Capsicum Carotenoids include the two structurally similar compounds Capsorubin and Capsanthin.
They are found in all capsicum vegetables and fruits, and are found in very high amounts in both deep red chillies, cayenne, and paprika; the latter ranging from 3-8g/kg total carotenoids. Specifically, the capsicum carotenoid content of cayenne is approximately 2.01 capsanthin and 0.31 capsorubin, and paprika has values of 2.19-3.49 capsanthin and 0.42 to 0.98 capsorubin (all numbers g/kg)
Multidrug Resistance proteins (MDRs) are protein transports on tumor cells and other cells such as intestinal cells. They serve to eject compounds that build up in a cell, and exist as a defense mechanism for said cell.
Both Capsorubin and Capsanthin are able to potently inhibit P-Glycoprotein and MDR-1, two well-characterized efflux proteins. Via this action they may increase the bioavailability of some compounds, such as Berberine.