Characterisation, structural investigations and biological activity of substituted salicylidene-based compounds

Abstract

Seven salicylidene base compounds (1 – 7), p-NO2-SalH-R, (R = halogen, hydroxyl, or nitro group on either the para (p-) or ortho (o-) position); were prepared by condensing 2-hydroxy-5-nitrobenzaldehyde with p-hydroxyaniline (1), p-nitroaniline (2), p-fluoroaniline (3), p-chloroaniline (4), p-bromoaniline (5) o-fluoroaniline (6) and o-hydroxyaniline (7), to form the respective ligands (1 – 7). The compounds were fully characterised via 1H and 13C NMR, IR, UV/Vis, and elemental analysis. Luminescence studies were performed and single crystals, suitable for X-ray diffraction, were obtained for four of the compounds. The compounds were assayed for cytotoxicity against human breast adenocarcinoma (MCF-7), human cervical cancer (HeLa), human lung adenocarcinoma (A549), liver hepatocellular carcinoma (HepG2), human colorectal adenocarcinoma (Caco-2) and African green monkey kidney (Vero) cell lines and for antibacterial activity against 3 nosocomial pathogenic bacteria (E. coli, E. faecalis, and S. aureus) to correlate between structural variations and bioactivity. Compound 2 showed anticancer activity against MCF-7 and HepG2 cell lines with LC50 values of 48.78 µM and 59.26 µM, respectively. Compound 7 exhibited anticancer activity against HeLa and A549 cell lines with LC50 values of 50.27 µM and 37.88 µM, respectively. Compounds 4 and 5 demonstrated anticancer activity against the MCF-7 cell line with LC50 values of 48.04 µM and 56.58 µM, respectively. The compounds showed no antibacterial activity against the three tested nosocomial pathogenic bacterial strains.