Water-Mediated Synthesis, Antibacterial and Antioxidant Evaluation of New Fused Pyrimido-pyrimidine and Pyrimido-purines Derived From Nucleobases

A simple and eco-friendly synthesis of novel substituted pyrimido[1,6-a]pyrimidine, pyrimido[1,2-g]purine, and pyrimido[2,1-e]purine was accomplished by refluxing of nucleobases (cytosine, adenine or guanine) and dibenzalacetone (DBA) in water using NaOH as a catalyst. The molecular structures of the resulting products were characterized by infrared spectroscopy (FT-IR), mass spectrometry, and proton (1H) and carbon (13C) nuclear magnetic resonance (NMR). The antibacterial activity of the newly fused heterocycles was assayed against the Gram-positive bacterium Staphylococcus aureus (ATCC 6538) and Gram-negative Escherichia coli (ATCC 8737) using gentamicin as a standard commercially available antibiotic. In addition, the antioxidant capacity was screened using the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH•) and the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+•) radicals scavenging assay.