Which alkaloid class is derived from tyrosine?

• A. Tropane alkaloids
• B. Quinoline alkaloids
• C. Isoquinoline alkaloids
• D. Indole alkaloids

Answer: (C)

Tyrosine feeds into the isoquinoline alkaloid pathway. In plants, tyrosine is first converted to tyramine, which then condenses with 4-hydroxyphenylacetaldehyde to form (S)-norcoclaurine. Through a sequence of methylations, oxidations, and rearrangements, this isoquinoline backbone is built, giving rise to many well-known isoquinoline alkaloids such as morphine-like compounds and berberine. That’s why this class is the one derived from tyrosine. Indole alkaloids come from tryptophan, tropane alkaloids from ornithine/lysine, and quinoline alkaloids have their own distinct origins, not the tyrosine route.