Synthesis, Characterization, and Biological Evaluation of 2-(p-Nitrophenyl)quinazolin-4(3H)-one Derivatives

A series of novel 2-(4-nitrophenyl)-3-(R-benzothiazol-2-yl)quinazolin-4(3H)-ones 4a–4g (R = Alk, AlkO, Hal, NO2) were synthesized from the corresponding substituted 2-aminobenzothiazoles and 2-(4-nitrophenyl)-4H-3,1-benzoxazin-4-one via a nucleophilic addition reaction. The structures of the novel compounds were assigned on the basis of the elemental analyses and FTIR, 1H NMR, and mass spectra. The synthesized compounds were tested for anticonvulsant, antimicrobial, and antioxidant activities. All the compounds increased the seizure latency compared to control. Compound 4b (R = 6-NO2) exhibited significant anticonvulsant activity, comparable to that of the standard drug Phenytoin. Antimicrobial activity testing revealed moderate to good activity in all the test compounds, and 4a (R = H) and 4b compared in activity with the standard drug Chloramphenicol. The antioxidant activity of compounds 4a, 4d (R = 5-Br), and 4f (R = 4,6-Me2) (IC50 39.30, 15.55, and 42.95 µg/mL, respectively) was found to be higher compared to the standard drug ascorbic acid (IC50 48.30 µg/mL).