Question

Choose the correct statement from the following:
(A) Tannin solution precipitate alkaloid
(B) Hydrolysable tannin produce gallic and ellagic acid by enzymatic and acid hydrolysis
(C) Condensed tannin converted into red color substance known as phlobaphene on acid and enzymatic hydrolysis
(D) Tannin are insoluble in water

• A. $ \text{A and C Only} $
• B. $ \text{B Only D Only} $
• C. $ \text{C Only} $
• D. $ \text{A, B and C are correct} $

Hint:

Tannins are classified into hydrolysable and condensed types—both have characteristic reactions important in crude drug analysis.

Answer 1

The Correct Option is D

- [A]: True. Tannins precipitate alkaloids, gelatin, and heavy metals due to their astringent and protein-binding properties. - [B]: True. Hydrolysable tannins are broken down by enzymatic or acidic hydrolysis to yield gallic acid and ellagic acid.
- [C]: True. Condensed tannins (catechol-type) are polymerized to form phlobaphenes, which are red-brown insoluble substances.
- [D]: False. Tannins are highly water-soluble, and aqueous extracts are commonly used in phytochemical tests.

Answer 2

This question presents four statements, A, B, C and D, about tannins and asks which combination of them is correct. Each option below can be checked against the known chemistry of tannins.

1. A and C Only: Statement A says tannin solutions precipitate alkaloids, a well known property used in general alkaloid extraction and testing, so A is true. Statement C says condensed tannins convert into phlobaphenes, red coloured insoluble substances, on acid and enzymatic hydrolysis, which is also true. However, restricting the answer to only A and C leaves out statement B, which is also a correct statement, so this option is incomplete.
2. B Only D Only: Statement B, that hydrolysable tannins yield gallic and ellagic acid on hydrolysis, is true, but statement D, that tannins are insoluble in water, is false since tannins are in fact freely soluble in water, a solubility that is used in most extraction and precipitation tests. Since this option depends on D being true, it cannot be correct.
3. C Only: While statement C about phlobaphene formation is correct on its own, this option ignores that statements A and B are also true, so limiting the answer to C alone is incomplete.
4. A, B and C are correct: Statement A, precipitation of alkaloids, statement B, gallic and ellagic acid from hydrolysable tannins, and statement C, phlobaphene formation from condensed tannins, are all supported by standard tannin chemistry, while statement D is false because tannins are water soluble. This makes A, B and C together the accurate set.

Checking every statement shows A, B and C hold true while D does not, since tannins are soluble, not insoluble, in water.

Therefore, the correct answer is A, B and C are correct.