Aromatic amino acids (AAAs) are amino acids that include an aromatic ring. Tryptophan (Trp), Phenylalanine (Phe), and Tyrosine (Tyr) are aromatic amino acids (AAAs) required for protein biosynthesis in all living cells. Phenylalanine and tryptophan are essential amino acids for animals. Since they are not synthesized in the human body, they must be derived from the diet.