phase II reaction

Phase II reactions, also known as conjugation reactions, are a crucial part of biotransformation in the body, primarily occurring in the liver. In this phase, an exogenous molecule, which has already been modified in Phase I reactions by the addition of a functional group, is joined with an endogenous molecule naturally found in the body.1

The main goal of Phase II reactions is to create a more water-soluble compound that can be easily excreted from the body, usually through urine or bile. Common endogenous molecules used in conjugation include glucuronic acid, glutathione, amino acids, and sulfate. For example, glucuronic acid conjugation results in the formation of glucuronides, which are more water-soluble and thus more easily excreted than the original chemical. While biotransformation generally aids in eliminating toxins, it's important to note that sometimes these processes can inadvertently create more toxic substances.1