1. PHENOLIC GLYCOSIDES 1
ASSOC. PROF. DR. MOSTAFA MAHMOUD HEGAZY

2.  content
 Classification of Phenolic glycosides
 Arbutin
 Gaultherin (primary glycoside) and Monotropin (2ry glycoside)
 Salicin
 Populin
 Coniferin

3. Glycosides Dr. Mostafa Hegazy
Phenolic glycosides
They classified according to their chemical structure into:
1- Simple phenolic glycosides e.g. Arbutin.
2- Phenolic and ester glycosides e.g. Gaultherin and Monotropin.
3- Phenolic and alcoholic glycosides e.g. Salicin and Populin.
4- Anthracene glycosides e.g. Sennosides.
5- Flavonoid glycosides e.g. Rutin and Hesperidin.
6- Coumarin glycosides e.g. Aesculin and Daphnetin.

4. Glycosides Dr. Mostafa Hegazy
1- Simple phenolic glycosides
• Arbutin (Hydroquinone glucoside)
• It occurs in the dried leaves of Bearberry (Uva ursi) (Ericaceae).
• Acid or enzymatic (emulsin) hydrolysis yields hydroquinone
and β-D-glucose
• Chemical tests
• Arbutin+ FeCl3  Blue color.
• Arbutin + HCl / heat  crystals of hydroquinone.
• Uses: Skin whitening creams, diuretic and urinary antiseptic.

5. Glycosides Dr. Mostafa Hegazy
Arbutin (Hydroquinone glucoside)
Uses:
1- As ingredient of pharmaceutical and
cosmetic skin whitening creams
2- As diuretic and urinary antiseptic.

6. Glycosides Dr. Mostafa Hegazy
2- Phenolic and ester glycosides
• Gaultherin (primary glycoside) and Monotropin (2ry
glycoside)
• They occur in Gaultheria procumbens (Wintergreen) and
Monotropa and Betula spp.
• Hydrolysis
• Hydrolysis of gaultherin or monotropin by the aid of acid or
gaultherase enzyme yields:
• The volatile aglycone, methyl salicylate or oil of
wintergreen
• The sugar part is the disaccharide primeverose in case of
gaultherin and glucose in case of monotropin.

7. Glycosides Dr. Mostafa Hegazy
Uses
The glycosides and their aglycone are used as
antipyretic, analgesic and anti-rheumatic.

8. Glycosides Dr. Mostafa Hegazy
3- Phenolic and alcoholic glycosides
Salicin (O-Hydroxybenzyl glucoside)
Salicin found in willow barks e.g. Salix fragilis
and Salix alba (White Willow) salicin content
ranged from 0.08 to 12.6%, and in Populus
spp.
Properties: It occurs as bitter crystals,
sparingly soluble in cold water.

9. Glycosides Dr. Mostafa Hegazy
Hydrolysis:
1- Enzymatic or mild acid hydrolyses
yield saligenin and glucose.
2- On heating for a long time in
presence of HCl, two molecules of
saligenin combine together
(dehydration) to give a water insoluble
compound called saliretin.

10. Glycosides Dr. Mostafa Hegazy
• Extract with hot water and filter.
• Add lead acetate solution to the filtrate (to precipitate tannins) and
mix well.
• Filter, pass H2S gas in the filtrate (to remove excess lead) then filter.
• Neutralize the filtrate with ammonia and concentrate.
• Cool to collect salicin crystals
Isolation from Salix (willow) bark

11. Glycosides Dr. Mostafa Hegazy
• Salicin+ conc. H2SO4  red color + H2O  disappearance of red
color.
• Salicin+ Froehd’s  violet color.
• Salicin+ Mandalin’s purple color.
• Salicin+ Erdman’s  red color.
• Salicin+ K2Cr4O7 + dilute H2SO4  odor of salicylaldehyde.
Chemical tests

12. Glycosides Dr. Mostafa Hegazy
• Uses: Low back pain, headache
and Osteoarthritis as analgesic,
antipyretic and anti-
inflammatory.
• Dosage: Standardized willow
extract providing 120-240 mg
salicin per day in divided doses
(250 mg white willow bark extract
contains 15% salicin)

13. Glycosides Dr. Mostafa Hegazy
POPULIN
• Populin (6'-Benzoyl salicin)
• Occurrence It is a sweet glycoside isolated from
Populus tremula.
• Chemical tests:
• Populin + Froehd’s reagent  violet color.

14. Glycosides Dr. Mostafa Hegazy
HYDROLYSIS OF POPULIN

15. Glycosides Dr. Mostafa Hegazy
SYNTHESIS OF POPULIN
• It can be obtained from salicin by treatment with benzoyl
chloride in alkaline medium
• Uses
• It is used as analgesic, antipyretic and anti-inflammatory.

16. Glycosides Dr. Mostafa Hegazy
CONIFERIN
• Coniferin (m-methoxy, p-hydroxy cinnamyl alcohol glucoside)
• It is found in the cambium tissues of pine trees and lignified tissues
of beet root.

17. Glycosides Dr. Mostafa Hegazy
CHEMICAL TESTS
• Coniferin+ concentrated HCl  blue color.
• Coniferin+ concentrated H2SO4  red color.
• Uses
• Coniferin and coniferyl alcohol were extensively used as starting
material for semi-synthesis of vanillin

18. Glycosides Dr. Mostafa Hegazy
SEMI-SYNTHESIS OF VANILLIN
• Semi-synthesis of vanillin: