From Monoamine Oxidases Inhibition to Antiproliferative Activity: New Biological Perspective for Polyamine Analogs

Monoamine oxidases (MAOs) are well-known pharmacological targets in neurological and neurodegenerative diseases. However, recent studies have revealed a new role for MAOs in certain types of cancer, such as glioblastoma and prostate cancer, where they have been found overexpressed. This finding is opening new frontiers for MAOs inhibitors as potential antiproliferative agents. In light of our previous studies demonstrating how a polyamine scaffold can act as MAOs inhibitor, our aim was to search for novel analogues with even greater inhibitory potency for human MAOs and, possibly, endowed with antiproliferative activity. A small in house library of polyamine analogs (2-7) was selected to investigate the effect of a constrained linkers between the inner amine functions of a polyamine backbone on the inhibitory potency. Compound 4 and 5, characterized by a dianiline (4) or dianilide (5) moiety emerged as the most potent, reversible and mainly competitive MAO inhibitors (Ki < 1uM). Additionally, they exhibited a high antiproliferative activity in three tumor cell lines, in particular in the LN-229 line, a glioblastoma model (GI50 < 1uM). The scaffold of compound 5, in particular, could represent a potential starting point for future development of anticancer agents endowed with MAO inhibitory activity.