Tryptophan containing dipeptides are interesting ingredients for functional foods as a natural prevention for hypertension with reduced side effects due to its selective inhibition of the C-domain.

Sincalide ammonium (Cholecystokinin octapeptide ammonium) is a rapid-acting amino acid polypeptide hormone analogue of cholecystokinin (CCK) for intravenous use in postevacuation cholecystography.

5-Hydroxymethyl-2-furancarboxylic acid (Sumiki's acid) is a naturally occurring human metabolite. Sumiki's acid was first identified in the urine of a leukemia patient who was excreting an abnormal amount of its glycine derivative. Sumiki's acid has been found to be a byproduct of the fungus Aspergillus and probably other species of fungi and yeast as well.