Basic structure of the proton pump inhibitors

• A. Carboxylic acid
• B. Ethanolamine
• C. Benzimidazole
• D. Ethylenediamine

Answer: (C)

The defining feature of proton pump inhibitors is a benzimidazole-based core. They are built around a benzimidazole ring that carries a sulfinyl linker to a substituted pyridine, forming the prodrug structure that is activated in acidic conditions to inhibit the proton pump. This benzimidazole backbone is what all PPIs share, dictating their chemical behavior and activation.

That’s why the correct option is benzimidazole: it matches the characteristic core scaffold of PPIs. The other groups—carboxylic acid, ethanolamine, and ethylenediamine—do not represent the essential PPI structural motif.