RESUMO
Molecular modeling in combination with X-ray crystallographic information was employed to identify a region of the kinesin spindle protein (KSP) binding site not fully utilized by our first generation inhibitors. We discovered that by appending a propylamine substituent at the C5 carbon of a dihydropyrazole core, we could effectively fill this unoccupied region of space and engage in a hydrogen-bonding interaction with the enzyme backbone. This change led to a second generation compound with increased potency, a 400-fold enhancement in aqueous solubility at pH 4, and improved dog pharmacokinetics relative to the first generation compound.
Assuntos
Desenho de Fármacos , Cinesinas/antagonistas & inibidores , Pirazóis/química , Pirazóis/farmacologia , Alquilação , Sítio Alostérico , Aminação , Animais , Cristalografia por Raios X , Cães , Hidroxilação , Cinesinas/química , Cinesinas/metabolismo , Mitose , Modelos Moleculares , Estrutura Molecular , Pirazóis/síntese química , Pirazóis/farmacocinética , Solubilidade , Relação Estrutura-Atividade , ÁguaRESUMO
Optimization of high-throughput screening (HTS) hits resulted in the discovery of 3,5-diaryl-4,5-dihydropyrazoles as potent and selective inhibitors of KSP. Dihydropyrazole 15 is a potent, cell-active KSP inhibitor that induces apoptosis and generates aberrant mitotic spindles in human ovarian carcinoma cells at low nanomolar concentrations. X-ray crystallographic evidence is presented which demonstrates that these inhibitors bind in an allosteric pocket of KSP distant from the nucleotide and microtubule binding sites.