Alizarin is a red coloring mordant dye extracted from the roots of madder plants (Rubia tinctorum L). Alizarin strongly inhibits P450 isoform CYP1A1, CYP1A2, and CYP1B1 with IC50 of 6.2 μM, 10.0 μM, and 2.7 μM, respectively in an enzymatic assay. There are also literature reports Alizarin increases the CYP1A1 enzymatic activity and acts as an agonist to the AHR receptor in HepG2 cells.