Lipoic acid is a heterocyclic thia fatty acid comprising pentanoic acid with a 1,2-dithiolan-3-yl group at the 5-position. It has a role as a fundamental metabolite. It is a member of dithiolanes, a heterocyclic fatty acid and a thia fatty acid. It derives from an octanoic acid. It is a conjugate acid of a lipoate.