209FREE RADICAL SCAVENGING ACTIVITIES OF 4-(3H)-QUINAZOLINONE DERIVATIVES CONTAINING THIADIAZOLE AND OXADIAZOLE UNITSA series of 6,8-(un/mono/di)-bromo-2-Phenyl-3-subtituted-Quinazolin-4-(3H)-One derivatives were synthesized from 6, 8-( Un / mono/ di)-bromo-2-Phenyl-1,3-Benzoxazin-4-one (4a-c) as an intermediate. The chemical structures of the synthesized compound were confirmed by mean of FT-IR, 1H-NMR, Mass spectral and Elemental analysis. All the test compounds were screened for anti-oxidant activity by DPPH, H2O2 free scavenging activity methods. 5c and 5f were exhibited highest scavenger activity among the synthesized compounds. Brominated compounds exhibited better activity than unsubstituted one.vgirijasastry@yahoo.comResearch422013Quinazoline-4-(3H)-one,Thiadiazole,Anti-oxidant activityPraveen Kumar Kusuma,Girijasastry V,Kiran GDepartment of Pharmaceutical Chemistry, Vaagdevi Pharmacy College, Bollikunta,Warangal-506005, A.P, India., Department of Pharmaceutical Chemistry, Andhra University College of Pharmacy, Visakhapatnam-530003, A.P, India.,Department of Pharmaceutical Chemistry, Kakatiya Institute of Pharmaceutical Sciences, Pembarthy, Hasanparthy, Warangal-506371, A.P, India.