New polyamine analogues as potential antineoplastic agents

The naturally occurring polyamines play an essential role in cell growth and proliferation. The levels of polyamines have been shown to increase in rapidly proliferating cancer cells. Therefore, compounds that inhibit enzymes in polyamine biosynthetic pathway may have therapeutic potential. Compounds capable of providing both in vitro and in vivo inhibition of almost all enzymes in the polyamine biosynthetic pathway are known. An exception is the lack of an agent that inhibits spermidine/spermine N 1 -acetyltransferase (SSAT), the rate-limiting enzyme in the catabolism of polyamines. The design, synthesis and characterization of five new polyamine analogues as potential inhibitors of SSAT are presented. Three compounds, N 1 -[3-(propenamido) propyl]-1,4-diaminobutane dihydrochloride 5 , N 1 -[3-(maleimido)propyl]-1,4-diamino-butane dihydrochloride 7 and N 1 -[3-(2-bromoacetamido)propyl]-1,4-diaminobutane dihydrochloride 9 , were designed as active-site-directed affinity label inhibitors. Two compounds, N-[N-(5-acetamido-2-hydroxypentyl-3-aminopropyl)]-1,4-diaminobutane trihydrochloride 12 and N-[3-(2-hydroxyethylamino)propyl]-1,4-diaminobutane trihydrochloride 14 , were designed as transition state-like analogue inhibitors. These compounds were synthesized using one key intermediate, N-(3-aminopropyl)-N,N ′ -bis-(tert-butoxycarbonyl)-1,4-diaminobutane 3 . Three of these synthesized compounds, 5 , 7 and 12 were evaluated for their ability to inhibit SSAT. The enzyme used was a crude extract of human large cell undifferentiated lung carcinoma cell line NCI H157 cells. These synthetic analogues when tested against the crude enzyme extract at concentrations of 0.05, 0.1, 1 and 5 μM appeared to show no effects on the activity of SSAT