Aconitic acid is an organic acid. The two isomers are cis-aconitic acid and trans-aconitic acid. The conjugate base of cis-aconitic acid, cis-aconitate is an intermediate in the isomerization of citrate to isocitrate in the citric acid cycle. It is acted upon by the enzyme aconitase. Aconitic acid can be synthesized by dehydration of citric acid using sulfuric acid: A mixture of isomers are generated in this way. Aconitic acid was originally isolated from Aconitum napellus by Swiss chemist and apothecary Jacques Peschier in 1820. It was first prepared by thermal dehydration. Like the conjugate bases of other polycarboxylic acid, acotinic acid forms a variety of coordination complexes. One example is the coordination polymer [Zn3(C6H3O6)2(H2O)6]n.