Amino acid phenylalanine is the precursor of all the following, except:
Phenylalanine hydroxylase conves phenylalanine to tyrosine. The amino acid tyrosine is the staing point in the synthesis of the catecholamines and of the thyroid hormones tetra iodothyronine (thyroxine; T4) and triiodothyronine (T3). Tyrosine is also conveed into DOPA, dopamine, norepinephrine and finally epinephrine. Ref: Harper's Illustrated Biochemistry, 26th Edition, Pages 239, 255, 266-267; Textbook of Biochemistry By D M Vasudevan, 3rd Edition, Pages 185, 187
Tyrosine
Epinephrine
Thyroxine
Melatonin