Dual-target inhibitor screening against thrombin and factor Xa simultaneously by mass spectrometry

- A dual-target assay was developed for drug discovery of anticoagulation therapy.
- The assay screened for the inhibitors of thrombin and factor Xa simultaneously.
- Enzyme kinetics and inhibition kinetics were performed to validate the assay.
- Three marine-oriented polysaccharides showed potential as anticoagulant agents.

An accurate, rapid, and cost-effective methodology for enzyme assay is highly demanded to screen the effect of compounds on target at the molecular level. Thrombin (EC 3.4.21.5) and factor Xa (FXa, EC 3.4.21.6) have been identified as the critical targets for the development of potential drugs with anticoagulant activity. In this study, a rapid, sensitive and accurate assay based on UHPLC-MS/MS method has been developed for inhibitor screening against thrombin and factor Xa simultaneously. For thrombin and factor Xa, the Michaelis-Menten constants (Km) were calculated to be 6.14 and 57.27 μM, respectively. The inhibition constants (Ki) for two known inhibitors, argatroban and rivaroxaban, were determined to be 16.23 and 0.41 nM, respectively. The assay was further validated through the determination of a high Z′ factor value of 0.89. Finally, the developed assay was applied to screen a chemical library against two enzymes. Three hit compounds belonging to a class of sulfated polysaccharides were identified and their targets of inhibition action were further evaluated. The results indicated that the dual-target assay by UHPLC-MS/MS analysis could be used as a reliable method for screening anticoagulant agents.

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