Background: Pyrimidines have widespread activity and have shown potent antibacterial and anticancer activity.
Objective: To synthesise a range of pyrimidine diones and test them for their antibacterial and anticancer activity.
Method: The pyranopyrimidin-2,4-dione derivatives (1-7) were synthesized in a one-pot reaction by reacting
malononitrile and barbituric acid with several aromatic aldehydes in the presence of 1,4-diazabicyclo[2.2.2]octane
(DABCO) in aqueous medium. The compounds were tested for their antibacterial activity using the broth
microdilution method and for their cytotoxicity against three cell lines, HeLa (cervical cancer), Caco-2 (human colon
adenocarcinoma) and HEK 293 (human embryonic kidney cells) using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide) assay.
Results: Compounds 1-7 were successfully synthesized in yields of >90%. The 3,4-dihydroxyaryl (3) and the 2,5-
dimethoxyaryl (7) derivatives were novel. Compounds 3, 5 (4'-methoxy derivative) and 6 (2',3'-dimethoxy derivative)
showed antibacterial activity comparable to or better than the standard ampicillin. All the test compounds 1-7 showed
good anticancer activity. The IC50 values ranged from 3.46 to 37.13 μM (HeLa); 136.78 to 297.05 μM (Caco-2) and
137.84 to 333.81 μM (HEK293). The best activity was seen in the HeLa cell line when compared to the standard 5FU
(5-Fluorouracil IC50 of 41.85 μM), with 1, 2, 5 and 7 having IC50 values of 10.64, 3.46, 4.36 and 4.44 μM respectively.
Additionally, two representative compounds (1 and 7) found to be potent against the two cell lines (HeLa and HEK
293) were docked into the binding site of human kinesin Eg5 with the aim of predicting their binding propensities and
to establish their mechanism of action. The Lipinski parameters of these compounds were also computed and analysed
for their drug-likeness.
Conclusion: Compound 6 is an excellent candidate for a broad spectrum antibiotic with MBCs of 45.6-365.2 μM,
while both 3 and 6 have the potential to be developed into an antibiotic against MRSA, with MBCs of 183-199 μM.
Since all synthesized compounds showed IC50 values of 10 μM or less especially against the HeLa cells, they can be
considered good lead compounds for anticancer agents. Additionally, the docking simulations suggested a good
binding affinity of the compounds with Eg5 and indicated their anti-cancer action, at least partially, through its
inhibition. The predicted Lipinski descriptors also indicated the potential of these compounds as an orally active drug.