Question

The chemical structure shown in the image is also known as?

• A. 5-hydroxytryptamine (5-HT)
• B. N-methyl phenylamine
• C. 3-Methoxytyramine
• D. Phenethylamine

Hint:

Look for an indole ring with a 5-OH and an ethylamine tail - that is serotonin.

Answer 1

The Correct Option is A

Step 1: The structure shown is serotonin, whose chemical name is 5-hydroxytryptamine (5-HT). It is an indoleamine (a monoamine) neurotransmitter built on a tryptamine backbone carrying a hydroxyl group at position 5 of the indole ring.
Step 2: Biosynthesis explains the name. Dietary tryptophan is first hydroxylated by tryptophan hydroxylase to 5-hydroxytryptophan, which is then decarboxylated by aromatic L-amino acid decarboxylase to give 5-hydroxytryptamine. Thus the molecule literally is tryptamine with a 5-OH group.
Step 3: Functionally, 5-HT is a potent vasoconstrictor and stimulator of smooth muscle contraction, and it acts widely in mood, gut motility, and platelet aggregation.
Step 4: The distractors are catecholamine or phenethylamine derivatives and do not match an indole nucleus. 3-Methoxytyramine is a dopamine metabolite, phenethylamine and N-methyl phenylamine are simple aromatic amines without the indole 5-OH pattern. Hence the correct answer is 5-hydroxytryptamine.