Novel biologically active N-substituted benzimidazole derived Schiff bases: design, synthesis and biological evaluation

Abstract Herein we present the design and synthesis of novel N-substituted benzimidazole derived Schiff bases, and the evaluation of their antiviral, antibacterial and antiproliferative activity. One of the goals was to study the impact on the biological activity of substituents placed at the N atom of benzimidazole nuclei as well as the type of substituents placed at the phenyl ring. The synthesized Schiff bases were evaluated for their in vitro antiviral activity against different viruses, antibiotic activity against a panel of bacterial strains and antiproliferative activity on several human cancer cell lines, thus enabling the study of structure − activity relationships. Some mild antiviral effects were noted, although at higher concentrations as compared to the included reference drugs. Additionally, some derivatives showed moderate antibacterial activity, with precursor 23 proving broadly active against most of the bacterial strains tested. Lastly, Schiff base 40, a 4-N,N-diethylamino-2-hydroxy substituted derivative bearing a phenyl ring at the N atom on benzimidazole nuclei, displayed strong antiproliferative activity against several cancer cell lines (IC50 1.1–4.4 µM). The strongest antitumoral effect was observed towards acute myeloid leukemia (HL-60).