As an antioxidant and a coenzyme for enzymes such as pyruvate dehydrogenase and glycine decarboxylase, exogenous lipoic acid is reduced by two or more intracellular enzymes.The reduced form affects the process of cellular free radical scavenging, increases glutathione synthesis, and modulates the activity of transcription factors.It reduces the phagocytosis of myelin by macrophages.