A metabolite of riboflavin binds to the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) receptor

A cytosolic receptor to which TCDD binds with high affinity has been reported in a number of rodent tissues, but the endogenous/natural ligand is not known. However, lumichrome, a metabolite of riboflavin, competed with 3H-TCDD for binding to the cytosolic receptor. Neither riboflavin nor riboflavin-5-phosphate competed for binding to the TCDD receptor in rat liver cytosol. Lumichrome is the first known endogenous chemical in the rat to exhibit affinity for the TCDD receptor.