Question

What is the core skeleton of tetracycline antibiotics?

• A. Four fused benzene rings
• B. Macrocyclic lactone
• C. Quinoline nucleus
• D. Phenothiazine nucleus

Hint:

Tetracyclines are named for their four fused ring system.

Answer 1

The Correct Option is A

Concept:
Tetracyclines are broad-spectrum antibiotics. Their name is related to their four-ring structure.

Step 1: Meaning of tetracycline.
The term “tetra” means four. Tetracyclines contain four fused cyclic rings.

Step 2: Core skeleton.
The core structure of tetracycline antibiotics consists of four fused rings.

Step 3: Checking other options.
Macrocyclic lactone is the core structure of macrolide antibiotics such as erythromycin.
Quinoline nucleus is present in quinoline antimalarials.
Phenothiazine nucleus is present in drugs like chlorpromazine.
Tetracyclines have a four fused ring skeleton.

Step 4: Final answer.
Therefore, the core skeleton of tetracycline antibiotics is four fused benzene rings. \[ \boxed{\text{Four fused benzene rings}} \]