Cardiac Glycosides - Classification, Isolation and Chemical Test

Cardiac Glycosides

The cardiac glycosides are basically steroids with an inherent ability to afford a very specific and powerful action mainly on the cardiac muscle when administered through injection into man or animal. 

Small amount would exhibit a much needed stimulation on a diseased heart, whereas an excessive dose may cause even death.

Lactones ring is very important for therapeutic activity. 

Removal of lactone ring or even a slight disturbance to the lactone ring means that the activity of the activity is lost. 

Cardiac glycosides contain a special sugar called digitoxose; through they do carry other sugar like glucose and rhamnose. 

Very often diuretic action is also associated with steroidal glycosides as they also promote improved circulation of blood through kidneys.

Classification of cardiac glycosides


They are C23 steroids that have a 17-β side chain and α, unsaturated β-membered lactone ring.


Digitalis, Quabain, Strophanthin, etc


The bufadienolides are C24 homologues of the cardenolides and carry a doubly unsaturated 6- membered lactone ring  at the 17-position. 

The bufadienolides derived  their name from the genetic name for the toad, Bufo (the prototype compound bufalin was isolated from the skin of toads).


Squill, etc

Chemical tests for cardiac glycosides:

1. Raymond’s test:


To the drug, add a few ml of 50% ethanol and 0.1 ml of 1 % solution of m- dinitrobenzene in ethanol.

To  this  solution,  add  2-3  drops  of  20%  sodium  hydroxide  solution.  Violet  colors appears, this is due to presence of active methylene group.


2. Legal test:


To the drug, add few ml of pyridine and 2drops of nitroprusside and a drop of 20% sodium hydroxide solution. A deep red colour is produced.


3. Killer killiani test:


Glycoside is dissolved in a mixture of 1 % ferric sulphate solution in (5%) glacial acetic acid. Add one or two drop of concentrated sulphuric acid. A blue colour develops due to the presence of deoxy sugar.


4. Xanthydrol test:


The crude is heated with 0.1 to 5% solution of Xanthydrol in glacial acetic acid containing 1% hydrochloric acid. 

A red colour is produced due to the presence of 2-deoxysugar.


5. Baljet test:


Take a piece of lamina or thick section of the leaf and add sodium picrate reagent. If glycoside is present yellow to orange colour will be seen.

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