Question

Match the following toxic chemicals with the suitable conjugants for the process of detoxification.
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Choose the correct answer from the options given below:

• A. A - II, B - V, C - IV, D - I, E - III
• B. A - IV, B - V, C - II, D - III, E - I
• C. A - III, B - IV, C - I, D - V, E - II
• D. A - II, B - IV, C - V, D - I, E - III

Hint:

The conjugation of benzoic acid with glycine to form hippuric acid is a classic physiological test historically used to evaluate liver function.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Xenobiotics and toxic substances are metabolized in the body via biotransformation pathways.
These are classified into Phase I (oxidation, reduction, hydrolysis) and Phase II (conjugation) reactions, which increase water solubility to facilitate excretion.

Step 2: Detailed Explanation:
Let us analyze the conjugation and detoxification pathways for each chemical:
- A. Morphine: Undergoes Phase II conjugation with glucuronic acid catalyzed by UDP-glucuronosyltransferase, forming morphine-3-glucuronide and morphine-6-glucuronide (A - IV).
- B. Lead: A heavy metal detoxified by chelation therapy using British Anti-Lewisite (BAL Dimercaprol), which binds the metal ions to allow urinary excretion (B - V).
- C. Sulphanilamide: An antimicrobial drug metabolized primarily via acetylation in the liver using acetyl-CoA and N-acetyltransferase, producing acetylated derivatives (C - II).
- D. Benzoic Acid: Conjugated with the amino acid glycine in mitochondria to form hippuric acid, which is then excreted in the urine (D - III).
- E. Cyanide: Highly toxic cyanide is converted by the enzyme rhodanese into less toxic thiocyanate using thiosulphate as a sulfur donor (E - I).
This matching corresponds to: A-IV, B-V, C-II, D-III, E-I.

Step 3: Final Answer:
The correct matching is A - IV, B - V, C - II, D - III, E - I.