Question

Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Digitonin of Digitalis is an example of saponin with distinctive property of frothing. Reasons (R): Saponin are plant glycosides and they are non-crystalline and dissolve in water with colloidal solutions. In the light of the above statements, choose the most appropriate answer from the options given below :

• A. \( \text{Both (A) and (R) are true and (R) is the correct explanation of (A)} \)
• B. \( \text{Both (A) and (R) are true but (R) is NOT the correct explanation of (A)} \)
• C. \( \text{(A) is true but (R) is false} \)
• D. \( \text{(A) is false but (R) is true} \)

Hint:

\textbf{Pharmacognosy: Saponins.} Remember the key characteristics of saponins: they are plant glycosides, often non-crystalline, form colloidal solutions in water with frothing, and can have various pharmacological activities. Digitonin serves as a classic example of a saponin.

Answer 1

The Correct Option is A

Assertion (A) is true: Digitonin is a steroidal saponin found in Digitalis purpurea (Foxglove). Saponins are known for their characteristic ability to produce stable foam or froth when shaken with water, due to their amphipathic nature (having both hydrophilic and hydrophobic parts). Digitonin exhibits this property prominently. Reason (R) is true: Saponins are indeed plant glycosides, characterized by a sugar moiety linked to a non-sugar moiety (aglycone or sapogenin). They are typically non-crystalline solids and when dissolved in water, they form colloidal solutions due to the aggregation of saponin molecules, resulting in the characteristic frothing. Reason (R) is the correct explanation of (A): The fact that digitonin is a saponin (as stated in the reason), which are plant glycosides with the property of forming colloidal solutions and frothing in water, directly explains why digitonin from Digitalis exhibits this distinctive frothing property (as stated in the assertion).