3-Methylhistidine belongs to the class of organic compounds known as histidine and derivatives. Histidine and derivatives are compounds containing cysteine or a derivative thereof resulting from reaction of cysteine at the amino group or the carboxy group or from the replacement of any hydrogen of glycine by a heteroatom.

N-Lactoyl-Phenylalanine (Lac-Phe) is a peptide coupling of lactic acid and phenylalanine, one of the metabolites in acute exercise, which can be used in the study of obesity and metabolism-related diseases.

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