PGP and neoplasm: Marine alkaloids incorporating a 5,6-dihydro-1-phenylpyrrolo[2,1-a]isoquinoline (henceforth referred to as DHPPIQ) moiety into their structure, like type Ia (saturated) lamellarins (Figure 1), showed cytotoxicity to tumor cells and inhibition of P-glycoprotein (P-gp)-mediated multidrug resistance (MDR), some of them being more potent as P-gp inhibitors than the well-known verapamil [2].