#104 Design, synthesis and antimicrobial activity of some novel 2-phenyl, 3-substituted quinazolin-4(3H)-ones; nonclassical antifolates

Abstract

A new series of 2-phenyl-3-substituted quinazolin-4(3H)-one derivative was synthesized. All compounds were characterized by FTIR, ¹H-NMR, ¹³C-NMR, ESI-MS, and elemental analysis. Obtained compounds were evaluated for hDHFR inhibition compared to the reported drug Trimethoprim (IC₅₀=10 µM). Primarily test compounds have produced hDHFR inhibition in the range of 4-24 µM. Docking analysis of ligands with hDHFR (PDB ID: 2W3M) has shown a hydrophobic type of strong binding interaction and confirmed the perfect fit of ligands with the active binding domain of the target protein. The possible antimicrobial activity would be by inhibition of DHFR within microbes. In-vitro antimicrobial activity was performed by agar disc diffusion method against pathogenic gram-positive strains of Staphylococcus aureus, Bacillus subtilis, gram-negative strains of Escherichia coli, Pseudomonas aeruginosa and fungi like Candida albicans and Aspergillus niger. The activity of test compounds was compared with reported standards as Gentamycin, Ciprofloxacin, and Clotrimazole. Compounds found potent antibacterial activity were QIj, QIIf (MIC=0.1-0.2 µg/mL), moderate active were QIa-d, QIl-m and QIIId, QIIIe-f (MIC= 0.5-2.0 µg/mL) and less active were Qe-I, QIk, QIn, QIIac, QIIg-h, QIIIa-c, QIIIg (MIC=2.0-3.0 µg/mL). Compounds that showed potent antifungal activity were QIc, QIIb, and QIIIf (MIC=0.1-0.2 µg/mL), moderate active were QIc-e, QIg, QIm-n, QIId, QIIIb, QIIIe (MIC=0.5-2.0 µg/mL), whereas less active were QIIa-b, QIIg with MIC=2.0-3.0 µg/mL. Functional groups attached to the quinazolin-4(3H)-one scaffold and sharing this activity would be electron-donating groups like and electron-withdrawing groups. Designed and synthesized title compounds could be fruitful in developing newer antimicrobial agents and treating deadly pathogenic infectious disorders.