Abstract

Background of study: Schiff bases (imines) are characterized by a carbon-nitrogen double bond. Their versatility and documented biological activities contribute to their significance in organic chemistry. Objectives: The harmful effects of free-radicals to the human body and prevalence of microbial resistance to current anti-infective drugs led to the search for new molecules with better activities for these conditions. This search for novel pharmaceutically active compounds led to Schiff base synthesis using vanillin and two alkyl amines. Methodology: Vanillin was reacted separately with these amines leading to the imines. The antioxidant activity (IC₅₀) of these compounds was evaluated using the DPPH assay test. A comparison of the obtained antioxidant activities was done.. The agar-diffusion method was adopted for screening the compounds against Staphylococcus aureus, Escherichia coli and Candida albicans for antibacterial and antifungal potentials respectively. Results: The IR spectral technique has revealed that both synthesized imines are new. Consequently, their nomenclatures are vanillyl hexyl imine (Iyadimine A) and vanillyl heptyl imine (Iyadimine B ) respectively. Vanillin demonstrated a moderate antioxidant activity of 0.52 μg/mL while vitamin C was significant at 0.48 μg/mL. However, both Iyadimine A and Iyadimine B were marginally active at 1.93 and 1.03 μg/mL respectively with Iyadimine B being slightly more antioxidant. The antibacterial and antifungal activities elicited by both imines showed concentration-dependency. Furthermore, Iyadimine A was more antibacterial against S. aureus than E. coli while the converse was observed with Iyadimine B. However, both suppressed C. albicans. Conclusion: The two new imines demonstrated marginal antioxidant activities and good antimicrobial activities. Hence, the two compounds are promising lead templates in the search for newer and more efficacious biological agents especially in synergistic antimicrobial co-administration and formulation studies in drug development.

Keywords: Schiff base, Vanillyl hexyl imine, Vanillyl heptyl imine, Antioxidant, Antimicrobial