Development of YO-01027-Derived Signal Peptide Peptidase Inhibitors with Reduced γ-Secretase Inhibition

Abstract Signal peptide peptidase (SPP) is an endoplasmic-reticulum intramembrane aspartyl protease required for hepatitis C virus (HCV) core protein maturation, but many SPP inhibitors also inhibit γ-secretase. Here, we designed YO-01027-derived dibenzazepinone analogs to retain SPP inhibition while reducing γ-secretase liability. An initial set of analogs was evaluated using an AcGFP–HCV core reporter assay and an APPsw/Aβ production assay. SPP5 suppressed HCV core processing while showing a reduced effect on Aβ production relative to YO-01027. Among a subsequent structurally diverse set of analogs related to YO-01027 and SPP5, SPP17 reduced SPP-dependent core maturation, HCV propagation, infectious virus production, and NS5A-positive foci in Huh7 cells, while showing attenuated γ-secretase inhibition and no apparent cytotoxicity under the tested conditions. These results demonstrate that γ-secretase inhibitor scaffolds can be tuned to generate SPP-directed antiviral chemical probes.