Ochratoxin A is a phenylalanine derivative resulting from the formal condensation of the amino group of L-phenylalanine with the carboxy group of (3R)-5-chloro-8-hydroxy-3-methyl-1-oxo-3,4-dihydro-1H-2-benzopyran-7-carboxylic acid (ochratoxin alpha). It is among the most widely occurring food-contaminating mycotoxins, produced by Aspergillus ochraceus, Aspergillus carbonarius and Penicillium verrucosum. It has a role as a calcium channel blocker, a mycotoxin, a nephrotoxin, a carcinogenic agent, a teratogenic agent, an Aspergillus metabolite and a Penicillium metabolite. It is a phenylalanine derivative, an organochlorine compound, a member of isochromanes, a monocarboxylic acid amide and a N-acyl-L-phenylalanine. It is functionally related to an ochratoxin alpha. It is a conjugate acid of an ochratoxin A(1-).