Question

Caffeine is a plant-based drug that

• A. does not intercalate into DNA double helix
• B. inhibits cyclic AMP (cAMP) phosphodiesterase activity
• C. inhibits epinephrine response
• D. reduces the level of cellular cAMP

Hint:

Caffeine’s effect on increasing cAMP is a key reason for its stimulating properties in the central nervous system.

Answer 1

The Correct Option is B

Step 1: Understanding Caffeine's Action.
Caffeine works by inhibiting the activity of phosphodiesterase, an enzyme responsible for breaking down cyclic AMP (cAMP). This increases the concentration of cAMP in cells.
Step 2: Analyzing the Options.
- (A) Incorrect. Caffeine does not intercalate into DNA; it mainly affects cellular signaling pathways.
- (B) Correct. Caffeine inhibits the phosphodiesterase enzyme, increasing cAMP levels.
- (C) Incorrect. Caffeine does not directly inhibit the epinephrine response; instead, it stimulates it by increasing cAMP levels.
- (D) Incorrect. Caffeine increases, not reduces, the level of cAMP by inhibiting its breakdown.
Step 3: Conclusion.
Thus, the correct answer is (B).