Roquefortine C is a mycotoxin that was first isolated from a strain of P. roqueforti, a species of Penicillium commercially used to ripen blue-veined cheeses. It has also been isolated from other members of the Penicillium genus found in contaminated food products where it displays neurotoxic properties. It has been shown to both activate a P-glycoprotein transport system involved in the efflux of xenobiotics and to inhibit cytochrome P450 3A detoxification enzymes. It has also been used as a biomarker for penitrem A intoxication.