This document discusses glycosides, which are condensation products of sugars and organic hydroxy compounds. Glycosides are non-reducing, non-carbohydrate substances found widely in plants. They are colorless and crystalline, and soluble in both water and alcohol. Glycosides can be hydrolyzed to separate the sugar (glycone) and non-sugar (aglycone) components. Glycosides are classified based on the chemical nature of the aglycone, including cyanogenic, phenolic, anthraquinone, saponin, and cardiac glycosides. Extraction methods involve solvent extraction of plant materials to isolate crude glycosides, which are then further purified.

1. Phytochemistry
S.Y.B.Sc. Botany Paper III
Unit 1
Part 4

2. Phytochemistry
GLYCOSIDES

6. Glycosides
Glycosides may be broadly defined as
• The condensation products of sugars with
various organic hydroxy compounds

7. Glycosides - Properties
• They are non carbohydrate in nature.
• The are non-reducing organic substances
widely distributed in plants.
• On hydrolysis (either enzymatic or acid
hydrolysis) one or more sugar moieties and
non sugar moieties.
• They are colourless and crystalline.
• Optically active compounds mostly levo
rotatory.

8. Glycosides - Properties
• Soluble in both Water and Alcohol
• Can be hydrolysed with dilute Acid enzymes
• Non sugar component of the glycoside
= Aglycone moiety
• Sugar component of the glycoside
• = Glycone moiety
• Linkage between glycone and aglycone is
referred to as Glycosidic Linkage

9. Glycosides - Properties
• Stereochemically there are α and β isomers
but plant contain only β glycosides
• They are named as
– Glucoside – Glucose
– Rhamnoside – Rhamnose
– Monoside – Monosaccharides
– Pentoside – Pentose sugar

10. Glycosides - Sources
• Widely distributed in plant kingdom
• Many fruits, seeds, barks and leaves of plants
contain glycosides.
• Many glycosides are therapeutically active.
– Eg. Anthraquinone Glycosides – Senna(Laxative)
and Aloe
– Eg. Cardiac glycosides – Digitalis – Purpurea
glycosides
• Aglycone part is therapeutically active

11. Glycosides – Extraction Method
Finely Powdered plant part
Solvent used – Water or Alcohol
Extraction carried out in Soxhlet Apparatus
Special Care for Thermo labile glycosides
Concentrate the Extract
Crude glycoside
Further purification by selected solvent and
chemical nature of the glycoside

12. Glycosides – Extraction Method

13. Glycosides – Classification
• They are classified depending upon chemical
nature, pharmacological action of the
aglycone moiety.
• The major groups are as follows
– Cyanogenetic glycosides
– Phenolic glycosides
– Anthraquinone derivatives as glycosides
– Saponins
– Cardiac glycosides

14. Glycosides– Classification
Cyanogenetic glycosides
• Eg. Amygdalin ( Amyglaloside) –
Prunus amygdlus Fam. Rosaceae (Bitter
almond)

15. Cyanogenetic glycosides

16. Glycosides– Classification
Phenolic glycosides
• Wide spread in nature
• Depending upon their chemical structure can
be further divided into
– Phenolic glycosides
– Anthraquinone
– Coumarin glycoside
– Flavone glycosides

17. Glycosides– Classification
• Phenolic glycosides
• Anthraquinone

18. Glycosides– Classification
• Coumarin glycoside
• Flavone glycosides

19. Glycosides– Classification
Anthraquinone derivatives as glycosides
• Eg. Senna Cassia angustifolia Fam
Leguminosae Sennosides A,B,C and D
Aloe - Barbaloin Fam Liliaceae
Other families like Rubiaceae, Verbinaceae
and Euphorbiaceae
• Purgative glycoside

20. Glycosides– Classification
Saponins
• Further divided into
– Steroidal
– Triterpenoid
• Examples
– Ritha – Sapindus laurifolius Fam Sapindaceae
– Fenugreek – Trigonella sps. Fam Leguminosae
– Jeshthimadh – Glycyrrhiza glabra Fam Legumi

21. Glycosides– Classification
Cardiac Glycosides
• Contains cardiotonic glycosides
• Strengthening Weak heart
• Work more efficiently
• Cardiac muscles strengthening
• Examples –
– Digitalis purpuria – Purpurea glycosides A&B
– Black Mustard Seeds – Sinirgin
– Wintergreen – Gaultherin