Epinephrine is primarily metabolized by which enzymes?

Epinephrine is primarily metabolized by which enzymes?

• A. Monoamine oxidase and catechol-O-methyltransferase
• B. Cytochrome P450 enzymes
• C. Alcohol dehydrogenase
• D. Aldehyde oxidase

Answer: (A)

Epinephrine is a catecholamine that is inactivated mainly by two enzymes working in tandem: monoamine oxidase and catechol-O-methyltransferase. Monoamine oxidase performs oxidative deamination, while catechol-O-methyltransferase adds a methyl group to the catechol ring. Together, these pathways convert epinephrine into metanephrine and then into vanillylmandelic acid, which is ultimately excreted. This dual inactivation is the predominant route for epinephrine metabolism in tissues like the liver and sympathetic nerve terminals. Cytochrome P450 enzymes, alcohol dehydrogenase, and aldehyde oxidase are not the primary routes for epinephrine metabolism, so they’re not the best answer here.

Epinephrine is a catecholamine that is inactivated mainly by two enzymes working in tandem: monoamine oxidase and catechol-O-methyltransferase. Monoamine oxidase performs oxidative deamination, while catechol-O-methyltransferase adds a methyl group to the catechol ring. Together, these pathways convert epinephrine into metanephrine and then into vanillylmandelic acid, which is ultimately excreted. This dual inactivation is the predominant route for epinephrine metabolism in tissues like the liver and sympathetic nerve terminals. Cytochrome P450 enzymes, alcohol dehydrogenase, and aldehyde oxidase are not the primary routes for epinephrine metabolism, so they’re not the best answer here.