Chloro-substituted pyridine squaramates as new DNase I inhibitors: Synthesis, structural characterization, in vitro evaluation and molecular docking studies.

Having continued our recent study on the synthesis and DNase I inhibition of several monosquaramides, two new chloro-substituted pyridine squaramates were synthesized and their structure was identified by X-ray. Their inhibitory properties towards deoxyribonuclease I (DNase I) and xanthine oxidase (XO) were evaluated in vitro. 3-(((6-Chloropyridin-3-yl)methyl)amino)-4-ethoxycyclobut-3-ene-1,2-dione (compound 3a) inhibited DNase I with an IC value of 43.82 ± 6.51 μM, thus standing out as one of the most potent small organic DNase I inhibitors tested to date. No cytotoxicity to human tumor cell lines (HL-60, MDA-MB-231 and MCF-7) was observed for the tested compounds. In order to investigate the drug-likeness of the squaramates, the ADME profile and pharmacokinetic properties were evaluated. Molecular docking was performed to reveal the binding mode of the studied compounds on DNase I.