Revisiting the effect of cholesteryl sulfate on clotting and fibrinolysis: Inhibition of human thrombin and other human blood proteases
Research article published in Heliyon (2024)
Abstract
Cholesteryl sulfate (CS) was quantitatively synthesized by microwave-assisted sulfonation of cholesterol followed by sodium exchange chromatography. In vitro effects of CS on human thrombin and other serine proteases of the coagulation and fibrinolysis processes were investigated using a series of biochemical and biophysical techniques. CS was found to inhibit thrombin with an IC50 value of 140.8 ± 21.8 μM at pH 7.4 and 25 ○C. Michaelis-Menten kinetics indicated that thrombin inhibition by CS is non-competitive (allosteric) in nature. Fluorescence-based binding studies indicated that CS binds to thrombin with a KD value of 180.9 ± 18.9 μM. Given the lack of competition with heparins and a hirudin peptide in competitive inhibition assays, it appears that CS does not bind to thrombin's exosites 1 or 2 and it rather recognizes a different allosteric exosite. CS was found to partially inhibit thrombin-mediated fibrinogen activation with an IC50 value of 175.5 ± 17.5 μM and efficacy of ∼26.0 ± 6.6%. Likewise, CS selectively doubled the activated partial thromboplastin time with EC2x of 521 μM. Interestingly, CS was found to also inhibit factors Xa and XIa as well as plasmin with IC50 values of ∼85-250 μM and efficacy of 94-100%. Nevertheless, CS most potently inhibited factor XIIa with an IC50 Value of ∼17 μM and efficacy of 60%. Surprisingly, CS did not inhibit factor IXa. These results encourage further in vitro and in vivo investigation of CS to better understand its (patho-) physiological roles in coagulation and hemostasis.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Cholesteryl sulfate (CS) was quantitatively synthesized by microwave-assisted sulfonation of cholesterol followed by sodium exchange chromatography.
Por qué esto importa para la hirudoterapia
This in vitro study synthesized cholesteryl sulfate (CS) and characterized its inhibitory effects on human thrombin and other coagulation/fibrinolysis proteases. CS inhibited thrombin (IC50 ~140.8 μM) via non-competitive (allosteric) binding, partially inhibited fibrinogen activation, and prolonged aPTT; it also inhibited factors Xa, XIa, XIIa, and plasmin, but not factor IXa. Competitive inhibition assays showed no competition with heparins or a hirudin peptide, indicating CS binds a distinct allosteric exosite on thrombin. For ASH's domain, the connection is indirect: a hirudin peptide is used as a tool to map thrombin exosite-1 binding, confirming CS acts elsewhere, but hirudin is not the investigational agent. The study concerns a synthetic sterol sulfate, not leech therapy or the leech secretome; the relevance is limited to providing mechanistic context about thrombin inhibition distinct from hirudin's mode.
Citación
Revisiting the effect of cholesteryl sulfate on clotting and fibrinolysis: Inhibition of human thrombin and other human blood proteases
Al-Horani RA · Heliyon, 2024
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Añadido a la biblioteca ASH: May 27, 2026 · Última actualización del sitio: June 18, 2026