RESUMO
Antagonism of the Toll-like receptors (TLRs) 7 and TLR8 has been hypothesized to be beneficial to patients suffering from autoimmune conditions. A phenotypic screen for small molecule antagonists of TLR7/8 was carried out in a murine P4H1 cell line. Compound 1 was identified as a hit that showed antagonistic activity on TLR7 and TLR8 but not TLR9, as shown on human peripheral blood mononuclear cells (hPBMCs). It was functionally cross reactive with mouse TLR7 but lacked oral exposure and had only modest potency. Chemical optimization resulted in 2, which showed in vivo efficacy following intraperitoneal administration. Further optimization resulted in 8 which had excellent in vitro activity, exposure and in vivo activity. Additional work to improve physical properties resulted in 15, an advanced lead that had favorable in vitro and exposure properties. It was further demonstrated that activity of the series tracked with binding to the extracellular domain of TLR7 implicating that the target of this series are endosomal TLRs rather than downstream signaling pathways.
Assuntos
Piperazina/química , Receptor 7 Toll-Like/metabolismo , Receptor 8 Toll-Like/metabolismo , Administração Oral , Animais , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos , Meia-Vida , Humanos , Interferon gama/metabolismo , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Piperazina/administração & dosagem , Piperazina/farmacocinética , Piperazina/farmacologia , Baço/citologia , Baço/efeitos dos fármacos , Baço/metabolismo , Relação Estrutura-Atividade , Receptor 7 Toll-Like/antagonistas & inibidores , Receptor 8 Toll-Like/antagonistas & inibidoresRESUMO
To discover leads for next-generation chemoprotective antimalarial drugs, we tested more than 500,000 compounds for their ability to inhibit liver-stage development of luciferase-expressing Plasmodium spp. parasites (681 compounds showed a half-maximal inhibitory concentration of less than 1 micromolar). Cluster analysis identified potent and previously unreported scaffold families as well as other series previously associated with chemoprophylaxis. Further testing through multiple phenotypic assays that predict stage-specific and multispecies antimalarial activity distinguished compound classes that are likely to provide symptomatic relief by reducing asexual blood-stage parasitemia from those which are likely to only prevent malaria. Target identification by using functional assays, in vitro evolution, or metabolic profiling revealed 58 mitochondrial inhibitors but also many chemotypes possibly with previously unidentified mechanisms of action.