1. Keep silence…!

2. “In the name of Allah the most beneficent and merciful”.

3. Glycosides GLYCOSIDES Dr. Tahir Ali RIPS
Riphah International University, Lahore, PK.

4. GLYCOSIDE
“A glycoside is an organic compound, usually of plant origin maybe of animal origin, that is composed of a sugar portion linked to a non-sugar moiety”.
Glycone: The sugar residue of a glycoside.
Aglycone / Genin: An aglycone is the non-sugar part of gycoside.

5. Example

6. Example

7. Example

8. Types O- glycosides N- glycosides S- glycosides C- glycosides
Based on atoms involved in glycosidic linkage:
O- glycosides
N- glycosides
S- glycosides
C- glycosides

9. O- glycosides The O-glycosides are usually represented as follows:
In these glycosides the sugar is combined with aglycone through O-linkages e.g. digitoxin.
The O-glycosides are usually represented as follows:
Aglycone—OH + HO—C6H11O5 ——>  —O—C6H11O5 O-Glycoside
These are most abundantly found in nature in the higher plants, such as: senna, rhubarb and frangula.
Examples: Rhein-8-glucoside obtained from rhubar

10. N- glycosides
In these glycosides, nitrogen of amino group is condensed with a sugar, e.g. nucleosides.
The N-glycosides may be represented as shown below:
Aglycone=N—H + HO—C6H11O5 ——>  =N—C6H11O5 N-Glycoside
The most typical example of N-glycosides is the nucleosides, wherein the respective amino group of the base ultimately reacts with —OH group ribose/deoxyribose.
Examples: Adenosine: 

11. S- glycosides
These glycosides contains a sugar moiety attached to the sulphur of the aglycone, e.g.isothiocynate glycosides.
The S-glycosides are normally designated as below:
—SH HO—C6H11O5 ——>  S—C6H11O5 S-Glycoside
E.g: Sinigrin,obtained from black mustard seeds. (i.e., Brassica campestris Family: Cruciferae)

12. C- glycosides
Condensation of sugar directly to a carbon atom gives rise to C-glycosides, e.g. aloin & cascarosides.
The C-glycosides may be designated as shown under:
CH HO—C6H11O5 ——> C—C6H11O5 C-Glycoside
C-Glycosides are present in a variety of plant substances, such as: aloin or barbaloin:  in Aloe.

13. Types O- glycosides N- glycosides S- glycosides C- glycosides
Based on atoms involved in glycosidic linkage:
O- glycosides
N- glycosides
S- glycosides
C- glycosides

14. Classification
(a) Cardioactive glycosides: Digitalis, Strophanthus and white squill (b) Anthraquinone glycosides: Cascara, Aloe, Rhubarb, Cochineal and Senna (c) Saponin glycosides: Glycyrrhiza, Sarsaparilla (d) Cyanophore glycosides: Wild cherry (e) Isothiocyanate glycosides: Black Mustard (f) Lactone glycosides: Cantharide (g) Aldehyde glycosides: Vanilla (h) Miscellaneous glycosides: Gentian, Quassia, Dioscorea

15. Part 2

16. Sugar molecules in glycosides
Glucose
Fructose
Rhamnose
Cymarose
Digitoxose
Glucoside ?

17. Glucosides (the glycone is glucose).
Galacosides (the glycone is galacose).
Mannosides (the glycone is mannose).
Arabinosides (the glycone is arabinose).

18. Primary glycosides e.g. purpurea glycoside A,
Secondary glycosides e.g., digitoxin.

19. STEROL OR CARDIAC GLYCOSIDES

20. Introduction
Plants containing cardiac steroids have been used as poisons and heart drugs at least since 1500 B.C.
Were used as arrow poisons, emetics, diuretics and heart tonics.
These drugs all act by affecting the availability of intracellular Ca+2 for myocardial contraction or increasing the sensitivity of myocardial contractile proteins.

21. Cardiac glycosides
Cardiac glycosides are composed of two structural features: the sugar (glycone) and the nonsugar (aglycone– steroid) moieties.
The steroid nucleus has hydroxyls at 3- and 14-positions of which the sugar attachment uses the 3-OH group. 14-OH is normally unsubstituted.
Many genins have OH groups at 12- and 16-positions.
These additional hydroxyl groups influence solubility in aqueous medium and greatly affect the duration of action.
The lactone moiety at C-17 position is an important structural feature

22. Two classes have been observed in nature—the cardenolides and the bufadienolides.
The cardenolides have an unsaturated butyrolactone ring while the bufadienolides have a pyrone ring.
C23 steroids Leguminosae, Cruciferae, Euphorbiaceae,
C24 steroids (Liliaceae, Ranunculaceae).

23. DIGITALIS Botanical Origin: Family: Part used: Digitalis purpurea
Scrophulariaceae
Part used:
Dried leaves

24. Common Name: Vernacular Names:
Foxglove, purple foxglove, finger flower, fairy glove.
Vernacular Names:
English: Fairy fingers, Witchs bells.

25. Distribution:
Digitalis is native to Western Europe. It can also be located in Asia, North Africa, Canada and much of the US.
Introduction:
Digitalis is a genus of about 20 species, that was traditionally palced in the figwort family Scrophulariaceae.
Due to new genetic research, it has now been placed in the much enlarged family Plantaginaceae.

26. leaves Dark greyish green in colour Odourless Bitter taste
Shape; lanceolate to broadly ovate
Size 10–30 cm long and 4–10 cm wide

28. Purpurea glycoside A

30. Part 3

31. Digitalis purpurea VS D. lanata

32. Purple foxglove Vs Grecian foxglove

33. More differences ?????
Book  Pharmacognosy by Varro E. Tyler (9th Ed.)
Chapter  Steroids
Page #  to 171

34. Digitalis ferruginea

35. Digitalis lutea

36. SOURCE D. purpurea, and D. lanata Family – Scrophularaceae.
The structures of the common aglycones of the digitalis group are: -
Compounds R1 R2
Digitoxigenin H
Gitoxigenin OH
Digoxigenin

37. 1- Glycosides derived from Digitoxigenin:
DX = Digitoxose, DX (AC)=Acetyldigitoxose,G = Glucose.
1- Glycosides derived from Digitoxigenin:
a- Lanatoside A = Digitoxigenin---DX---DX----DX(AC)---G.
b-Acetyl-digitoxin= Digitoxigenin---DX---DX----DX---(AC).
c- Digitoxin = Digitoxigenin------DX---DX----DX.
d- Purpurea gly A = Digitoxigenin---DX---DX----DX---G
2- Glycosides derived from Gitoxigenin:
a- Lanatoside B = Gitoxigenin---DX---DX----DX(AC)---G.
b- Gluco-gitoroside = Gitoxigenin---DX----G
c- Gitoxin = Gitoxigenin------DX---DX----DX.
d- Purpurea gly B = Gitoxigenin---DX---DX----DX---G

38. 3- Glycosides derived from Digoxigenin:
a- Lanatoside C = Digoxigenin---DX---DX----DX(AC)---G.
b- Acetyl-digoxin = Digoxigenin---DX---DX----DX--- Dx(AC).
c- Digoxin = Digoxigenin------DX---DX----DX.
d- Deslanoside = Digoxigenin---DX---DX----DX---G

40. Mechanism of action Mechanism of action of cardiac glycosides?
Book  Pharmacognosy by Varro E. Tyler (10th Ed.)
Chapter  Steroids
Page #  or (164 …… 9th ed.)

41. Thank