This matching involves understanding the mechanisms of action (MOA) of key anti-tubercular drugs used in the treatment of tuberculosis:
\begin{itemize}
\item Ethambutol — Inhibits arabinosyl transferase, an enzyme essential for the polymerization of arabinogalactan, a crucial component of the mycobacterial cell wall. (1)-(R)
\item Para-aminosalicylic acid (PAS) — Acts as a structural analog of PABA and inhibits folate synthase, thereby interfering with folate metabolism. (2)-(S)
\item Rifampicin — Inhibits DNA-dependent RNA polymerase in mycobacteria, preventing transcription and RNA synthesis. (3)-(P)
\item Bedaquiline — Specifically targets and inhibits the mycobacterial ATP synthase enzyme, leading to depletion of cellular energy (ATP) in Mycobacterium tuberculosis. (4)-(Q)
\end{itemize}
Matching accordingly:
- (1)-(R) Ethambutol
- (2)-(S) Para-aminosalicylic acid
- (3)-(P) Rifampicin
- (4)-(Q) Bedaquiline
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Approach Solution -2
This question matches four anti-tubercular drugs to their mechanism of action. Instead of going straight down the list, matching each drug to its known cellular target directly confirms the pairing.
(1)-(R), (2)-(S), (3)-(P), (4)-(Q): Ethambutol blocks arabinosyl transferase, the enzyme that builds arabinogalactan into the mycobacterial cell wall, so drug 1 pairs with target R. Para-aminosalicylic acid mimics PABA and blocks folate synthase, interfering with folate production needed for bacterial growth, pairing drug 2 with target S. Rifampicin binds and blocks DNA-dependent RNA polymerase, stopping transcription in the bacteria, pairing drug 3 with target P. Bedaquiline shuts down mycobacterial ATP synthase, cutting off the organism's energy supply, pairing drug 4 with target Q. Every pair matches its known target correctly.
(1)-(Q), (2)-(S), (3)-(P), (4)-(R): This assigns ATP synthase inhibition to drug 1 and cell wall enzyme inhibition to drug 4, but ethambutol's actual target is arabinosyl transferase, not ATP synthase, so the first and last pairings are swapped from the correct assignment.
(1)-(R), (2)-(Q), (3)-(P), (4)-(S): This gives drug 2 an ATP synthase target and drug 4 a folate synthase target, but para-aminosalicylic acid's real target is folate synthase and bedaquiline's real target is ATP synthase, so these two pairings are reversed here.
(1)-(Q), (2)-(R), (3)-(S), (4)-(P): This scrambles three of the four pairings away from their known targets, misassigning ATP synthase, arabinosyl transferase, and folate synthase inhibition among the wrong drugs.
Matching each drug to the single target it is actually documented to act on confirms only the first option is fully correct.
So the correct answer is (1)-(R), (2)-(S), (3)-(P), (4)-(Q).
