A convenient, one-pot synthesis of 3-substitutedquinazolinone derivatives by the reaction of anthranalic acid, ortho formates and aryl or alkyl amines in presence of 1-Butyl-3-methylimidazolium tetrafluoroborate [BMIM+][BF4-] as a green, efficient reusable catalyst has been described. The reaction proceeded within few minutes with excellent yields. The simplicity of the experimental procedure as well as the re-usability of the catalyst are the significant advantages of this protocol. All the compounds synthesized were screened for their anti-bacterial, anti-asthmatic and anti-diabetic activities.