Phosphorylcholine is a small haptenic molecule is found in a wide variety of organisms. Human hepatic tumors undergo an elevation in the concentration of phosphorylcholine as the principal metabolic change is observed .

2-Ketoglutaric acid is a key molecule in the tricarboxylic acid cycleis also connected to glutamic acid and glutamine metabolisms through the transamination reactions.

(3-Carboxypropyl)trimethylammonium chloride is a synthetic carnitine related compound used as a transporter substrate in the cloning and sequencing of human carnitine transporter 2 (CT2).