Biological Studies of Pyrido [2, 3-d: 6, 5-d/] Dipyrimidine with Synthesis

Fused pyrimidines,2,4,6,8-Tetrahydro-5-(4/-ethylphenyl)-10-aryl-2,4,6,8-tetraoxo-5H,10H-pyrido[2,3-d:6,5-d/]dipyrimidines, were prepared in good yield through a simple, clean and three-component one-pot cyclo-condensation reaction of a barbituric acid, aromatic aldehyde and 4-ethylaniline under reflex in a nitrogen atmosphere. The synthesized products were characterized by IR, NMR spectroscopy and elemental analyses are in good agreement with their expected molecular structure. All the compounds have been screened for their antimicrobial activity with four human pathogenic bacteria: Bacillus cereus, Salmonella typhi, Shigella dysenteriae, Listeria monocytogenes and four phytopathogenic fungi: Macrophomina phaseolina, Fusarium equiseti, Colletotrichum corchori and Alternaria alternata. The precursor barbituric acid was compared with the activity exhibited for the synthesized fused pyridopyrimidines, which show the increased inhibition against the bacterial growth after cyclization. The enhanced ability to inhibition may be due to the stability and aromaticity of heterocyclic synthesized in this study.