Synthesis and antiproliferative activity of various novel indole Mannich bases

Various secondary and primary amines were converted into bis-indolyl Mannich bases with good to excellent yields via double condensation reactions with indole and glutaraldehyde. The expected bis-indolyl Mannich bases (2, 3 and 4) were formed by using piperazinehexahydrate and 4,4′-trimethylenedipiperidine. Whereas, the use of primary amines, phenylhydrazine, amino acids and primary diamine produced the corresponding bis-indolyl-1,2,6-trisubstituted pipridines (5a-e) and indolyl-quinolizine (6) and dibis-indolyl-1,2,6-trisubstituted pipridines (7). All analytical and spectral data of these bis-indolyl Mannich bases have been determined. Six of the synthesized bis-indolyl Mannich bases have been subjected for antiproliferative activity screening at National Cancer Institute (NCI), Egypt, towards three human tumor cell lines representing different tumor types: breast adenocarcinoma cell (MCF-7), non-small lung cancer cell (NCI-H460), and central nervous system (CNS) cancer cell (SF-268). Compound (4) indicated the best and highest inhibitory effect against all three tested tumor cell lines with inhibition of 50% concentration (IC 50 ) for MCF - 7 (0.08 µmol/L), NCI - H460 (0.05 µmol/L) and SF - 268 (0.01 µmol/L).