Glycosylation Modification Balances the Aqueous Solubility of Lipidated Peptides and Facilitates Their Biostability.

Protein tyrosine phosphatase N1 (PTPN1) is a key regulator of insulin and leptin signaling pathways, making it an attractive therapeutic target for type 2 diabetes. Recent studies have identified fatty acid conjugated BimBH3 analogues as promising PTPN1 inhibitors with antidiabetic potential. Peptide therapeutics have proven successful in the treatment of a wide range of medical conditions, yet challenges such as poor aqueous solubility, proteolytic degradation, and limited bioavailability still hinder their clinical application. In this study, we developed a series of novel BimBH3 peptide analogues through dual modifications involving fatty acid lipidation and glycosylation to address these limitations. These modifications significantly improved the peptides' solubility, proteolytic stability, and plasma half-life while preserving potent PTPN1 inhibitory activity, which is essential for enhancing insulin signaling in type 2 diabetes treatment. Among the analogues, compound L3 exhibited the most balanced profile, with an aqueous solubility increase over 10-fold, a half-life extension in rat plasma of 9.92-fold compared to the lead compound, and an IC₅₀ of 0.78 μM against PTPN1. In vivo studies further demonstrated L3's efficacy in lowering blood glucose levels in mice. This study demonstrates the utility of glycosylation in overcoming the solubility and stability challenges associated with lipidated peptides. The optimized analogue L3 could serve as a proof of concept for developing novel long-acting PTPN1 inhibitors.