Cholic acid derivatives as novel PTP1B inhibitors: Their synthesis, inhibition mechanism, and hypoglycemic effects

Protein tyrosine Phosphatase 1B (PTP1B) is a validated therapeutic target for type 2 diabetes mellitus (T2DM). In this study, 37 cholic acid derivatives were designed and synthesized via a molecular hybridization strategy. Biological evaluation identified the 4-fluorophenylalanine derivative 6h as the most potent PTP1B inhibitor (IC₅₀ = 32.70 μM) with a selectivity index of 7.0 over TCPTP. Structure-activity relationship (SAR) studies revealed that the 3-hydroxy-7-oxo steroid core, a free carboxylic acid group, and electron-withdrawing aromatic substituents are essential for maintaining activity. Mechanistic investigations demonstrated that 6h acts as a reversible mixed-type inhibitor of PTP1B by forming a 1:1 complex (K_D = 36.0 μM), and induces conformational changes as evidenced by fluorescence quenching, CD, and IR spectroscopy. Molecular docking further supported the binding mode via hydrogen bonds and hydrophobic interactions. In insulin-resistant HepG2 cells, 6h significantly promoted glucose uptake by 11.8% at 20 μM, comparable to rosiglitazone. In vivo tests, 6h dose-dependently enhanced glucose tolerance and Insulin sensitivity in both normal and diabetic mice. Moreover, 6h significantly reduced random and fasting blood glucose levels in STZ-induced diabetic mice. ADMET predictions indicated favorable oral absorption, Caco-2 permeability, and low toxicity. Collectively, 6h represents a promising PTP1B selective inhibitor exerting hypoglycemic effects through enhanced Insulin signaling and inhibition of gluconeogenesis, warranting further investigation as a novel anti-T2DM candidate.