Chemical Synthesis and Biochemical Evaluation of Decasulfated Galloylglucopyranose Heparin Mimetic

Introduction:: Thrombosis remains a major global health burden, necessitating safer and more effective antithrombotic strategies. Current therapies, including vitamin K antagonists, heparin derivatives, and direct oral anticoagulants, are limited by bleeding risks despite the availability of reversal agents. Factor XIa (FXIa), a serine protease in the intrinsic coagulation pathway, has emerged as a promising target due to its central role in thrombosis while having minimal impact on hemostasis. Previous studies identified Sulfated Pentagalloyl Glucopyranose (SPGG) as a potent, selective, but heterogeneous allosteric inhibitor of FXIa. The study aimed to design and synthesize a chemically homogeneous derivative of SPGG (inhibitor 2) and to evaluate its potency, selectivity, and effect on human plasma coagulation, to identify a potentially safer FXIa-targeted anticoagulant candidate. Methods:: To address the heterogeneity of SPGG, inhibitor 2, a per-sulfated, chemically homogeneous derivative, was designed and synthesized through a three-step synthetic route. The inhibitory activity of inhibitor 2 against FXIa was evaluated, along with its selectivity against thrombin and FXa. Furthermore, its effect on human plasma coagulation was assessed by measuring the Activated Partial Thromboplastin Time (APTT). Results:: Inhibitor 2 demonstrated potent inhibition of FXIa with an IC₂⁽ of 1.42 ± 0.10 μM and showed marked selectivity over thrombin and FXa. Treatment with inhibitor 2 significantly prolonged the APTT of human plasma, indicating effective modulation of the intrinsic coagulation pathway. Discussion:: Inhibitor 2 overcomes the chemical heterogeneity of SPGG while retaining strong selectivity for FXIa over thrombin and FXa. It effectively prolongs APTT with minimal effect on PT, indicating selective targeting of the intrinsic pathway. These results demonstrate that chemical homogeneity can be achieved without compromising functional selectivity. Conclusion:: Inhibitor 2 represents a chemically homogeneous, selective, and potent FXIa inhibitor. These findings support its potential as a lead candidate for the development of FXIatargeted anticoagulants with a potentially reduced bleeding risk.