PB0532 - Deciphering the role of small sulfated molecule PTS on AT3 structure and in vitro clot formation.

Background: The human population suffers due to the disease burden caused by thromboembolic disorders. Thrombosis is a major life-threatening condition with a high prevalence of cardio-cerebrovascular complications. Antithrombin (AT3) is a serpin that inhibits thrombin, factor Xa. Anticoagulants are inhibitors (direct or indirect) of enzymes involved in the coagulation pathway. They enhance the proteinase inhibitory activity of AT3. The search is going on for new anticoagulants with significant activity and lesser side effects.

Aims: Our aim is here to design a new molecule pyrogallol trisulfate (PTS) and check its role in AT3 structure and clot formation.

Methods: The identification of PTS binding with AT3 was performed by molecular docking. Synthesis of PTS was achieved using triethylamine-sulfur trioxide adduct and purified by RP-HPLC. Structural modifications were characterized by FTIR, NMR, and Mass spectrometry. The cytotoxicity of pyrogallol and PTS was checked by MTT assay using a human embryonic kidney cell line (HEK-293). The in vitro efficacy of PTS for its anticoagulant potential was performed by clotting assays APTT, PT, and TT. The impact of PTS interaction with AT3 on its secondary and tertiary structure was validated using Far-UV CD and fluorescence spectrometry.

Results: The molecular docking results suggested PTS binds to AT3. PTS does not show cellular cytotoxicity even at the higher dosage tested. The results hinted that addition of sulfate moieties contributed to reduced cytotoxicity. In vitro anticoagulant assay of PTS with human plasma for clot formation, demonstrated a potentially prolonged effect on APTT, a moderate effect on PT and TT. This indicates the delay in clot formation upon plasma treatment with PTS. Far-UV CD spectral analysis showed a marginal effect on the secondary structure while PTS treated AT3 showed changes in tertiary structure conformation.

Conclusion(s): The study suggests a potential anticoagulant effect of PTS in clot reduction with promising applications.