Synthesis, In Vitro, and In Silico studies of imide derivatives of phthalic anhydride as potential antimicrobial agents.

This study reports the synthesis and assessment of a series of imide derivatives of phthalic anhydride (phthalimides) for their potential antimicrobial activities. Phthalic acid was first converted into phthalic anhydride using acetic anhydride, which was then reacted with various L-amino acids to obtain phthalimides in high yields. Compounds HUPB, HUPC, HUPF, and HUPH exhibited promising antimicrobial activity, with HUPF and HUPH being the most potent. HUPF exhibited significant antimicrobial activity, showing inhibition zones of 24 mm versus Staphylococcus aureus (at 2000 µg/mL), 17 mm versus Escherichia coli (at 2000 µg/mL), and 18 mm against Candida albicans (at 1000 µg/mL). The minimum inhibitory concentrations (MICs) were 16 µg/mL, 24 µg/mL, and 24 µg/mL for S. aureus, E. coli, and C. albicans, respectively. HUPH demonstrated strong antimicrobial activity, exhibiting inhibition zones of 23 mm versus S. aureus, 19 mm versus E. coli, and 20 mm versus C. albicans, with corresponding MICs of 20 µg/mL, 28 µg/mL, and 20 µg/mL, respectively. Molecular docking reinforced these results, demonstrating effective bindings for HUPF and HUPH, suggesting their potential as antimicrobial agents. Both compounds adhered to Lipinski's Rule of Five, signifying decent oral bioavailability, gastrointestinal absorption (≥0.55), and no PAINS (pan-assay interference compounds) alerts. Density functional theory (DFT) calculations revealed that HUPF and HUPH possess narrow HOMO-LUMO energy gaps and elevated dipole moments, indicating high chemical reactivity, and strong polarity, which further support their enhanced antimicrobial potential. These results highlight the therapeutic potential of the two compounds for further development as novel antimicrobial agents.