Starting from compound 16,
several derivatives, in which the D - Phe (4 - F) 1 moiety was replaced by various
aromatic amino acids, while maintaining the same configuration of [D - Phe (4 - F) 1, L - Arg2] fragment, have been synthesized.
As the flea pierces the dog's skin to enjoy a meal, it introduces
several potential allergens including
amino acids,
aromatic compounds, polypeptides and phosphorus.