Synthesis and SAR study of 4,5-diaryl-1H-imidazole-2(3H)-thione derivatives, as potent 15-lipoxygenase inhibitors.

A series of 4,5-diaryl-1H-imidazole-2(3H)-thione was synthesized and their inhibitory potency against soybean 15-lipoxygenase and free radical scavenging activities were determined. Compound 11 showed the best IC(50) for 15-LOX inhibition (IC(50) = 4.7 μM) and free radical scavenging activity (IC(50) = 14 μM). Methylation of SH at C(2) position of imidazole has dramatically decreased the 15-LOX inhibition and radical scavenging activity as it can be observed in the inactive compound 14 (IC(50) >250 μM). Structure activity similarity (SAS) showed that the most important chemical modification in this series was methylation of SH group and Docking studies revealed a proper orientation for SH group towards Fe core of the 15-LOX active site. Therefore it was concluded that iron chelating could be a possible mechanism for enzyme inhibition in this series of compounds.