End product of catecholamine metabolism is -

Ans. is 'b' i.e., Vanillyl Mandelic Acid* Catecholamines are monoamines with amino group attached to dihydroxybenzene.* They include Epinephrine , Norepinephrine and Dopamine* They are specialised products obtained from the two aromatic aminoacids - phenylalanine and tyrosine.* Dopamine is acted upon by Monoaminooxidase (MAO) in the dopaminergic nerves first and then by catecholamine O methyl transferase (COMT) in liver to form Homovandellic acid.* Norepinephrine of noradrenergic nerve endings are also acted upon by Monoamine Oxidase to form Dihydoxyphenylglycol. Dihydroxyphenyl glycol reaches liver, where it is converted by Catecholamine - O Methyl transferase to form Vanillyl Mandelic Acid.* Epinephrine and norepinephrine of adrenal medullary chromaffin cells are acted upon by catecholamine O methyl transferase and is converted to metanephrine and normetanephrine. Metanephrine and normetanephrine through circulation reach liver. In liver, metanephrine and normetanephrine are acted upon monoamine oxidase and are converted to Vanillyl Mandelic Acid (VMA).