Direct Determination of Enzymes in Dried Blood Spots by High-Performance Liquid Chromatography – Mass Spectrometry (HPLC-MS) for the Screening of Antithrombotic Agents

Thrombosis is the main cause of many cardiovascular diseases. The conventional pharmaceuticals used for preventing thrombosis can induce significant adverse side effects, especially bleeding risk. Hence, the development of more effective and safe antithrombotic agents is strongly demanded to improve clinical treatment. In order to rapidly screen and identify novel antithrombotic substances from natural marine products, a multi-target screening strategy is reported to quantify the antithrombotic activity with high-performance liquid chromatography – mass spectrometry (HPLC-MS). Five key thrombosis-related targets, including thrombin, coagulation factors Xa, XIa and XIIa and platelet phosphodiesterase 3, were selected to establish the multi-target antithrombotic activity screening assay. The Michaelis-Menten constants (Km) were 8.16 µM, 58.85 µM, 120.03 µM, 35.24 µM and 79.67 µM, respectively. Five known inhibitors, namely argatroban, rivaroxaban, benzamidine, 3-carboxamide-coumarinand, and milrinone, were used for validation. The reproducibility of the screening strategy was verified by calculating the overall average Z′ value, which was 0.88. Subsequently, this method was assessed by screening a small marine library of 78 compounds. Five coumarin compounds were selected, and their antithrombotic activities were further validated in standard assessments of enzyme inhibition and on the coagulometer. According to the validation, the multi-target assay based on dried blood spots and HPLC-MS was suitable for screening antithrombotic substances with considerable reliability.