Design, synthesis and biological evaluation of benzo[1.3.2]dithiazolium ylide 1,1-dioxide derivatives as potential dual cyclooxygenase-2/5-lipoxygenase inhibitors.

3-(4-Bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide (5) was discovered as a new prototype for dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). Thus, the structure-activity relationships of benzo[1.3.2]dithiazolium ylide 1,1-dioxide skeleton were carried out. The 6-NO(2) group played an essential role in the inhibitory activity. In addition, moderate-sized lipophilic substituents at the para-position of the 3-aryl moiety were required for dual COX-2/5-LOX inhibitory activity. Among the identified potent dual inhibitors, 3-(4-tbutylphenyl) derivative 30c (IC(50) values of 0.27 µM and 0.30 µM against COX-2 and 5-LOX, respectively) and 3-(4-biphenyl) derivative 30f (IC(50) values of 0.50 µM and 0.15µM against COX-2 and 5-LOX, respectively) were the most potent dual COX-2/5-LOX inhibitors. Intraperitoneal administration of 30c at 100mg/kg demonstrated potent acute anti-inflammatory activity. As a result, benzo[1.3.2]dithiazolium ylide 1,1-dioxide represented a novel scaffold for the exploitation in developing dual COX-2/5-LOX inhibitors.

Discovery of 3-(4-bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide as a novel dual cyclooxygenase/5-lipoxygenase inhibitor that also inhibits tumor necrosis factor-alpha production.

In the present study we have discovered compound 1, a benzo[1.3.2]dithiazolium ylide-based compound, as a new prototype dual inhibitor of cyclooxygenase (COX) and 5-lipoxygenase (5-LOX). Compound 1 was initially discovered as a COX-2 inhibitor, resulting indirectly from the COX-2 structure-based virtual screening that identified compound 2 as a virtual hit. Compounds 1 and 2 inhibited COX-1 and COX-2 in mouse macrophages with IC(50) in the range of 1.5-18.1microM. Both compounds 1 and 2 were also found to be potent inhibitors of human 5-LOX (IC(50)=1.22 and 0.47microM, respectively). Interestingly, compound 1 also had an inhibitory effect on tumor necrosis factor-alpha (TNF-alpha) production (IC(50)=0.44microM), which was not observed with compound 2. Docking studies suggested the (S)-enantiomer of 1 as the biologically active isomer that binds to COX-2. Being a cytokine-suppressive dual COX/5-LOX inhibitor, compound 1 may represent a useful lead structure for the development of advantageous new anti-inflammatory agents.