Hydroxyphenylacetylglycine (p-Hydroxyphenylacetylglycine) is an endogenous human metabolite.

p-Methylphenyl potassium sulfate is a prototype protein-bound uremic toxin derived from the metabolites of tyrosine and phenylalanine through liver.

Glucagon-like peptide 2 (GLP-2) is a recently identified intestinal epithelium-specific growth factor that has been shown to reduce the severity of inflammatory disorders of the intestine in rodent models. Currently Glucagon-Like Peptide 2 is used as a potential therapeutic agent for the human subjects with a broad variety of intestinal diseases characterized by intestinal damage and insufficiency.