Synthesis and biological evaluation of N-mercaptoacylcysteine derivatives as leukotriene A4 hydrolase inhibitors.

We studied synthetic modifications of N-mercaptoacylamino acid derivatives to develop a new class of leukotriene A(4) (LTA(4)) hydrolase inhibitors. S-(4-Dimethylamino)benzyl-l-cysteine derivative 2a (SA6541) showed inhibitory activity against LTA(4) hydrolase (IC(50), 270nM) and selectivity over other metallopeptidases except angiotensin-converting enzyme (ACE, IC(50), 520nM). Modification at the para-substituent of the phenyl ring of compound 2a improved LTA(4) hydrolase inhibitory activity as well as selectivity over ACE. Finally, we obtained S-(4-cyclohexyl)benzy-l-cysteine derivatives 11l and 16i as potent and selective LTA(4) hydrolase inhibitors.