Question

Which one of the following is an S-containing vitamin?

• A. Thiamin
• B. Niacin
• C. Pyridoxine
• D. Folacin

Hint:

Sulfur-Containing Biomolecules:
Sulfur Vitamins = THIAMIN (Thiazole ring) & BIOTIN (Thiophene ring).
Sulfur Amino Acids = Methionine, Cysteine, Cystine.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Chemical structural classification of water-soluble vitamins: thiamin and biotin contain heterocyclic sulfur atoms.
Key Formula or Approach:
\[ \text{Thiamin (Vitamin B}_1\text{)} = \text{Substituted Pyrimidine Ring} + \text{Sulfur-Containing Thiazole Ring} \]

Step 2: Detailed Explanation:
Chemical structures of water-soluble vitamins:
1. Thiamin (Vitamin $\text{B}_1$): Consists of an aminopyrimidine ring connected via a methylene bridge to a sulfur-containing thiazole ring ($-S-$). (Biotin also contains sulfur in a tetrahydrothiophene ring).
2. Niacin: Pyridine ring (contains nitrogen).
3. Pyridoxine: Pyridine derivative.
4. Folacin (Folic acid): Pteridine ring $+$ PABA $+$ Glutamic acid.
Therefore, Thiamin is the sulfur-containing vitamin.

Step 3: Final Answer:
Thus, Thiamin is an S-containing vitamin, matching option (A).