PHARMACOGNOSY I (6)
Outline of Flavonoid Glycosides Course
1. Introduction to Flavonoid Glycosides
Course: Pharmacognosy I (PHAR301)
Lecturer: Dr. Beste Atli
Focus: Flavonoid Glycosides
2. General Characteristics of Flavonoids
Solubility:
Water and water-alcohol mixtures: soluble
Organic solvents: not soluble
Aglycones: soluble in non-polar solvents
Crystallization:
Often crystallized compounds
Yellow solution in alkaline medium; color disappears upon adding acid
3. Extraction of Flavonoids
Methods:
Different methods for flavonoids and glycosides present
Extraction Solvents:
Acetone, ethanol, or methanol combined with water
Liquid-Liquid Extraction:
Petroleum Ether: extracts chlorophyll/pigments
Diethyl Ether or CHCl3: targets aglycones
EtOAc: extracts glycosides
4. Concentrated Extraction Process
Overview:
Use concentrated acetone-, ethanol-, or methanol-aqueous extracts
Final Products:
Chloroform fraction: contains free flavonoids
EtOAc fraction: contains glycosides
Very polar glycosides and saccharides in residue
5. Extracting Various Flavonoids
Key Classes:
Isoflavones, Flavanones: use chloroform, ether, ethyl acetate
Flavones, Flavonols: extracted with acetone, alcohol, and water mixtures
Other compounds: biflavonoids, aurones, chalcones, flavondiols, catechol, procyanidols
6. Chromatographic Techniques for Separation
Techniques:
Polyamide, Sephadex, silica gel, and alumina
High-Performance Liquid Chromatography (HPLC)
7. Determination Reactions of Glycosides
Observations:
Chromatography exhibits fluorescence under UV light
Alkaline medium: yellow color
Aurones and chalcones visible with ammonia vapors: orange/red colors