Synthesis, Antibacterial and Antioxidant Activities of Some Tridentate Substituted Salicylaldimines

Five substituted tridentate salicylaldimines, (E)-2-((2-hydroxybenzylidene)amino)phenol, (E)-2-(((2-hydroxyphenyl)imino)methyl)-4-nitrophenol, (E)-4-chloro-2-(((2-hydroxyphenyl)imino)methyl) phenol, (E)-2-(((2-hydroxyphenyl)imino)methyl)-4-methoxyphenol, (E)-4-bromo-2-(((2-hydroxy-phenyl)imino)methyl)-6-methoxyphenol were synthesised and characterised by elemental analysis, IR, UV and NMR (1H and 13C). They were screened against some multi-drug resistance Gram-positive (Streptococcus agalactiae and Staphylococcus aureus), and Gram-negative (Escherichia coli, Klebsiella pneumonia, Proteus mirabilis, Pseudomonas aeruginosa and Salmonella typhimurium) organisms by the agar-well diffusion method. The total antioxidant capacities of the salicylaldimines were determined by the phosphomolybdenum assay. Their antibacterial and antioxidant activities were screened to understand the substituents effects. The result showed that the methoxy-substituted compound exhibited the highest antibacterial and antioxidant activities while the nitro-substituted compound exhibited the least activities. This implies that the electron-donating group of the compound increases its antibacterial and antioxidant activities. The one-way analysis of variance was performed with MINITAB 17 at 95% confidence level.