Glycosides & its Identification Tests

• Glycosides & its Identification Tests involve detecting sugar-linked compounds with therapeutic significance.
• Glycosides & its Identification Tests include Keller–Killiani, Borntrager’s, and Legal’s test for confirmation.

Definition

• Glycosides are compounds that consist of a sugar (glycone) and a non-sugar (aglycone or genin) part, linked by a glycosidic bond.

Examples

• Cardiac glycosides (e.g., Digoxin from Digitalis purpurea)
• Anthraquinone glycosides (e.g., Senna from Cassia angustifolia)
• Saponin glycosides (e.g., Diosgenin from Dioscorea species)

Properties of Glycosides & its Identification Test

• Bitter or astringent taste.
• Some glycosides are water-soluble.
• Hydrolyzed by acids or enzymes into sugar and aglycone.

Tests for Identification:

1. Keller-Killiani Test (for Cardiac Glycosides):

   • Reagent: Ferric chloride and concentrated sulfuric acid.
   • Positive Result: Reddish-brown ring at the interface.

2. Borntrager’s Test (for Anthraquinone Glycosides):

   • Reagent: Ammonia or sodium hydroxide.
   • Positive Result: Pink to red color in the alkaline layer.

3. Foam Test (for Saponin Glycosides):

   • Shake the extract with water.
   • Positive Result: Persistent frothing indicates saponins.

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