Page 86 - Pharmd general phytochemistry I-Final2024_LEUCTERS

Properties

Solubility:
• they are usually soluble in water, aqueous alcohol, but almost
insoluble in fat solvents (petroleum ether)
• As a rule, the higher the number of the sugar units, the
greater the solubility in water, but the lower the solubility in
chloroform.

Stability:

1- Effect of acids:
• - Treatment of cardiac glycosides with dilute acids result in

hydrolysis of glycosidic bonds and liberation of the aglycones
and the individual sugar units.
• - More drastic acidic conditions or elevated temperature lead
to elimination of the C-14 hydroxy group with the formation of
14, 15- anhydro derivatives.

2-Effect of alkalis:
 Mild alkali (Na2CO3) results in deacylation of acylated sugars

to yield the deacylated glycoside
 Strong alkali (NaOH) results in opening of lactone ring

3- Enzymatic hydrolysis:
 Removes the terminal sugar unit e.g. glucose in a primary

glycoside is liberated by glucosidase enzyme to yield the
secondary glycoside.

4- Drying and storage:
It is required by many pharmacopeias that cardiac glycosides

containing drugs Must contain not more than specific moisture

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