Antibacterial effect of some substituted tricyclic quinazolines and their synthetic precursors

Eleven substituted tricyclic quinazolines and their synthetic precursors we re tested for antibacterial effects. 3-Chloromethylcarbonyl-2-methylquinazo l-4-thione and 5-phenyl-2,3-dihydro-1,2,4-triazolo[4,3-c]quinazolin-3-one h ad the highest antibacterial effect against Bacillus subtilis, the MIC valu es being 50 mg/L. Two tested derivatives were more active against Pseudomon as aeruginosa than ampicillin, the IC50 values being 80 and 100 mg/L. The m ost effective derivatives contained in the structure generally pharmacologi cally active chromophores - methyl group in position 2 and a chloromethyl c onfiguration on the carbonyl group in position 3.