Synthesis and Biological Evaluation of Acridone Derivatives for Antimicrobial and Antifungal Applications

Acridones are heterocyclic alkaloids characterized by a tricyclic ring structure, featuring nitrogen at the 10th position and a carbonyl group at the 9th position. These compounds exhibit notable antibacterial and antifungal activities, positioning them as possible candidates for medicinal uses.

This research focused on the synthesis of N10-acetyl-3,4-dimethylacridone (Compound 3), a new acridone derivative, and the evaluation of its antifungal and antibacterial qualities against Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli.

Compound 3 was synthesised using anthranilic acid and 2,3-dimethyl aniline, followed by acetylation with acetic anhydride and cyclisation with sulphuric acid. The compound underwent characterisation using IR, NMR, and elemental analysis techniques. The antimicrobial and antifungal activities were evaluated using the agar well diffusion method, with inhibition zones recorded at concentrations of 50, 100, 300, and 400 mg/mL.

Compound 3 exhibited significant antibacterial efficacy at a concentration of 400 mg/mL. The inhibitory zones measured 35 mm for Pseudomonas aeruginosa and 26 mm for Escherichia coli, notably exceeding the conventional antibiotic gentamicin, which recorded 25 mm and 28 mm, respectively. Moderate action was noted against Staphylococcus aureus (19 mm) and Candida albicans (20 mm), but gentamicin and ketoconazole exhibited no inhibitory effect on Staphylococcus aureus at the tested concentration.

N10-acetyl-3,4-dimethylacridone (Compound 3) exhibits considerable antibacterial and antifungal properties, surpassing conventional antibiotics such as gentamicin in efficacy against Pseudomonas aeruginosa and Escherichia coli. The results indicate that Compound 3 may serve as an effective antibacterial agent and necessitates further exploration for therapeutic use in addressing bacterial and fungal illnesses.