentacyclic Triterpenoid saponins



The following are the drugs containing saponin glycosides
i. Glycyrrhiza
ii. Ginseng
iii. Discorea
iv. Sarasaparilla
v. Senega



1.DIOSCOREA

Synonyms:Yam, Rheumatism root.

Biologcal Source:
It consists of dried tubers of plants, Dioscorea deltoidea, D.composita,and other species of Dioscorea, family Dioscoreaceae.

Geographical Source:
Found in North Western Himalayas upto an altitude of 1000-3000m,and also in Jammu and Kashmir,Himachal Pradesh.



CULTIVATION AND COLLECTON:
Mainly grown in TamilNadu, West Bengal, Maharashtra,Karnataka and Jammu and Kashmir.
 As raising the crop from seeds has disadvantages like longer time and variability in progeny(off spring),healthy tubers of about 70-80 gm in weight are selected for cultivation.
 They are sown in nursery beds after treating with fungicide
 It takes 30-40 days for their sprouting .
 After 3-4 months they are transplanted in field .
 They are placed at a distance of 30x60 cm.
 Trellis(support for climbing trees) are used.
 Inter-cropping with legumes can be done
 Diosgenin content is found to be high as well as rhizomes lose about 50% of their weight on drying.

MICROSCOPIC STRUCTURES:

Colour: slightly brown.
Odour: odourless.
Taste: bitter.
Size: varies dipending on sizes rhizomes.

MACROSCOPIC CHARACTERS:

Epidermis:Absent in transverse section of drug.
Cork: Few layers followed by parenchymatous.
Stele:Major part of drug and consists of close Collateral fibro-vascular bundles.
Endodermis and pericycle is indistinguishable.



CHEMICAL CONSTITUENTS :

Rhizome contain 75% of starch.It contains diosgenin ,steroidal sapogenin(4-6%), its glycosides , smilagenin and epismilagenin and β-isomer yammogenin.
Rhizomes also contain sapogenase.Diosgenin is the hydrolytic product of saponin dioscin.

USES:
Used in synthesis of corticosteroids , sex harmones , oral contraceptives and used in treatment of rheumatic arthritis(inflammation and deformation of bone), asthma, eczema.
Isolation:
Hydrolysis of dioscin is done by mineral acids.Diosgenin is liberated and extracted with the help of non polar solvents like benzene or solvent ether.
Diosgenin is degraded to 16-dehydro pregnenelone acetate.This is used for synthesis of
a. Corticosteroids like cortisone, hydrocortisone, prednisolone
b. Pregnenes like progesterone, 17-α-hydroxy progesterone
c. Androstanes like testosterone. Methyl testosterone, etc,and
d. 19-NOR steroids like estrone, 17- α-ehynyl estradiol and norethisterone acetate.
The above steps are done by microbial transformations.