Synthesis and DNase I inhibitory properties of new benzocyclobutane-2,5-diones

Aim: Eight new benzocyclobutane-2,5-diones (1a-1h) were synthesized, and their inhibitory properties against bovine pancreatic DNase I were examined in vitro. Methods & results: Compounds 1a-1h were synthesized using photocycloaddition of duroquinone with various phenyl-substituted ethylenes in the presence of 18W compact fluorescent lamp (visible light). Two compounds, 1,3,4,6-tetramethyl-7-phenylbicyclo[4.2.0]oct-3-ene-2,5-dione (1a) and 1,3,4,6-tetramethyl-7-p-tolylbicyclo[4.2.0]oct-3-ene-2,5-dione (1b) inhibited DNase I in a noncompetitive manner with IC₅₀ values below 150 μM and showed to be more potent DNase I inhibitors than crystal violet, used as a positive control. In order to analyze potential binding sites for the studied compounds with DNase I, molecular docking study was performed. Conclusion: The studied benzocyclobutane-2,5-diones offer a good starting point for a design of new DNase I inhibitors.