Synthesis, antimicrobial activity and molecular modeling study of substituted 5-aryl-pyrimido[5,4-c]quinoline-2,4-diones.

A series of pyrimido[5,4-c]quinoline-2,4-dione derivatives 5a-k were synthesized in moderate yields via a thermolysis reaction of equimolar ratio of 5-arylidine-1,3-dimethylbarbituric acid derivatives 3a-d with aniline derivatives 4a-d at 150-180 °C for 1-2 h. Eight of the synthesized compounds were chosen for a primary in vitro one-dose anticancer assay performed using the full NCI 60 cell panel. Only compound 5b showed moderate GI% at the used dose (10 μM) against four of the tested cell lines corresponding to leukemia SR (GI%: 51), non small-cell lung cancer HOP-92 (GI%: 63), melanoma UACC-62 (GI%: 53) and renal cancer UO-31 (GI%: 69). On the other hand, antimicrobial screening of the whole set of the synthesized compounds was performed against three Gram +ve and two Gram -ve bacterial strains. Results of the antimicrobial screening showed that compounds 5d, 5e, 5f, 5h and 5k have broad-spectrum antibacterial efficacy being moderately active against all the tested Gram +ve and two Gram -ve bacteria. Also, compound 5a showed interesting results being only active against Streptococcus faecalis and both tested Gram -ve strains viz. E. coli and P. aeruginosa. In order to compare the binding mode of the most active compounds 5e and 5f along with the inactive compound 5c we docked these compounds into the empty binding site of topoisomerase II DNA gyrase (PDB ID: 1KZN), and results were compared with the bound inhibitor Clorobiocin.