6-Hydroxy-2-piperidinone, is a building block used in various chemical synthesis. It has also shown to be used as a biomaker for monitoring CYP2E1 activity through metabolomic phenotyping. Cytochrome P 450 2E1 (CYP2E1) is a key enzyme in the metabolic activation of many low mol. wt. toxicants and also an important contributor to oxidative stress.