The amino acid tryptophan is the precursor for the synthesis of Melatonin and Serotonin, Estrogen and Progestrone, Cortisol and Cortisone, or Thyroxine and Trudothyronine?

Tryptophan serves as precursor for the synthesis of the neurotransmitters serotonin and tryptamine as well as, for the synthesis of the antipellagra vitamin nicotinic acid and the epiphyseal hormone melatonin.