Synthesis and Biological Activity Studies of Novel Pyrido[2,3-d]pyrimidines and Pyrido[2,3-d]triazines

Novel derivatives of pyrido[2,3- d ]pyrimidin-2,4(1 H ,3 H )-dithione, 2,3- d imethylpyrido[2,3- d ]pyrimidin-4-one, 4-chloro-2-methypyrido[2,3- d ]pyrimidine and pyrido[2,3- d ]1,2,3 triazin-4-one were synthesized and screened for their anti-microbial and cytoxic activities. 5,7-diphenyl-pyrido[2,3- d ]pyrimidin-2,4(1 H ,3 H )-dithione, 5-(4-methoxyphenyl)-7-phenyl-pyrido[2,3- d ]pyrimidin-2,4(1 H ,3 H )–dithione, 5,7-diphenyl-2,3- d imethylpyrido[2,3- d ]pyrimidin-4-one, 4-chloro-5,7-diphenyl-2-methypyrido[2,3- d ]pyrimidine, 4-chloro-7-(4-chlorophenyl)-5-phenyl-2-methypyrido[2,3- d ]pyrimidine, 5,7-diphenyl-3,4-dihydropyrido[2,3- d ]1,2,3-triazin-4-one, 5-(4-methoxyphenyl)-7-phenyl-3,4-dihydropyrido[2,3- d ]1,2,3-triazin-4-one and 7-(4-chlorophenyl)-5-phenyl-3,4-dihydropyrido[2,3- d ]1,2,3-triazin-4-one showed excellent anti-microbial activities against all the tested bacteria and fungi compared to the reference drugs. Furthermore, they exhibited high safety profile in cytotoxicity test except 5,7-diphenyl-2,3- d imethylpyrido[2,3- d ]pyrimidin-4-one and 4-chloro-7-(4-chlorophenyl)-5-phenyl-2-methypyrido[2,3- d ]pyrimidine. The structures of the newly synthesized compounds were confirmed by spectral data and elemental analysis.