Synthesis and cytotoxic evaluation of 1-carboxamide and 1-amino side chain substituted β-carbolines.

The condensation of alkylenediamine with ethyl β-carboline-1-carboxylate and 1-bromo-β-carboline gave β-carboline-1-carboxamides and 1-amino-β-carbolines, respectively. Some of these β-carbolines were active against a panel of human tumor cell lines, and 1-amino derivatives were more potent than their 1-carboxamide congeners. In particular, among the 1-amino-β-carbolines, the N(9)-arylated alkyl substituted β-carbolines exhibited the most interesting cytotoxic activities with IC(50) value of lower than 20 μM. The preliminary structure-activity relationships (SARs) analysis suggested that (1) 1-amino substituents were the advisable pharmacophoric group for enhanced cytotoxic activities; (2) the introduction of appropriate arylated alkyl groups into position-9 of β-carboline facilitated their cytotoxic potencies.