Cardiac glycosides are steroidal compounds that act as cardiotonic agents, enhancing the tone and contractibility of cardiac muscle. They contain a steroidal aglycone linked to a sugar moiety. The two main types are cardenolides, found in plants like Digitalis, and bufadienolides, found in substances like toad venom. Cardenolides contain an unsaturated lactone ring and include compounds like digitoxin and digoxin. Bufadienolides have a doubly unsaturated lactone ring and include substances from squill. Cardiac glycosides are used medicinally as cardiotonics to treat congestive heart failure and other conditions, with digoxin being one of

1. CARDIAC GLYCOSIDES
• The genins or aglycones of all cardiac
glycosides are steroidal in nature
• May be referred to as steroid glycosides
• They act as cardiotonic agents

2. • Enhance the tone of the heart
• Excitability
• Contractibility of the cardiac muscle
• Also the improved circulation tends to
improve renal secretion
• This relieves oedema often associated
with heart failure

3. Structural Characteristics of
Cardiac Glycosides
• This is always involved in a glycosidic
linkage to a mono, di, tri, or tetra
saccharide

4. • Most sugars that are found in cardiac
glycosides are uncommon deoxy-sugars
• E.g Digitoxose, Cymarose, Thevetose

5. C
CHO
C
C
C
CH3
OH
OH
OH
H2 C
CHO
C
C
CH3
OH
OH
H2
CHO
C
C
CH OH
H
C OCH3
OH
HCH3O
C OHH
CH3
Digitoxose Cyamarose Thevetose

6. O
R
OH
CH3
Sugar
Lactone ring
1
2
3
4
5
10
6
7
8
9
11
12
13
14
15
16
17

7. Types of cardiac glycosides
• The steroid aglycones or genins are of 2
types
• Cardenolides
• Bufadienolides

8. THE CARDENOLIDES
• They are more prevalent in nature
• Cardenolides are C23 steroids
• These have α,β-unsaturated 5-membered
lactose ring in position C-17
2 main types:
• Digitalis glycosides
• Strophanthus glycosides

9. O
R
OH
CH3OH
Sugar
1
2
3
4
5
10
6
7
8
9
11
12
13
14
15
16
17
O O
Cardenolides
Digitalis glycosides R=CH3
Strophanthus glycosides R=CHO OR CH2OH

10. The Digitalis group
These include:
• D. purpurea, D. dubia, D. ferruginea
• D. lanata, D. grandiflora, D. nervosa
• D. lutea D. mertonensis, D. subalpina
• D. thapsi

11. Chemical constituents
• digitoxin
• gitoxin
• digoxin

12. Digoxin
• Digoxin is the most widely used of
cardiotonic glycosides
• Obtained from the leaves of D. lanata

13. THE BUFADIENOLIDES
• This group of cardioactive agents includes
the following:
• Squill glycosides (scillarins)
• Toad poison (Bufotoxin)

14. Botanical source
• Obtained from the bulbs of varieties of
squill
• Family = Liliaceae

15. • Derives name from the generic name for
the toad (Bufo)
• Possesses doubly unsaturated 6-
membered lactone ring in position C-17
• Bufadienolides are C24 steroid

16. O
OH
R1
R2
Sugar
1
2
3
4
5
10
6
7
8
9
11
12
13
14
15
16
17
O
O
Bufadienolides
Squill glycosides R1=OH, R2=H
Bufotoxin R1 & R2 = ester group

17. Bufadienolides from Squill
• These glycosides include the following:
• Scillarin A
• Scillarin B
Uses
• A potent cardiotonic
• As expectorant specially in chronic
bronchitis

18. • As stimulant
• It is used as a very effective expectotant
both in asthma and chronic bronchitis
• It may possess anticancer
• Produces diuresis
• It causes emesis in relatively higher doses

19. • Chemical colour reactions have been
evolved to be used as the qualitative tests
either for:
• the various glycosides
• or their corresponding aglycones
TEST FOR CARDIAC
GLYCOSIDES

20. 1 Kellar-Kiliani
Test
The glycoside is
dissolved in glacial acetic
acid containing a trace of
FeCl3, add conc. H2SO4
along the side of the test
tube to settle at the
bottom (for deoxy sugars
e.g. digitoxose)
A reddish
brown colour
changing to
bluish green
colour appears
at the junction
of two reagents
within 2-5
minutes
spreading
slowly into the
acetic acid layer

21. 2. Kedde’s Test A solution of
glycosides is treated
with a small amount
of Kedde’s reagent
(Cardenolides)
Development
of a blue or
violet colour
that fades out
in 1- 2 hours
shows its
presence

22. MEDICINAL IMPORTANCE OF
CARDIAC GLYCOSIDES
• Cardiotonics
• Congestive heart failure
• Rheumatic heart disease
• Atherosclerosis
• Diuretics

23. Official Cardiac Drugs
• Digitalis leaf (digitalis tablets)
• Digitoxin tablets
• Digoxin injection