Identification of highly selective inhibitors of collagenase-1 from combinatorial libraries of diketopiperazines

Thiol-containing diketopiperazines have been recently identified as novel h eterocyclic inhibitors of matrix metalloproteinase (MMPs). The compounds de scribed had similar activities against the MMPs collagenase-1 and gelatinas e-B. An inhibitor that showed greater than 10-fold selectivity for collagen ase-1 over gelatinase-B was desired. Previously published work with peptidy l hydroxamates and thiols indicated that while preparing gelatinase selecti ve inhibitors was straightforward, there was not an obvious route to select ive inhibitors of collagenase-1. Combinatorial libraries were prepared and evaluated for their ability to inhibit collagenase-1 and gelatinase-B subst rate hydrolysis. A method for estimating the IC50 values of compounds gener ated by high-throughput parallel synthesis aided in the identification of c ompounds with the desired properties. We have found that thiol diketopipera zines derived from nitrophenylalanine are both potent and selective inhibit ors of collagenase-1. In addition, we have demonstrated that combinatorial chemistry can be utilized to identify molecules with a desired selectivity profile without access to the traditional tools of rational drug design.