This paper covers the synthesis, in vitro urease inhibition, enzyme kinetic parameters, and anti-oxidant studies of a novel series of quinazolinone derivatives containing an acyl hydrazone skeleton. Compounds 3a, 3b, 5a, and 5b, having IC50 values ranging from 1.86 +/- 0.07 to 6.38 +/- 0.11 mu g mL(-1), show greater inhibitory activity than the standard inhibitor, thiourea. Among the products, (2-[2-(3-methoxybenzyl)-4-oxoquinazolin-3(4H)-yl]acetohydrazide) proves to be the most potent, exhibiting enzyme inhibition activity with an IC50 value of 1.86 +/- 0.07 mu g mL(-1). Kinetic studies involving the Lineweaver-Burk plots reveal that the inhibition mechanism of the most active compounds (3a, 3b, 5a, and 5b) on urease activity are found to be in competitive mode. Also, the anti-oxidant activity and radical-scavenging properties of the synthesized compounds are evaluated using cupric reducing anti-oxidant activity, ferric reducing anti-oxidant capacity, 2,2 '-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), and 2,2-diphenyl-1-picrylhydrazyl assays. Compounds 3a, b and 5a, b have good anti-oxidant properties and radical-scavenging activity at various final concentrations.