Synthesis and Biological Investigations of Vanillin and its Nitrated Derivative

Abstract

Vanillin is a well-known natural flavoring agent with remarkable biological and pharmacological properties, including antimicrobial and antioxidant activities. The aim of this study was to synthesize nitrovanillin from vanillin and evaluate its antioxidant, antibacterial, and antifungal activities.

Nitrovanillin was synthesized using nitric acid as a nitrating agent, with dichloromethane (DCM) as the solvent, resulting in a favorable yield. The compound was characterized by ultraviolet-visible (UV–Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, thin-layer chromatography (TLC), and melting point determination.

Antioxidant activity was assessed through several assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), phenanthroline, and silver nanoparticles (AgNPs). Antibacterial activity was evaluated by the agar disc diffusion method against Escherichia coli, Bacillus cereus, and Staphylococcus aureus, while antifungal activity was tested using the well diffusion method against Fusarium oxysporum grown on potato dextrose agar (PDA).

The results revealed that nitrovanillin exhibited strong antioxidant activity, particularly in the phenanthroline and AgNP assays. It showed potent antifungal activity with 90% inhibition of F. oxysporum at 200 μg/mL. Regarding antibacterial activity, vanillin inhibited S. aureus (14 mm) and E. coli (8 mm), while nitrovanillin demonstrated stronger inhibition against S. aureus (32 mm) and B. cereus (38 mm).

Overall, the introduction of a nitro group significantly enhanced the biological potential of vanillin, making nitrovanillin a promising compound for further investigation in biomedical and material applications.