Abstract

Introduction: The unending interest in the study of Schiff base ligands arise from the ease of their preparation and their versatility in several fields of Chemistry and Biochemistry. Some of the major biochemical processes such as trans-amination and glycosylation involve the formation of Schiff base intermediates. In addition, compounds containing the azomethine group have been found to often possess different biological activity such as anti-microbial, anti-viral and anti-inflammatory activity. In most cases, the extent of the potency depends on the nature of the constituent amino and or aldehyde moiety. Aims: The aim of this study was to synthesize, characterize and evaluate the antimicrobial activity of Schiff base ligands derived from p-vanillin and vanillin. Materials and Methods: The Schiff base ligands were prepared by condensing p-vanillin and vanillin with substituted aniline, aminonaphthalene and 3-aminopyridine respectively. The ligands have been characterized by elemental analysis, 1H- & 13C-NMR, infrared, Raman and electronic spectral data. The antimicrobial study was carried out by screening the prepared ligands against Staphylococcus aureus subsp. aureus ATCC® 6538™, Bacillus substillis subsp. spizizenii ATCC® 6633™*, Escherichia coli ATCC® 8739™* and Candida albicans ATCC® 2091™* using agar diffusion technique. Results: The azomethine, HC=N, 1H- & 13C-NMR signals were observed at 8.66-8.30 ppm and 164.42-157.99 ppm respectively. The infrared band appeared at 1622-1607 cm-1. The p-vanillin ligands exhibited higher activity than the vanillin based ligands. The p-hydroxyl and 3-aminopyridine ligands possess significant antimicrobial activity especially, antifungal activity. Conclusion: The spectroscopic spectral data of the compounds confirmed the formation of the Schiff base ligands. The antimicrobial activity of the compounds depends largely on the nature of the aldehyde moiety.

Keywords: Salicylaldehyde, Schiff bases, Anti-fungal agents, and vanillin