Drug containing Glycosides

Learning Objectives

Define and classify glycosides.
List general properties of glycosides.
Identify crude drugs containing glycosides along with their biological sources, main chemical constituents, and uses.

Glycosides: Compounds that yield one or more sugars upon hydrolysis.
- Composed of two moieties:
  - Glycone: Sugar portion.
  - Aglycone (or Genin): Non-sugar portion.

Extensive presence in the plant kingdom, often formed from phenols, steroids, or terpenoidal alcohols.
D-glucose is the most prevalent sugar, with others like L-rhamnose and D-fructose occurring frequently.
Sugar moiety can be linked to aglycone in various ways:
- O-glycoside: via oxygen.
- C-glycoside: via carbon.
- N-glycoside: via nitrogen.
- S-glycoside: via sulfur.
Important pharmaceutically and medicinally due to aglycone and/or sugar structure.

Appear as solids (amorphous or crystalline), non-volatile, often bitter in taste.
Soluble in water and polar organic solvents.
Can reduce Fehling’s solutions post-hydrolysis.

Involves:
- Destruction of hydrolyzing enzymes.
- De-fating or purification of plant material.
- Extraction, concentration, and purification steps.

Based on Sugar Component:
- Glucosides (glucose), fructosides (fructose), galactosides (galactose).
Based on Aglycone Structure:
- Includes anthraquinone, flavonoid, iridoid, lignan, and steroid glycosides.
Based on Properties or Functions:
- Saponins (soap-like properties), cyanogenic glycosides (liberate HCN), cardiac glycosides (affect heart muscle).

Keller-Kiliani Test: Identifies deoxy-sugars in cardiac glycosides via color change with concentrated sulfuric acid.
Borntrager’s Test: Identifies anthraquinone glycosides through color change after reaction with dilute sulfuric acid.
Cyanogenic glycosides can be tested using sodium picrate paper for HCN detection.
Liebermann’s Test: Used for identifying steroidal or cardiac glycosides.

Cardiac Drugs: e.g., digitalis glycosides for heart conditions.
Laxatives: e.g., anthraquinone glycosides from senna, aloes, cassara.
Counter Irritants and Analgesics: e.g., thioglycosides and methylsalicylate.
Anti-inflammatory and anticancer agents include glycyrrhizin and amygdalin.

Have anthraquinone skeleton, used primarily for laxative effects, short-term usage recommended.

Characterized by structural features affecting cardiac function, with sub-classes like cardenolides and bufadienolides.
Found in several plants indicating significant usage in medicine.

Form foams, good emulsifying agents, used in food and medicine but can be toxic when injected.

Liquorice (Glycyrrhiza glabra): Sweet triterpenoidal saponins, used in treating ulcers and inflammatory conditions.
Senna: Source of dianthrone glycosides, acts as a stimulant laxative.
Aloes: Known for purgative qualities with barbaloin as the active glycoside.
Hypericum (St John's Wort): Contains phenolic derivatives used as antidepressants.

Glycosides play a vital role in pharmacology and plant biochemistry, with diverse applications for their medicinal properties.