Antibacterial effect of substituted 4-quinazolyl-hydrazines and their arylhydrazones determined by a modified microdilution method.

Eight 4-quinazolylhydrazines and eleven their arylhydrazones have been tested for antibacterial effects and for structure-activity relationships by a modified microdilution method. The derivative 6-chloro-2-morpholino-4-quinazolyl-5'-nitro-2'-furylhydrazone++ + had the highest antibacterial effect, the MIC values being 100 mg/L for E. faecalis, 250 mg/L for S. aureus, 200 mg/L for P. aeruginosa and 350 mg/L for E. coli. The most effective derivatives were those with the benzene ring substituted with chlorine or methyl group in position 6 or 8 and with pyrimidine ring substituted with a secondary amine in position 2. The modified microdilution method did not give rise to any statistically significant deviations in the MIC values for ampicillin in comparison with reported reference collection values.