Pyrrolo[2,1-a]isoquinoline scaffold in drug discovery: advances in synthesis and medicinal chemistry

Pyrrolo[2,1-a]isoquinoline (PIq) is a nitrogen heterocyclic scaffold of diverse alkaloids endowed with several biological activities, including antiretroviral and antitumor activities. Several 5,6-dihydro-PIq (DHPIq) alkaloids, belonging to the lamellarins' family, have proved to be cytotoxic to tumor cells, as well as reversers of multidrug resistance. In this review, we provide an overview of the main achievements over the last decade in the synthetic approaches to access libraries of PIq compounds along with a survey, as comprehensive as possible, of bioactivity, mechanism of action, pharmacophore and structure-activity relationships of synthetic analogs of DHPIq-based alkaloids. The focus ismainly on the potential exploitation of the (DH)PIq scaffold in design and development of novel antitumor drugs.